Chao Li

Chao Li
Chengdu University of Technology | CDUT · Institute of Sedimentary Geology

PhD

About

113
Publications
42,921
Reads
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Introduction
My research interests focus on the paleoenvironmental reconstruction, particularly on Cambrian and Proterozoic ocean redox chemistry evolution and its coevolution with life in recent years. Biogeochemical processes that dominate carbonate platforms and anoxic marine basins are at the heart of this research. Thus, I am also interested in exploring the underlying biogeochemical mechanisms and processes which contributed to the coevolution of atmosphere, ocean and life in early Earth history. Multiple sedimentary geochemcial approaches are used in my research, including Fe speciation, S-, C- and Mo-isotopes, trace elements as well as organic biomarkers and their C- and H-isotopes. These methodologies help me to track the signals of microbially mediated cycling of sulfur, carbon, metals as well as redox evolution of the Earth’s surface preserved in ancient sedimentary rocks.
Additional affiliations
April 2011 - present
China University of Geosciences
Position
  • Professor of Biogeochemistry
July 2009 - March 2011
University of California, Riverside
Position
  • Associate Research Specialist
April 2007 - June 2009
University of California, Riverside
Position
  • Assistant Reseach Specialist
Education
September 1996 - February 2002
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences
Field of study
  • Geochemistry
September 1992 - June 1996
China University of Geosciences (Wuhan)
Field of study
  • Geochemistry

Publications

Publications (113)
Article
The Ediacaran–Cambrian (E–C) transition witnessed remarkable environmental changes, the extinction of the Ediacaran biota, and subsequent rapid diversification of Cambrian animals. However, the linkages between environmental and biological evolution are still under debate at this critical time. Here, we present new Hg abundance and Hg isotopes in s...
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Full-text available
The late Mesoproterozoic Era (1300–1000 Ma) was a critical period that witnessed the origin and early evolution of multicellular eukaryotes. Multiple studies have reported observations that the carbon isotope composition of carbonate (δ¹³Ccarb) underwent a substantial increase after ca. 1250 Ma. The high δ¹³Ccarb values suggest that the fraction of...
Article
The Ediacaran Period (∼635 to 541 Ma) witnessed the early diversification and radiation of metazoans, in the form of the Ediacaran Biota. This biological revolution, beginning at ∼575 Ma, has been widely attributed to a temporally restricted episode of deeper ocean oxygenation, potentially caused by a contemporaneous rise in atmospheric oxygen leve...
Article
Full-text available
The sulfur isotopic composition (δ³⁴S) of Carbonate Associated Sulfate (CAS) is widely used to track changes in the isotopic composition of ancient seawater sulfate which signify the global sulfur cycle, Earth's surface redox evolution, and biological activity. However, our understanding of to what extent the isotopic composition of CAS records amb...
Article
Microbe-metazoan transitions (MMTs), representing a switch from microbe-mediated to metazoan-mediated carbonate production, have been linked to major changes in Earth-surface conditions. The ‘late Cambrian MMT’ (nomen novum), during which microbial reefs were replaced by maceriate and lithistid sponge reefs, coincided with a sharp rise in atmospher...
Article
Iron in the early anoxic oceans of Archean age (4000-2500 million years ago) is believed to have been oxidized to form banded iron formations (BIF). Previously, it has been proposed that iron was oxidized either by free oxygen, H2O2, microbial oxidation, or photo-oxidation. However, these mechanisms are difficult to reconcile with evidence for the...
Article
As the electrical connections of different functional components, printed silver wires are widely used in flexible electronics. With the development trend toward miniaturization and high-performance enhancement, the current density in electronic devices increases continuously. The damage and failure of interconnects under high-density current, incl...
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Full-text available
Member IV of the Ediacaran Doushantuo Formation records the recovery from the most negative carbon isotope excursion in Earth history. However, the main biogeochemical controls that ultimately drove this recovery have yet to be elucidated. Here, we report new carbon and nitrogen isotope and concentration data from the Nanhua Basin (South China), wh...
Article
The Ediacaran Period (~635-539 Ma) witnessed the largest negative inorganic carbon isotope (δ 13 C carb) excursion in Earth's history (i.e., the Shuram Excursion), which is characterized by decoupling from the organic carbon isotope (δ 13 C org) record. The cause(s) of this event remains highly debated. Here, we report a major (~8-9-Myr-long) episo...
