Preprints
Filtering by Subject: Geochemistry
Volcanic-plutonic parity and the differentiation of the continental crust
Published: 2018-10-04
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Volcanology
The continental crust is central to the biological and geological history of Earth. However, crustal heterogeneity has prevented a thorough geochemical comparison of its primary igneous building blocks – volcanic and plutonic rocks – and the processes by which they differentiate to felsic compositions. Our analysis of a comprehensive global dataset of volcanic and plutonic whole-rock geochemistry [...]
Statistical geochemistry reveals disruption in secular lithospheric evolution about 2.5 Gyr ago
Published: 2018-10-03
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
Secular cooling of the Earth is required by surface heat loss and declining radiogenic heat production over the last 4.5 billion years. Igneous geochemistry has been used to understand how changing heat flux influenced Archean geodynamics, but records of systematic geochemical evolution are complicated by heterogeneity of the rock record and uncertainties regarding selection and preservation [...]
A stochastic sampling approach to zircon eruption age interpretation
Published: 2018-10-03
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Volcanology
The accessory mineral zircon is widely used to constrain the timing of igneous processes such as magma crystallization or eruption. However, zircon U-Pb ages record zircon crystallization, which is not an instantaneous process. Zircon saturation calculations link zircon crystallization, temperature, and melt fraction, allowing for the estimation of zircon crystallization distributions as a [...]
Plate tectonics and continental basaltic geochemistry throughout Earth history
Published: 2018-10-03
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
Basaltic magmas constitute the primary mass flux from Earths mantle to its crust, carrying information about the conditions of mantle melting through which they were generated. As such, changes in the average basaltic geochemistry through time reflect changes in underlying parameters such as mantle potential temperature and the geodynamic setting of mantle melting. However, sampling bias, [...]
Temporal variation in relative zircon abundance throughout Earth history
Published: 2018-10-03
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
Zircon is the preeminent chronometer of deep time on Earth, informing models of crustal growth and providing our only direct window into the Hadean Eon. However, the quantity of zircon crystallised per unit mass of magma is highly variable, complicating interpretation of the terrestrial zircon record. Here we combine zircon saturation simulations with a dataset of ∼52,000 igneous whole rock [...]
Statistics and segmentation: Using Big Data to assess Cascades Arc compositional variability
Published: 2018-09-24
Subjects: Applied Mathematics, Applied Statistics, Earth Sciences, Geochemistry, Geology, Multivariate Analysis, Physical Sciences and Mathematics, Statistics and Probability, Volcanology
Primitive lavas erupted in the Cascades arc of western North America demonstrate significant patterns of along-arc heterogeneity. Such compositional diversity may be the result of differences in mantle melting processes, subduction geometry, regional tectonics, or compositions of the slab, mantle or overlying lithosphere. Previous authors have partitioned the arc into four geochemically distinct [...]
Dalangtan Saline Playa in a Hyperarid Region of Tibet Plateua-III: Correlated Multiscale Surface Mineralogy and Geochemistry Survey
Published: 2018-08-15
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
We report the first multiscale, systematic field-based testing of correlations between orbital scale advanced spaceborne thermal emission and reflection radiometer visible near-infrared (VNIR)/shortwave infrared (SWIR) reflectance and thermal infrared relative emissivity and outcrop scale Raman spectroscopy, VNIR reflectance, X-ray diffraction (XRD), and laser-induced breakdown spectroscopy [...]
Capturing the Mesoarchean Emergence of Continental Crust in the Coorg Block, Southern India
Published: 2018-07-17
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Tectonics and Structure
The emergence of Earths continental crust above sea‐level is debated. To assess whether emergence can be observed at a regional scale, we present zircon U‐Pb‐Hf‐O isotope data from magmatic rocks of the Coorg Block, southern India. A 3.5 Ga granodiorite records the earliest felsic crust in the region. Younger phases of magmatism at 3.37‐3.27 Ga and 3.19‐3.14 Ga, comprising both reworked crust and [...]
