Preprints
Filtering by Subject: Geochemistry
Anomalous structure of MgCO3 liquid and the buoyancy of carbonatite melts
Published: 2019-04-23
Subjects: Earth Sciences, Geochemistry, Mineral Physics, Physical Sciences and Mathematics
MgCO3 is one of the most important components of mantle-derived carbonatite melts, and yet also one of the most difficult to study experimentally. Attempts to constrain its thermodynamic properties are hampered by decarbonation, which occurs at only ~500 °C, far below its metastable 1 bar melting temperature. Molecular dynamic simulations, however, can predict the thermodynamic properties of the [...]
Scaled Random Number Simulation of High Correlation Coefficients for Gasoline Range Compound Concentrations
Published: 2019-04-05
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
It has been common practice to plot gasoline range parameters as absolute concentrations within crude oils of either single compounds, sums of compound pairs, or the square root of the products of concentrations of compounds. If a sample of crude such as a condensate has a relatively high concentration of volatile components, then the concentration of all of the gasoline range components tends to [...]
Determining cooling rates from mica 40Ar/39Ar thermochronology data: effect of cooling path shape
Published: 2019-04-02
Subjects: Earth Sciences, Geochemistry, Geology, Other Earth Sciences, Physical Sciences and Mathematics
Tectonic models are commonly underpinned by metamorphic cooling rates derived from diffusive-loss thermochronology data. Such cooling ages are usually linked to temperature via Dodson’s 1973 closure temperature (TC) formulation, which specifies a 1/time-shaped cooling path. Geologists, however, commonly discuss cooling rates as a linear temperature/time shape. We present the results of a series [...]
A macroscale hydrogeological numerical model of the Suio hydrothermal system (central Italy)
Published: 2019-04-01
Subjects: Earth Sciences, Environmental Sciences, Geochemistry, Geology, Natural Resources and Conservation, Physical Sciences and Mathematics, Water Resource Management
The complex behaviour of the Suio hydrothermal system (central Italy) and its potential exploitation as a renewable energy source are still unclear. To quantitatively evaluate the geothermal resource, the Suio hydrothermal system has been investigated with a hydrogeological numerical model that couples fluid flow, thermal convection, and transport of diluted species inside a hybrid [...]
Direct observations of the coupling between quartz dissolution and Mg-silicate formation
Published: 2019-03-19
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
Although quartz is a stable mineral at Earth surface conditions, field samples have shown its rapid dissolution in combination with the precipitation of Mg-silicate phases. Atomic force microscopy (AFM) experiments were performed to investigate the dissolution of quartz and the precipitation of secondary phases in high-pH, Mg-rich solutions both in-situ and ex-situ. Experiments were conducted at [...]
New insights on lake sediment DNA from the catchment: importance of taphonomic and analytical issues on the record quality
Published: 2019-02-27
Subjects: Earth Sciences, Ecology and Evolutionary Biology, Geochemistry, Geology, Life Sciences, Physical Sciences and Mathematics, Sedimentology, Soil Science, Terrestrial and Aquatic Ecology
Over the last decade, an increasing number of studies have used lake sediment DNA to trace past landscape changes, agricultural activities or human presence. However, the processes responsible for lake sediment formation might affect DNA archiving via taphonomic and analytical processes. It is crucial to understand these processes to ensure reliable interpretations for “palaeo” studies. Here, we [...]
Core Formation and Geophysical Properties of Mars
Published: 2019-02-25
Subjects: Earth Sciences, Geochemistry, Mineral Physics, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Sciences
The chemical and physical properties of the interiors of terrestrial planets are largely determined during their formation and differentiation. Modeling a planet’s formation provides important insights into the properties of its core and mantle, and conversely, knowledge of those properties may constrain formational narratives. Here, we present a multi-stage model of Martian core formation in [...]
