Article
Geology
K. Hickman-Lewis, B. Cavalazzi, K. Giannoukos, L. D'Amico, S. Vrbaski, G. Saccomano, D. Dreossi, G. Tromba, F. Foucher, W. Brownscombe, C. L. Smith, F. Westall
Summary: This study presents advanced reconstructions of the characteristics and taphonomy of permineralized stromatolites from the Dresser Formation in Western Australia. The findings suggest a biogenic origin of the stromatolites and their relevance as analogues for potential microbialites on Mars.
Article
Geology
K. Hickman-Lewis, B. Cavalazzi, K. Giannoukos, L. D'Amico, S. Vrbaski, G. Saccomano, D. Dreossi, G. Tromba, F. Foucher, W. Brownscombe, C. L. Smith, F. Westall
Summary: This passage discusses the advanced reconstructions of Paleoarchean stromatolites in Western Australia, highlighting their mineralogy, trace element geochemistry, and taphonomy. The compositions of rare earth elements and yttrium suggest a marine-influenced paleodepositional setting, with syndepositional hydrothermal influence and silicification promoting high-fidelity microstructural preservation. The presence of various morphological characteristics suggests a biogenic origin and the stromatolite eco-system being dominantly phototrophic, making them relevant analogues for potential microbialites on Mars.
Article
Geochemistry & Geophysics
Janet R. Muhling, Sarah E. Gilbert, Birger Rasmussen
Summary: This study presents in situ LA-ICP-MS analysis of REY abundances in well-preserved laminated greenalite-bearing cherts from pre-GOE ferruginous cherts and BIFs in Western Australia. Different REY patterns are observed in cherts from different depositional environments, reflecting differing source fluids and deposition environments. Furthermore, the REY patterns in greenalite-bearing cherts may differ from bulk samples of the same formations, possibly due to diagenetic overprint in the bulk samples.
Article
Geosciences, Multidisciplinary
David T. Murphy, Daniel Wiemer, Vickie C. Bennett, Thomas Spring, Jessica Trofimovs, Henrietta E. Cathey
Summary: Archean greenstone belts contain unique variolitic textures in volcanic rocks, which may have formed through rapid undercooling, magma mingling, and liquid immiscibility. Study of samples from Paleoarchean variole-bearing pillow lavas suggests that the variolitic texture may have resulted from an immiscibility reaction involving hydrous fluxed melting. Analysis of mineral and isotope compositions provides insights into the volcanic processes and magma genesis in these ancient greenstone belts.
PRECAMBRIAN RESEARCH
(2021)
Article
Engineering, Geological
Xingsen Guo, Zhenwen Liu, Jiewen Zheng, Qianyu Luo, Xiaolei Liu
Summary: This study analyzed the penetration mechanism of a T-bar in deep-sea surficial sediments using computational fluid dynamics. It proposed a methodology to evaluate the undrained shear strength of deep-sea sediments and established corresponding equations. This provides a basis for marine engineering geology survey, engineering construction, and hazard assessment.
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
(2023)
Article
Geosciences, Multidisciplinary
Zoe Phelps-Barber, Allan Trench, David I. Groves
Summary: The discovery and development of world-class Lithium-Caesium-Tantalum (La) spodumene-bearing pegmatites in Western Australia have led to the growth of a significant new sector in its mining industry. The recently delineated spodumene discoveries in the Yilgarn and Pilbara Cratons have similar geological features to other world-class pegmatites globally. Based on consistent exploration criteria and favorable capital market conditions, further spodumene discoveries are likely in the Archean terranes of Western Australia.
APPLIED EARTH SCIENCE-TRANSACTIONS OF THE INSTITUTIONS OF MINING AND METALLURGY
(2022)
Article
Geosciences, Multidisciplinary
Jian-Wei Zi, Stephen Sheppard, Janet R. Muhling, Birger Rasmussen
Summary: There is uncertainty about the nature and timing of magmatism, deformation, and metamorphism in the Paleoproterozoic Wisconsin magmatic terranes. New in situ U-Pb geochronology of igneous zircon reveals magmatic episodes synchronous with bimodal volcanism in the Wausau domain and Marshfield terrane. The study also identifies an overprinting metamorphic event related to the Yavapai-interval accretion.
GEOLOGICAL SOCIETY OF AMERICA BULLETIN
(2022)
Article
Multidisciplinary Sciences
Sarah P. Slotznick, Jena E. Johnson, Birger Rasmussen, Timothy D. Raub, Samuel M. Webb, Jian-Wei Zi, Joseph L. Kirschvink, Woodward W. Fischer
Summary: Based on chemical datasets and mineral characteristics, it is suggested that oxygen levels in the environment were very low approximately 150 million years before the Great Oxygenation Event (GOE), and the presence of certain redox-sensitive elements actually developed during postdepositional events.
Article
Geochemistry & Geophysics
Jian-Wei Zi, Birger Rasmussen, Janet R. Muhling, Ian R. Fletcher
Summary: Zircon U-Pb geochronology is crucial for calibrating the geologic timescale. This study found that zircon grains in the Brockman Iron Formation yielded ages younger than the host sedimentary rock. In situ U-Pb dating techniques were used to directly analyze zircon crystals, and the results were consistent with independent age constraints. The study also discovered that young zircon dates could be attributed to hydrothermal alteration.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2022)
Article
Geology
Birger Rasmussen, Jian-wei Zi, Janet Muhling
Summary: The early Paleoproterozoic was a time of significant changes in Earth's climate and surface environment. By studying the supracrustal sequences in the southern Pilbara craton in northwestern Australia, researchers have discovered a previously overlooked pre-Ophthalmia deformational event. This finding provides new insights into the timing and origin of major geological events during this period of global environmental change.
