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Lithium BrinesA Global Perspective
... Salt lakes have attracted much attention due to their rich reserves of strategic resources like K, Li and B (Zhang 1987;Zheng et al. 1998Zheng et al. , 2016Munk et al. 2016). Due to the close relationship between salt lake resource elements and regional hydrological conditions, early research on salt lake resource elements mainly relied on the hydrochemical and isotopic compositions of various water samples in the basin to trace the material sources of resource elements (Tan et al. 2012;Miao et al. 2022;Zhang et al. 2022;Xue et al. 2024), investigate their enrichment and mineralization processes (Godfrey et al. 2013;Munk et al. 2016;Miao et al. 2022), and assess resource reserves (Kesler et al. 2012;Munk et al. 2016). ...
... Salt lakes have attracted much attention due to their rich reserves of strategic resources like K, Li and B (Zhang 1987;Zheng et al. 1998Zheng et al. , 2016Munk et al. 2016). Due to the close relationship between salt lake resource elements and regional hydrological conditions, early research on salt lake resource elements mainly relied on the hydrochemical and isotopic compositions of various water samples in the basin to trace the material sources of resource elements (Tan et al. 2012;Miao et al. 2022;Zhang et al. 2022;Xue et al. 2024), investigate their enrichment and mineralization processes (Godfrey et al. 2013;Munk et al. 2016;Miao et al. 2022), and assess resource reserves (Kesler et al. 2012;Munk et al. 2016). The importance of sediment in the cycle of salt-forming elements in the supergene environment of salt lake regions is frequently underestimated. ...
... Salt lakes have attracted much attention due to their rich reserves of strategic resources like K, Li and B (Zhang 1987;Zheng et al. 1998Zheng et al. , 2016Munk et al. 2016). Due to the close relationship between salt lake resource elements and regional hydrological conditions, early research on salt lake resource elements mainly relied on the hydrochemical and isotopic compositions of various water samples in the basin to trace the material sources of resource elements (Tan et al. 2012;Miao et al. 2022;Zhang et al. 2022;Xue et al. 2024), investigate their enrichment and mineralization processes (Godfrey et al. 2013;Munk et al. 2016;Miao et al. 2022), and assess resource reserves (Kesler et al. 2012;Munk et al. 2016). The importance of sediment in the cycle of salt-forming elements in the supergene environment of salt lake regions is frequently underestimated. ...
To deepen the comprehension of the geochemical behaviour of salt-forming elements (K, Li, B, Ca, Mg, Sr) and distribution patterns in the primary lithium-rich salt lake region of Qaidam Basin, 31 river and lake surface sediments from various hydrogeological settings spanning high mountain to terminal salt lake regions were gathered from the Nalenggele River, the primary feeder river of the lithium-rich salt lakes. Through sequential extraction procedure, we identified notable variances in the chemical speciation of elements across various hydrological environments. Excluding elements bound to the residual fraction, all other chemical speciation content of salt-forming elements show distinct regional variations, suggesting a predominant influence of evaporation and hydrodynamic and the inherent chemical properties of elements are also very important in determining their chemical speciation distribution characteristics. Meanwhile, we have found that in addition to being absorbed and fixed by secondary clay minerals, Li bound to Fe–Mn oxides may also play a crucial role in Li isotope fractionation from the river to the terminal salt lake brine and the precipitation of evaporation salt minerals could influence the B isotope fractionation to a certain extent. Furthermore, The Li and B lost to sediments during the migration process have potential utility and there is scope for enhanced exploitation in the future. Therefore, the results obtained from the sequential extraction procedure of sediments evidently serve as a valuable method for understanding the geochemical behaviour of salt-forming elements in the epigenetic environment.
... Most known Li resources belong to deposits of the continental brine type (e.g., Cabello, 2021;Munk et al., 2016;Garrett, 2004). Salar deposits are not typically primary deposits, but are derived through secondary enrichment (leaching) of Li-enriched igneous rocks (granites, felsic volcanic rocks) or of inactive paleo-salars. ...
... Li is mobilized when minerals are weathered at the surface or in the shallow subsurface. This is the case for the Chilean deposits such as the Salar de Atacama located next to volcanic activity and where ignimbrites are thought to be the ultimate Li source (100 to 1000 mg/kg) (Munk et al., 2016) (1000-4000 mg/L Li brine) or of Clayton Valley brines in Nevada (Coffey et al., 2021;Munk et al., 2016;Garrett, 2004) (100-800 mg/L Li brine) where Li is associated with Miocene felsic volcanic rocks rich in Li (≥200 mg/kg) and uplifted lake beds with hectorite (Bradley et al., 2013). ...
... Li is mobilized when minerals are weathered at the surface or in the shallow subsurface. This is the case for the Chilean deposits such as the Salar de Atacama located next to volcanic activity and where ignimbrites are thought to be the ultimate Li source (100 to 1000 mg/kg) (Munk et al., 2016) (1000-4000 mg/L Li brine) or of Clayton Valley brines in Nevada (Coffey et al., 2021;Munk et al., 2016;Garrett, 2004) (100-800 mg/L Li brine) where Li is associated with Miocene felsic volcanic rocks rich in Li (≥200 mg/kg) and uplifted lake beds with hectorite (Bradley et al., 2013). ...
The amount of lithium (Li) required to support the energy transition underscores the need to develop Li sources beyond the traditional hard-rock mining and surface continental brines. The objective of this study was to explore the potential for Li production from oilfield waters in the U.S. Gulf Coast region. Data on Li concentrations were obtained from ~2450 formation water samples taken in states along the greater Gulf Coast (NM, TX, OK, LA, AR, and MS). The dataset contains geochemical analyses that spans >70 years, including the USGS database (v2.3), compilation of recent data previously published by the authors, analyses from recently collected samples and from archived samples, and data from U.S. Bureau of Mines reports. Aqueous Li distribution is lognormal, typical of trace elements, with background levels in the 0-20 mg/L range. High concentrations (≥80 mg/L) are restricted to some intervals at certain locations: Jurassic Smackover Formation, a well-known brine deposit in Arkansas (300+ mg/L Li), but also along the Gulf Coast in Texas, Louisiana, and Mississippi (several samples ≥100 mg/L Li); Permian and Pennsylvanian Granite Wash in the Anadarko Basin of Texas (several samples >100 mg/L Li) (not confirmed); and Cretaceous Edwards Formation of South Texas (several samples ≥100 mg/L Li). Genetic models for Li enrichment are lacking, but high Li seems to be related to the noted fact that Li concentrations increase with depth and with total dissolved solids. Other common characteristics of high-Li brines in the Gulf Coast are high K, Ca, and B, which reflect water-rock interactions , presence of major faults, and association with higher permeability intervals that can spread Li-bearing fluids. Host rocks for high-dissolved Li brines commonly are carbonates, possibly because of their limited sorption opportunities. Close connection to an igneous basement or to a depositional environment that supported accumulation of surface continental brines does not seem to be required.
... It is likely, a combination of these parameters may represent the lithium evolution environment within the basin. Excluding (6), Munk et al. (2016) elaborates how these parameters may be implemented to help lithium ore exploration features on a global scale. They present and discuss eighteen basins that share these parameters, however how each of these characteristics are correlated with respect to lithium evolution has not yet been fully explored , accordingly variation in the spatial regional lithium concentrations pattern have not been fully developed (López Steinmetz et al., 2020). ...
... To date, there has been limited work to identify possible correlations (e.g., similarities and outliers) in salars' system considering the deposit model parameters mentioned by Bradley et al. (2013) and Munk et al. (2016), have been reported in the literature. Here, regional correlations of 29 salars are examined based on a deposit model and is used to identify anomalies in the salars within the Lithium Triangle, to further understand a series of questions: (1) Why do apparently similar salars have different lithium concentrations? ...
... The use of a deposit model to characterise lithium occurrence within salars and associated parameters have been proposed by Bradley et al. (2013) and Munk et al. (2016). Their work is extended here and are based on data availability as presented in Table 1. ...
... Most known Li resources belong to deposits of the continental brine type (e.g., Cabello, 2021;Munk et al., 2016;Garrett, 2004). Salar deposits are not typically primary deposits, but are derived through secondary enrichment (leaching) of Li-enriched igneous rocks (granites, felsic volcanic rocks) or of inactive paleo-salars. ...
... Li is mobilized when minerals are weathered at the surface or in the shallow subsurface. This is the case for the Chilean deposits such as the Salar de Atacama located next to volcanic activity and where ignimbrites are thought to be the ultimate Li source (100 to 1000 mg/kg) (Munk et al., 2016) (1000-4000 mg/L Li brine) or of Clayton Valley brines in Nevada (Coffey et al., 2021;Munk et al., 2016;Garrett, 2004) (100-800 mg/L Li brine) where Li is associated with Miocene felsic volcanic rocks rich in Li (≥200 mg/kg) and uplifted lake beds with hectorite (Bradley et al., 2013). ...
... Li is mobilized when minerals are weathered at the surface or in the shallow subsurface. This is the case for the Chilean deposits such as the Salar de Atacama located next to volcanic activity and where ignimbrites are thought to be the ultimate Li source (100 to 1000 mg/kg) (Munk et al., 2016) (1000-4000 mg/L Li brine) or of Clayton Valley brines in Nevada (Coffey et al., 2021;Munk et al., 2016;Garrett, 2004) (100-800 mg/L Li brine) where Li is associated with Miocene felsic volcanic rocks rich in Li (≥200 mg/kg) and uplifted lake beds with hectorite (Bradley et al., 2013). ...
... Lithium is a critical and technologically important element used in batteries, the nuclear industry, ceramics, glass, medicine, aerospace, and other fields. With the soaring demand for lithium resources in the global market recently, the trend of resource bottleneck is highlighted (Kesler et al., 2012;Munk et al., 2016). Lithium-rich brines are the planet's most economically recoverable Li source (Munk et al., 2016;Boschetti, 2022). ...
... With the soaring demand for lithium resources in the global market recently, the trend of resource bottleneck is highlighted (Kesler et al., 2012;Munk et al., 2016). Lithium-rich brines are the planet's most economically recoverable Li source (Munk et al., 2016;Boschetti, 2022). Therefore, it is essential to understand the genesis of these deposits to develop exploration models for the continued discovery of new deposits. ...
... According to the above discussion, the critical genetic factors of Lirich brine deposits in the NRB are consistent with the common characteristics of continental lithium brines summarized by Munk et al. (2016), such as arid climate, closed basin containing salt lakes, associated Li-rich hydrothermal activity, significant inflow waters, sufficient time for lithium accumulation in brines. However, as a typical Li-rich brine deposit of QTP, the NRB lithium brines also have unique characteristics in the formation mechanisms. ...
The salt lakes fed by the Nalenggele River in the Qaidam Basin, located on the northeastern Qinghai Tibetan Plateau (QTP), are major brine lithium reservoirs in China. The quantitative identifications of the Li sources and their dynamic behavior shed light on the formation mechanism of the brine Li deposits in closed-basin of arid regions. This study presents Li and Sr isotope ratios (δ⁷Li, ⁸⁷Sr/⁸⁶Sr) and other hydrogeochemical parameters for river waters, springs, spring river waters, shallow groundwaters, surface brines, and intercrystalline brines around the Nalenggele River Basin (NRB) and its adjacent small watersheds. The results indicate that the Nalenggele River water is a mixing product of hot springs and regional surface meltwater, and the source of dissolved Li in the NRB is mainly supplied by the hot springs. With multi-tracer models, it is confirmed that around 84.9% - 93.4% of dissolved Li is provided by the Li-rich hot spring waters, which account for only 3-5% of the total water input. Furthermore, the dissolved Li in the streams of different hydrological regions shows various isotopic fractionation behavior. In general, the lower average δ⁷Li values (average of +5.6‰) with more enriched Li with respect to Na in the waters of the piedmont Gobi region indicates a significant additional input of dissolved Li from bedrock and sediments. The second-stage alluvial fan of the NRB produces ⁷Li enrichments and Li-depleted waters (compared with Na), which can be explained by the adsorption of clay or Fe (Mn) oxide phases that fractionate Li isotopes. The highest average δ⁷Li values (+12.76‰) are observed when Li is not adsorbed by the scarce fine clastic sediments in the hypersaline environment of the salt lake region. It can be concluded that the continuous halite precipitation during the brine evolution not only causes the abnormal enrichment of Li in the brine (compared with Na) but also continuously sequesters the ⁶Li from the brines, resulting in a significant ⁷Li enrichment. Overall, these findings advance the understanding of the lithium sources of Li-rich brines and its enrichment and metallogenic process during water migration in hyper-arid regions and have crucial indicative significance for lithium cycling under a strong evaporation environment.
... This transition and the explosion of the electric vehicle industry has consequently led to an increased demand for lithium (Li) as one of the major components of batteries for electric vehicles with a projected compound annual growth rate of 18% until 203018% until (Roskill, 2020. Lithium is primarily found in three main deposits: (a) pegmatites, (b) continental brines, and (c) clays (Benson et al., 2017;Kavanagh et al., 2018;Mohr et al., 2012;Munk et al., 2016) but emerging Li deposit types such as geothermal waters and oilfield brines are Abstract Despite current and projected future reliance on lithium (Li) as a resource, deficiencies remain in genesis models of closed-basin Li brines. Subsurface geochemical interactions between water and bulk solid phases from lacustrine sediments, are shown here to be the most important process for brine genesis and sustainability of the Clayton Valley, NV brine deposit. ...
