Marga García

• Postdoc
• Researcher at Instituto Español de Oceanografia

The identification of drowned paleovalleys provides valuable insight into the hydrological and sedimentary dynamics of ancient fluvial systems that were established on modern shelves during previous time intervals. This study is based on a combined seismic stratigraphic and sedimentological analysis, focusing on evidences of incised paleovalley sys...

The postglacial sea-level rise after the Last Glacial Maximum provided ideal conditions to study the transgressive sedimentary response to sudden shelf flooding driven by different rates of sea-level rise. In this study, a high-resolution seismic stratigraphic interpretation and sedimentological analysis were conducted on data from the northern Gul...

The Bransfield Strait (Antarctica) is an important region for evaluating changes in Weddell Sea shelf waters on geological time scales because of its restricted connections to the surrounding ocean. However, the detailed oceanographic consequences of the opening of the strait remain unclear. We present bottom-current-related sedimentary features in...

Antarctica is one of the most vulnerable regions to climate change on Earth and studying the past and present responses of this polar marine ecosystem to environmental change is a matter of urgency. Sedimentary ancient DNA (sedaDNA) analysis can provide such insights into past ecosystem-wide changes. Here we present authenticated (through extensive...

Early Pleistocene Marine Isotope Stage (MIS)‐31 (1.081–1.062 Ma) is a unique interval of extreme global warming, including evidence of a West Antarctic Ice Sheet (WAIS) collapse. Here we present a new 1,000‐year resolution, spanning 1.110–1.030 Ma, diatom‐based reconstruction of primary productivity, relative sea surface temperature changes, sea‐ic...

Ice loss in the Southern Hemisphere has been greatest over the past 30 years in West Antarctica. The high sensitivity of this region to climate change has motivated geologists to examine marine sedimentary records for evidence of past episodes of West Antarctic Ice Sheet (WAIS) instability. Sediments accumulating in the Scotia Sea are useful to exa...

The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report a high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our deep-...

The eastern Scotia Sea is known as Iceberg Alley, where large numbers of icebergs are brought to the Antarctic Circumpolar Current via the Weddell Sea Gyre. Icebergs transported through Iceberg Alley today can have traveled in the coastal current from anywhere around the Antarctica margin, but are sourced mostly from the Weddell Sea sector. The Wed...

The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report the first high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. O...

We present a high-resolution analysis of seven marine sediment records from the western Mediterranean in a transect from the Algero-Balearic basin to the Alboran Sea, spanning the last 20 ka, to decipher the paleoenvironmental and paleoceanographic evolution of the Western Mediterranean Sea. To do so, diverse elemental ratios have been used for rec...

The Antarctic Circumpolar Current (ACC) acts as a critical component to regulate the global thermohaline circulation and climate. However, active debate remains about the relative strength of ACC during current/past warm periods and underlying driving mechanisms. Here, we present sortable silt mean grain size records from the Scotia Sea to infer th...

Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report the first high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our d...

Multibeam bathymetric imagery and acoustic sub-bottom profiles are used to reveal distribution patterns of sub-surface sedimentation in Dove Basin (Scotia Sea). The goals of the study are to determine the imprint of the inflow of deep Antarctic water masses from the Weddell Sea into the Scotia Sea, to establish the factors driving the styles of con...

In this work, we characterize the morphology and recent sedimentary processes of two shelf-indenting submarine canyons (Motril and Carchuna) on the northern margin of the Alboran Sea. To achieve this aim, we used multibeam bathymetric data, seafloor imagery and short sediment cores (up to 50 cm). The Carchuna Canyon is deeply incised in the shelf,...

Incised valleys constitute the main course for sediment transport on continental margins from a source-to-sink perspective. This study describes two paleovalley systems off the Portuguese coast on the Gulf of Cadiz continental shelf, an offshore region that presently receives only insignificant fluvial supply. We aim to establish the controlling fa...

Resumen Durante la subida posglacial del nivel del mar se produjeron unas condiciones ideales para estudiar la respuesta sedimentaria a los procesos de inundación repentina de la plataforma continental, debido a la alternancia de períodos con distinta tasa de subida del nivel del mar. En este trabajo, mediante el análisis e interpretación de perfil...

Submarine canyons are major morphological features incising continental margins and constitute the main pathways for shelf-to-basin sediment transfer and flux of contaminants and waste. The effectiveness of present-day canyon sediment transport depends largely on the proximity to a major sediment source from the continent, such as riverine or litto...

International Ocean Discovery Program (IODP) Site U1536 (proposed Site SCO-13) is located 235 km northwest of the South Orkney Islands at 59°26.46′S, 41°3.66′W in 3220 m of water. Site U1536 is the first of two sites drilled in Dove Basin, which is located in the southern Scotia Sea. This site was targeted to recover a com- plete Neogene record of...

