Jun Shen

• PhD
• Professor at China University of Geosciences

The latest Permian mass extinction, the most devastating biocrisis of the Phanerozoic, has been widely attributed to eruptions of the Siberian Traps Large Igneous Province, although evidence of a direct link has been scant to date. Here, we measure mercury (Hg), assumed to reflect shifts in volcanic activity, across the Permian-Triassic boundary in...

Enhanced regional subduction-related volcanism in the South China craton concurrent with Siberian Traps large igneous province magmatism was a likely contributor to major biotic and environmental stresses associated with the Permian-Triassic boundary (ca. 252 Ma) mass extinction. However, the timing, intensity, and duration of this regional volcani...

Direct evidence of intense chemical weathering induced by volcanism is rare in sedimentary successions. Here, we undertake a multiproxy analysis (including organic carbon isotopes, mercury (Hg) concentrations and isotopes, chemical index of alteration (CIA), and clay minerals) of two well-dated Triassic-Jurassic (T-J) boundary sections representing...

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...

Although the productivity of modern volcanic soils is well established, the fertilization effects of ancient volcanic ash on aqueous ecosystems remains contentious. Here we demonstrate volcanic fertilization effects on a Late Triassic lacustrine ecosystem based on micropaleontological and geochemical records from the Yanchang Formation of North Chi...

Mercury (Hg) concentrations normalized to their dominant hosts have been widely used to identify geological events such as massive volcanic eruptions. However, the modern Hg cycle has significantly changed, and the implications of host-normalized Hg concentrations for the Hg dynamics in contemporary coastal environments (e.g., sources, delivery mec...

During the Late Ordovician Hirnantian Ice Age, the South China Craton experienced large changes in climate, eustasy, and environmental conditions, but their impact on the watermass architecture of the Yangtze Sea has not been thoroughly evaluated to date. Here, we reconstruct the salinity-redox structure of the Yangtze Sea based on five Upper Ordov...

The evolution of oxygen cycles on Earth’s surface has been regulated by the balance between molecular oxygen production and consumption. The Neoproterozoic–Paleozoic transition likely marks the second rise in atmospheric and oceanic oxygen levels, widely attributed to enhanced burial of organic carbon. However, it remains disputed how marine organi...

Several mass extinction events and major paleoenvironmental perturbations during the Phanerozoic have been linked to massive volcanic eruptions, especially those associated with large igneous province (LIP) emplacement. Because magmatism during LIPs can be accompanied by the release and widespread dispersal of mercury (Hg), Hg concentration in sedi...

The End-Triassic Mass Extinction (ETME) was broadly coincident with the emplacement of the Central Atlantic Magmatic Province (CAMP). However, the relationship between evolutionary phases of CAMP (i.e. prolonged shallow intrusive pulses and later extrusives) and the ETME is not clear. Here, a high-resolution record of changing magmatic activity is...

The transition from the middle to late Permian (Guadalupian–Lopingian) is claimed to record one or more extinction events that rival the ‘Big Five’ in terms of depletion of biological diversity and reorganization of ecosystem structure. Yet many questions remain as to whether the events recorded in separate regions were synchronous, causally relate...

Theory regarding the causation of mass extinctions is in need of systematization, which is the focus of this contribution. Every mass extinction has both an ultimate cause, i.e., the trigger that leads to various climato-environmental changes, and one or more proximate cause(s), i.e., the specific climato-environmental changes that result in elevat...

Available online xxxx Editor: B. Wing Keywords: redox structure photic zone euxinia Mesoproterozoic Hg isotope eukaryote evolution Studies of Mesoproterozoic ocean chemistry have converged on a widely accepted scenario where a stable shallow layer of oxic waters occurred over deeper anoxic ferruginous waters, with mid-depth euxinic waters restricte...

The Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma) was a major hyperthermal event that has been linked to CO 2 release from the North Atlantic Igneous Province (NAIP). Anomalously high sedimentary mercury (Hg) concentrations, a proxy for volcanism, have been recorded across the PETM, but the precise mechanistic links between NAIP emplacement and t...

The latest Permian mass extinction (LPME) was triggered bymagmatism of the Siberian Traps Large Igneous Province (STLIP), which left an extensive record of sedimentary Hg anomalies at Northern Hemisphere and tropical sites. Here, we present Hg records from terrestrial sites in southern Pangea, nearly antipodal to contemporaneous STLIP activity, pro...

What caused ocean/climate changes that drove Marinoan deglaciation, and the subsequent genesis of Ediacaran cap carbonates remains unclear. To address this issue, we examined the Hg records in Ediacaran cap carbonates from shelf to slope depositional settings in exposures from South China. These cap carbonates show higher total Hg (THg) concentrati...

Although both sedimentary rocks and petroleum generally contain detectable levels of Hg, the characteristics of Hg isotope fractionation and its transformation from biomass to sedimentary rocks to petroleum have not been sufficiently investigated to date. Here, we report Hg contents and isotope compositions in source rocks and crude oils from the P...