... The geologic requirements to form closed-basin Li-enriched brines are summarized in Bradley et al. (2013) and Munk et al. (2016). From those works and contributions from Hofstra et al. (2013) and Benson et al. (2017) the viable sources for Li to closed-basin brines include magmatic fluids, high silica vitric volcanic rocks, hectorite or other Li-bearing clay minerals, and ancient salt deposits. ...
... Leaching experiments conducted by Araoka et al. (2014) on Clayton Valley playa surface sediments show results of ẟ 7 Li from leachates that indicate the Li was supplied mainly by Li-enriched hydrothermal fluids resulting from high temperature water-rock interaction and not directly through low-temperature weathering. Munk et al. (2016) theorized that the Li may be sourced by a combination of hydrothermal activity and leaching from clays and volcanic ash found in the basin fill. It is relatively well established that clay minerals can sequester Li in the octahedral layer where it increases with increasing concentration of Li in formation solutions, temperature, and time (Decarreau et al., 2012). ...
Despite current and projected future reliance on lithium as a resource, deficiencies remain in genesis models of closed-basin Li brines. Subsurface geochemical interactions between water and bulk solid phases from lacustrine sediments, are shown here to be the most important process for brine genesis and sustainability of the Clayton Valley, NV brine deposit. A new subsurface basin model was developed and used to select Li-bearing solids to test the release mechanisms for Li. Ash (20-350 ppm Li) and bulk sediments (1000-1700 ppm Li) samples across depths in the basin represent the majority of the subsurface Li-bearing materials. Temperature dependent (25-95 oC) batch reaction experiments using low-salinity groundwater from the basin indicate a positive relationship between the amount of Li released and temperature. Four-step sequential extractions on a subset of bulk sediments indicate most Li is released from water and weak acid-soluble portions with approximately 30% of the total Li contained in the sediments released overall. We conceptualize that lithium is released from these samples via three mechanisms: 1) release of adsorbed Li; 2) cation exchange of Li and Mg and; 3) possible minor release from silicate structure at elevated temperatures. Based on these results and the abundance of Li-bearing sediments in the subsurface we estimate the mean Li mass in the basin materials to be between 24.4 to 58.0 Mt. This Li provides a continuous supply from water-rock interactions. This is now the largest known accumulation of Li in a basin-fill continental setting on a global scale.
... It corresponds to a semi-closed basin, bordered by high mountains including a metamorphic core complex and normal fault system. The sediments deposited in the basin are primarily silt, sand and gravel interbedded with illite, smectite and kaolinite clays (Munk et al., 2016) and references therein). The basin is also filled by Miocene to Pliocene silicic tuffs and rhyolites and tuffaceous lacustrine facies which contain significant lithium, 215 to 490ppm Li2O in average (Munk et al., 2016) and references therein). ...
... The sediments deposited in the basin are primarily silt, sand and gravel interbedded with illite, smectite and kaolinite clays (Munk et al., 2016) and references therein). The basin is also filled by Miocene to Pliocene silicic tuffs and rhyolites and tuffaceous lacustrine facies which contain significant lithium, 215 to 490ppm Li2O in average (Munk et al., 2016) and references therein). The alternation of dry and wet periods during the Pleistocene are responsible for the formation of layers of clays (Hectorite), evaporites and associated brines and the variations in the amount of clastic versus evaporite sediment fill, combined with faulting, have generated at least six separate brine-bearing aquifers. ...
... The alternation of dry and wet periods during the Pleistocene are responsible for the formation of layers of clays (Hectorite), evaporites and associated brines and the variations in the amount of clastic versus evaporite sediment fill, combined with faulting, have generated at least six separate brine-bearing aquifers. A combination of hydrothermal activity and leaching from volcanic ash and clays may be the major sources of Li in the aquifers in Clayton Valley, Nevada (Munk et al., 2016). The lithium brines are located within 6 aquifer units of various nature (volcanic ash layers, halite layers, tuffs layers, travertine layers, gravels layers). ...
This report gives a summary of models for the formation and the processes that are operating during the formation of lithium, cobalt and graphite deposits . The aim of this report is to provide support material to the delivereables D5.1 and D.5.3 and D.5.6 of the work package 5 of the FRAME project. The differences and complexities of the geology between lithium cobalt and graphite is very large, this is also reflected in the content and overall layout of this report. This report is made as concise as possible, however the nature of the topic are such that certain level of geological backround is needed to fully appreciate the descriptions.
... Brine mineral systems comprise salt lakes and oilfield formation waters ( Figure 2D; Risacher and Fritz, 2009;Kesler et al., 2012;Munk et al., 2016). These mineral systems represent approximately 64% of the Li 2 O tonnages reported by . ...
... Examples include the Uyuni Salt Flat (Bolivia) and Salar de Atacama (Chile). The hot and arid climate of these regions is essential for concentrating lithium during evaporation (Munk et al., 2016). As a result, brine mineral systems are geographically restricted to hot and arid climates in mountains and/or near the equator. ...
Disruptions to the global supply chains of critical raw materials (CRM) have the potential to delay or increase the cost of the renewable energy transition. However, for some CRM, the primary drivers of these supply chain disruptions are likely to be issues related to environmental, social, and governance (ESG) rather than geological scarcity. Herein we combine public geospatial data as mappable proxies for key ESG indicators (e.g., conservation, biodiversity, freshwater, energy, waste, land use, human development, health and safety, and governance) and a global dataset of news events to train and validate three models for predicting “conflict” events (e.g., disputes, protests, violence) that can negatively impact CRM supply chains: (1) a knowledge-driven fuzzy logic model that yields an area under the curve (AUC) for the receiver operating characteristics plot of 0.72 for the entire model; (2) a naïve Bayes model that yields an AUC of 0.81 for the test set; and (3) a deep learning model comprising stacked autoencoders and a feed-forward artificial neural network that yields an AUC of 0.91 for the test set. The high AUC of the deep learning model demonstrates that public geospatial data can accurately predict natural resources conflicts, but we show that machine learning results are biased by proxies for population density and likely underestimate the potential for conflict in remote areas. Knowledge-driven methods are the least impacted by population bias and are used to calculate an ESG rating that is then applied to a global dataset of lithium occurrences as a case study. We demonstrate that giant lithium brine deposits (i.e., >10 Mt Li 2 O) are restricted to regions with higher spatially situated risks relative to a subset of smaller pegmatite-hosted deposits that yield higher ESG ratings (i.e., lower risk). Our results reveal trade-offs between the sources of lithium, resource size, and spatially situated risks. We suggest that this type of geospatial ESG rating is broadly applicable to other CRM and that mapping spatially situated risks prior to mineral exploration has the potential to improve ESG outcomes and government policies that strengthen supply chains.
... This is despite all brine deposits with economic Li concentrations being associated with (fossil) geothermal systems ; e.g., Clayton Valley, CA, USA (Davis et al., 1986;NBMG, 2014), Qaidam basin, China (Yu et al., 2013), southern Tibet, China (Li et al., 2022). However, in the Li enrichment models of Bradley et al. (2013Bradley et al. ( , 2017 and Munk et al. (2016), the role of geothermal is limited to sequestration of Li derived from magmatic fluids in clays around hot springs. So, it is not surprising that none of the works on Li deposits in Chile on Salar de Atacama (e.g., Lowenstein and Risacher, 2009;Godfrey and Á lvarez-Amado, 2020;Marazuela et al., 2018Marazuela et al., , 2019aMarazuela et al., , 2019bMarazuela et al., , 2020aMarazuela et al., , 2020b, where the largest Li deposits in Chile are located (Cabello, 2021(Cabello, , 2022, mentions the role of the thermal waters, despite the proximity of a volcanic arc with high geothermal activity in the vicinity. ...
... Since non-thermal devitrification and weathering processes can also liberate Li from volcanic rocks (Price et al., 2000;Hofstra et al., 2013), geothermal activity has not been considered a prerequisite for Li brine formation by these authors or in general, as evident from the prevalent Li enrichment models (Bradley et al., 2013(Bradley et al., , 2017Munk et al., 2016). However, thermal waters can more efficiently release Li by accelerating the dissolution of Li-rich glassy volcanic rocks and selectively dissolving more Li than other elements. ...
The association between geothermal fluids and lithium-rich brines in salt flats has been evaluated in a unique natural laboratory in the Chilean Andes. The area encompasses Laguna Verde (LV), a hypersaline lake, and a salt flat (salar) within a closed basin surrounded by volcanoes. The predominant lithology consists of andesitic-dacitic rocks, with limited occurrences of rhyolitic rocks. The LV geothermal system exhibits surface manifestations, including over 20 hot springs reaching 47 • C along the lake's southern margin. The upflow zone is represented by the fumarolic field in the Nevado Ojos del Salado volcano, 25 km southwest of LV. Lithium concentrations range from 2.76 to 4.46 mg/L in thermal water and 0.59 to 0.76 mg/L in the Peñas Blancas river water, which feeds into LV after passing through a volcanic environment rich in lithium-bearing rocks. However, the thermal waters contribute over six times more lithium than non-thermal waters, highlighting their significance in releasing and transporting lithium from the source rocks to its eventual accumulation in LV. This natural laboratory at LV provides an excellent opportunity to evaluate the association between geothermal fluids and lithium-rich brines, offering valuable insights into the processes involved in lithium enrichment in similar geological and climatic conditions in other geographic areas.
... Those are attention to the stability of the soil of ponds intended for the collection of seawater and their evaporation under the influence of sunlight, the Li concentration in seawater, alkaline earth elements, the alkali metals ratio, the complexity of chemical phases [84]. ...
... The salt concentration was taken into account and normalized according to the ratio with lithium [84]. ...
Lithium compounds (carbonate, chloride) are the most widely used materials in glass, ceramics, pharmaceuticals, and electric vehicle batteries. The production of vehicles runs on electricity, and some of the devices having electronic circuits gradually increased the Li demand for the derivatives. The material base is mainly focused on Li production and Li derivatives. Lithium reserves account for 70-80% of Salt Lake waters; marine and geothermal waters account for the total lithium reserves and can be used as the best raw material for Li extraction. Many ways of extracting Li have been investigated using water resources. The adsorption method is the most effective method among those. This article provides information about some sorbents which is used in the process of Li extraction by adsorption method, their merits and demerits, as well as their impact on the environment. The use of the efficient and most promising selective type of sorbents with higher functionality, lower energy consumption, and environmental safety ensures the achievement of high economic performance.
... Lithium has become a new in-demand element, and the lithium-rush is pushing the Central Andean salar deposits Editorial handling: B. Lehmann into the spotlight. Despite conceptual models of the genesis of Li brine deposits (e.g., Munk et al. 2016), detailed case studies of Li sources and the generation of Li-rich brines in individual Andean salar deposits are still rare. Munk et al. (2016) presented a list of six characteristics that continental Li-rich salar deposits have in common, including: (1) arid climate; (2) closed basin containing a salar, a salt lake, or both; (3) associated igneous and/or hydrothermal activity; (4) tectonically driven subsidence; (5) suitable Li sources; and (6) sufficient time to concentrate Li. ...
... Despite conceptual models of the genesis of Li brine deposits (e.g., Munk et al. 2016), detailed case studies of Li sources and the generation of Li-rich brines in individual Andean salar deposits are still rare. Munk et al. (2016) presented a list of six characteristics that continental Li-rich salar deposits have in common, including: (1) arid climate; (2) closed basin containing a salar, a salt lake, or both; (3) associated igneous and/or hydrothermal activity; (4) tectonically driven subsidence; (5) suitable Li sources; and (6) sufficient time to concentrate Li. Of these, the source of Li is probably the most discussed topic, together with the processes involved in mobilizing Li from the primary source rocks and concentrating in salt pans. ...
Salars with lithium-rich brines are a characteristic feature of the Central Andes, but knowledge about the main sources of lithium and the mobilization processes of lithium in the salar deposits is still incomplete. This work focuses especially on the Salar de Diablillos (southern Puna) as part of a larger area that includes the neighboring Salar Centenario and Salar de Ratones. Building on the ability of Li as a tracer of silicate weathering, we investigate the Li content and isotope composition of samples from the depocenter and catchment of the Diablillos basin (3-D) and conduct a surface reconnaissance in the Centenario and Ratones depocenters to identify the key metallogenic processes. Radiogenic Sr and Nd isotope compositions are also provided to discriminate the main local Li sources. The isotope data in all three depocenters show that most of the Li in the brines and evaporite deposits are derived from Cenozoic volcanic rocks, despite the dominance of the Paleozoic basement in the catchment. In the Centenario and Ratones depocenters, near-surface chemical weathering appears to be the dominant Li mobilization process. In contrast, hydrothermal mobilization of Li also plays a role in the Salar de Diablillos, possibly related to the presence of a fractured basement with pressure zones and artesian conditions in the aquifer at depth. These fluids also show a larger element contribution from the basement.
... Among these sources, brine-type Li resources are extensively utilized due to their abundant reserves and ease of extraction (Liu et al. 2023). Brine-type Li deposits account for approximately 65% of the global proven Li mine resources, with 75% of Li products being derived from these deposits globally (USGS 2020; Munk et al. 2016;He et al. 2020). Salt lakes are the primary locations of brine-type Li deposits (Liu et al. 2021). ...
