Preprints
Filtering by Subject: Physical Sciences and Mathematics
An Ice-Free Arctic Ocean During the Last Interglacial: An unsupported statement
Published: 2023-09-01
Subjects: Physical Sciences and Mathematics
The Last Interglacial has attracted the attention of researchers as it was globally characterized by a climate optimum warmer than that of the preindustrial period. In particular, several attempts at reconstructing the Arctic Ocean sea-ice extent of this interval were made based on marine sedimentary archives, all failed to find clear evidence of sea-ice-free conditions. An article published [...]
Towards an astrochronological framework for the lower Paleoproterozoic Kuruman and Brockman Iron Formations
Published: 2023-09-01
Subjects: Earth Sciences, Physical Sciences and Mathematics, Stratigraphy
Recent evidence for astronomical-induced cycles in banded iron formations (BIFs) hints at the intriguing possibility of developing astrochronological, i.e. precise time-stratigraphic, frameworks for the earliest Proterozoic as also reconstructed for parts of the Mesozoic and Paleozoic. The ca 2.47-Ga Kuruman Iron Formation (Griqualand West Basin, South Africa) and Dales Gorge Member of the [...]
SeisMIC - an Open Source Python Toolset to Compute Velocity Changes from Ambient Seismic Noise
Published: 2023-09-01
Subjects: Computer Sciences, Earth Sciences, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We present SeisMIC, a fast, versatile, and adaptable open-source software to estimate seismic velocity changes from ambient seismic noise. SeisMIC includes a broad set of tools and functions to facilitate end-to-end processing of ambient noise data, from data retrieval and raw data analysis via spectrogram computation, over waveform coherence analysis, to post-processing of the final velocity [...]
The Whakamaru Magmatic System (Taupō Volcanic Zone, New Zealand), Part 1: Evidence from tephra deposits for the eruption of multiple magma types through time
Published: 2023-08-31
Subjects: Physical Sciences and Mathematics
The Whakamaru group eruptions (349 ± 4 ka; Downs et al., 2014) are the largest known eruptions in the history of the young Taupō Volcanic Zone, Aotearoa New Zealand. The complex field relationships of the ignimbrites have thus far obscured the timing and history of their eruption(s). We present new evidence from fall deposits correlated with the Whakamaru eruptions to complement the ignimbrite [...]
The Whakamaru Magmatic System (Taupō Volcanic Zone, New Zealand), Part 2: Evidence from ignimbrite deposits for pre-eruptive distribution of melt-dominated magma and magma mushes
Published: 2023-08-31
Subjects: Physical Sciences and Mathematics
The complex volcanology and petrology of the Whakamaru volcanic deposits in Aotearoa New Zealand have thus far obscured the number of eruptive phases and the relative timing of these eruption(s). We investigate pumice clasts from multiple localities to elucidate the relative timing of the eruptions, with a focus on the pre-eruptive conditions of the melt-dominated magma bodies that fed the [...]
Independent estimates of net carbon uptake in croplands: UAV-LiDAR and machine learning vs. eddy-covariance
Published: 2023-08-30
Subjects: Engineering, Life Sciences, Physical Sciences and Mathematics
Understanding sequestration of organic carbon (C) in agroecosystems is of primary importance for greenhouse gas (GHG) accounting in managed ecosystems, reducing the environmental footprint of land use, and inform crediting programs. However, a broader application of precise C accounting is currently constrained by a limited number of direct flux measurements. Aside well-studied ecosystems via the [...]
What can radar-based measures of subglacial hydrology tell us about basal shear stress? A case study at Thwaites Glacier, West Antarctica
Published: 2023-08-29
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
Ice sheet models use observations to infer basal shear stress, but the variety of methods and datasets available has resulted in a wide range of estimates. Radar-based metrics such as reflectivity and specularity content have been used to characterize subglacial hydrologic conditions that are linked to spatial variations in basal shear stress. We explore whether radar metrics can be used to [...]
Lithium isotope constraints on the plumeworld hypothesis for the Marinoan Snowball Earth
Published: 2023-08-26
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
The Snowball Earth hypothesis predicts that continental chemical weathering was curtailed substantially during but rebounded strongly after the Marinoan ice age some 635 million years ago. Defrosting the planet would result in a plume of fresh glacial meltwater with a different chemical composition than underlying hypersaline seawater, generating an onshore-offshore geochemical gradient. Here we [...]
Sea Ice Loss, Water Vapor Increases, and Their Interactions with Atmospheric Energy Transport in Driving Seasonal Polar Amplification
Published: 2023-08-25
Subjects: Physical Sciences and Mathematics
The ice-albedo feedback associated with sea ice loss contributes to polar amplification, while the water vapor feedback contributes to tropical amplification of surface warming. However, these feedbacks are not independent of atmospheric energy transport, raising the possibility of complex interactions that may obscure the drivers of polar amplification, in particular its manifestation across the [...]
Determining the Pressure – Temperature – Composition (P-T-X) conditions of magma storage
Published: 2023-08-24
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
Determining the pressures and temperatures at which melts are stored in the crust and upper mantle, and the major element composition, redox state and volatile contents of these melts, is vital to constrain the structure and dynamics of magmatic plumbing systems. In turn, constraining these parameters helps understand the geochemical and structural evolution of the Earth’s lithosphere, and [...]
Biomarker Indicators of Past Climate
Published: 2023-08-24
Subjects: Physical Sciences and Mathematics
The molecular remainders of living organisms, found in sedimentary records, reflect past ecological, environmental and climatic conditions. Occurrence, abundance, relative distribution and even isotopic composition of these lipid biomarkers can be linked to climatic conditions. This chapter reviews organic proxies for past temperature, salinity, hydrology, sea ice conditions and biomass burning.
Earth's tectonic and plate boundary evolution over 1.8 billion years
Published: 2023-08-23
Subjects: Physical Sciences and Mathematics
Understanding the intricate relationships between the solid Earth and its surface systems in deep time necessitates comprehensive full-plate tectonic reconstructions that include evolving plate boundaries and oceanic plates. In particular, a tectonic reconstruction that spans multiple supercontinent cycles is important to understand the long-term evolution of Earth's interior, surface [...]
A proxy implementation of thermal pressurization for earthquake cycle modeling on rate-and-state faults
Published: 2023-08-22
Subjects: Physical Sciences and Mathematics
The reduction of effective normal stress during earthquake slip due to thermal pressurization of fault pore fluids is a significant fault weakening mechanism. Explicit incorporation of this process into frictional fault models involves solving the diffusion equations for fluid pressure and temperature outside the fault at each time step, which significantly increases the computational complexity. [...]
GossenAIA2015-RapaNuislides
Published: 2023-08-21
Subjects: Earth Sciences, Environmental Sciences, Physical Sciences and Mathematics
A slide presentation from AIA 116th Annual Conference, New Orleans, Jan 8-11 2015. The 149 slides in pdf format are from the original Keynote presentation: Deforestation, Drought and Humans: The Collapse Theory is Dead-New Evidence of Sustainability and Survival.
Temperature and hydrological variations during the Late-Glacial in the central Mediterranean: application of the novel ostracod-clumped isotope thermometer
Published: 2023-08-19
Subjects: Physical Sciences and Mathematics
This study shows, for the first time, the absence of a vital effect in the clumped isotope carbonate (Δ47) fossil ostracod signal and confirms the ability of the novel ostracod-Δ47 thermometer to reconstruct past temperatures and hydrological conditions in complex lacustrine systems. Furthermore, the application of Δ47 analyses on the ostracod species Candona angulata and Cyprideis torosa from [...]