Article
The delayed diversification of early animals until the middle Ediacaran Period, despite their likely origin in the Cryogenian Period or earlier, has been attributed to low levels of dissolved O2 in global seawater. To provide more robust constraints on the extent of global-ocean oxygenation during the mid-Cryogenian Period, we analyzed paired U (δ²...
Article
The long history of life on Earth has unfolded as a cause-and-effect relationship with the evolving amount of oxygen (O2) in the oceans and atmosphere. Oxygen deficiency characterized our planet's first 2 billion years, yet evidence for biological O2 production and local enrichments in the surface ocean appear long before the first accumulations of...
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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
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Silver micro/nanomaterials have attracted a great deal of attention due to their superior physicochemical properties. The atomic migration driven by electromigration or stress-induced migration has been demonstrated to be a promising method for the fabrication of metallic micro-/nanomaterials because of the advantage of simple processing. However,...
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Full-text available
The widely developed black shales deposited during the early Cambrian recorded paleoenvironmental information about co-eval seawater. Numerous studies have been conducted on these shales to reconstruct the paleomarine environment during this time period. However, most research has been conducted on stratigraphic sections in South China, and equival...
Article
In order to explore Cryogenian seawater chemistry and its underlying controls, we present an integrated study of iron speciation, major and trace elements, and carbon isotopes of Mn‑carbonates and their host black shales in the Datangpo Formation from three drillcores (Gaodi, Xixibao and Changxingpo) in the Nanhua Basin, South China. A key aspect o...
Article
Benthic oxygen oases linked to photosynthetic mats have been reported in modern anoxic aquatic systems. Benthic macroalgal blooms were common in stratified, anoxic Neoproterozoic oceans, leading us to hypothesize the existence of benthic oxygen oases at that time. This hypothesis has significant implications regarding the bioavailability of transit...
Article
Large datasets increasingly provide critical insights into crustal and surface processes on Earth. These data come in the form of published and contributed observations, which often include associated metadata. Even in the best-case scenario of a carefully curated dataset, it may be non-trivial to extract meaningful analyses from such compilations,...
Article
The widely developed black shales deposited during the early Cambrian recorded paleoenvironmental information about coeval seawater. Numerous studies have been conducted on these shales to reconstruct the paleomarine environment during this time period. However, most research has been conducted on stratigraphic sections in South China, and equivale...
Article
Throughout the Ediacaran Period, variable water-column redox conditions persisted along productive ocean margins due to a complex interplay between nutrient supply and oceanographic restriction. These changing conditions are considered to have influenced early faunal evolution, with marine anoxia potentially inhibiting the development of the ecolog...
Article
The Ediacaran radiation of metazoans is widely thought to have been triggered by an increase in atmospheric and oceanic oxygen levels. Although supported by other proxies, rising oxygen levels were deduced to a significant degree from sedimentary enrichments of redox-sensitive trace elements (RSTEs). However, some organic-rich shales of this period...
Article
Phosphorus is considered the ultimate limiting nutrient in the oceans over geological timescales. Phosphate (PO4³⁻) availability consequently exerts control on the global carbon cycle and atmospheric/oceanic redox conditions over million-year timescales. Despite its importance, there are no established tools that can directly and continuously recon...
Article
The Cryogenian Period was characterized by global glaciations, imposing extreme environmental stresses on early multicellular organisms. Globally distributed diamictite deposits are the major evidence for these glaciation events, but the glacial origin of at least some of these diamictite deposits has been disputed, complicating interpretations of...
Article
The rapid diversification of early animals during the Ediacaran (635-541 Ma) and early Cambrian (ca. 541-509 Ma) has frequently been attributed to increasing oceanic oxygenation. However, the pattern of oceanic oxygenation and its relationship to early animal evolution remain in debate. In this review, we examine the redox structure of Ediacaran an...
Article
Full-text available
Major phosphogenic events took place in the late Paleoproterozoic and the Ediacaran, both of which followed an episode of atmospheric oxygenation. These apparent coincidences have led to suggestions that the Precambrian phosphorus cycle was partly regulated by oceanic redox conditions, although direct evidence is lacking. In this paper, we report t...
Article
Major phosphogenic events took place in the late Paleoproterozoic and the Ediacaran, both of which followed an episode of atmospheric oxygenation. These apparent coincidences have led to suggestions that the Precambrian phosphorus cycle was partly regulated by oceanic redox conditions, although direct evidence is lacking. In this paper, we report t...