Reconstructing historical atmospheric oxygen (O2) levels at finer temporal resolution is a top priority for exploring the evolution of life on Earth. This goal, however, is challenged by gaps in traditionally employed sediment-hosted geochemical proxy data. Here, we propose an independent strategy—machine learning with global mafic igneous geochemi...

The Permian–Triassic Mass Extinction (PTME), life’s most severe crisis1, has been attributed to intense global warming triggered by CO2 emissions from Large Igneous Province volcanism2–8. It remains unclear, however, why super-greenhouse conditions persisted for around five million years after the volcanic episode, when Earth system feedbacks shoul...

Keywords: volcanism mass extinction large igneous province anoxia black shale isotopic fractionation Ordovician-Silurian transition (OST) sections of South China contain extremely high mercury (Hg) concentrations (>1000 ppb) of uncertain provenance. The main hypotheses concerning their origin are: (1) contemporaneous elevated seawater Hg concentrat...

The Permian-Triassic mass extinction (PTME), the most severe biocrisis of the Phanerozoic, has been widely attributed to intense volcanism. Although the Siberian Traps Large Igneous Province is regarded as the main trigger of this bioevent, volcanic-arc activity around the margins of the Tethys Ocean may have played a significant role also. Here, w...

The Late Ordovician mass extinction (LOME), the second-largest biodiversity crisis of the Phanerozoic, occurred in two discrete pulses, the causation of both of which has been linked to environmental stresses induced by the onset and termination of the Hirnantian Glaciation. Recent studies have inferred significant mercury (Hg) anomalies, mainly fr...

This study reviews plant species richness and abundance change from the End Permian to Middle Triassic in South China and examines the co-evolutionary relationship between the flora and the environment through this critical interval in the history of terrestrial biotas. A normalized macro-fossil plant record, that considers only one taxon per whole...

Mercury (Hg) concentrations and isotopes are widely used as proxies for volcanic inputs to paleode-positional systems. Enhanced volcanism during the Late Devonian was previously mainly inferred in the western Paleo-Tethys Ocean region from high Hg enrichments around the Upper Kellwasser horizon (UKW) and Frasnian-Famennian Boundary (FFB). In this s...

The early Toarcian Oceanic Anoxic Event (T-OAE, or Jenkyns Event, ~183 million years ago) was a major hyperthermal and global carbon-cycle perturbation, likely associated with the release of a substantial volume of ¹²C-enriched carbon to the Earth's surface. Seawater deoxygenation and the associated deposition of organic-rich facies during this eve...

Late Sturtian deglaciation, resulting in development of oxic conditions and deposition of banded iron formations (BIFs), was a pivotal period in evolution of global ocean chemistry. The driving forces behind these Neoproterozoic BIFs and climatic/oceanic changes remain controversial, however. Here we use mercury (Hg) to elucidate the cause(s) of th...

Volcanism is one of the most important geological processes that impact Earth's surface system. However, little is known about how a volcanic eruption in the past could cause environmental changes in the sea and its impact on organic matter (OM) accumulation due to the difficulties in gaining high-resolution sedimentary records. Here we conducted a...

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...

Research on mercury (Hg), a naturally occurring element in Earth’s lithosphere, has been extremely hot in the past few decades due to the outbreak of a series of disastrous poisoning incidents. However, such studies might provide us a biased view towards Hg if no thorough review about its long-term effects on living organisms from a multi-timescale...

Snowball Earth glaciations are the most extreme climate perturbations recorded in Earth’s history. It has been argued that the termination of these events was characterized by a single rapid transition from near-global ice coverage to an ice-free greenhouse climate state. Notably, this deviates with more extended transition periods of ice sheet wax...

An ice-free greenhouse interval (ca. 660 ∼ 650 Ma) occurred between the global Sturtian (ca. 717 Ma ∼ 660 Ma) and Marinoan glaciation (ca. 650 Ma ∼ 635 Ma) during the Cryogenian. While volcanic CO 2 emissions have been suggested as a trigger for this ice-free interval, evidence for volcanism has been lacking. In this study, spikes in both Hg concen...

The early Cambrian was an important interval in Earth history, marked by significant evolution of both life and the marine environments it inhabited. While enhanced hydrothermal activity has been proposed as a trigger for ecosystem perturbations in the early Cambrian, it remains unclear how intense and how long such perturbations may have been. To...

Barium (Ba) isotopic compositions (δ¹³⁸Ba) have been advocated as a novel paleo-productivity proxy, because of the strong control of biological productivity on the distribution of the Ba isotopic composition in the modern oxic oceans. However, the ocean was dominantly anoxic throughout the majority of the Earth’s history, and the biogeochemical cyc...

The North American Midcontinent Sea (NAMS) covered a vast area during Late Pennsylvanian glacio-eustatic highstands, providing a laboratory for analysis of the internal watermass dynamics of large cratonic seas (of which few exist in the Recent). In this study, a novel proxy, copper (Cu) isotopes, was used to gain a better understanding of NAMS wat...