The availability of lithium resources is of great significance for the development of modern technologies, as well as for civil and military industries. The Qinghai-Tibet Plateau is a region known for its abundance of lithium-rich salt lakes. However, the specific origin of lithium in these lakes is still unknown, which hinders the advancement of the lithium resource business in this region. To research this issue, this study involved the collection of 20 samples from Lakkor Co Salt Lake on Qinghai-Tibet Plateau, encompassing samples of surface brine, cold springs, fresh lakes, and recharge rivers. The composition of anions and cations in these samples was determined. Furthermore, the analysis extensively utilized the Piper three-line diagram, Gibbs model, and ion proportion coefficient. The findings of this study indicate that as the moves from the recharge water system to salt lake, there is a transition in water type from strong carbonate to moderate carbonate and weak carbonate, as well as Na sulfate. This research based on a similar source of both lithium and boron, utilized ion correlation analysis and boron isotope study in the Lakkor Co area, and analyzed the source and transporting process of lithium. The main origin of lithium in Lakkor Co is the dissolution of lithium-rich rocks, recharge water systems, and deep hydrothermal fluids. These findings are highly significant in enhancing the foundational data of lithium-rich brine resources in the Qinghai-Tibet Plateau and are beneficial for assessing the future development of such deposits.
... Lithium (Li) is a silver-white-colored soft metal belonging to the alkali metal group, and is found in brines (saline waters), hard rock pegmatite ore, and clay minerals. Brines are the main Li sources recorded in different stages of geological development in North and South American countries such as Argentina, Bolivia, Chile, and the United States [1]. However, during the last two decades, the uses of Li have drastically increased over 256% due to the growing intensive demands for this fuel by the green energy revolution and technologies [2,3]. ...
he aim of this study was to evaluate the acute lethality and chronic sublethal effects
of lithium (Li) on Rhinella arenarum tadpoles as model organisms. First a 96 h toxicity assay was
performed by exposing tadpoles to Li concentrations from 44.08 to 412.5 mg L−1 to estimate the
mortality, and lethal and sublethal effects. Another bioassay was carried out by exposing tadpoles
to two environmentally relevant Li concentrations (2.5 and 20 mg L−1) for one and two weeks. The
sublethal effects of Li on tadpoles were evaluated by analyzing biochemical, genotoxic, and physi-
ological biomarkers. The mortality in Li-exposed tadpoles increased over time. The median lethal
concentration (LC50) ranged from 319.52 (281.21–363.05) mg L−1 at 48 h to 66.92 (52.76–84.89) mg L−1
at 96 h. Exposure to Li at 2.5 and 20 mg L−1 induced alterations in enzymes related to detoxification,
antioxidant, and hepatic mechanisms, endocrine disruption of thyroid hormones, genotoxicity, and
effects on the physiology of the heart and gastrointestinal systems. Tadpoles exposed to the highest
concentration in the chronic bioassay (20 mg L−1 Li), which is the concentration commonly recorded
in Li mining sites, showed significant mortality after one week of exposure. These results warn about
the high ecotoxicological risk of Li as a contaminant of emerging concern for amphibians.
... At present, lithium resources mainly exist in the form of solid lithium ore and liquid lithium resources in salt lake brine. Lithium extracted from salt lake brine accounts for 75% of the world's lithium production [14][15][16] and involves lower energy consumption and costs than those of ore lithium. With the increasing demand for lithium resources, the exploration of lithium in deep underground brines in petroliferous basins has attracted increasing attention [17][18][19][20]. ...
There are considerable reserves of low-grade solid potash resources in the shallow part of Mahai Salt Lake in the Qaidam Basin, and the lithium brine resources resulting from solid–liquid conversion and mining are quite abundant. The comprehensive utilization of these resources is an important and urgent problem. In this study, to fully utilize these resources, the shallow low-grade solid potash ore in Mahai Salt Lake was used for systematic simulated ore dissolution experiments, combined with geochemical and X-ray diffraction analyses. The following key results were obtained: (1) Most Li+ in the Mahai mining area was deposited on the soluble salt minerals in silt or clay, and the appropriate concentration of solvent can help to dissolve more Li+ and K+; (2) the saturation time of Li+ was longer than that of K+. Therefore, the dissolution time for the mine can be appropriately extended during the production process to dissolve more Li+; (3) the solid–liquid conversion aqueous solution mining method can separate the lithium part of clay deposits and is associated with salt rock in the brine, which is a potential lithium resource. These experimental results provide a theoretical basis for salt pan production.
... 대륙성 고염수(brine) 광상은 위 두 유형에 비해 탐사 및 개발이 유리하여 현재 리튬 생산의 70%를 차지하고 있다 (Bowell et al., 2020;Sterba et al., 2019). 대륙성 염 수는 증발량이 강우량에 비해 많은 건조하고 고도가 높 은 지역에서 주로 형성되며, 'lithium triangle이라 불리는 아르헨티나, 볼리비아, 칠레에서 세계 리튬 공급의 59%(2019 년 기준)가 이루어지고 있다 (Kesler et al., 2012) (Sanjuan et al., 2020(Sanjuan et al., , 2022 (Li et al., 2022;Marazuela et al., 2020;Munk et al., 2016;Sanjuan et al., 2022), 특히 티 베트 고원과 시베리아 퇴적층에서 수백 mg/L의 리튬이 검출되기도 하여 (Alexeev et al., 2020;Li et al., 2018 (Choi et al., 2014;Lee et al., 2013). 심부 지하수 내 리튬 함량은 진척된 물-암석 반응에 따 라 지하수의 용존물질(total dissolved solid) 농도가 증가 하면서 함께 증가되며, 리튬이 농집된 염수와의 혼합에 의해서도 크게 증가될 수 있다. ...
... Geologic evidence from the halite deposit suggests that the basin has received significant water inflow over at least 7 Ma (Corenthal et al., 2016), suggesting lithium brine formation at least over that time span. This largely coincides with Munk et al. (2016), who propose that the accumulation and concentration of brines likely occurred in the past 10 million years. ...
... Lithium is generally found in pegmatites, oilfield and geothermal brines, saline lakes, and lacustrine argillaceous sediments intercalating borate deposits within the Li-bearing minerals such as spodumene, lepidolite, hectorite, saponite, petalite, amblygonite, and jadarite are originated from several sources such as magmatic rocks, acidic to intermediate character Helvacı and Alonso, 2000;Mohr et al., 2012;Munk et al., 2016;Benson et al., 2017;Kavanagh et al., 2018;Jancsek et al., 2023). ...
Mineralogy, geochemistry, and genesis of lithium-bearing argillaceous
sediments associated with the borate deposit.
... Lithium is generally found in pegmatites, oilfield and geothermal brines, saline lakes, and lacustrine argillaceous sediments intercalating borate deposits within the Li-bearing minerals such as spodumene, lepidolite, hectorite, saponite, petalite, amblygonite, and jadarite are originated from several sources such as magmatic rocks, acidic to intermediate character Helvacı and Alonso, 2000;Mohr et al., 2012;Munk et al., 2016;Benson et al., 2017;Kavanagh et al., 2018;Jancsek et al., 2023). ...
Lithium distribution in Bigadiç Borate Deposit and lithium-borate relations
... Lithium is found in three main types of deposits: 1) Li-rich pegmatite magmatic deposits containing spodumene (LiAlSi 2 O 6 ) and rhyolitic tuffs containing Li, F and Be. 2) continental brines, and 3) hydrothermally altered clays, with hectorite (Na 0.3 (Mg,Li) 3 Si 4 O 10 (OH) 2 ) (Webmineral, 2022) formed by hydrothermal alteration of volcanoclastic rocks (Munk et al., 2016). Other secondary sources of lithium include: salt flats, and formational waters of oil fields, (Dill, 2010;Pohl, 2011;USGS, 2022). ...
Lithium is considered a critical metal for its technological use. It was proposed to carry out the geochemical prospecting study in favorable environments to host possible lithium mineralization, in specific sectors of Ecuador. This would be important, as no anomalies of economic interest have been discovered to date. The content of Li in solid samples and hydrothermal waters in brines in the Guaranda sector, Bolívar province, was evaluated. Likewise, a mineralogical analysis of the solid samples and a multivariate statistical analysis of the data was carried out. The values of sub-anomalies of Li (median 222.46 mgL-1 in brines and Li in solids from Guaranda (median 201.5 ppm), may be comparable to exploitable Li deposits worldwide, which is interesting for its possible economic use. Based on the multivariate statistical analysis, chemical and mineralogical results, Li is associated with Be, and Na mainly in the solids analyzed, this is evidenced by the detection of saponite and fluoroferroleakeite. The chemical composition of the sampled waters could be the result of several processes that include: the dissolution of minerals by water-rock interaction, hydrothermal fluids related to active volcanism and/or recharge by meteoric waters. Caracterización geoquímica de salmueras con litio de Guaranda, Ecuador.
... The brine-based resources dominate due to cheaper production costs. The lithium-rich brine system generally has six common characteristics such as (i) arid environment, (ii) closed basin containing Salar, Salt Lake or both, (iii) associated igneous or geothermal activity, (iv) tectonically driven subsidence, (v) suitable lithium sources and (vi) enough time to concentrate brines (Munk et al. 2016;Sanjuan et al. 2022). However, since lithium demand and prices have risen, alternate sources of lithium have become more popular such as hard rock (pegmatite) ores and the recycling of Li-ion batteries (Asadi Dalini et al. 2021;Jafari et al. 2022;Meng et al. 2021;Reich et al. 2022;Nikoloski 2020, 2021;Traore and Kelebek 2022). ...
The need for lithium in energy storage systems has risen dramatically due to the development of renewable energy technology, portable devices, and electric cars. The current review focuses on the existing worldwide resources of lithium ore, along with the production, demand, and mineralogy of lithium-bearing minerals, in addition to lithium recovery from hard pegmatite ore using different beneficiation techniques. Lithium ore is beneficiated using various methods, including magnetic separation, gravity concentration, electrostatic separation, and flotation to separate gangue minerals. Flotation is the most frequently utilized beneficiation technique. It is found that gravity concentration and flotation are the main beneficiation methods used in many plants around the world. In flotation, reagent chemistry, surface properties, and water quality were critical in spodumene’s efficient recovery. A summary of several reagent regimes, surface properties, flotation conditions, and prospective future studies for technical viability are provided. The current review paper also discusses the beneficiation flowsheet widely used to recover spodumene, lepidolite, and petalite from pegmatite ore. Also, it is tried to discuss the key future research areas along with the cost economics aspect of processing such ore deposits to recover lithium.
... The record of Li-rich fluids trapped in pristine magmatic biotites from unmineralized, young volcanic deposits has important implications for the evolution of magmatic systems in the shallow crust and the transition from magmatic to hydrothermal conditions. First, the partitioning of Li into a MVP provides a mechanism to concentrate Li, and the fate of this MVP may be an important control on the generation of economic Li deposits as either brine deposits (Munk et al., 2016) or pegmatites (Troch et al., 2021). Second, the potential for biotites to contain "invisible" fluid inclusions between crystal layers may play a role in the occurrence of "too-old" 40 Ar/ 39 Ar ages that have previously been reported both from the Kos Plateau Tuff (Bachmann et al., 2010) and elsewhere (Hora et al., 2010). ...
The magmatic-hydrothermal transition is key in controlling the fate of many economically important elements due to the change in partitioning when melt and magmatic fluid coexist. Despite its increasing economic importance, the behavior of lithium (Li) in such environments remains poorly known. We illustrate how compositionally unusual biotites from the rhyolitic Bishop Tuff (California, USA) and Kos Plateau Tuff (Greece) may contain a magmatic volatile phase trapped between layers of biotite crystals. Despite originating in pristine deposits and showing the expected X-ray diffraction spectra, these biotites return low (<95 wt%) analytical totals via electron microprobe (EMP) consistent with the presence of considerable amounts of light elements (non-measurable by EMP). Lithium contents and isotope ratios in these biotites are remarkable, with abundances reaching >2300 ppm, exceptionally light Li isotopic compositions (δ7Li as low as –27.6‰), and large isotopic fractionation between biotite and corresponding bulk samples (Δ7Libt–bulk as low as –36.5‰). Other mineral phases, groundmass glass, and melt inclusions from the same units do not support an extremely Li-rich melt prior to eruption. Biotites from phonolitic systems (Tenerife [Canary Islands] and Campi Flegrei [Italy]) do not show such extreme compositional differences, with biotite and melt showing roughly equivalent Li contents, underscored by significantly reduced Δ7Libt–bulk to a maximum of –10.9‰. We ascribe the difference in behavior to the near-liquidus appearance of biotite in alkaline magmatic suites, before widespread exsolution of a magmatic volatile phase in the magma reservoir, while in rhyolitic suites, biotite crystallizes at low temperature, trapping the coexisting exsolved fluid phase in the reservoir.
... Despite relative geological abundance, policy makers and downstream manufacturers are concerned about supply. One reason is deposits' variation in quality (Munk et al. 2016). Another is the regulatory frameworks that condition lithium's profitability and the lapse between discovery and production, which can result in supply lagging behind demand. ...
The political economy of lithium, a “critical mineral” for the renewable energy transition, is marked by two striking developments. First, Global North governments that have historically offshored mining are onshoring lithium to enhance “supply chain security.” Second, these governments have committed to “sustainably sourcing” lithium. In this article, I theorize both developments in terms of a novel security–sustainability nexus: an interlocking set of policies and justifications that promote lithium extraction and emphasize the environmental credentials of Global North mining. The security–sustainability nexus evidences an alignment between state and corporate interests. For public officials, onshoring policies counter China’s “dominance” over battery supply chains. For mining and auto firms, onshoring translates into lucrative incentives, supply security, and reputational benefits. However, despite this state–corporate alignment, the tensions within the security–sustainability nexus illuminate the contradictions of green capitalism. I conclude that the geopolitical and socioenvironmental conflicts over the material foundations of the energy transition are reshaping the inequalities linked to extractive sectors.