International Ocean Discovery Program (IODP) Site U1535 (proposed Site SFSD-02A) is located on the northern flank of a large trough ~668 km east of the Strait of Magellan at 53°11.49′S, 58°38.60′W in 647 m of water. The site is situated at Common Depth Point 9220 on Seismic Reflection Profile SGFI93-107. Site U1535 is the second of a pair of sites....

This section provides an overview of operations, depth conven- tions, core handling, curatorial procedures, and analyses performed on the R/V JOIDES Resolution during International Ocean Discov- ery Program (IODP) Expedition 382. This information applies only to shipboard work described in the Expedition reports section of the Expedition 382 Procee...

International Ocean Discovery Program Expedition 382, Iceberg Alley and Subantarctic Ice and Ocean Dynamics, investigated the long-term climate history of Antarctica, seeking to understand how polar ice sheets responded to changes in insolation and atmospheric CO2 in the past and how ice sheet evolution influenced global sea level and vice versa. F...

International Ocean Drilling Program (IODP) Site U1538 (pro- posed Site SCO-11) is located 365 km north-northeast of the South Orkney Islands at 57°26.52′S, 43°21.47′W in 3131 m of water. The site lies in Pirie Basin and is situated at Shotpoint 4900 on Seismic Reflection Profile SCAN2013-13, 9 km east of Crossing Line SCAN2013-11. Site U1538 is lo...

International Ocean Discovery Program (IODP) Site U1534 (proposed Site SFSD-03A) is located at 53°11.38′S, 58°45.65′W in 605 m of water. The site is situated on the northern flank of an east– west trending trough on the continental shelf ~660 km east of the Strait of Magellan at Common Depth Point 10005 on Seismic Re- flection Profile SGFI93. Site...

International Ocean Discovery Program Expedition 382, Ice- berg Alley and Subantarctic Ice and Ocean Dynamics, investigated the long-term climate history of Antarctica, seeking to understand how polar ice sheets responded to changes in insolation and atmo- spheric CO2 in the past and how ice sheet evolution influenced global sea level and vice vers...

International Ocean Drilling Program (IODP) Site U1537 (pro- posed Site SCO-18) is located 265 km northwest of the South Or- kney Islands at 59°6.65′S, 40°54.37′W in 3713 m of water. The site lies in the northeast part of Dove Basin in a ~1 km thick contourite drift and is situated at Shotpoint 4900 on Multichannel Seismic (MCS) Reflection Profile...

The Western Mediterranean Sea is a natural laboratory to address questions about the formation and evolution of continental margins and the relationship between surface and deep processes. The evaporites deposited during the late Miocene’s Messinian Salinity Crisis (MSC) strongly impact its sedimentological and geomorphological evolution. Hereafter...

International Ocean Discovery Program (IODP) Expedition 382 in the Scotia Sea’s Iceberg Alley recovered among the most continuous and highest resolution stratigraphic records in the Southern Ocean near Antarctica spanning the last 3.3 Myr. Sites drilled in Dove Basin (U1536/U1537) have well‐resolved magnetostratigraphy and a strong imprint of orbit...

Scotia Sea and the Drake Passage is key towards understanding the development of modern oceanic circulation patterns and their implications for ice sheet growth and decay. The sedimentary record of the southern Scotia Sea basins documents the regional tectonic, oceanographic and climatic evolution since the Eocene. However, a lack of accurate age e...

This article offers an overview of the main sedimentary systems defining the geomorphology of deep sea environments from low to high latitudes. Mass-transport deposits, turbidite systems, contourites, volcaniclastic aprons, glacial trough mouth systems, carbonate mounds and other bathyal systems, such as pelagites, hemipelagites, mid-ocean channels...

A morphological and seismic-stratigraphic analysis of the Gulf of Cadiz area near the Strait of Gibraltar is presented in this work, focused on the sedimentary evolution of the upper and proximal middle-continental slope since the Mid-Pleistocene. Based on the analysis of seismic reflection profiles and swath bathymetry data, this work analyses the...

Patterns of variability in Pleistocene magnetic susceptibility (k) from deep-sea sediment cores from the Scotia Sea show a striking similarity to patterns of dust flux recorded in the EPICA Dronning Maud Land (EDML) ice core. Antarctic marine k records broadly reflect the interplay of lithogenic sediment provenance, biological productivity, sedimen...

The Iberian margin in the Gulf of Cádiz hosts a fluid venting area embedded into a contourite depositional drift and is a natural laboratory to study how multiple interacting processes shape the seafloor. A high-resolution morpho-sedimentary analysis, based on geophysical data, sediment samples and submarine imagery, has been carried out; the onset...

