Gordon Love - US grants

The Neoproterozoic geological record contains evidence for extreme climatic change which may have profoundly influenced the course of biological evolution, particularly around the so-called Snowball Earth episodes of the Sturtian, Marinoan and Gaskiers glaciations. During the Neoproterozoic, body fossils and molecular biomarkers interpreted as being derived from multicellular animals have been reported although the radiation of basal animals is presently poorly constrained at sometime between the Sturtian and Marinoan glaciations. In this study, we aim to produce detailed temporal records of Neoproterozoic marine biogeochemistry from molecular biomarker analyses, organic and inorganic stable isotope records (including 13C, 2H and 34S) and from inorganic geochemical proxies of paleoredox for four sections in the Nanhua Basin in South China. This will allow us to investigate the effects of low-latitude Neoproterozoic glaciation on primary production, carbon cycling and redox structure applied to a shallow shelf-to-deep basinal paleoenvironmental transect.

Given the scientific interest in fossilized animal fauna and other fossils from the Doushantuo Formation in South China, it may seem surprising that no detailed molecular biomarker records currently exist for the Neoproterozic in South China. This is undoubtedly due to the high thermal maturity of some sections and due to the inherent problems of discerning low concentrations of genuine Neoproterozic biomarker signals above a significant background of petroleum-derived contaminants. A scoping study has revealed that the thermal maturity of strata in our four sections in Nanhua Basin is not problematic for preserving detectable biomarker hydrocarbon signals. The originality and principal strength of the biomarker lipid work proposed here lies in obtaining kerogen-bound biomarker records which allow us to access a high proportion of the preserved biomarker record in Nanhua Basin essentially free from contamination effects. The PI's research has demonstrated the efficacy of a continuous flow catalytic hydropyrolysis (HyPy) technique for fragmenting kerogen and releasing covalently-bound biomarker constituents to essentially ground-truth all the biomarker lipid data obtained.

We will address some fundamental questions regarding the biogeochemical history of the Neoproterozoic in South China:
-Can we detect significant changes in marine redox structure in the immediate aftermath of the Sturtian and Marinon glaciations using our inorganic and biomarker proxies and, if so, is there strong evidence for concomitant fluctuations in source organism input?
-Can we discern significantly different responses of shallow- versus deep-water settings to the aftermath of the glaciations in terms of their redox profiles and biota?
-Can we detect specific steroid markers for basal animals (sponges) in the Nanhua Basin and, if so, when do these first appear relative to the Sturtian and Marinoan glaciations?

Broader Impacts. The research will significantly improve our understanding of the extent to which the intense climatic shock of the Sturtian and Marinoan glaciations impacted on marine microbial communities by modifying nutrient cycling, dissolved oxygen availability and creating environmental niches in low latitude marine environments. In terms of providing educational opportunities, Love and Lyons will participate during each of the project years in the UCR Mentoring Summer Research Internship Program, whereby undergraduate students from ethnic groups historically underrepresented in the sciences (particularly the earth sciences) will receive hands-on experience in the two labs. Finally, our project will benefit greatly from collaboration with Professor Xuelei Chu (Institute of Geology and Geophysics, Chinese Academy of Sciences) and his research group, who have considerable experience of studying Neoproterozoic glacial strata in South China. Chu and colleagues will visit the Southern California biogeochemical community at Caltech and UCR during the course of the project to discuss findings and to promote long-term collaborative links.

ELT Collaborative Research: Beyond the Boring Billion: Late Proterozoic Glaciation, Oxygenation and the Proliferation of Complex Life

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Timothy Lyons, Univ. California, Riverside, EAR-1338299
Nicholas Planavsky, Dartmouth College, EAR-1338208
Christopher Reinhard, Georgia Tech, EAR-1338290

ABSTRACT
The middle chapters in Earth's history, roughly 1.8 to 0.8 billion years ago, were defined by remarkable stability in generally low but persistent oxygen levels in the ocean and atmosphere and stifled development of early organisms for a billion years. How and when this cycle was broken are among the central unanswered questions in the history of life on Earth. The eventual rise to higher oxygen levels and ultimately the appearance of animals correspond generally with history's most extreme climatic events and mountain building episodes, and the timing and cause-and-effect relationships among all these events and processes are frontiers ripe for study. To this end, we will construct an unusually comprehensive chemical data set for rocks from Australia and Arctic Canada deposited directly within the transition between the stable 'boring' billion and the major milestones that followed.

The onset of global-scale glaciation 0.7 to 0.8 billion years ago is without question one of the most dramatic environmental transitions in Earth history, and the generally synchronous radiation of eukaryotic organisms, with greater complexity than their microbial ancestors, and the emergence of animals are among the most remarkable evolutionary events in the long history of life. The proposed multidisciplinary team will illuminate the timing of these key events and their likely links to Earth's oxygenation, while probing the cause-and-effect relationships among biological innovation, oxygen, and the onset of global-scale glaciation. The study's full range of impacts will reach far beyond the intrinsic scientific merit, including high-level research opportunities for the diverse undergraduate populations at all three institutions. We will also reach out into the community through sponsorship of science fair projects and through many different contributions to the new Riverside STEM Academy, including organization of a lecture series that will bring prominent scientists and engineers into the school. The study also includes plans for collaborative mentoring of graduate students, including student exchanges, and is an important step in the early careers of two new professors.

RUI, Collaborative Research: A High resolution Paleontological, Ichnological, and Chemostratigraphic Study of Late Devonian Mass Extinctions

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Diana Boyer, EAR-1348981, SUNY Oswego
Gordon Love, EAR-1348988, Univ. California, Riverside

ABSTRACT
The rock record preserves a detailed history of past events in life history, and understanding these events, particularly episodes of unusual biotic turnover, is of paramount importance, particularly in this time of our current diversity crises. There have been many large scale extinction events throughout geologic history, and despite extensive study, the Late Devonian mass extinction events in the Frasnian-Famennian still remain enigmatic in terms of a causal mechanism. Although numerous kill mechanisms have been proposed, marine anoxia is widely thought to be a major contributing factor, in part because of the pervasiveness of organic-rich black shale. This study will test for extensive anoxic and/or pervasive euxinic (sulfidic water column) conditions associated with several biotic turnover events preserved in a Laurentian basin. PIs will use an integrated paleontological, inorganic geochemical, and lipid biomarker approach performed at high spatial resolution to reconstruct secular changes in ancient microbial and metazoan source organism inputs, and marine redox structure in these ancient epeiric seaways. They will test for a correlation between the magnitude and timing of extinction events and patterns of oxygen and euxinic stress which prevailed.
The utility of combining paleontological and geochemical proxies to recognize bottom water oxygen levels on a fine-scale in black shale facies has been realized (Boyer et al., 2011), but not yet applied to understand the dynamics of major events in the history of life. The new light we are shedding on Late Devonian biospheric and environmental evolution in North America will inform and direct future work in biogeochemistry, paleontology/paleobiology, evolutionary biology, and ocean-atmosphere evolution. Central to this research is a unique bridging of organic and inorganic geochemical methods with paleontology within a broad field-based template to yield high-resolution bio- and chemostratigraphic records that span the Late Devonian mass extinction events and their aftermath. At the heart of this research proposal is the training and education of a group of talented graduate, undergraduate and K-12 school students in the geosciences at UCR and SUNY Oswego, many from underrepresented ethnic groups, through a combination of direct involvement in the research project or through a variety of outreach ventures.