Shane D. Schoepfer

Shane D. Schoepfer
Western Carolina University | WCU · Department of Geosciences and Natural Resources

PhD, University of Washington 2014

About

61
Publications
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1,235
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Introduction

Publications

Publications (61)
Article
Although marine productivity is a key parameter in the global carbon cycle, reliable estimation of productivity in ancient marine systems has proven difficult. In this study, we evaluate the accumulation rates of three commonly used proxies for productivity from a set of primarily Quaternary sediment cores at 94 marine sites, compiled from 37 publi...
Article
Models of mass extinctions caused by greenhouse warming depend on the ability of warming to affect the oxygenation of the ocean, either through slowing circulation or changes in biological productivity and the organic carbon budget. Opal Creek, Alberta, Canada is a biostratigraphically continuous Permian–Triassic Boundary (PTB) section deposited in...
Article
Full-text available
Seymour Island, in the James Ross Basin, Antarctica, contains a continuous succession of latest Cretaceous sediments deposited in a shallow marine environment at high latitude, making it an ideal place to study environmental changes prior to the K–Pg mass extinction. We measured major and trace elements and conducted petrographic analysis of two se...
Article
Full-text available
The term refuge describes, in both ecology and paleoecology, an ecosystem that acts as a sanctuary during times of environmental stress. This study tests the concept by examining the fate of a single community that lived ~50 k.y. after the end-Permian mass extinction (EPME). An assemblage of trace fossils, bivalves, and echinoids, living on a micro...
Article
Full-text available
The sources of isotopically light carbon released during the end-Triassic mass extinction remain in debate. Here, we use mercury (Hg) concentrations and isotopes from a pelagic Triassic-Jurassic boundary section (Katsuyama, Japan) to track changes in Hg cycling. Because of its location in the central Panthalassa, far from terrigenous runoff, Hg enr...
Article
While the end-Triassic mass extinction has been linked to emplacement of the Central Atlantic Magmatic Province (CAMP), evidence for environmental stresses appears hundreds of thousands of years prior to the extinction in some sections from the Panthalassic Ocean. In this study, we measured carbon, sulfur, and mercury concentrations in the Kurusu s...
Article
Full-text available
The end-Permian mass extinction (EPME) represents the largest biocrisis in Earth’s history, a result of environmental perturbations following volatiles released during Siberian Traps magmatism. A leading hypothesis links the marine mass extinction to the expansion of oceanic anoxia, although uncertainties exist as to the timing and extent. Thallium...
Article
Full-text available
Geobiology explores how Earth's system has changed over the course of geologic history and how living organisms on this planet are impacted by or are indeed causing these changes. For decades, geologists, paleontologists, and geochemists have generated data to investigate these topics. Foundational efforts in sedimentary geochemistry utilized sprea...
Article
Full-text available
The composition of continental crust records the balance between construction by tectonics and destruction by physical and chemical erosion. Quantitative constraints on how igneous addition and chemical weathering have modifed the continents' bulk composition are essential for understanding the evolution of geodynamics and climate. Using novel data...
Article
The end-Permian mass extinction (EPME) was known as the most severe biocrisis of the past 600 Ma. In order to explore the redox state of deep water environments, and the causal relationship between anoxia/euxinia and the EPME, this study selected the Penglaitan section in Guangxi, China, and measured the iron speciation and concentrations of trace...
Preprint
Full-text available
The composition of continental crust records a history of construction by tectonics and destruction by physical and chemical erosion. Quantitative constraints on how both igneous addition and chemical weathering have modified the continents' bulk composition are essential for understanding the evolution of geodynamics and climate. We have extracted...
Article
The end-Permian marine extinction (EPME) eliminated >80% of species globally, making it the most severe extinction of the Phanerozoic. Anoxia and euxinia are potential kill mechanisms that may have contributed to this biotic crisis. However, redox changes in the atmosphere-ocean system are likely to have been complex, with both the vertical locatio...
Article
The majority of the deep ocean was likely under ferruginous conditions during the first four billion years of Earth's history. As the atmosphere was gradually oxygenated, the sources, sinks, redox cycling, and reservoir size of dissolved iron in the deep ocean are likely to have changed dramatically. Whether deep water was thoroughly oxygenated by...
Article
Full-text available
Previous studies of the end-Permian mass extinction have established that it was geologically rapid, but condensed sections have made it difficult to establish the exact timing of the extinction relative to fluctuations in the ocean carbon cycle, oxygen levels, and temperature. Integrated high-precision U-Pb geochronology, biostratigraphy, and chem...
Article
Nearly all extant animal phyla first appeared during the Ediacaran-Cambrian transition. A revolution in primary producer ecology and marine productivity has been proposed as a bottom-up ecological driver for this rapid diversification of metazoans. However, the control(s) driving the evolution of primary producers and primary productivity around th...
Article
The “Cambrian explosion” is one of the most fascinating episodes of diversification in the history of life; however, its relationship to the oxygenation of the oceans and atmosphere around the Ediacaran–Cambrian transition is not fully understood. Marine inventories of redox-sensitive trace elements reflect the relative balance of oxidative weather...