Ona Basin, the westernmost oceanic basin in the southern Scotia Sea, is affected by the opposite flows of Circumpolar Deep Water (CDW) and Weddell Sea Deep Water (WSDW); thus, it represents a key location for exploring seafloor morphologies influenced by bottom currents. The present study aims to capture the spatial arrangement of recent subsurface...

Recent International Ocean Discovery Program (IODP) drilling in the Scotia Sea’s “Iceberg Alley” at Sites U1536 and U1537 recovered stratigraphic records from the late Pliocene to the Holocene and represent some of the most continuous and highest resolution records ever recovered near Antarctica. These records have excellent magnetostratigraphy and...

In the early Pleistocene, the 41-kyr obliquity period dominates major climate proxy records such as δ18O. This observation is difficult to reconcile with the classic Milankovitch orbital forcing model that predicts that global ice volume is controlled by summer insolation that is dominated by both the 23-ky precession period and 41-kyr obliquity pe...

The large-scale reconstruction of the opening of the Drake Passage and the formation of the Scotia Sea has been attempted in previous works mainly based on integration of different geophysical datasets. However, the lack of consensus on timing and development models has prevented an accurate reconstruction of the major regional events and their glo...

This work uses seismic records to document and classify contourite features around the Iberian continental margin to determine their implications for depositional systems and petroleum exploration. Contourites include depositional features (separated, sheeted, plastered and confined drifts), erosional features (abraded surfaces, channels, furrows a...

Diapir piercement through the ocean floor marks the final stages of a dynamic migration path. Once exhumed, a diapir extrudes from the seafloor, placing an obstacle for the flow of ocean bottom currents. While the hydrodynamic response of the flow has been previously studied, the detailed depositional and weathering modifications involved in the pi...

Clinoform depositional features along the Iberian Mediterranean margin are investigated in this study, with the aim of establishing the causes of their varied shapes and other characteristics. We have analyzed the broad-scale margin physiography and seismic stratigraphic patterns based on high-resolution bathymetric data and previously interpreted...

The main aim of this study is to explore the spatial patterns of the shelf-scale erosional unconformity related to the last glacial maximum (LGM), particularly in terms of the role of underlying geology and the presumed primary influence of sea-level changes. This involved a detailed mapping of the most recent and widespread erosional shelf surface...

The Gebra–Magia Complex is an important example of a submarine mass-movement composite located on the lower continental slope of the Antarctic Peninsula (Central Bransfield Basin). Continuous instability dynamics over time is inferred to have affected the palaeo-trough-mouth fans present in the study area. The depositional architecture and the outs...

Detailed bathymetric and sub-bottom acoustic observations in Bourgeois Fjord (Marguerite Bay, Antarctic Peninsula) provide evidence on sedimentary processes and glacier dynamics during the last glacial cycle. Submarine landforms observed in the 50 km-long fjord, from the margins of modern tidewater glaciers to the now ice-distal Marguerite Bay, are...

Detailed bathymetric and sub-bottom acoustic observations in Bourgeois Fjord (Marguerite Bay, Antarctic Peninsula) provide evidence on sedimentary processes and glacier dynamics during the last glacial cycle. Submarine landforms observed in the 50 km-long fjord, from the margins of modern tidewater glaciers to the now ice-distal Marguerite Bay, are...

Evidence of the former extent and dynamics of the Greenland Ice Sheet is preserved on the continental margin of NE Greenland (Fig. 1). The continental shelf is incised by a number of deep (up to 500 m) cross-shelf troughs (Batchelor & Dowdeswell 2014; Arndt et al. 2015) (Fig. 1a), which are interpreted to have been occupied intermittently and erode...

Recent sedimentation patterns of presumed Quaternary age in the Scotia Sea appear to be dominated by contourite drifts generated by the influence of the Antarctic Circumpolar Current (ACC), the Weddell Sea Deep Water (WSDW) and/or the interaction between both water masses. Intercalated between stratified contourite deposits, chaotic lenses interpre...

A seismic analysis of the Pliocene and Quaternary stratigraphy was conducted in the Alboran Sea (westernmost Mediterranean) using more than 1250 profiles consisting of single- and multi-channel seismic records. This allowed for the updating and renaming of the stratigraphic boundaries and the establishment of a new Pliocene and Quaternary seismic s...

The analysis of a data set of multibeam bathymetry plus high resolution seismic and parametric profiles allow us to characterize the geomorphologic units on the Alboran Sea-floor as well as the evolution of morpho-sedimentary systems along the Pliocene and Quaternary, later than the main erosive Messinian event. Since the opening of the Gibraltar S...

Morphological features (escarpments, depressions and valleys) identified on the Guadalquivir Bank, within the middle slope of the Gulf of Cadiz, have been investigated based on high- and mid-resolution geophysical datasets. Themorphological and seismic stratigraphic analyses allowed their interpretation as the result of the interaction between ocea...