Article
Geosciences, Multidisciplinary
M. Ingalls, J. P. Grotzinger, T. Present, B. Rasmussen, W. W. Fischer
Summary: Phosphorus is crucial for cell biology, but it is scarce in modern marine environments due to its consumption by life or formation of apatite minerals through calcium titration. In this study, we measured the phosphate concentrations in Neoarchean carbonate facies and found that carbonates from that period were significantly enriched in carbonate-associated phosphate compared to modern marine carbonates. This suggests that early biosphere productivity was limited by electron availability rather than phosphate or other nutrients, which helps explain the central role of phosphorus in cellular molecules, metabolisms, and bioenergetics.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Raphael J. Baumgartner, Bronwyn L. Teece, Birger Rasmussen, Janet Muhling, William D. A. Rickard, Bobby Pejcic, Siyu Hu, Julien Bourdet, Stefano Caruso, Martin J. Van Kranendonk, Kliti Grice
Summary: This study reports on well-preserved organic matter (OM) within black smoker-type sulfide mineralizations from a 3.24 billion years old volcanic-hosted massive sulfide deposit in northwestern Australia. Through various techniques, the researchers traced the formation process of the mineralizations and found different degrees of thermal degradation. The results suggest that ancient marine hydrothermal systems can preserve OM and provide insights into its sourcing, cycling, and deposition.
Article
Geochemistry & Geophysics
Birger Rasmussen, Jian-Wei Zi, Janet R. Muhling
Summary: Tectonic fluid expulsion in permeable foreland basin sequences has been examined, and it has been discovered that fluids migrate through low-permeability successions. U-Pb data from the Hamersley region in Australia indicate that fluids expelled during tectonic compression migrated through older shales by fracture permeability and enhanced diffusion. The timing of veining was not random, but coincided with major orogenic events, linking fluid overpressure and hydraulic fracturing to the expulsion of heated orogenic fluids. These findings provide insight into fluid flow in geological processes.
EARTH AND PLANETARY SCIENCE LETTERS
(2023)
Article
Geosciences, Multidisciplinary
M. Ram Mohan, Neal J. McNaughton, D. Srinivasa Sarma, M. Rajamanickam, Ian R. Fletcher, Simon A. Wilde, Birger Rasmussen, Bryan Krapez, S. Balakrishnan
Summary: This study presents new SHRIMP U-Pb zircon and titanite ages, whole-rock geochemical and Sm-Nd isotopic data for granitoids in the Chitradurga Greenstone Belt. The results show that the growth of the belt is related to horizontal tectonics since at least 3.2 Ga.
JOURNAL OF ASIAN EARTH SCIENCES
(2023)
Article
Multidisciplinary Sciences
Birger Rasmussen, Janet R. Muhling
Summary: Carbon is crucial to the development of life, and its presence in ancient sedimentary rocks plays a vital role in understanding early life on Earth. The discovery of well-preserved carbon in 3.5-billion-year-old black chert provides evidence of its association with hydrothermal vent systems and suggests a microbial origin. The study of black chert veins in Australia further supports the hypothesis of carbon precipitation from silica-rich hydrothermal fluids, offering insight into a prebiotic world abundant in terrestrial organic compounds.
Article
Geology
Birger Rasmussen, Janet R. Muhling, Nicholas J. Tosca, Woodward W. Fischer
Summary: Phosphorus availability is important for primary productivity in global oceans, but its role prior to the Great Oxygenation Event (GOE) is unclear. We provide evidence for seawater precipitation of Ca-phosphate nanoparticles in iron formations deposited on a marine shelf before the onset of the GOE. Our modeling suggests that high concentrations of dissolved P in ferruginous seawater could have fueled a rapid rise in atmospheric oxygen through increased primary productivity.
Editorial Material
Multidisciplinary Sciences
Sarah P. Slotznick, Jena E. Johnson, Birger Rasmussen, Timothy D. Raub, Samuel M. Webb, Jian-Wei Zi, Joseph L. Kirschvink, Woodward W. Fischer
Summary: Sedimentological, textural, and microscale analyses of the Mount McRae Shale revealed a previously unrecognized complex postdepositional history, challenging previous claims of oxygen presence based on bulk geochemical studies. Metal enrichments were found to be associated with late-stage pyrite instead of depositional organic carbon.
Article
Geochemistry & Geophysics
Janet R. Muhling, Sarah E. Gilbert, Birger Rasmussen
Summary: This study presents in situ LA-ICP-MS analysis of REY abundances in well-preserved laminated greenalite-bearing cherts from pre-GOE ferruginous cherts and BIFs in Western Australia. Different REY patterns are observed in cherts from different depositional environments, reflecting differing source fluids and deposition environments. Furthermore, the REY patterns in greenalite-bearing cherts may differ from bulk samples of the same formations, possibly due to diagenetic overprint in the bulk samples.