... The work presented here builds on decades of research on salars, including the geochemical evolution of inflow waters to brines (e.g., Hardie and Eugster, 1970;Nesbitt, 1974), the geochemical and/or isotopic investigations specifically for South American salars (e.g. Alpers & Whitmore, 1990;Boschetti et al., 2007;Carmona et al., 2000;Corenthal et al., 2016;Godfrey and Amado-Alvarez, 2020;Moraga et al., 1974;Munk et al., 2016;Munk et al., 2018;Rettig et al., 1980;Risacher & Fritz, 2009;Spiro & Chong, 1996), the sedimentology and stratigraphy of closed-basin continental salars (e.g., Benison & Goldstein, 2001;Hardie et al., 1978;Smoot & Lowenstein, 1991 [and refs. therein]; Warren, 2006 [and refs. ...
The Salar de Atacama contains one of the world's most important lithium resources and hosts unique and fragile desert ecosystems. Water use issues of the hyper‐arid region have placed it at the center of global attention. This work combines geochemical and hydrogeologic data with remote sensing analysis to address differences in water zones in the marginal environments of the salar. Water samples from across the inflow to brine transition were collected over the period 2012‐2016 and analyzed for ẟD, 3H, 87Sr/86Sr and major and minor elements. The ẟD values range from about ‐64 to +20 ‰, 3H as Rmod from 0.01 to 0.36 and the 87Sr/86Sr from 0.70750 to 0.70804 with highest ẟD and 3H occurring in the regions of open water. Geochemical modeling results indicate inflow and shallow transition zone waters are saturated with respect to calcite, whereas all others are saturated with respect to calcite, gypsum, and halite. Long‐term remote‐sensing of surface water body extents indicate that extreme precipitation events are the primary driver of surface area changes as exemplified by an increase in size of the lagoons by a factor of 2.7 after a storm. A new conceptual model of the freshwater to brine transition zone that incorporates variability in aquifer geology, hydrology and geochemistry to explain important marginal water bodies is presented. The subsurface brines in the transition zone and the halite nucleus are geochemically distinct compared to the groundwater discharge features (e.g. lagoons) over modern time scales which aids in conceptualizing the transition zone system.
... The work presented here builds on decades of research on salars, including the geochemical evolution of inflow waters to brines (e.g., Hardie and Eugster, 1970;Nesbitt, 1974), the geochemical and/or isotopic investigations specifically for South American salars (e.g. Alpers & Whitmore, 1990;Boschetti et al., 2007;Carmona et al., 2000;Corenthal et al., 2016;Godfrey and Amado-Alvarez, 2020;Moraga et al., 1974;Munk et al., 2016;Munk et al., 2018;Rettig et al., 1980;Risacher & Fritz, 2009;Spiro & Chong, 1996), the sedimentology and stratigraphy of closed-basin continental salars (e.g., Benison & Goldstein, 2001;Hardie et al., 1978;Smoot & Lowenstein, 1991 [and refs. therein]; Warren, 2006 [and refs. ...
The Salar de Atacama contains one of the world’s most important lithium resources and hosts unique and fragile desert ecosystems. Water use issues of the hyper-arid region have placed it at the center of global attention. This investigation is the first robust assessment of a salar system to incorporate geology, hydrogeology, and geochemistry of the aquifer system in the inflow, transition zone and the nucleus. Multiple physico-chemical parameters including conductivity, temperature, Li and Na, and multiple isotopic indicators (3H, ẟD, and 87Sr/86Sr) all conclude that the transition zone water zones are distinct and separated from the brine in the halite nucleus. Geochemical modeling indicates that the inflow and transition waters are saturated with respect to calcite whereas lagoons, transition zone margin, halite nucleus margin and nucleus waters are saturated with respect to calcite, gypsum, and halite, and the transition zone brines at depth display a broader range of saturation states as compared to the nucleus brines. Long-term remote-sensing of surface water body extents suggest that extreme precipitation events are the primary driver of surface area changes (by a factor of 2.7 after storm). A major finding from this work is that the subsurface brines in the transition zone and the halite nucleus are geochemically and hydraulically disconnected from the groundwater discharge features (lagoons) over modern time scales which has far reaching implications for understanding the link between brine and freshwater.
... The evaporation/precipitation steps take up between 9 and 14 months from the beginning of the extraction process (brine pump out of the underground aquifers). The extraction process into brines naturally occur at high altitude and in desert areas [21], [22], solar/wind evaporation is a cost effective method for concentrating brines and precipitating salts [20]. ...
... One of the most important global target elements is lithium, which is considered to be a 'green' metal required for the strategic technologies of the 21st century. Sources of lithium include pegmatites, continental brines and hydrothermally altered clays (Munk et al. 2016). Due to the increasing demand for lithium, regional exploration for this element is carried out in many countries (Kesler et al. 2012). ...
Geochemical exploration for rare metals, specifically lithium, is essential on a regional scale based on their demand and consumption in recent years. The main objective of this study was to delineate lithium anomalies in regional exploration utilizing the geochemical mapping prospectivity index (GMPI), staged factor analysis (SFA), and a concentration-number (C-N) fractal model based on stream sediments. The case study area is 26000 km ² and is located in the Khorasan Razavi province (NE Iran). In addition, rock samples were used to validate the Li anomalies identified. Results derived via the SFA show that Li was located on a factor denoted as F1-3 with Be, Cs, F, Nb, Sn, Th, U and W, which was used for calculation of the GMPI values. The GMPI data were classified by the C-N fractal method for determination of the Li anomalies. The main anomalies with GMPI ≥ 0.7 and Li ≥ 48 ppm were situated in the SE, SW, north and south parts of the study region. Li grades of rock samples were categorized by the C-N fractal technique for validation of F2-2 anomalies using a log-ratio matrix. The main anomalies were correlated with related lithological units of Li mineralization types. This correlation indicates that the main GMPI–Li anomalies are associated with granitic–pegmatitic units in the central and SE parts, and overlap with clay minerals in the northern and southern sectors of this region. There is good potential for Li mineralization as demonstrated by this hybrid method.
Lithium is a critical raw material for the energy transition and the salar brine deposits of South America host ∼70% of global resources. However, there are concerns regarding water use, and the associated impacts, of lithium production from these deposits. Life Cycle Assessment (LCA) is becoming increasingly prevalent in the analysis of raw materials sustainability, but current methods are regarded as unsatisfactory for assessing water use impacts related to lithium production from salar deposits. This work explores the challenges and opportunities for improvement in this context. We outline how the classification and assessment of water types could be improved and identify Water Availability Assessments, groundwater specific CFs, salar-specific methodologies and multiple mid-point indicators as areas for further investigation. This will aid the development of LCA methodology and enable an improved assessment of the sustainability of lithium production from salar deposits in South America and by extension help decouple decarbonisation efforts from negative impacts.
A thorough understanding of the evolution of coastal brine-bearing groundwater systems under the influence of human activities contributes to the sustainable use of coastal groundwater resources. Therefore, this study comprehensively investigated the processes associated with hydrochemical changes in groundwater during brine exploitation based on long-term monitoring data. The dataset comprised 102 samples (including groundwater, seawater, rain and river samples) collected from 1966 to 2021 to capture the hydrochemical variability. Significant changes in the brine water table and concentration between the pre-overexploitation period (1965–2000) and the exploitation period (2000−2021) are observed. From the relationship between stable isotope (δ¹⁸O and δ²H) values and Cl⁻ contents, shallow saline water (SSW) near the drawdown cone (with δ¹⁸O and δ²H values of −4.66 ‰ ~ −3.57 ‰ and − 42.1 ‰ ~ −32.8 ‰, respectively) is similar geochemically to the brine inside the drawdown cone (with values of −4.30 ‰ ~ −3.10 ‰ and − 39.0 ‰ ~ −32.3 ‰, respectively), indicating that the SSW has a recharge effect on the underground brine. The delta values of major cations were calculated to analyze the hydrochemical processes at different water quality interfaces (saline/freshwater interface, saline/brine interface). The results demonstrated that the SSW and deep saline water (DSW) at the offshore brine/saline water interface undergo seawater intrusion, where SSW undergoes a salinization process with cation exchange (Na⁺ is exchanged for Ca²⁺ and Mg²⁺ in clay), while DSW undergoes a freshening process. The SSW at the saline water/freshwater interface is affected by freshwater pumping, and the DSW undergoes a salinization process influenced by brine intrusion presenting the common salinization process with cation exchange. The hydrochemical model shows that the brine concentration recovered during the restricted exploitation stage due to the dissolution of gypsum and halite. If no measures are taken to restrict exploitation, then brine will eventually be replaced by saline water.
Demand for lithium for batteries is growing rapidly with the global push to decarbonize energy systems. The Salar de Atacama, Chile holds ∼42% of the planet's reserves in the form of brine hosted in massive evaporite aquifers. The mining of these brines and associated freshwater use has raised concerns over the environmental responsibility of lithium extraction, yet large uncertainties remain regarding fundamental aspects of governing hydrological processes in these environments. This incomplete understanding has led to the perpetuation of misconceptions about what constitutes sustainable or renewable water use and therefore what justifies responsible allocation. We present an integrated hydrological assessment using tritium and stable oxygen, and hydrogen isotopes paired with remotely sensed and terrestrial hydroclimate data to define unique sources of water distinguished by residence time, physical characteristics, and connectivity to modern climate. Our results describe the impacts of prolonged drought on surface and groundwaters and demonstrate that nearly all inflow to the basin is composed of water recharged >65 years ago. Still, modern precipitation is critical to sustaining important wetlands around the salar. Recent large rain events have increased surface water and vegetation extents and terrestrial water storage while mining‐related water withdrawals have continued. As we show, poor conceptualizations of these complex hydrological systems have perpetuated the misallocation of water and the misattribution of impacts. These fundamental issues apply to arid regions globally. Our new framework for hydrological assessment in these basins moves beyond calculating gross inputs‐outputs at a steady state to include all compartmentalized stores that constitute “modern” budgets.
Imaging geological layers beneath lakes, rivers, and shallow seawater provides detailed information critical for hydrological modeling, geologic studies, contaminant mapping, and more. However, significant engineering and interpretation challenges have limited the applications, preventing widespread adoption in aquatic environments. We have developed a towed transient electromagnetic (tTEM) system for a new, easily configurable floating, transient electromagnetic instrument (FloaTEM) capable of imaging the subsurface beneath both freshwater and saltwater. Based on the terrestrial tTEM instrument, the FloaTEM system utilizes a similar philosophy of a lightweight towed transmitter with a trailing offset receiver pulled by a small boat. The FloaTEM system is tailored to the specific freshwater or saltwater application as necessary, allowing investigations down to 100 m in freshwater environments and up to 20 m on saline waters. Through synthetic analysis, we show how the depth of investigation of the FloaTEM system greatly depends on the resistivity and thickness of the water column. The system has been successfully deployed in Denmark for a variety of hydrologic investigations, improving the ability to understand and model processes beneath water bodies. We present two freshwater applications and a saltwater application. Imaging results reveal significant heterogeneities in the sediment types below the freshwater lakes. The saline water example demonstrates that the system is capable of identifying and distinguishing clay and sand layers below the saline water column.
There are three broad types of economic lithium deposit: 1) peralkaline and peraluminous pegmatite deposits and their associated metasomatic rocks; 2) Li-rich hectorite clays derived from volcanic deposits; 3) salar evaporites and geothermal deposits. Spodumene-bearing pegmatites are the most important and easily exploitable Li deposits, typically containing 0.5 Mt Li. Salar deposits hold the largest Li reserves, can reach up to 7 Mt Li, but are more difficult to exploit. Allowing for recycling, the current predicted demand up to the year 2100 is 20 Mt Li; world resources are currently estimated at more than 62 Mt Li. Thus, abundant resources exist, and no long-term shortage is predicted.
Fault zone architecture and related permeability structures form primary controls on fluid flow in upper-crustal, brittle fault zones. Qualitative and quantitative schemes for evaluating fault-related permeability structures are developed by using results of field investigations, laboratory permeability measurements, and numerical models of flow within and near fault zones. The fault core and damage zone are distinct structural and hydrogeologic units that reflect the material properties and deformation conditions within a fault zone. Whether a fault zone will act as a conduit, barrier, or combined conduit-barrier system is controlled by the relative percentage of fault core and damage zone structures and the inherent variability in grain scale and fracture permeability.