Beo v1.0: Numerical model of heat flow and low-temperature thermochronology in hydrothermal systems
Published: 2019-01-28
Subjects: Earth Sciences, Geochemistry, Geology, Hydrology, Physical Sciences and Mathematics
Low-temperature thermochronology can provide records of the thermal history of the upper crust and can be a valuable tool to quantify the history of hydrothermal systems. However, existing model codes of heat flow around hydrothermal systems do not include low-temperature thermochronology. Here I present a new model code that simulates thermal history around hydrothermal systems on geological [...]
Are U-Th dates correlated with historical records of earthquakes? Constraints from co-seismic carbonate veins within the North Anatolian Fault Zone
Published: 2019-01-22
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
U-Th dating of carbonate veins in connection with active tectonics has recently been used as an attractive tool for constraining the absolute timing of late Quaternary crustal deformations. In this study, for the first time we correlate U-Th ages of travertine deposits in co-seismic fissures along the North Anatolian Fault Zone (NAFZ) with records of Paleoseismological studies supported by [...]
Cooperative chemical-mechanical interactions during ion exchange promote rotational ordering in hydrated montmorillonite
Published: 2019-01-09
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
Ion exchange in clays plays a major role in water, nutrient, and contaminant storage and transport in clay-rich media including soils, sediments, and suspensions. Here, we show that ion exchange between sodium and potassium in hydrated montmorillonite is a cooperative process that couples ionic transport to interlayer forces that alter mesoscale particle structures. Fluctuations in cation [...]
Neoproterozoic glacial origin of the Great Unconformity
Published: 2019-01-07
Subjects: Earth Sciences, Geochemistry, Geology, Glaciology, Physical Sciences and Mathematics
The Great Unconformity, a profound gap in Earths stratigraphic record often evident below the base of the Cambrian system, has remained among the most enigmatic field observations in Earth science for over a century. While long associated directly or indirectly with the occurrence of the earliest complex animal fossils, a conclusive explanation for the formation and global extent of the Great [...]
Structural evolution and medium-temperature thermochronology of central Madagascar: implications for Gondwana amalgamation
Published: 2019-01-06
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Madagascar occupied an important place in the amalgamation of Gondwana and preserves a record of several Neoproterozoic events that are linked to orogenesis of the East African Orogen. In this study, we integrate remote sensing, field data and thermochronology to unravel complex deformation in the Ikalamavony and Itremo domains of central Madagascar. The deformation sequence comprises a gneissic [...]
Evolving marginal terranes during Neoproterozoic supercontinent reorganisation: constraints from the Bemarivo Domain in northern Madagascar
Published: 2018-11-29
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Madagascar is important for unravelling the geodynamic evolution of the transition between the Rodinia and Gondwana supercontinents as it contains several suites of c. 850–700 Ma magmatic rocks that have been postulated to correlate with other ex-Rodinia terranes. The Bemarivo Belt of northern Madagascar contains the youngest suite of these magmatic rocks that date to c. 750–700 Ma. We present [...]
Palaeoenvironmental and tectonic significance of Miocene lacustrine and palustrine carbonates (Ait Kandoula Formation) in the Ouarzazate Foreland Basin, Morocco.
Published: 2018-11-06
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Sedimentology
The Ouarzazate Basin is the southern foreland basin to the High Atlas Mountains in Morocco. The sedimentary fill records a sequence from the Eocene to Pleistocene that records the interplay between tectonics and climate. This study presents the first stable isotope and facies analyses of the Middle to Late Miocene Aït Ibrirn lacustrine Member (Aït Kandoula Formation). These data test whether [...]
New constraints from Central Chile on the origins of enriched continental compositions in thick-crusted arc magmas
Published: 2018-10-31
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics, Volcanology
Magmas from continental arcs built on thick crust have elevated incompatible element abundances and “enriched” radiogenic isotope ratios compared to magmas erupted in island and continental arcs overlying thinner crust. The relative influence of the slab, mantle, and upper plate on this variability is heavily debated. The Andean Southern Volcanic Zone (SVZ; 33-46° S) is an ideal setting to [...]