In order to investigate the influence of volcanism on the enrichment mechanism of organic matter in black mudstone, we analysis mercury, total sulfur, total organic carbon and barium concentrations from core JY 143-5 in Wulong District, Chongqing, exploring the relationship between volcanisms and enrichments of organic matter near the Ordovician-Si...

Abundant metazoans phyla made their first appearances in the fossil record during a relatively short time span in the Ediacaran-Cambrian interval (560–520 Ma) and rapidly expanded ecologically during the early Cambrian, leading to the establishment of metazoan-dominated ecosystems accompanied by widespread biomineralization. This unique evolutionar...

The Siberian Traps large igneous province (STLIP) was the likely trigger for the ca. 252 Ma latest Permian mass extinction (LPME), but direct evidence for global volcanic effects on land remains rare. Here, we used mercury (Hg) enrichments, a proxy for ancient volcanic activity, to assess volcanic inputs to two terrestrial Permian-Triassic boundary...

Oceanic environments and biotas were in a state of near-continuous perturbation during the Early Triassic, the ~5-million-year interval following the latest Permian mass extinction (LPME), but the underlying cause(s) remain uncertain. The role of episodic volcanic or intrusive magmatic activity in triggering global-scale perturbations during this i...

Mercury (Hg) enrichment in stratigraphic successions is now widely used as a proxy for volcanic inputs, often for the purpose of documenting a relationship between large igneous province (LIP) magmatism and ecosystem perturbations. Earlier studies of Hg in Ordovician/Silurian boundary (OSB) sections in South China and Laurentia identified transient...

The Permian-Triassic boundary (PTB) at ~252 Ma coincided with the largest mass extinction of the Phanerozoic. Previous research on diversity and abundance changes during this event has focused mainly on the terrestrial vertebrate and marine invertebrate records, with little attention to date given to the phytoplankton that form the base of the mari...

The Smithian-Spathian boundary (SSB) was an interval characterized by a major global carbon cycle perturbation, climatic cooling from a middle/late Smithian boundary hyperthermal condition, and a major setback in the recovery of marine necto-pelagic faunas from the end-Permian mass extinction. Although the SSB has been linked to changes in oceanic...

The Late Devonian Frasnian–Famennian (F–F) event, consisting of the Lower and Upper Kellwasser events, had a severe impact on shallow-water ecosystems, while the effect on deep-water ecosystems is ambiguous. In order to recognize the Kellwasser events and to evaluate their influences on the deep-water ecosystems, a newly refined conodont biostratig...

The relationship between metazoan evolution and ocean-atmosphere oxygen levels has been extensively debated. Similarly, there is no consensus on the factors controlling the evolution of the marine redox landscape. The early Cambrian is a particularly critical time interval to examine, as there is a marked increase in metazoan body plan diversity an...

Relatively high-resolution clay mineralogical and chemical index of alteration (CIA) analyses were conducted on the terrestrial Lubei section in southwestern China, to gain a better understanding of the paleoclimatic/paleoenvironmental evolution on land during the Permian-Triassic transition (P-Tr transition). Clay-mineral species include illite-sm...

Although oceanic anoxia is regarded as a leading cause of the Permian-Triassic boundary (PTB) mass extinction, its timing, extent, and underlying causes remain unclear. Here, we conducted a high-resolution Fe-S-C-Mo geochemical study of the entire Changhsingian and lowermost Induan succession in a carbonate-ramp setting at Ganxi, western Hubei Prov...

Research on the dynamics of body-size changes in varied water depths can provide important insights into the evolution of palaeoenvironments through time. This paper attempts to investigate how the body sizes of two most commonly found chonetid brachiopod species in the uppermost Permian in South China varied with palaeo-bathymetry. The result show...

High–resolution clay mineralogical investigations were conducted on the Permian–Triassic (P–Tr) carbonate– and siliceous rocks from the Shangsi section, South China. The clay mineralogy is dominated by illite and illite/smectite mixed–layers (I/S) throughout the sampled section with subordinate chlorite and vermiculite emerging from bed 24 (approac...

Pyrite morphology, iron speciation, and pyrite sulfur isotope data from the Xiakou section (Hubei Province, South China) were integrated to explore oceanic environmental variations through the Permian–Triassic transition and their possible relationsto the largest mass extinction in Earth history. High ratios of highly-reactive iron to total iron (F...

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.

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...

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...

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...

The change of the primary productivity across the Permian-Triassic boundary (PTB) remains controversial. In this study, records from two deep-water sections in South China (Xiakou and Xinmin sections) show the primary productivity decreased gradually from the latest Permian to the earliest Triassic, and five evolutionary stages Increase-Decrease-Re...

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...

sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.full/10.2110/palo.2013.p13-035r BioOne (www.bioone.org) is a nonprofit, online aggregation of core rese...