Our inability to determine the growth history and growth mechanism of the Tibetan plateau may be attributed in part to the lack of detailed geologic information over remote and often inaccessible central Tibet, where the Eastern Kunlun Range and Qaidam basin stand out as the dominant tectonic features. The contact between the two exhibits the largest and most extensive topographic relief exceeding 2 km across their boundary inside the plateau. Thus, determining their structural relationship has important implications for unraveling the formation mechanism of the whole Tibetan plateau. To address this issue, we conducted field mapping and analysis of subsurface and satellite data across the Qimen Tagh Mountains, part of the western segment of the Eastern Kunlun Range, and the Yousha Shan uplift in southwestern Qaidam basin. Our work suggests that the western Eastern Kunlun Range is dominated by south-directed thrusts that carry the low-elevation Qaidam basin over the high-elevation Eastern Kunlun Range. Cenozoic contraction in the region initiated in the late Oligocene and early Miocene (28-24 Ma) and has accommodated at least 48% upper-crustal shortening (i.e., ∼150 km shortening) since that time. In order to explain both the high elevation of the Eastern Kunlun Range and the dominant south-directed thrusts across the range, we propose that the Cenozoic uplift of the range has been accommodated by large-scale wedge tectonics that simultaneously absorb southward subduction of Qaidam lower crust below and southward obduction of Qaidam upper crust above the Eastern Kunlun crust. In the context of this model, the amount of Qaidam lower-crust subduction should be equal to or larger than the amount of shortening across Qaidam upper crust in the north-tapering thrust wedge system, thus implying at least 150 km of Qaidam lower-crust subduction since the late Oligocene and early Miocene. The late Oligocene initiation of contraction along the southern margin of Qaidam basin is significantly younger than that for the northern basin margin in the Paleocene to early Eocene between 65 and 50 Ma. This temporal pattern of deformation indicates that the construction of the Tibetan plateau is not a simple process of northward migration of its northern deformation fronts. Instead, significant shortening has occurred in the plateau interior after the plateau margins were firmly established at or close to their current positions. If Cenozoic crustal deformation across the Eastern Kunlun and Qaidam regions was accommodated by pure-shear deformation, our observed >48% upper-crustal shortening strain is sufficient to explain the current elevation and crustal thickness of the region. However, if the deformation between the upper and lower crust was decoupled during the Cenozoic Indo-Asian collision, lower-crustal flow or thermal events in the mantle could be additional causes of plateau uplift across the Eastern Kunlun Range and Qaidam basin.
During the middle Cenozoic, from 36 to 18 Ma, one of the greatest global expressions of long-lived, explosive silicic volcanism affected a large segment of southwestern North America, including central Nevada and southwestern Utah in the southern Great Basin. The southern Great Basin ignimbrite province, resulting from this flareup, harbors several tens of thousands of cubic kilometers of ash-flow deposits. They were created by more than two hundred explosive eruptions, at least thirty of which were super-eruptions of more than 1000 km(3). Forty-two exposed calderas are as much as 60 km in diameter. As in other parts of southwestern North America affected by the ignimbrite flareup, rhyolite ash-flow tuffs are widespread throughout the southern Great Basin ignimbrite province. However, the province differs in two significant respects. First, extrusions of contemporaneous andesitic lavas were minimal. Their volume is only about 10% of the ignimbrite volume. Unlike other contemporaneous volcanic fields in southwestern North America, only a few major composite (strato-) volcanoes predated and developed during the flareup. Second, the central sector and especially the eastern sector of the province experienced super-eruptions of relatively uniform, crystal-rich dacite magmas; resulting deposits of these monotonous intermediates measure on the order of 16,000 km(3). Following this 4 m.y. event, very large volumes of unusually hot and dry trachydacitic magmas were erupted. These two types of magmas and their erupted volumes are apparently without parallel in the middle Cenozoic of southwestern North America. A fundamental goal of this themed issue is to present basic stratigraphic, compositional, chronologic, and paleomagnetic data on the unusually plentiful and voluminous ignimbrites in the southern Great Basin ignimbrite province. These data permit rigorous correlations of the vast outflow sheets that span between mountain-range exposures across intervening valleys as well as correlation of the sheets with often-dissimilar accumulations of tuff within dismembered source calderas. Well-exposed collar zones of larger calderas reveal complex wall-collapse breccias. Calculated ignimbrite dimensions in concert with precise Ar-40/Ar-39 ages provide insights on the growth and longevity of the colossal crustal magma systems. Exactly how these subduction-related magma systems were sustained for millions of years to create multicyclic super-eruptions at a particular focus remains largely unanswered. What factors created eruptive episodes lasting millions of years separated by shorter intervals of inactivity? What might have been the role played by tears in the subducting plate focusing a high rate of mantle magma flux into the crust? What role might have been played by an unusually thick and still-warm crust inherited from earlier orogenies? Are the numerous super-eruptions, especially of the unusual monotonous intermediates and succeeding trachydacitic eruptions, during the Great Basin ignimbrite flareup simply a result of the coupling effect of high mantle-magma flux and a thick crust, or did other factors play a role?
En el presente trabajo se identifican, describen y se muestra la distribución areal de las facies y evapofacies asociadas al ambiente evaporítico del Salar Hombre Muerto, ubicado en el borde oriental de la Puna Austral, en una zona con una amplia difusión de yacimientos de boratos. El salar puede ser dividido en dos subcuencas, la occidental y la oriental, ambas separadas por el islote central de Farallón Catal. La subcuenca oriental es boratífera, con bajo contenido en cloruros, mientras que la subcuenca occidental presenta tanto en superficie como en profundidad potentes acumulaciones de halita (hasta 900 m) y es prácticamente estéril en boratos. Se plantean varias hipótesis sobre la génesis de la evapofacies boratífera, representada mineralógicamente por el borato ulexita. Esta es la evapofacies de interés económico y que se explota en el salar, donde además se extraen salmueras de litio.
A belt of low-angle normal (or detachment) faults 250 km long extends from the northern end of the Salton Trough, California to southern Laguna Salada, Baja California, Mexico. The detachment system is divided into two principal segments. The northern segment, here termed the “west Salton detachment system,” comprises top-to-the-east detachment faults along the eastern Peninsular Ranges that root under the Salton Trough. The southern segment, here termed the Laguna Salada detachment system, comprises top-to-the-west detachment faults in northeastern Baja California and the Yuha Desert region of the southwesternmost Salton Trough. Detachments of that system root under Laguna Salada and the Peninsular Ranges of northern Baja California. Both of these systems experienced a major episode of activity in late Miocene to Pleistocene time, synchronous with deposition of the Imperial and Palm Spring formations, and the Laguna Salada detachment system may still be active. Thus, their activity temporally overlapped, partly or completely, with activity on dextral faults of the San Andreas boundary between the Pacific and North American plates, and with accretion of new transitional crust. Some of the detachment faults in the northern segment may have had mid-Miocene normal slip and/or Cretaceous thrust or normal slip as well, although compelling evidence for either is lacking. These detachment faults are distinctly younger than detachments east of the San Andreas fault, which generally ceased activity by middle or late Miocene time and are overlapped by marine or lacustrine rocks (Bouse Formation); these units are equivalent in age to the syntectonic strata of the Salton Trough but are much thinner and essentially undeformed.
Lithium-rich brine within the sub-surface of the Salar del Hombre Muerto (SHM) salt pan in the Andes of northwestern Argentina has a chemical and isotopic composition which is consistent with Li derived from several sources: the modern halite saturated lagoon, Li-rich salts and brines formed recently, and dissolution of halite which precipitated from ancient saline lakes. SHM lies in the closed basin that includes part of the massive Cerro Galán caldera which is drained by the Río los Patos, which is responsible for 90% of surface runoff into the salar. The low Li isotope composition, +3.4‰, of this river is consistent with significant contributions of geothermal spring water. As water drains through the volcaniclastic deposits which cover a large proportion of the basin, Li removal, as indicated by decreasing Li/Na, occurs but without significant isotope fractionation. This indicates a mechanism of surface sorption onto smectite or ferrihydrite rather than Li incorporation into octahedral structural sites of clays. These observations suggest that conditions in this high altitude desert have limited the dilution of hydrothermal spring water as well as the formation of clay minerals, which jointly have allowed the Li resource to accumulate rapidly. Changes in climate on a multi-millennial time scale, specifically in the hydrologic budget, have resulted in solute accumulation rates that have been variable through time, and decoupled Li and Na fluxes. Inflow to the salar under modern conditions has high Li/Na (7.9 × 10−3 by wt) with δ7Li indistinguishable from basement rocks (−0.3‰ to +6.4‰), while under pluvial climate conditions the Li/Na of the saline lake was 40 times lower than the modern lagoon (0.1–0.3 × 10−3 compared to 10.6–13.4 × 10−3) with slightly higher δ7Li, +6.9‰ to +12.3‰, reflecting the uptake of 6Li into secondary minerals which formed under a wetter climate.
The Lípez region of southwest Bolivia is the locus of a major Neogene ignimbrite flare-up, and yet it is the least studied portion of the Altiplano-Puna volcanic complex of the Central Andes. Recent mapping and laser-fusion 40Ar/39Ar dating of sanidine and biotite from 56 locations, coupled with paleomagnetic data, refine the timing and volumes of ignimbrite emplacement in Bolivia and northern Chile to reveal that monotonous intermediate volcanism was prodigious and episodic throughout the complex. The new results unravel the eruptive history of the Pastos Grandes and Guacha calderas, two large multicyclic caldera complexes located in Bolivia. These two calderas, together with the Vilama and La Pacana caldera complexes and smaller ignimbrite shields, were the dominant sources of the ignimbrite-producing eruptions during the ~10 m.y. history of the Altiplano-Puna volcanic complex. The oldest ignimbrites erupted between 11 and 10 Ma represent relatively small volumes (approximately hundreds of km3) of magma from sources distributed throughout the volcanic complex. The first major pulse was manifest at 8.41 Ma and 8.33 Ma as the Vilama and Sifon ignimbrites, respectively. During pulse 1, at least 2400 km3 of dacitic magma was erupted over 0.08 m.y. Pulse 2 involved near-coincident eruptions from three of the major calderas resulting in the 5.60 Ma Pujsa, 5.65 Ma Guacha, and 5.45 Ma Chuhuilla ignimbrites, for a total minimum volume of 3000 km3 of magma. Pulse 3, the largest, produced at least 3100 km3 of magma during a 0.1 m.y. period centered at 4 Ma, with the eruption of the 4.09 Ma Puripicar, 4.00 Ma Chaxas, and 3.96 Ma Atana ignimbrites. This third pulse was followed by two more volcanic explosivity index (VEI) 8 eruptions, producing the 3.49 Ma Tara (800 km3 dense rock equivalent [DRE]) and 2.89 Ma Pastos Grandes (1500 km3 DRE) ignimbrites. In addition to these large calderarelated eruptions, new age determinations refine the timing of two little-known ignimbrite shields, the 5.23 Ma Alota and 1.98 Ma Laguna Colorada centers. Moreover, 40Ar/39Ar age determinations of 13 ignimbrites from northern Chile previously dated by the K-Ar method improve the overall temporal resolution of Altiplano-Puna volcanic complex development. Together with the updated volume estimates, the new age determinations demonstrate a distinct onset of Altiplano-Puna volcanic complex ignimbrite volcanism with modest output rates, an episodic middle phase with the highest eruption rates, followed by a decline in volcanic output. The cyclic nature of individual caldera complexes and the spatiotemporal pattern of the volcanic field as a whole are consistent with both incremental construction of plutons as well as a composite Cordilleran batholith.
Summaries of the major features of the geology of North America and the adjacent oceanic regions are presented. Twenty chapters include concise reviews of current thinking about Precambrian basement, Phanerozoic orogens, cratonic basins, passive-margin geology of the Atlantic and Gulf Coast regions, marine and terrestrial geology of the Caribbean region, marine geology of the North Atlantic and northeast Pacific oceans, Quaternary geology, hydrogeology, and economic geology. An excellent text for a graduate course or upper-level undergraduate course in regional geology. Includes tables of contents for the other volumes in this series. Extended selected references also available.
The enigma of continental plateaus formed in the absence of continental collision
is embodied by the Altiplano-Puna, which stretches for 1800 km along the Central
Andes and attains a width of 350–400 km. The plateau correlates spatially and
temporally with Andean arc magmatism, but it was uplifted primarily because
of crustal thickening produced by horizontal shortening of a thermally softened
lithosphere. Nonetheless, known shortening at the surface accounts for only 70–
80% of the observed crustal thickening, suggesting that magmatic addition and
other processes such as lithospheric thinning, upper mantle hydration, or tectonic
underplating may contribute significantly to thickening. Uplift in the region of the
Altiplano began around 25 Ma, coincident with increased convergence rate and
inferred shallowing of subduction; uplift in the Puna commenced 5–10 million
years later.
The recent increase in demand for lithium has led to the development of new brine prospects, particularly in the Central Andes. The brines are hosted in closed basin aquifers of two types: mature, halite dominant, and immature, clastic dominant. The estimate of elemental resources in these salars depends on a detailed knowledge of aquifer geometry, porosity, and brine grade. The geometry of the aquifers can be evaluated by classical geophysical and drilling techniques, but because the resource is a fluid, with the attendant problems of in-aquifer mixing and reorganization, existing codes for filing resource and reserve estimates need modification. Total porosity is relatively straightforward to measure, but effective porosity and specific yield, which are required to estimate the resource, are more difficult. Recovery factors are low compared with most metalliferous and industrial mineral deposits due to reliance on pumping of the brine from wells for extraction. These and related issues lead us to believe that modifications to the existing standards for reporting mineral resources and reserves are required for these prospects.
