Andrew L. Leier

• Professor (Associate) at University of South Carolina

Wind-blown dust from southern South America links the terrestrial, marine, atmospheric, and biological components of Earth’s climate system. The Pampas of central Argentina (~33°–39° S) contain a Miocene to Holocene aeolian record that spans an important interval of global cooling. Upper Miocene sediment provenance based on n = 3299 detrital-zircon...

The spatial variations in Quaternary sediments on the inner continental shelf are produced by the progression of depositional environments during the latest sea-level rise, and this sedimentary architecture plays a fundamental role in controlling groundwater discharge. However, coincident seismic mapping, sediment cores, and hydrological studies ar...

The Tafí del Valle depression (~27° S) in the eastern Andes of Argentina provides a record of late Pleistocene dust deposition in the subtropics of South America. We present large-n U-Pb geochronology data for detrital zircons from upper Pleistocene loess-paleosol deposits. When compared to regional data, the age spectra from the Tafí del Valle sam...

The Pampas of Argentina contain a broad distribution of Pleistocene to Holocene loessic sediments and eolian dune deposits. Models describing the sediment provenance of this eolian system have, at times, conflicted. We address the provenance of these deposits through U-Pb detrital-zircon geochronology. Our results indicate broad similarity in age d...

Lower Eocene strata exposed in the hinterland of the southern Canadian Cordillera were deposited in extensional-transtensional basins and provide insights into the evolution of the orogen. We measured stratigraphic sections and collected 22 sandstone samples for detrital zircon uranium‑lead (UPb) geochronology (n = 2995) and hafnium isotope (εHf) v...

The Bell River hypothesis proposes that an ancestral, transcontinental river occupied much of northern North America during the Cenozoic Era, transporting water and sediment from the North American Cordillera to the Saglek Basin on the eastern margin of the Labrador Sea. To explore this hypothesis and reconstruct Cenozoic North American drainage pa...

Marine tracer studies indicate that large volumes of saline groundwater discharge to the ocean in passive margin settings. These results have not found widespread recognition because the location and cause(s) of this submarine groundwater discharge (SGD) are unclear. Here we report observations from a new long‐term seafloor monitoring network in th...

Plan-view exposures of the Salt WashMember of theMorrison Formation in central Utah provide unique insights into the characteristics of fluvial sandstone bodies associated with ancient distributive fluvial systems (DFS). Here, we use field-based observations and data from an unmanned aerial vehicle and structure-from-motion photogrammetry to docume...

The Garzón Massif, is an active Laramide style basement uplift flanked by the Upper Magdalena Valley (UMV) and the Putumayo Basin. In this paper we use new gravity, magnetic, well and seismic data for the first geophysical interpretation of the Garzón Massif. The Garzón/Algeciras fault has been previously interpreted as a right-lateral strike-slip...

Recently developed data collection techniques allow for improved characterization of sedimentary outcrops. Here, we outline a workflow that utilizes unmanned aerial vehicles (UAV) and structure-from-motion (SfM) photogrammetry to produce sub-meter-scale outcrop reconstructions in 3-D. SfM photogrammetry uses multiple overlapping images and an image...

Environmental parameters that influence the isotopic composition of meteoric water (δ18O and δD) are well characterized up the windward side of mountains, where orographic precipitation results in a predictable relationship between the isotopic composition of precipitation and elevation. The topographic and climatic evolution of the Andean Plateau...

The Lower Cretaceous McMurray Formation of northeastern Alberta hosts most of the bitumen resources of the Athabasca Oil Sands. Despite its importance, the sedimentary provenance and corresponding Early Cretaceous paleodrainage system associated with these fluvial deposits remain poorly understood. We collected 18 sandstone samples from five cored...

The Cenozoic of Western Canada and northern United States was marked by a change from compressional to extensional tectonics. The result was regional uplift and magmatic events. The uplift resulted in a major unconformity and deposition of extensive regional sheets of gravel and sand, of which only isolated remnants remain. These units are the Eoce...

A sediment column (0-110 cm) from Squires Ridge (38ED365), a stratified archaeological site on the Tar River in North Carolina, was analyzed to evaluate magnetic microspherules and other geochemical markers reported for the Younger Dryas Boundary (YDB). Here we report on microspherules using a Scanning Electron Microscope (SEM) and Energy Dispersiv...