Article
Paleozoic and Precambrian sedimentary successions frequently contain massive dolomicrite [CaMg(CO 3 ) 2 ] units despite kinetic inhibitions to nucleation and precipitation of dolomite at Earth surface temperatures (<60 °C). This paradoxical observation is known as the “dolomite problem.” Accordingly, the genesis of these dolostones is usually attri...
Article
Existing redox classifications and the calibrations of elemental proxies to modern environmental redox scales are in need of re-evaluation. Here, we review environmental redox classifications, commonly used elemental redox proxies, and their intercalibration, and we propose a novel approach to improve the calibration of such proxies, using datasets...
Article
Marine redox conditions and their dynamic variations in the early Cambrian are thought to have strongly influenced the evolution of early animals. However, the patterns and mechanisms of contemporaneous marine redox variation remain poorly understood. The Nanhua Basin (South China) was a failed rift basin located between the Yangtze Block (NW margi...
Article
Oxygenation of the early Cambrian ocean is commonly ascribed to high organic export to the sediment due to the rise of algae and filter-feeding animals, but direct evidence of elevated export fluxes has been lacking to date. Here, we report an integrated proxy dataset (U-Mo isotopes, Fe speciation, and major and trace elements) for lower Cambrian b...
Article
The Mesoproterozoic Era (1.6–1.0 Ga), long regarded as an interval of sluggish biotic evolution and persistently low atmospheric-oceanic oxygen levels, has become the subject of recent controversy regarding putative large-scale oxygenation events. In this study, we conducted a comprehensive investigation of redox, productivity, seawater sulfate con...
Article
Rationale: Carbonate clumped isotope (Δ47 ) thermometry examines the temperature-dependent excess abundance of the 13 C-18 O bond in the carbonate lattice. Inconsistent temperature calibrations and standard values have been reported among laboratories, which has led to use of equilibrated gases and carbonate standards for standardization. Furtherm...
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Full-text available
The unprecedented positive δ¹³C excursion in carbonates deposited between 2.2 and 2.0 Ga, known as the Lomagundi-Jatuli Event (LJE), has been documented globally and linked to the rise of atmospheric oxygen. Increasing oxidation inevitably changed the atmosphere-hydrosphere system, but few chemostratigraphic or quantitative constraints for the afte...
Article
Full-text available
Current-induced changes of surface morphology in printed Ag thin wires were investigated by current stressing tests and numerical simulation. The samples were printed Ag thin wires on a flexible substrate with input and output pads. Different experimentalresults were obtainedthroughchangingthe current density after current supply and the mechanism...
Article
Full-text available
Early Triassic marine ecosystems experienced multiple environmental perturbations and a delayed biotic recovery following the end-Permian mass extinction. The Smithian–Spathian boundary (SSB), in the late Early Triassic, marks a major shift toward a less intensely warm climate, ameliorated marine environmental conditions, and the onset of a more su...
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The role of O2 in the evolution of early animals, as represented by some members of the Ediacara biota, has been heavily debated because current geochemical evidence paints a conflicting picture regarding global marine O2 levels during key intervals of the rise and fall of the Ediacara biota. Fossil evidence indicates that the diversification the E...
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The China Seas include the South China Sea, East China Sea, Yellow Sea, and Bohai Sea. Located off the Northwestern Pacific margin, covering 4700000 km² from tropical to northern temperate zones, and including a variety of continental margins/basins and depths, the China Seas provide typical cases for carbon budget studies. The South China Sea bein...
Article
Although oxic surface, ferruginous deep, and euxinic intermediate waters have been documented, the redox heterogeneity of early Cambrian oceans remains largely unclear, precluding our understanding of the relationship between marine redox evolution and early animal diversification. In this study, we analyzed iron species, redox-sensitive trace elem...
Article
The exceptionally preserved Chengjiang Biota (Yunnan, China) is significant for understanding the rapid development of complex animal-rich ecosystems during the evolutionary radiation of the Cambrian. However, the ecological signal provided by the fossils captured in this deposit may not reflect accurately the in-life community, with transport and...
Article
It is generally agreed that early diversification of animals and significant rise of atmospheric and oceanic oxygen (O2) levels occurred in the Ediacaran (635–541 million years ago, Ma) and early Cambrian (ca. 541–509 Ma). The strength and nature of their relationship, however, remain unclear and debated. A recent wave of paleoredox research — with...