Precise dating of sanidine from proximal ash flow Bishop Tuff and air fall Bishop pumice and ash, California, can be used to derive an absolute age of the Matuyama Reversed-Brunhes Normal (M-B) paleomagnetic transition, identified stratigraphically close beneath the Bishop Tuff and ash at many sites in the western United States. An average age of 758.9+/-1.8ka, standard error of the mean (SEM), was obtained for individual sanidine crystals or groups of several crystals, determined from ~70 individual analyses of sanidine separates from 11 sample groups obtained at five localities. The basal air fall pumice (757.7+/-1.8ka) and overlying ash flow tuff (762.2+/-4.7ka) from near the source yield essentially the same dates within errors of analysis, suggesting that the two units were emplaced close in time. A date on distal Bishop air fall ash bed at Friant, California, ~100 km to the west of the source area, is younger, 750.1+/-4.3ka, but not significantly different within analytical error (+/-1 standard deviation). Previous dates of the Bishop Tuff, obtained by others using conventional K-Ar and the fission track method on zircons, ranged from ~650 ka to ~1.0 Ma. The most recent, generally accepted date by the K-Ar method on sanidine was 738+/-3ka. We infer, as others before, that many K-Ar dates on sanidine feldspar are too young owing to incomplete degassing of radiogenic Ar during fusion in the K-Ar technique and that many older K-Ar dates are too old owing to detrital or xenocrystic contamination in the larger samples that are necessary for the technique. The new dates are similar to recent 40Ar/39Ar ages of the Bishop Tuff determined on individual samples by others but are derived from a larger proximal sample population and from multiple analysis of each sample. The results provide a definitive and precise age calibration of this widespread chronostratigraphic marker in the western United States and northeastern Pacific Ocean. We calculated the age of the M-B transition at five sites, assuming constant sedimentation rates, the age of the Bishop ash bed and one or more well-dated chronostratigraphic horizons above and below the Bishop Tuff ash bed and M-B transition, and stratigraphic separations between these datum levels. The age of the M-B transition is 774.2+/-2.8ka, based on the average of eight such calculations, close to other recent determinations, and similar to that determined from the astronomically tuned polarity timescale. Our approach provides an alternative and surprisingly precise method for determining the age of the M-B and other chronostratigraphic levels. The above dates, calculated using U.S. Geological Survey values of 27.92 Ma for the Taylor Creek (TC) sanidine can be recalculated to other widely used values for these monitors. For example, using recently published values of 28.34 Ma (TC) and 523.1 Ma (McLure Mountain hornblende, MMhb-1), the resulting ages are ~774 ka for the Bishop Tuff and ash bed and ~789 ka for the M-B transition.
The western flank of the Central Andean Plateau is a crustal-scale monoclinal fold, expressed in the geomorphology and in the westward tilt of fore-arc basin strata. Data from three fore-arc basins quantify the magnitude and time of displacement of the plateau system relative to the fore arc. From 18°30′S to 22°S there is a single monocline strand. There, other authors documented ∼2000 m (±500 m) of early and middle Miocene structural relief growth across small-scale monoclines, and our data reveal 810 m (±640 m) of ∼11–5 Ma relief growth and 400 m (±170 m) relief growth since ∼5 Ma across a long-wavelength monoclinal fold limb. This structural relief growth since ∼11 Ma approximates the topographic relief growth between the fore arc and the Altiplano plateau. From 22°S to 24°S there are two subparallel long-wavelength monoclines. Structural relief on the east side of the fore arc increased by 2840 m (±2510 m) during ∼17–10 Ma and by 2320 m (±1050 m) since ∼10 Ma. Some part of this monoclinal limb rotation led to topographic uplift of the adjacent Puna plateau. Rotation across the western monocline could have increased the altitude of the fore-arc basins by
Lakes in the Bonneville basin have fluctuated dramatically in response to changes in rainfall, temperature, and drainage diversion during the Quaternary. We analyzed tufas and shells from shorelines of known ages in order to develop a relation between Sr-87/Sr-86 ratio of carbonates and lake level, which then can be used as a basis for constraining lake level from similar analyses on carbonates in cores. Carbonates from the late Quaternary shorelines yield the following average Sr-87/Sr-86 ratios: 0.71173 for the Stansbury shoreline (22-20 C-14 ka; 1350 m), 0.71153 for the Bonneville shoreline (15.5-14.5 C-14 ka; 1550 m), 0.71175 for the Provo shoreline (14.4-14.0 C-14 ka; 1450 m), 0.71244 for the Gilbert shoreline (-10.3-10.9 C-14 ka; 1300 m), and 0.71469 for the modern Great Salt Lake (1280 m). These analyses show that the Sr-87/Sr-86 ratio of lacustrine carbonates changes substantially at low- to mid-lake levels but is invariant at mid- to high-lake levels. Sr-isotope mixing models of Great Salt Lake and the Bonneville paleolake system were constructed to explain these variations in Sr-87/Sr-86 ratios with change in lake level. Our model of the Bonneville system produced a Sr-87/Sr-86 ratio of 0.71193, very close to the observed ratios from high-shoreline tufa and shell. The model verifies that the integration of the southern Sevier and Beaver rivers with the Bear and others rivers in the north is responsible for the lower Sr-87/Sr-86 ratios in Lake Bonneville compared to the modern Great Salt Lake. We also modeled the Sr-87/Sr-86 ratio of Lake Bonneville with the upper Bear River diverted into the Snake River basin and obtained an Sr-87/Sr-86 ratio of 0.71414. Coincidentally, this ratio is close to the observed ratio for Great Salt Lake of 0.71469. This means that Sr-87/Sr-86 ratios of >0.714 for carbonate can be produced by climatically induced low-lake conditions or by diversion of the upper Bear River out of the Bonneville basin. This model result also demonstrates that the upper Bear River had to be flowing into the Bonneville basin during highstands of other late Quaternary lake cycles: carbonates from the Little Valley (130-160 ka) and Cutler Dam (59 5 ka) lake cycles returned Sr-87/Sr-86 ratios of 0.71166 and 0.71207, respectively, and are too low to be produced by a lake without the upper Bear River input.
Discoidal gypsum crystal cavities occur in quartzites that host varying amounts of strata-bound scheelite mineralization near Halls Creek in Western Australia. The host quartzites have been regionally metamorphosed to greenschist facies and are contained within a Middle Proterozoic sequence that includes pelites, mafic and felsic volcanics, and volcaniclastic rocks. Textural, fluid inclusion, and oxygen isotope data indicate that scheelite was present in the host quartzites prior to regional metamorphism. The presence of crystal cavities after gypsum in the quartzites implies an evaporitic origin for this sequence. The continental-sabkha playa basins of the Mojave Desert, California, are suggested to be possible modern analogs-e.g., Searles Lake, where the tungsten content is up to 70 ppm WOâ in brines and 118 ppm in muds, and exceeds the amount of tungsten in all known deposits in the United States. Metamorphism of a continental evaporitic sequence containing tungsten could produce an assemblage of rocks very similar to those reported from several stratabound tungsten deposits. Some of these, such as at Halls Creek, may be related to original accumulations of tungsten in nonmarine evaporitic environments.
Uncertainty surrounds the fate of the orogenic plateau in what is now the Great Basin in western Utah and Nevada, which resulted from the Mesozoic and earliest Cenozoic contractile deformations and crustal thickening. Although there is some consensus regarding the gravitational collapse of the plateau by extensional faulting and consequent crustal thinning, whether or not the plateau existed during the middle Cenozoic Great Basin ignimbrite flareup – one of the grandest expressions of continental volcanism in the geologic record – had remained in doubt. We use compositions of contemporaneous calc-alkaline lava flows as well as configurations of the ignimbrite sheets to show that the Great Basin area during the middle Cenozoic was a relatively smooth plateau underlain by unusually thick crust. We compare analyses of 376 intermediate-composition lava flows in the Great Basin that were extruded at 42–17 Ma with compositions of >6000 analyses of the late Cenozoic lava flows in continental volcanic arcs that correlate roughly with known crustal thickness. This comparison indicates that the middle Cenozoic Great Basin crust was much thicker than the present ca. 30 km thickness, likely as much as 60–70 km. If isostatic equilibrium prevailed, this unusually thick continental crust must have supported high topography. This high terrain in SE Nevada and SW Utah was progressively smoothed as successive ignimbrite outflow sheets were emplaced over areas currently as much as tens of thousands of square kilometres to aggregate thicknesses of as much as hundreds of metres. The generally small between-site variations in the palaeomagnetic directions of individual sheets lend further support for a relatively smooth landscape over which the sheets were draped. We conclude that during the middle Cenozoic, especially towards the close of the ignimbrite flareup, this Great Basin area was a relatively flat plateau, and because it was also high in elevation, we refer to it as an Altiplano. It was not unlike the present-day Altiplano-Puna in the tectonically similar central Andes, where an ignimbrite flareup comparable to that in the Great Basin occurred at ca. 9–3 Ma. Outflow ignimbrite sheets that were deposited from 35 to 23 Ma on the progressively smoothed Altiplano in south-eastern Nevada were derived from source calderas to the west. Of the 12 major sheets from seven sources, nine are distributed unevenly east of their sources while the remaining three sheets are spread about as far east as west of their sources. This eccentricity of sources near the western margin of 75% of the sheets indicates the existence of a NS-trending topographic barrier in central Nevada that restricted westward dispersal of ash flows. In a symmetric manner, eastward dispersal of ash flows from sources farther west seemed to have been impeded by this same topographic barrier. The westward dispersal was controlled in part by westward-draining stream valleys incised in the sloping flank of the Great Basin Altiplano in western Nevada and adjacent California; at least one of these ash flows travelled as far west as the western foothills of the Sierra Nevada. The nature and origin of the implied topographic barrier are uncertain. It is possible that heavy orographic precipitation on the western slope of the Altiplano and consequent focused denudation and isostatic uplift created a NS-trending topographic high at the crest of the western slope and facing the smoothed Altiplano to the east. The barrier also lies near and essentially parallel to the buried western edge of the Precambrian basement and to a zone of thermal-diapiric domes that were spawned in thickened crust as the basement edge was overrun by late Palaeozoic–Mesozoic thrust sheets.
Since 90 Ma, the nonmarine Salar de Atacama Basin has been the largest, deepest, and most persistent sedimentary basin of northern Chile. Integration of 200 km of two-dimensional seismic reflection data with surface geological data clarifies Oligocene and Neogene evolution of the northern part of the basin. A normal fault with 6 +/- 1 km of vertical separation controlled the western boundary of the basin during the accumulation of the Oligocene-lower Miocene Paciencia Group. The combination of this structure, a similar one in the Calama Basin, and regional structural data suggests that localized extension played an important role within a tectonic environment dominated by margin-perpendicular compression and margin-parallel strike-slip deformation. Seismic data substantiate the surface interpretation that much of the Cordillera de la Sal ridge resulted from diapiric flow of the Paciencia Group. Diapiric flow initiated during the late early Miocene or middle Miocene, associated with a deep reverse fault.
The spatial distribution of some major and trace element and isotopic characteristics of backarc Plio-Quaternary basaltic to high-Mg andesitic (51% to 58% SiO2) lavas in the southern Puna of the Central Andean Volcanic Zone reflect varying continental lithospheric thickness and the thermal state of the underlying mantle wedge and subducting plate. The eruption of intraplate mafic lavas, the change in regional stress orientation, and the high elevation of the southern Puna are suggested to be the result of the late Pliocene mechanical delamination of a block (or blocks) of continental lithosphere. The loss of this lithosphere resulted in an influx of asthenosphere that caused heating of the subducting slab and yielded intraplate basic magmas that produced extensive melting at the base of the thickened crust. -from Authors
Lithium-bearing brines occur in Clayton Valley, an undrained structural depression filled with Quaternary unconsolidated sediments consisting chiefly of clays and saline minerals. The lithium occurs in a sodium chloride brine which contains subordinate amounts of potassium and minor amounts of magnesium and calcium. Although lithium-bearing hot springs are present at the periphery of the playa, the evolution of Clayton Valley strongly suggests that the lithium has been derived from the leaching and weathering of Tertiary lacustrine and volcanic sediments exposed east of the valley. Concentration of the lithium-bearing solutions into brines was accomplished by solar evaporation.
The pronounced chemical fractionation that takes place in hydro logically closed basins between dilute inflow and concentrated brines can be accounted for by a variety of mechanisms. These include mineral precipitation, selective dissolution of efflorescent crusts and sediment coatings, sorption on active surfaces, degassing, and reactions. Major solutes are differentially affected by these mechanisms, and their response may differ from basin to basin. Using data from Lake Magadi, Kenya; Lake Abert, Oreg; Devils Lake, N. Dak; Deep Springs Lake, Calif.; Basque Lake, British Columbia; and Great Salt Lake, Utah, some of these differences can be delineated. -from Authors
The lithium-rich brines pumped from beneath Clayton Valley, Nevada, provide about one-third of the present United States requirements for lithium. Although the pre-Tertiary rocks in the vicinity do not contain anomalous amounts of lithium, the Tertiary volcanics that abound in the area could have been the origin of the lithium. Extensive diagenetic alteration of vitric material has taken place, and high lithium concentrations are associated with smectite in the Miocene Esmeralda Formation exposed east of the playa. The brines contain about 20 percent sodium chloride and as much as about 320 parts per million of lithium. The brine results from solution by ground water of halite beds that are high in lithium. These salt beds probably were formed during the desiccation of a small saline lake that occupied the position of the present playa.