The Lower Cretaceous Isachsen Formation is a widespread, siliciclastic succession up to 1.4 km thick that records the northwestward progradation of fluvio-deltaic environments into the Sverdrup Basin in the Canadian Arctic. Although the Isachsen Formation is a prominent unit with proven oil and gas reserves, detailed outcrop descriptions of its sed...

The McMurray Formation of the Athabasca Oil Sands represents one of the largest hydrocarbon resources on Earth and contains an extensive record of Early Cretaceous sedimentation. The provenance of the sandstones that constitute this formation has remained largely unknown. New U-Pb detrital zircon ages (n=848) record a complicated and variable prove...

Understanding aquifer architecture is critical for managing groundwater resources in western Canada. Recent regulations have yielded abundant new gamma-ray well log data from the principal aquifer in Alberta, the Paleocene Paskapoo Formation. A major obstacle to utilizing this data is the fact that gamma-ray measurements in the shallow subsurface a...

Middle to Upper Devonian strata of the Franklinian Basin in the Canadian Arctic contain a rich record of Phanerozoic tectonic events along the northern margin of Laurentia. We report detrital thermochronometric zircon (U–Th)/He ages (ZHe; number of aliquots, n = 72) and apatite (U–Th)/He ages (AHe; n = 38) from these Paleozoic strata in an effort t...

The Alberta foreland basin is a classic ex-ample of a retro-arc foreland basin, yet the early stages of its development remain poorly understood. Several contrasting hypotheses have been proposed to explain the source areas and dispersal patterns of sediment in western Canada during the Late Jurassic initiation of the foreland basin. Here, we use d...

The entire Late Jurassic–Early Cretaceous stratal package between the Fernie Formation and the Cadomin Formation, from Townships 62–74 in the subsurface of northwestern Alberta, is assigned to the Monteith Formation (Minnes Group). Three mappable units are present, informally termed Monteith A, B and C, from youngest to oldest. The Monteith C was d...

New detrital zircon uranium-lead (U-Pb) ages and initial epsilon hafnium (εHf(i)) data from the Devonian clastic succession of the Canadian Arctic Islands refines the provenance of strata within the Franklinian Basin and provides constraints on the geologic evolution of the landmass responsible for the Ellesmerian Orogen. This study contributes mor...

More than 1800 detrital zircon uraniumlead (U-Pb) ages collected from Franklinian Basin sedimentary strata of the Canadian Arctic Islands provide important insights into the depositional and tectonic evolution of the northern margin of Laurentia from the late Neoproterozoic to the Late Devonian. The Franklinian Basin succession is composed of strat...

Paleoelevation histories from mountain belts like the Central Andes of Bolivia provide important constraints on the timing and geodynamic mechanisms associated with surface uplift. New stable isotope data from paleosol carbonate nodules in the Altiplano and Eastern Cordillera of the Central Andes of Bolivia indicate a previously undocumented episod...

The Melvillian Disturbance in the Sverdrup Basin of the Canadian Arctic occurred between early and middle Permian time and is characterized by angular unconfomities, basaltic flows, and is linked to a broader mid-Permian circum-Arctic tectonic event.We examined the lower-middle Permian Sabine Bay and Assistance formations exposed in northwestern El...

Lower Cretaceous strata and the underlying sub-Cretaceous unconformity in western North America record a profound, but poorly understood change in sedimentation patterns and basin dynamics in the Cordilleran foreland basin. To better understand the regional sedimentary systems and provenance during Early Cretaceous time, we sampled 10 Lower Cretace...

The Altiplano Plateau is a high-elevation, internally drained basin located in the hinterland of the Central Andean fold-thrust belt of Bolivia. Cenozoic strata exposed along the margins of the basin provide a unique record of deposition and deformation in this region and can also be applied to understanding synorogenic sedimentation in other fold-...

A foreland basin system is an elongate region of accommodation that forms between an orogenic belt and the adjacent craton. Foreland basin successions commonly consist of basal backbulge deposits, a forebulge unconformity, and foredeep deposits. Foredeep sediments are normally sourced from the tectonically active fold and thrust belt with minor con...

Cretaceous sedimentary strata of the western United States provide a critical window into the depositional history and tectonic evolution of the region. Here we describe the Upper Cretaceous Bacon Ridge Sandstone of northwestern Wyoming, a largely unstudied marginal marine system deposited in a relatively high accommodation - high sediment supply a...

