Preprints
Filtering by Subject: Geochemistry
The Petrology, Geochemistry, and Origin of the East Australian Potassic Suite: Bulk Chemistry and Genesis
Published: 2025-03-26
Subjects: Earth Sciences, Geochemistry, Geology, Volcanology
The Eastern Australian Potassic Suite (EAPS) is an alkaline volcanic province made up of over 20 widely dispersed outcrops that extend almost 700 km, forming the southern portion of the world’s longest continental hotspot track, the Cosgrove track. In contrast to the large basaltic volcanic complexes to the east and north, the EAPS occurs exclusively as mafic potassium–rich occurrences with [...]
Weakening of AMOC linked to past Greenland Ice Sheet retreat
Published: 2025-03-21
Subjects: Atmospheric Sciences, Climate, Earth Sciences, Geochemistry, Geology, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Paleontology, Physical Sciences and Mathematics
A weakening of the Atlantic Meridional Overturning Circulation (AMOC) is predicted to occur under multiple scenarios of future warming. However, the effect of meltwater from a decaying Greenland Ice Sheet (GrIS) on AMOC is uncertain. Using a basin-wide network of North Atlantic sediment cores, we show that the largescale melting of the GrIS during a previous interglacial (Marine Isotope Stage 11c [...]
Warm deep ocean temperatures from clumped isotopes suggest high climate sensitivity in early Cenozoic hothouse
Published: 2025-03-19
Subjects: Earth Sciences, Geochemistry
The early Cenozoic was characterized by the warmest climates and highest atmospheric CO2 levels of the past 85 Myrs. Reconstructions of deep ocean temperatures based on benthic foraminiferal oxygen isotope records are typically used to infer Earth’s global climate state during this hothouse world. However, this approach requires uncertain assumptions, regarding the seawater isotope composition [...]
Origin of the Harappan Ernestites: Fabrication and Raw Materials
Published: 2025-03-17
Subjects: Geochemistry, Geology, Other Earth Sciences
Significant developments in stone bead technology in South Asia, including drilling techniques, happened during the Harappan civilization. Among the stone drill bits used for bead making, long and constricted cylindrical drill bits made from a unique stone named Ernestite were exclusive to the Harappan civilization. Most Ernestites have been discovered in the Harappan cities in Gujarat, India. [...]
Modern Cave Monitoring Informs Interpretations of Past Climate Change: Applications to Titan Cave, Wyoming
Published: 2025-03-10
Subjects: Earth Sciences, Environmental Monitoring, Environmental Sciences, Geochemistry, Geology, Geomorphology, Hydrology, Speleology
Monitoring of cave environments is an essential process for deciphering records of past climate change preserved in the geochemical composition of speleothems, or mineral cave deposits. This study presents data from a multi-year monitoring effort in Titan Cave, Wyoming, a site of interest due to the abundance of speleothems suitable for paleoclimate reconstruction. Titan Cave exhibits annual cave [...]
Orange and Orange-Volcanoes: a New Open and Collaborative Platform to Perform Data-Driven Investigations and Machine Learning Analyses in Petrology and Volcanology
Published: 2025-03-05
Subjects: Earth Sciences, Geochemistry, Multivariate Analysis, Volcanology
Orange-Volcanoes is an extension of the open-source Orange data mining platform specifically tailored for geochemical, petrological, and volcanological investigations. Orange-Volcanoes enhances the original platform by incorporating specialized tools to enable interactive data-driven investigations in geochemistry, such as performing Compositional Data Analysis (CoDA). Applying CoDA [...]
Effects of mineralogy on ∆47 and ∆48 of carbonate-derived CO2 below analytical resolution
Published: 2025-02-18
Subjects: Geochemistry
Due to the lack of direct methods capable of determining the abundance of isotopologues containing multiple heavy isotopes within the crystal lattice, carbonates are typically reacted with phosphoric acid to produce CO2 analyte for clumped isotope analyses. This reaction is associated with fractionations of both bulk oxygen and clumped isotopes. Accurate knowledge of the effect of cation [...]