Article
Full-text available
The end-Permian mass extinction represents the most severe biotic crisis for the last 540 million years, and the marine ecosystem recovery from this extinction was protracted, spanning the entirety of the Early Triassic and possibly longer. Numerous studies from the low-latitude Paleotethys and high-latitude Boreal oceans have examined the possible...
Conference Paper
The Lower Triassic Montney Formation of the Peace River Basin, British Columbia, is a complex succession dominated by siltstone and sandstone with shale and bioclastic packstone occurring in some areas. The facies in the Montney Formation represent a wide variety of depositional environments, ranging from middle to upper shoreface sandstones, middl...
Article
To better understand the alteration of volcanic ash in different depositional environments, we measured the clay mineralogy, major and trace element geochemistry, and Sr and Nd isotopic composition of altered ashes in two Permian-Triassic boundary (PTB) successions in southern China. The Pengda and Xinmin sections, in Guizhou Province, represent di...
Article
The causes of the greatest known mass extinction in Earth’s history, in the latest Permian, remain actively debated. Here we use Se isotopes and abundances in marine sediments from an outer-shelf environment to test one of the most commonly cited hypotheses about the collapse of the biosphere, i.e. widespread euxinia in the open ocean. Our data sho...
Article
Severe changes in ocean redox, nutrient cycling, and marine productivity accompanied most Phanerozoic mass extinctions. However, evidence for marine photic zone euxinia (PZE) as a globally important extinction mechanism for the end-Triassic extinction (ETE) is currently lacking. Fossil molecular (biomarker) and nitrogen isotopic records from a sedi...
Article
The latest Permian mass extinction (LPME) coincidedwithmajor changes in the composition ofmarine plankton communities, yet little is known about concurrent changes in primary productivity. Earlier studies have inferred both decreased and increased productivity inmarine ecosystems immediately following the end-Permian crisis.
Article
Full-text available
The lastest Permian mass extinction (LPME) coincided with major changes in the composition of marine plankton communities, yet little is known about concurrent changes in primary productivity. Earlier studies have inferred both decreased and increased productivity in marine ecosystems immediately following the end-Permian crisis. Here, we assess se...
Article
The recovery of marine ecosystems following a mass extinction event involves an extended interval of increasing biotic diversity and ecosystem complexity. The pace of recovery may be controlled by intrinsic ecosystem or extrinsic environmental factors. Here, we present an analysis of changes in marine conditions following the end-Permian mass extin...
Article
Full-text available
The extant species of Nautilus and Allonautilus (Cephalopoda) inhabit fore-reef slope environments across a large geographic area of the tropical western Pacific and eastern Indian Oceans. While many aspects of their biology and behavior are now well-documented, uncertainties concerning their current populations and ecological role in the deeper, f...
Article
Although marine productivity is a key parameter in the global carbon cycle, reliable estimation of productivity in ancient marine systems has proven difficult. In this study, we evaluate the accumulation rates of three commonly used proxies for productivity froma set of primarily Quaternary sediment cores at 94 marine sites, compiled from 37 publis...
Article
While the end-Permian extinction in the marine realm is well known from the Tethys Ocean, it remains little studied in the vast Panthalassic Ocean. Opal Creek, Alberta, Canada is a biostratigraphically continuous Permian-Triassic Boundary (PTB) section that is interpreted to have been deposited in a deep outer shelf setting along the Panthalassic w...
Article
Full-text available
Balancing selection has been invoked to explain the apparent maintenance of polymorphisms at the mannose-6-phosphate isomerase (Mpi) and glucose-6-phosphate isomerase (Gpi) loci in a diverse array of organisms. However, in many cases the agents of selective stress and the gram size of environmental heterogeneity necessary to preserve genetic variat...
Article
Unaweep Canyon is an enigmatic wind gap across the Uncompahgre Plateau in western Colorado. It is widely accepted that the ancestral Gunnison River once flowed through Unaweep Canyon and Cactus Park, a tributary to Unaweep Canyon. Newly discovered lake deposits in Cactus Park raise several important questions regarding the timing of events leading...
Chapter
The Black Canyon of the Gunnison and Unaweep Canyon in western Colorado have long been viewed as classic examples of post-Laramide Plio-Pleistocene uplift, which in the case of Unaweep, is thought to have forced the Gunnison River to abandon the canyon. Ongoing field studies of the incision histories of these canyons and their surrounding regions,...
Article
Full-text available
Solidification of a magma ocean will be affected by the rate at which dense solid mineral grains can settle out of a turbulently convecting fluid. We describe laboratory experiments that address the question of whether and for how long turbulent convectio

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Projects

Projects (5)
Project
The term refuge broadly refers to an ecosystem that acts as a sanctuary during times of environmental stress. This concept is important in understanding ecosystem recovery following mass-extinction events and can be used to strengthen modern conservation strategies. Despite the utility of this concept, refugia remain poorly understood, largely due to the lack of consistent criteria used to identify them. This disparity has led to various interpretations making it difficult to further develop the concept. My primary research interest includes developing and testing parameters that can accurately identify a refuge in deep time.
Archived project
To better understand marine environmental changes during the Triassic-Jurassic transition and their relationship to ultimate forcing mechanisms