Cyclic CO2 – H2O injection and residual trapping: implications for CO2 injection efficiency and storage security
Published: 2018-06-28
Subjects: Earth Sciences, Environmental Sciences, Geochemistry, Geology, Oil, Gas, and Energy, Physical Sciences and Mathematics, Sustainability
To meet the Paris Agreement target of limiting global warming to 2ºC or below it is widely accepted that Carbon Capture and Storage (CCS) will have to be deployed at scale. The influence of residual trapping on CO2 well injectivity and its response over time has a major impact on the injection efficiency and storage capacity of CO2 storage sites. For the first time, experiments have been [...]
A fossiliferous spherule-rich bed at the Cretaceous-Paleogene (K-Pg) boundary in Mississippi, USA: implications for the K-Pg mass extinction event in the MS Embayment and Eastern Gulf Coastal Plain
Published: 2018-06-14
Subjects: Astrophysics and Astronomy, Earth Sciences, Geochemistry, Geology, Paleobiology, Paleontology, Physical Sciences and Mathematics, Sedimentology
We describe an outcrop of the Cretaceous–Paleogene (K–Pg) boundary exposed due to construction near New Albany, Union County, Mississippi. It consists of the Owl Creek Formation and overlying Clayton Formation. The Owl Creek Formation is rich in the ammonites Discoscaphites iris and Eubaculites carinatus, which, along with biostratigraphically important dinoflagellate cysts and calcareous [...]
Insights into agricultural influences and weathering processes from major ion patters
Published: 2018-06-04
Subjects: Chemistry, Earth Sciences, Environmental Chemistry, Environmental Sciences, Geochemistry, Hydrology, Physical Sciences and Mathematics, Water Resource Management
Karst areas and their catchments pose a great challenge for protection because fast conduit flow results in low natural attenuation of anthropogenic contaminants. Studies of the hydrochemistry of karst sources and river solutes are an important tool for securing and managing water resources. A study of the geochemical downriver evolution of the Wiesent River and its tributaries, located in a [...]
Experimental and Geochemical Modeling Evidences of Mineral Sequestration of CO2 in Saline Siliciclastic aquifers
Published: 2018-05-22
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The validity of mineral sequestration in saline siliciclastic aquifers in sedimentary basins is assessed in this paper. Mineral sequestration is the precipitation of carbonates due to the dissolution of silicates upon the injection of CO2 in deep geological formations, while solubility trapping is the dissolution of CO2 in the formation water. Saline reservoirs in sedimentary basins seem to [...]
Metabolite cycling indicated by long-range correlation in a sediment bioreactor mixed microbial community
Published: 2018-05-16
Subjects: Biogeochemistry, Earth Sciences, Environmental Sciences, Geochemistry, Physical Sciences and Mathematics
Geophysical surveys add value to biogeochemical studies because of their ability to characterize systems remotely, and their precise time resolution. One limitation, however, is their lack of biogeochemical process specificity. Here, electrochemical time series from an oxic-anoxic cyclical bioreactor experiment were reanalyzed with detrended fluctuation analysis (DFA) to distinguish dominant [...]
The Mesozoic and Palaeozoic granitoids of north-western New Guinea
Published: 2018-05-09
Subjects: Earth Sciences, Geochemistry, Geology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
A large portion of the Birds Head Peninsula of NW New Guinea is an inlier that reveals the pre-Cenozoic geological history of the northern margin of eastern Gondwana. The peninsula is dominated by a regional basement high exposing Gondwanan (Australian) Palaeozoic metasediments intruded by Palaeozoic and Mesozoic granitoids. Here, we present the first comprehensive study of these granitoids, [...]
Late Pliocene marine pCO2 reconstructions from the Subarctic Pacific Ocean
Published: 2018-04-30
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
The development of large ice-sheets across the Northern Hemisphere during the late Pliocene and the emergence of the glacial-interglacial cycles that punctuate the Quaternary mark a significant threshold in Earths climate history. Although a number of different mechanisms have been proposed to initiate this cooling and the onset of major Northern Hemisphere glaciation, reductions in atmospheric [...]