The Diego Cao channel is located on the central-north middle slope of the Gulf of Cadiz. It separates the Bartolomeu Dias and Faro sheeted drift plateaus to the north of the Guadalquivir Bank margin uplift. A striking linear series of circular depressions occur parallel to the channel on the Bartolomeu Dias sheeted drift (western channel flank), wh...

Contourite drifts are one the main morphosedimentary features in the Alboran Sea and their sediments are important archives of the past oceanographic conditions and sedimentary processes. The end-member modelling approach lets to decompose multimodal grain-size distribution into genetically meaningful subpopulation that may be related to different...

The current interpretation of the Messinian Salinity Crisis (MSC) involves the deposition of peripheral or marginal evaporites in onshore basins as well as the erosion of the margin and the deposition of thick evaporites in deep basins. The so-called intermediate basins are formed in domains between the onland outcrops and the deep basins. The Bale...

We present an interdisciplinary study of the geomorphology, sedimentology and physical oceanography of the Alboran Sea (south-western Mediterranean Sea) to evaluate the potential role of bottom currents in shaping the Spanish andMoroccan continental margins and adjacent basins. Bathymetric and seismic data have allowed the recognition of the contou...

Turbidite systems or submarine fans are considered the most important clastic accumulations in the deep sea and represent the sediment-transfer system between the hinterland source area and the deep-sea depositional sink. Their deposits contain information about global factors and local factors. Different scales and varying observational methods ha...

The products of bottom current circulation around the Iberian continental margin are characterised by large erosional and depositional features formed under a variety of geological and oceanographic contexts. The Iberian margins are influenced by several water masses that mainly interact along the upper and middle continental slopes, as well as alo...

Seismic profiles and sedimentological data (bulk fraction) of two sediment cores recovered from the Djibouti Ville Drift (SW Mediterranean Sea) indicate that bottom currents have played a fundamental role in shaping the sediment drift. The deposits are composed of biogenous to mixed muddy and silty contourites. A grain size analysis of the terrigen...

Seismic profiles and sedimentological data (bulk fraction) of two sediment cores recovered from the Djibouti Ville Drift (SW Mediterranean Sea) indicate that bottom currents have played a fundamental role in shaping the sediment drift. The deposits are composed of biogenous to mixed muddy and silty contourites. A grain size analysis of the terrigen...

The Gulf of Cadiz records the interplay of a variety of sedimentary processes related to the circulation of water masses. The most important one is the Mediterranean Outflow Water (MOW) that exits the Mediterranean Sea, but other water masses also affect the seafloor, with complex variations along time and space. This work studies the interplay bet...

Multidisciplinary work between oceanography, geomorphology and sedimentology has uncovered evidence explaining the uneven development of the turbidite systems (TSs) in the Alboran Sea. Nine TSs have been mapped in the Spanish margin, ranging from sandy to mixed sand-mud fans, and which become sandier towards the Strait of Gibraltar; in contrast TSs...

A multiple Contourite Depositional System has been defined in the Plio-Quaternary sedimentary register in the Alboran Sea. This multiple system formed by the Atlantic and the low density and high density Mediterranean Waters, which shaped the margins and basins since the opening of the Gibraltar Strait. Three different (paleo)circulation scenarios...

The southern margin of the Scotia Sea hosts the convergent boundary between the Scotia and Antarctic plates where a number of small basins are sitated. Mass transport deposits (MTDs) within two of these small basins, Dove and Scan basins, reveal the importance of seismicity, slope instabilities and depositional processes in their growth patterns. S...

The Gulf of Cadiz records the interplay of a variety of sedimentary processes related to the flow of the Mediter-ranean Outflow Water (MOW) exiting the Mediterranean Sea, with downslope sedimentary processes and the topography of the region. This work presents detailed morphological features of the Guadalquivir Ridge area, based on high resolution...

We characterize the eastern Gulf of Cadiz, proximal to the Strait of Gibraltar, using a multidisciplinary approach that combines oceanographic, morphosedimentary, and stratigraphic studies. Two terraces (upper and lower) were identified along the middle slope. They are composed of several associated morphologic elements, including two large erosive...

The Quaternary stratigraphic architecture of seamounts and surrounding deposits in the eastern Alboran Sea reveals at least 53 stacked MTDs in the Pollux Bank, Sabinar Bank (Sabinar Platform and Western Sabinar), Maimonides Ridge, and Adra Ridge. These MTDs are grouped into two types based on their size: small-scale MTDs (length <5 km and thickness...

The Quaternary stratigraphic architecture of seamounts and surrounding deposits in the eastern Alboran Sea reveals at least 53 stacked MTDs in the Pollux Bank, Sabinar Bank (Sabinar Platform and Western Sabinar), Maimonides Ridge, and Adra Ridge. These MTDs are grouped into two types based on their size: smallscale MTDs (length <5 km and thickness...