Fundamental to understanding the late Cenozoic evolution of the central Andes is knowledge of the age that the Puna-Altiplano plateau became a unique tectonomorphic entity within the orogen. The two attributes that define the Puna-Altiplano are: 1) its average elevation of ≥3 km and 2) regions of high elevation that correspond spatially to regions with internal drainage. It is shown that, for the southern Puna, internal drainage was established between 14.1, and 24.2 Ma, and probably by ~15 Ma. These results corroborate and refine other workers' inferences that the Puna-Altiplano plateau became uplifted and paleogeographically isolated from the adjacent fore arc and foreland during middle to late Miocene time. -from Authors
A late Permian 2 km thick volcaniclastic succession is well exposed in the area between the Cerros de Cas and Cerro Lanquir at the eastem margin of!he Salar de Atacama in northem Chile. From base to top it consists of 1he three members of the Peine Formation and !he three members of the Cas Formation. The terreslrial succession is dom naled by producls of andesitic to rflyodacitic effusive and explosive volcanism. Only in the Middle Member of!he Peine Fonnation sedimentary deposits are predominan!. Here, lacustrian, flood and braid plain facies interfinger late rally in a basin-basin margin setting. Deposition was accompanied by extensional lectonics. From sedimentary and volcanic paleocurrent indi::alors of!he Peine and Cas Formations, and geochemical dala of magmatic rocks of the region, it is inferred that the succession was formed al the easlem margin of an exlensional inlra-arc basin. Volcanic facies analyses reveal that, at least, some of the basic and silica-rich volcanic centres were located close to or even within the field area. The thick ignimbriles and proximal fall out deposits of the Middle Member of the Cas Formation are supposed to belong, together with ring dyke and central intrusions, to a late Permian caldera complex, which is localed in the Cerro Lanquir area (Lanquir Caldera Complex). Key words: Late Permian, Peine Forma/ion, Cas Formation, Stra/igraphy, Volcanism, In/ra-are extens/on, Northem Chile. RESUMEN Las formaciones Peine y Cas del Pérmico tardío en el margen oriental del Salar de Atacama, norte de Chile: estratigrafía, facies volcánica y tectónica. Una sucesión volcaniclástica del Pérmico tardío, de 2 km de espesor, aflora excepcionalmente en el área entre Cerros de Cas y Cerro de Lanquir, en el margen oriental del Salar de Atacama. De la base al techo, la sucesión consiste en los tres miembros de la Formación Peine y los tres miembros de la Formación Caso Las rocas terrestres se componen, principalmente, de productosandesíticos a riodacíticosde un volcanismo efusivo y explosivo. Sólo en el Miembro Medio de la Formación Peine predominan depósitos sedimentarios, con facies lacustre, de planicies de inundación, y de planicies de ríos anastomosados, que engranan lateralmente en un ambiente de cuenca y de margen de cuenca. La deposición estuvo acompañada por una tectónica exlensional. En base a indicadores de paleocorrientes sedimentarias y volcánicas en las formaciones Peine y Cas, además de datos geoquímicos de rocas magmáticas de la región, se presume que la sucesión se formó al borde oriental de una cuenca intra-arco exlensional. El analisis de facies volcánicas indica que por lo menos, algunos de los cenlros volcánicos tanlo de bajo como de alto contenido de snice, estuvieron situados en, o cerca del área estudiada. Se supone que los depósitos ignimbríticos de gran espesor, los depósitos proximales de carda de pómez del Miembro Medio de la Formación Cas, así como de las intrusiones centrales y anulares forman parte de un complejo de caldera pérmico tardío, en el área de Cerro Lanquir (Complejc Caldera Lanquir).
The modern climate over much of the Andes between 22° and 26°S is very dry. Dated sediment cores from desiccated lake beds contain saline deposits (salars) that have halite fabrics that indicate during previous, less arid climates saline lakes existed at Salar de Hombre Muerto (northwest Argentina, Andean plateau) and Salar de Atacama (northern Chile, west flank of Andes). Paleoclimate conditions are reconstructed from the stable isotope composition of paleo-saline lake waters trapped in fluid inclusions in lacustrine halite. Models of isotopic steady state are applied to estimate the isotopic composition of inflow (meteoric) water to the paleo-lake and paleo-atmospheric water vapor. The two salars’ climate records differ. The timing of Atacama saline lakes is similar to lake level highstands on the Altiplano to the northeast with the deepest lake occurring between 24 and 19.8 ka. The modern meteoric water source for Atacama and the Central Andes is currently the tropical Atlantic, via the Amazon Basin, and stable isotopic evidence indicates the same source of water for the paleo-lakes in the Atacama. In contrast, to the southeast, at Hombre Muerto, the lakes that intermittently occupied the salar became progressively smaller since 45 ka. Water isotope composition today reflects atmospheric recycling by evaporation–condensation, as it did between 24 and 20 ka, whereas water transported to the earlier lakes does not indicate significant isotopic recycling. Using knowledge of modern-day atmosphere/oceanic circulation and forcing mechanisms, we hypothesize that the shifts in moisture transport to these Andean sites are directly tied to equatorial and South Atlantic atmospheric and oceanic surface circulation.
The hinterland (Puna and Altiplano) region of the central Andes contains
numerous Miocene to Recent sedimentary basins that record enigmatic
subsidence not attributable solely to local thrust-loading. The Arizaro
basin in NW Argentina is exemplary: it consists of a Miocene basin fill,
and a modern active salar. The Miocene basin (at 3800-4300 m elevation)
is filled by >3 km of predominantly lacustrine and eolian sediment,
and has a broadly symmetrical shape in cross-section that does not
exhibit obvious subsidence control by neighboring thrust-faulted
uplifts. The succession fines upward, with local conglomerate and
fluvial-eolian sandstone in the lower part and >1000 m of evaporitic
mudstone in its upper part. U-Pb ages on detrital zircons and zircons
from tuff layers bracket deposition between ~20 and 14 Ma. A previously
reported ca. 11 Ma zircon fission track age from the top of the section
provides a minimum age. A subsidence curve exhibits crudely sigmoidal
shape, with initial moderately rapid subsidence followed by extremely
rapid subsidence (>0.5 km/Myr), waning to near zero by 11 Ma. The
basin fill is locally folded by upright chevron folds with steep hinge
surfaces and no preferred vergence. A minor reverse fault juxtaposes
Cambro-Ordovician granitoid rocks with basin fill in the center of the
outcrop area. The geological evidence indicates deposition between 20-11
Ma, followed by internal shortening, followed by exhumation, all of
which is consistent with models for surface subsidence, deformation, and
rebound in response to formation and removal of a gravitational
instability in the upper mantle. The modern Salar de Arizaro directly
west of the Miocene basin occupies a region of lower elevation (3470 m),
but is locally fringed by outcrops of redbeds correlative with the
Miocene Arizaro basin fill. Small volume basaltic flows <1 Ma are
widespread along the western flank of the modern Salar. Modern crustal
thickness beneath the entire Arizaro region is only 42 km (Yuan et al.,
2002), considerably less than expected from the present high elevations.
Subsidence of the modern Salar de Arizaro may be related to removal of
mantle lithosphere. By analogy, the Miocene Arizaro basin may be an
older depocenter related to partial mantle lithosphere removal.
Preliminary modeling of the response to Stokes settling of a spherical
density anomaly suggests ~90 km radius, which in turn suggests that
mantle removal in the region was a piecemeal process, rather than a
regionally uniform wholesale event. Widespread hinterland basins may be
useful gauges of the scale and timing of mantle lithosphere throughout
the Andean hinterland.
To evaluate whether anatectic and/or highly fractionated lithophile element-enriched rhyolite tuffs deposited in arid lacustrine basins lose enough lithium during eruption, lithification, and weathering to generate significant Li brine resources, pre-eruptive melt compositions, preserved in inclusions, and the magnitude of post-eruptive Li depletions, evident in host rhyolites, were documented at six sites in the western United States. Each rhyolite is a member of the bimodal basalt-rhyolite assemblage associated with extensional tectonics that produced the Basin and Range province and Rio Grande rift, an evolving pattern of closed drainage basins, and geothermal energy or mineral resources. Results from the 0.8 Ma Bishop tuff (geothermal) in California, 1.3 to 1.6 Ma Cerro Toledo and Upper Bandelier tephra (geothermal) and 27.9 Ma Taylor Creek rhyolite (Sn) in New Mexico, 21.7 Ma Spor Mountain tuff (Be, U, F) and 24.6 Ma Pine Grove tuff (Mo) in Utah, and 27.6 Ma Hideaway Park tuff (Mo) in Colorado sup
Previous studies of the availability of lithium for use in batteries to power electric vehicles (EVs) have reached the generally encouraging conclusion that resources are sufficient to meet growing demand for the remainder of the 21st century. However, these surveys have not looked past estimates of lithium resource to the geological constraints on deposit size and composition that will allow the resources to be converted to reserves from which lithium can be produced economically. In this survey, we review the relevant geological features of the best characterized pegmatite, brine and other types of lithium deposits and compare their potential for large-scale, long-term production.
A wide variety of Upper Cenozoic ignimbrite centres have been identified and studied on Landsat imagery of the Central Andes: some have been investigated in the field. Lower Miocene ignimbrite centres are distributed along an arc which, in north Chile, diverges markedly from the line of the present trench and parallels an arc of Lower Miocene plutons in the Eastern Cordillera of Bolivia. Much of the ignimbrite erupted since the late Miocene has been erupted around the faulted margins of the Altiplano basin of western Bolivia, particularly where the Western and Eastern Cordilleras converge.Typical examples of ignimbrite centres are described. Some centres take the form of ignimbrite shield volcanoes. Other ignimbrite sheets are more widely dispersed. The degree of dispersal probably relates to the height of the eruption column. Partial or total caldera formation sometimes took place and a few of these calderas have resurgent centres. Late-stage lava extrusions are common and some of these are located on caldera ring fractures.
Two Pleistocene eruptions are studied, linked to an increment in the tectonic activity of an extensive system related to Calama Olacapato El Toro Fault (COT Fault). The first one, consisting of dense pyroclastic flows and pyroclastic surges interbedded with fall deposits, was caused by a phreatoplinian eruption. The second one, consisting of a succession of pyroclastic surges, derived from a phreatic eruption. Both eruption vents have been located in en echelon normal faults with an NNE trend, and conjugated to strike faults following an NNW trend. In both episodes pyroclastic deposits and ballistic blocks follow an E SSE trend, the direction to which the fault planes and topographical slope lean. The obsidianic deposit filling the first eruption vent has the same trend and dip as the main fault plane and provides (preliminary) evidences of syntectonic emplacement. On the other hand, pyroclastic surge deposits linked to the second episode offer evidences of syndepositional faulting with listric growth faults. It is concluded that this local horizontal area linked to the COT fault was intensely active during the Pleistocene and triggered both eruptions.
Sedimentary basins of the Altiplano-Puna Plateau within the Andean Plateau in South America contain the record of retro-arc foreland basin evolution during the Cenozoic. The deformation of these basins is characterized by high angle reverse faults and thrusts deforming crystalline basement and sedimentary covers. The mechanism/s responsible for deformation within the region are not fully understood in detail. The relative abundance of intercalated tuffs within these basins and those within the bounding Eastern Cordillera enables the spatial-temporal pattern of deformation across the orogen to be constrained. This study uses the systematic combination of structural, geochronologic and sedimentalogical techniques applied to Cenozoic sedimentary rocks within the Arizaro Basin to investigate the timing of deformation across within the region in order to test two end member models for basin deformation in response to lithospheric processes. The first model attributes the deformation of the basins to internal deformation within an orogenic wedge as part of the taper building process required prior to propagation eastward towards the foreland basin system. The second model attributes basin deformation to isostatic adjustments resulting from small-scale lithospheric foundering. Detailed geologic mapping of the Arizaro Basin reveals a complex interplay of coeval thick-skinned and thin-skinned deformation, which deforms the thick Miocene succession of fluvial-lacustrine strata in both a brittle and ductile manner. Zircon U-Pb analyses of intercalated tuffs from the Vizcachera Formation reveal that approximately three km of the section was deposited between the Early Miocene (ca. 18.3) and the Middle Miocene (ca. 13.9). One tuff in the uppermost Vizcachera Formation constrains the lower limit of timing of deformation for the Arizaro Basin to be 13.9 +/- 0.7 Ma. When combined with published geochronological data across the Puna Plateau and Eastern Cordillera, the new data presented in this study constrains timing of deformation within the basin and the greater Arizaro area to the Middle Miocene. This study also indicates that the spatial-temporal patterns of deformation are likely the result of a combination of both models mentioned above with critical taper theory dominating early deformation associated with basin formation and small-scale lithospheric foundering dominating the later deformation in the Middle Miocene. Deformation at the wedge tip continues in the Eastern Cordillera seemingly without interruption, suggesting that the effects of the isostatic pull-down associated with small-scale lithospheric foundering is localized and does not significantly affect the taper of the orogenic wedge as a whole. Thus, allowing the normal cycle of orogenic wedge propagation to occur, uninhibited.
Melt inclusions hosted in quartz from large-volume ignimbrites and related lava flows from the late Neogene to Pleistocene Altiplano-Puna Volcanic Complex, northern Chile, record the magmatic volatile evolution and constrain conditions of magma storage. Glasses from pristine and rehomogenized inclusions have high-Si rhyolitic compositions (average SiO2=77.5wt%). Their host rocks range from dacite to rhyodacite (SiO2=63.9-72.5wt%) and have a high abundance of phenocrysts (33-55%). Infrared spectroscopic analysis of inclusions from pumice samples typically yielded H2O contents between 3.0 and 4.0 wt% and relatively low and more variable CO2 contents
Understanding the timing of mountain glacier and paleolake expansion and retraction in the Great Basin region of the western United States has important implications for regional-scale climate change during the last Pleistocene glaciation. The relative timing of mountain glacier maxima and the well-studied Lake Bonneville highstand has been unclear, however, owing to poor chronological limits on glacial deposits. Here, this problem is addressed by applying terrestrial cosmogenic 10Be exposure dating to a classic set of terminal moraines in Little Cottonwood and American Fork Canyons in the western Wasatch Mountains. The exposure ages indicate that the main phase of deglaciation began at 15.7±1.3ka in both canyons. This update to the glacial chronology of the western Wasatch Mountains can be reconciled with previous stratigraphic observations of glacial and paleolake deposits in this area, and indicates that the start of deglaciation occurred during or at the end of the Lake Bonneville hydrologic maximum. The glacial chronology reported here is consistent with the growing body of data suggesting that mountain glaciers in the western U.S. began retreating as many as 4ka after the start of northern hemisphere deglaciation (at ca. 19ka).