Article
Full-text available
The ocean holds a tremendous reservoir of refractory dissolved organic carbon (RDOC) that plays an important role in carbon cycling and climate change [1]. However, the origin of the RDOC has been an enigma for half a century. This perspective is to address why the enigma deserves scientific efforts and illustrate a robust scheme—the Microbial Carb...
Article
The Ediacaran Shuram Excursion (SE) was a major negative δ¹³Ccarb excursion (to-12‰) thought to reflect significant atmosphericoceanic oxidation, although direct evidence is limited. Here, we model changes in seawater sulfate concentrations ([SO²⁻4]sw) during the SE by using paired S-isotope data of cogenetic sedimentary pyrite and carbonate-associ...
Article
The Neoproterozoic oxygenation event (NOE) likely began earlier than 800 Ma, raising oxygen levels in the Earth’s atmosphere-ocean system and, thus, setting the stage for the emergence and diversification of animals. However, the redox history of the oceans during the following Cryogenian Period (~720-635 Ma) remains poorly constrained. Here, we pr...
Article
The largest global carbon-cycle perturbation in Earth history was recorded in the Ediacaran—a persistent negative shift in the global marine dissolved inorganic carbon (DIC) reservoir that lasted for ∼25–50 million years, with a nadir of–12‰ (i.e., the Shuram Excursion, or SE). This event is considered to have been a result of full or partial oxida...
Article
The early-middle Cambrian (Fortunian to Age 4) is characterized by a significant increase in metazoan diversification. Furthermore, this interval is marked by a prominent environmental and ecological expansion of arthropod- and echinoderm-rich biotas. Recent redox work has suggested that this shift occurred during stable or decreasing marine oxygen...
Article
Many late Neoproterozoic to early Cambrian fossils of multicellular eukaryotes, including those of benthic animals, are found preserved under anoxic and even euxinic bottom-water conditions, which is contradictory to the consensus that oxygen is essential to eukaryotes. To investigate this conundrum, we conducted an integrated study of iron speciat...
Article
The Late Ordovician Period witnessed the second largest mass extinction in the Phanerozoic Eon and the Hirnantian glaciation. To infer ocean redox conditions across the Ordovician-Silurian transition, we measured the U (as δ²³⁸U relative to standard CRM145 = 0‰) and Mo (as δ⁹⁸Mo relative to standard NIST SRM 3134 = + 0.25‰) isotope compositions of...
Article
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...
Article
The early Cambrian Period was a key interval in Earth history with regard to changes in both ocean chemistry and animal evolution. Although increasing ocean ventilation has been widely assumed to have played a key role in the rapid appearance, diversification and spatial colonization of early animals, this relationship is in fact not firmly establi...
Article
Records of the Ediacaran carbon cycle (635-541 million years ago) include the Shuram excursion (SE), the largest negative carbonate carbon isotope excursion in Earth history (down to -12‰). The nature of this excursion remains enigmatic given the difficulties of interpreting a perceived extreme global decrease in the δ(13) C of seawater dissolved i...
Article
The Ordovician-Silurian (O-S) transition coincided with significant environmental and biological changes. In South China, the Yangtze Platform experienced both global and regional events at this time, including sea-level fluctuations, tectonic movements, volcanic eruptions, mass extinction, and widespread anoxia. The O-S transitional strata of the...
Article
Ambient Inclusion Trails (AITs) are intriguing microtubular structures that commonly occur in association with pyrite in Precambrian organic-rich cherts and phosphorites. They are thought to be created by the migration of pyrite or other crystal grains through a lithified substrate driven by pressure solution from the in situ thermal decomposition...
Article
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...
Article
The “Cambrian Explosion” is known for rapid increases in the morphological disparity and taxonomic diversity of metazoans. It has been widely proposed that this biological event was a consequence of oxygenation of the global ocean, but this hypothesis is still under debate. Here, we present high-resolution Fe–S–C–Al-trace element geochemical record...
Article
Molybdenum (Mo) concentrations and Mo isotopes have been widely used as proxies for local and global redox conditions in early oceans (>520 Ma) that were stratified and characterized by dynamically euxinic mid-depth waters. However, the nature of the Mo cycle and accompanying isotopic fractionations in such oceans remain poorly known. To fill this...