We measured δ18O and δ13C values of paleosol carbonate nodules from a variety of sedimentary units in southern Asia in order to reconstruct paleoenvironmental conditions and to evaluate for possible diagenetic alteration. Paleosol carbonate nodules were collected from Lower to Upper Cretaceous strata exposed in two locations in southern Tibet, and...

Photographs from the Rovers Spirit and Opportunity have revealed a wealth of detailed information about surface processes on Mars. One of the most enigmatic discoveries docu-mented uniform distributions of coarse (pebble to cobble sized) clasts at the Spirit landing site in Gusev Crater (Ward et al., 2005) (Fig. 1). Surfi cial deposits of this area...

Coarse (pebble to cobble sized) clasts on the intercrater plains of the Mars Exploration Rover Spirit landing site exhibit a nonrandom (i.e., uniformly spaced) distribution. This pattern has been attributed to the entrainment and redistribution of coarse clasts during extreme wind events. Here we propose an alternative mechanism readily observable...

For regional kinematic compatibility to be a valid boundary condition for continental tectonic reconstructions, there must be tests that validate or invalidate kinematic model predictions. In several reconstructions of western North America, the displacement history of the Mojave block continues to be unresolved. The magnitude of displacement along...

Sedimentary strata in southern Tibet indicate that upper crustal deformation occurred throughout the region during Early Cretaceous time, suggesting that construction of the Tibetan plateau commenced tens of millions of years before the Late Cretaceous-early Tertiary Indo-Asian collision. Lower Cretaceous strata in the northern portion of the Lhasa...

Sedimentary strata in the Lhasa terrane of southern Tibet record a long but poorly constrained history of basin formation and inversion. To investigate these events, we sampled Palaeozoic and Mesozoic sedimentary rocks in the Lhasa terrane for detrital zircon uranium–lead (U–Pb) analysis. The >700 detrital zircon U–Pb ages reported in this paper pr...

The Cretaceous-early Tertiary Gangdese arc in southern Tibet is generally attributed to the northward subduction of Neotethyan oceanic lithosphere prior to Indo-Asian collision. However, the history and tectonic significance of deformation and sedimentation in Tibet during this time interval have remained enigmatic. We show that contractional struc...

Our understanding of the processes involved in the Indo-Asian collision and the construction of the Tibetan Plateau are, in part, predicated on our understanding of the tectonic setting and crustal conditions of southern Tibet in the time period immediately preceding the Indo-Asian collision (Late Cretaceous). Several hypotheses have been proposed...

The outcrops of Marina's Cliff are part of the Punta Barrosa Formation along the eastern margin of the Andean fold-thrust belt in southernmost Chile (Figure 1). This formation was deposited during the first deep-water, coarse-grained clastic depositional stage that characterized the Late Cretaceous of the Magallanes retro-arc foreland basin. Deep-w...

The Eastern Cordillera of the Bolivian Andes forms the eastern boundary of the Altiplano plateau, an internally- drained hinterland basin that occupies an area of 150,000 km2 and has an average elevation of 4 km. Almost all tectonic models of the region indicate an important causal relationship existed between early Tertiary deformation in the East...

In certain cases, the rivers draining mountain ranges create unusually large fan-shaped bodies of sediment that are referred to as fluvial megafans. We combine information from satellite imagery, monthly discharge and precipitation records, digital elevation models, and other sources to show that the formation of fluvial megafans requires particula...

The Tibetan plateau is arguably the most important geological feature on Earth, yet its formation and evolution are poorly understood. This investigation utilizes Cretaceous sedimentary strata exposed in the Lhasa terrane of southern Tibet in order to constrain the paleogeography and tectonic setting of the region prior to the Indo-Asian collision....

Any model attempting to explain the relationship between the Indo-Asian collision and the uplift of the Tibetan plateau must first consider the tectonic circumstances in southern Asia immediately preceding the collision. Current hypotheses regarding Cretaceous tectonism in the Lhasa terrane of southern Tibet range between end-member models involvin...

Resolving the geodynamic evolution of intracratonic basins is often hampered by the inability to constrain important parameters such as lithospheric rheology and the size of the basin-forming load. The purpose of this study is to show: 1) peripheral bulges surrounding the Michigan Basin can be detected through stratigraphic and facies analyses; and...