The Salar de Atacama basin lies in the inner fore arc of northern Chile. Topographically and structurally, it is a first-order feature of the central Andes. The sedimentary fill of the basin constrains the timing and extent of crustal deformation since the mid-Cretaceous. We have studied good exposures along the western edge of the basin and have correlated them with seismic reflection sections and data from an exploration well. Throughout most of its history, the basin developed in a foreland setting, during periods of thin-skinned and thick-skinned thrusting. Growth strata provide evidence for coeval sedimentation and thrust motions during mid-Cretaceous, Paleogene, and Neogene times. Pre-Neogene deformation was significant in the basin and in surounding areas of the early central Andes. Models that attempt to explain the current thickness of the central Andes should consider Late Cretaceous and Paleogene shortening, as well as the more obvious Neogene and Quaternary shortening.
A tectonic reinterpretation is reported for the southeastern margin of the Salar de Atacama basin of northern Chile. Detailed structural mapping revealed the presence of an east vergent thin-skinned fold and thrust belt affecting Oligocene-Miocene Paciencia Group rocks and the overlying Plio-Pleistocene volcanic rocks. Along-strike segmentation of the main fold implies local foreland influence on footwall ramp geometry leading to local thrust sheet rotation. To the east the adjacent western slope of the Western Cordillera displays two different structural domains, probably controlled by preexisting basement structures. The southern domain comprises two N-S oriented sigmoidal belts of linear arranged pressure ridges, indicating left-lateral transpression. In contrast, the northern domain is characterized by east vergent fold and thrust belt structures and reactivated NW-SE striking sinistral strike-slip faults, governing clockwise block rotations. An indenter-driven deformation model is proposed to explain sinistral transpression and clockwise block rotations around vertical axes. This variant of a small-block rotation mechanism is discussed in the context of oroclinal bending of the central Andes, emphasizing the significance of ancient structures in controlling rotations.
Large paleolakes (∼33,000-60,000 km2) that once occupied the high-altitude Poopo, Coipasa, and Uyuni Basins in southern Bolivia (18-22°S) provide evidence of major changes in low-latitude moisture. In these now-dry or oligosaline basins, extensive natural exposure reveals evidence for two deep-lake and several minor-lake cycles over the past 120 k.y. Fifty-three new U-Th and 87 new 14C dates provide a chronologic framework for changes in lake level. Deposits from the "Ouki" deep-lake cycle are extensively exposed in the Poopo Basin, but no deep lakes are apparent in the record between 98 and 18.1 ka. The Ouki lake cycle was ∼80 m deep, and nineteen U-Th dates place this deep-lake cycle between 120 and 98 ka. Shallow lakes were present in the terminal Uyuni Basin between 95 and 80 ka (Salinas lake cycle), at ca. 46 (Inca Huasi lake cycle), and between 24 and 20.5 ka (Sajsi lake cycle). The Tauca deep-lake cycle occurred between 18.1 and 14.1 ka, resulting in the deepest (∼140 m) and largest lake in the basin over the past 120 ka. Multiple 14C and U-Th dates constrain the highest stand of Lake Tauca along a topographically conspicuous shoreline between 16.4 and 14.1 ka. A probable post-Tauca lake cycle (the Coipasa) produced a ≤55-m-deep lake that is tentatively dated between 13 and 11 ka. We suggest that paleolakes on the Bolivian Altiplano expanded in response to increased moisture in the Amazon and enhanced transport of that moisture onto the Altiplano by strengthened trade winds or southward displacement of the Intertropical Convergence Zone (ITCZ). Pole-to-equator sea-surface temperature (SST) and atmospheric gradients may have influenced the position of the ITCZ, affecting moisture balance over the Altiplano and at other locations in the Amazon Basin. Links between the position of the ITCZ and the ca. 23 ka precessional solar cycle have been postulated. March insolation over the Altiplano is a relatively good fit to our lake record, but no single season or latitude of solar cycling has yet to emerge as the primary driver of climate over the entire Amazon Basin. Temperature may influence Altiplano lake levels indirectly, as potentially dry glacial periods in the Amazon Basin are linked to dry conditions on the Altiplano. Intensification of the trade winds associated with La Niña - like conditions currently brings increased precipitation on the Altiplano, and deep-lake development during the Tauca lake cycle coincided with apparently intense and persistent La Niña - like conditions in the central Pacific. This suggests that SST gradients in the Pacific are also a major influence on deep-lake development on the Altiplano.
The Salar de Atacama in northern Chile accumulated halite during the Pliocene and Quaternary under conditions that alternated between a saline lake and a dry salt flat. Hidden beneath its uninterrupted flat surface is the Salar fault system. The halite deposits provide a high-resolution history of deformation. Contours on the ca. 5 Ma base of the halite unit in the southern salar, defined in a deep oil-exploration borehole and traced through reflection seismic lines, reveal that net reverse offset across the Salar fault system is down-to-the-east by ∼900 m; of that total, 200 m occurred during the Quaternary and 700 m during the Pliocene. Distributions, thicknesses, and geometries of eight stratigraphic sequences within the halite unit reveal a history of episodic faulting and demonstrate that faulting during approximately half the 5 m.y. interval, including the Holocene, did not generate fault scarps. We suggest that deposition caused by evaporation of ground water brines in the salt flat, rather than either dissolution or deflation, has smoothed the topography of the dry lake bed across the active fault zone. For the case of west-directed groundwater flow, we propose that the east-facing Salar fault system focuses groundwater flux along the eastern flank of the fault, which enhances halite precipitation in the down-thrown block during desiccated stages and counteracts fault-driven topographic relief. The realization that a seismic risk may exist even though the Salar fault system is hidden leads to the appreciation that leads to the appreciaton that similar unrecognized seismic risk may exist in more populous aric basins.
The Salar de Atacama basin of northern Chile preserves stratigraphic evidence for the evolution of the Andean cycle. It has evolved from a non-arc-related rift, through back-arc and inter-arc stages, to a Neogene fore-arc basin. Accumulation of the sedimentary succession was mainly due to extensional faulting. Important but short-duration contractional episodes do link to known first-order plate-margin changes, but their stratigraphic effect appears to be restricted to uplift-erosion rather than creation of significant flexural subsidence. -from Authors
The Salton Sea geothermal field lies in the Salton Trough, the landward extension of the Gulf of California, an area of active crustal spreading. Surface volcanic rocks of the field consist of five small rhyolite domes extruded onto Quaternary sediments of the Colorado River delta. Two domes are linked by subaqueous pyroclastic deposits; the others are single extrusions with or without marginal lava flows. The domes are low-calcium, alkali rhyolite with 1 to 2 percent crystals. Similar silicic rocks found in wells have been extensively altered by geothermal brines. Basaltic rocks occur as xenoliths in the domes and as subsurface dikes, sills, or flows. The xenoliths consist of low-potassium tholeiitic basalt similar to that of the East Pacific Rise. Subsurface basaltic rocks are mineralogically similar to the xenoliths but have undergone extensive hydrothermal alteration. Numerous partly melted granitic xenoliths in the domes show various degrees of either cotectic melting along quartz-feldspar grain boundaries or disequilibrium incongruent melting of hydrous ferromagnesian minerals. These rocks are sodic granite containing notably higher SiOâ, CaO, and NaâO and lower total iron than the enclosing rhyolite. Compositions and textures suggest that the granite xenoliths are fragments of basement rather than the crystallized equivalents of the rhyolite magma. The bimodal basalt-rhyolite assemblage of the Salton Sea geothermal field is believed to have formed by partial fusion in two stages of mantle peridotite, forming successive rhyolitic and basaltic melts. After formation, the rhyolitic magma was partly contaminated by continental crust material.
The basalts of the Black Rock Desert region in Utah have Sr87/Sr86 ratios that vary from 0.7044 to 0.7059. Although this variation may be explained by derivation from inhomogenous mantle, it is also broadly compatible with a fractionation-assimilation model proposed for these basalts. Basalts of the Ice Spring field show an increase in Sr87/Sr86 with decreasing Rb and Rb/Sr as a function of eruptive age. Such a trend may be explained by mixing of magmas having different differentiation-assimilation histories.
Strontium in the brines of Great Salt Lake appears to be isotopically homogeneous and has an average 87Sr/86Sr ratio of 0.7174 ± 0.0004 (1σ). The enrichment in radiogenic 87Sr compared to young volcanic rocks and modern sea water is consistent with the 87Sr/86Sr ratios in water from its major tributary rivers which drain the Wasatch Mountains east and southeast of the lake. Subsurface brines from the Great Salt Lake Desert west of the lake have significantly lower 87Sr/86Sr ratios averaging 0.7133 ± 0.0006 (1σ). A sample of salt from the Bonneville Salt Flats has an 87Sr/86Sr ratio of 0.7106 and water discharged by Locomotive Springs has a ratio of 0.7110. The high 87Sr/86Sr ratio of the brines in Great Salt Lake is fairly representative of the strontium released by chemical weathering of silicate rocks on the continents.
The Silver Peak volcanic center is part of a late Tertiary volcanic province in western Nevada and eastern California characterized by slightly alkaline, potassic lavas. The rocks of the Pliocene Silver Peak center have an alkali-lime index of 55.5, a K2O/K2O + Na2O ratio of 0.5 at 60 percent SiO2, and range in composition from trachybasalt to rhyolite, with latite the most voluminous. Chemical and mineralogical variations in the intermediate and silicic lavas are compatible with differentiation by crystal fractionation. The differentiation trend is similar to calc-alkaline suites with progressive enrichment in silica and alkalis but no relative enrichment in iron. Relatively high water pressures during crystallization are indicated by the ubiquitious presence of biotite or hornblende. The parent magma of the intermediate and silicic part of the series is believed to have a composition of trachyandesite with approximately 56 percent silica. The potassic nature of trachyandesite in this province is tentatively related to depths of a Tertiary subduction zone beneath western North America. Associated trachybasalts of the Silver Peak center are nepheline normative and characterized by high strontium contents, low Rb/K and Rb/Sr ratios, and relatively high Sr87/Sr86 ratios (.7061). These are believed to represent a separate parent magma derived from material previously depleted in rubidium.
The Honeycomb Hills rhyolite dome in western Utah displays chemical and mineralogical features characteristic of a rare-element pegmatite magma. The lavas show extreme enrichments in such trace elements as Rb (≤1960 ppm), Cs (≤78), Li (≤344), Sn (≤33), Be (≤270), and Y (≤156). Phenocrysts (10%-50% by volume) include sanidine (Or66-70), plagioclase (Ab83-92), quartz, biotite approaching fluorsiderophyllite, and fluortopaz, as well as accessory phases common to highly differentiated granites and pegmatites, including zircon, thorite, fluocerite, columbite, fergusonite, and samarskite. Low temperatures (600 to 640 °C), coupled with high phenocryst and silica content, might normally preclude eruption due to the extremely high viscosity of the melt. However, high concentrations of fluorine (2%-3%) could domal lavas significantly reduce viscosity and allow eruption of domal lavas even after dewatering of the mama during the initial pyroclastic phase of the eruptive cycle. Fractionation of phenocrysts and accessory phases, for which partition coefficients have been measured, is sufficient to account for most compositional gradients inferred in the preeruptive magma body, although transport by a fluid phase formed a may have caused upward enrichments in Li, Be, and Cs. If the Honeycomb Hills magma had crystallized at depth, it would have formed a rare-element pegmatite.
A Late Pleistocene shoreline at the overflow level of Searles Lake has been displaced 82 to 106 m in a left-lateral sense and 2.5 m (net) north side up along the Garlock fault, at the southeastern corner of Searles Valley. Previously published radiocarbon dates from both surface and subsurface strata indicate that the most recent highstand of Searles Lake ended sometime between 10,000 and 13,800 (C-14) years ago. The maximum slip rate of the Garlock fault in southeastern Searles Valley is thus 11 mm/(C-14) yr. If part of the offset of the shoreline occurred during older lakestands, then the slip rate may be somewhat less. A channel incised after the most recent highstand, however, is offset about 68 m, indicating that the minimum slip rate is 5 mm/(C-14) yr. Subjective evaluation of the constraints on the offset and on the age of the shoreline yields a preferred rate of 6-8 mm/(C-14) yr at this site. Assuming Bard et al.'s (1990) recent calibration of the radiocarbon time scale, the calibrated slip rate of the Garlock fault is between 4 and 9 mm/yr with a preferred value of 5-7 mm/yr. This estimate is similar to a previous estimate of the Holocene slip rate and is slightly less than an estimate derived from modelling of geodetic data. Extension north of the Garlock fault in Indian Wells and Searles valleys contributes no more than 3 mm/yr left slip to the Garlock fault.
The Merouane Chott, located in southeastern Algeria, is an ideal natural system for studying mineral dissolution and precipitation rates because it (1) undergoes annual cycles of filling and complete evaporation, and (2) has a simple, well defined hydrology. The major element concentrations of Merouane Chott lake waters were measured weekly from January to June 2003. These concentrations are used together with estimates of the Chott lake volume and infiltration rates to calculate the temporal evolution of the total mass of these major elements. Element precipitation rates are generated by dividing the first derivative of total mass of each element with respect to time by the Chott surface area. Mass balance considerations yield precipitation rate estimates for halite, calcite, and gypsum during the complete evaporation of the lake. These rates are compared with the saturation indexes of these minerals to deduce the degree to which they are consistent with laboratory measured rates available in the literature.