Geochemistry and Mineralogy of Ilmenite Exsolutions in Titanomagnetite and Their Implications for the Ore-Forming Process at the Damiao Deposit
Published: 2025-02-14
Subjects: Geochemistry, Geology
The Damiao Fe-Ti-P deposit, located within the Damiao anorthosite complex in northeastern China, features Fe-Ti oxide ores and nelsonites that occur as irregularly inclined stratiform-like bodies, lenses, or veins with sharp contacts against anorthosite and gabbronorite. This deposit is characterized by abundant titanomagnetite that hosts diverse ilmenite exsolution textures, including blocky, [...]
Glacially enhanced silicate weathering revealed by Holocene lake records
Published: 2025-02-07
Subjects: Biogeochemistry, Earth Sciences, Geochemistry, Physical Sciences and Mathematics
How glaciation affects CO2 drawdown by chemical weathering sets the strength of the weathering-climate feedback, which controls the exogenic carbon cycle and planetary habitability (Kump et al., 2000). However, the exact role of glaciers remains elusive as glaciation alters multiple factors controlling weathering, the net effect of which is ambiguous even in directionality. While illustrative, [...]
Widely variable granite production from a restitic metasedimentary terrane by volatile redistribution
Published: 2025-01-24
Subjects: Earth Sciences, Geochemistry, Geology, Other Earth Sciences
The amount of melt extracted from a metasedimentary source is a major parameter in quantitative models of crustal processes; however, quantification of melt volume is thwarted by the heterogeneity of the crust and a lack of estimates concerning the amount of fluid present. We observe that highly systematic trends in metasedimentary rocks allow treatment of protoliths as two component mixtures, [...]
Algal lipid distributions and hydrogen isotope ratios reflect phytoplankton community dynamics
Published: 2025-01-20
Subjects: Earth Sciences, Geochemistry, Paleobiology, Physical Sciences and Mathematics, Sedimentology
Reconstructions of past changes in algal community composition provide important context for future alterations in biogeochemical cycling. However, many existing phytoplankton proxies are indicative of individual algal groups and are not fully representative of the whole community. Here, we evaluated hydrogen isotope ratios of algal lipids (δ2HLipid) as a potential proxy for phytoplankton [...]
Divergent Paradigms of Porphyry Cu Deposits in Subduction and Collision Zones
Published: 2025-01-09
Subjects: Geochemistry, Geology, Natural Resource Economics, Physical Sciences and Mathematics
The prevailing view suggests that the formation of porphyry Cu deposits involves differentiation of water-rich, metal-bearing juvenile magmas, with subduction of oceanic slabs supplying the necessary volatiles. However, the occurrence of significant porphyry Cu deposits in continental collision zones, where such volatile sources are absent, challenges this paradigm. We analyze a global dataset of [...]
Water Storage in Hydrous Minerals in the Shallow Martian Mantle
Published: 2025-01-05
Subjects: Earth Sciences, Geochemistry, Geology, Planetary Geochemistry
In this paper we investigate the possibility of storing water in the shallow martian mantle under water-saturated fluid absent conditions for different bulk silicate mars (BSM) compositions. We performed phase equilibria experiments on two BSM compositions with comparable Mg number for pressure between 2 and 4 GPa, temperatures between 950 to 1150°C, and for a water content of 0.3 % wt. The [...]
Cambrian foreland phosphogenesis in the Khuvsgul Basin of Mongolia
Published: 2024-12-26
Subjects: Earth Sciences, Geochemistry, Geology, Sedimentology, Stratigraphy, Tectonics and Structure
Ediacaran-Cambrian phosphorite deposits in northern Mongolia have been associated with a putative increase in nutrient delivery to the global oceans that drove oxygenation and the rise of animals. However, like many phosphorites from this ~130 Myr interval, the precise age and depositional setting of these deposits remain poorly constrained. Here, we integrate new geological mapping, [...]
Disappearance of Homo floresiensis from Liang Bua alongside seasonal aridification of Flores 61,000-47,000 years ago
Published: 2024-12-10
Subjects: Atmospheric Sciences, Climate, Environmental Indicators and Impact Assessment, Fresh Water Studies, Geochemistry, Hydrology, Paleobiology, Physical Sciences and Mathematics, Speleology
The cause of the disappearance of the primitive hominin, Homo floresiensis, from the Indonesian island of Flores ~50,000 years ago is a key question in palaeoanthropology. The potential roles of human agency and climate change continue to be debated, but the history of freshwater availability critical to survival at the type locality, Liang Bua, remains unknown. Although speleothem 18O is used [...]