Preprints
Filtering by Subject: Geology
Controls of inherited lithospheric heterogeneity on rift linkage: Numerical and analog models of interaction between the Kenyan and Ethiopian rifts across the Turkana depression
Published: 2017-11-06
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Inherited rheological structures in the lithosphere are expected to have large impact on the architecture of continental rifts. The Turkana depression in the East African Rift connects the Main Ethiopian Rift to the north with the Kenya rift in the south. This region is characterized by a NW-SE trending band of thinned crust inherited from a Mesozoic rifting event, which is cutting the [...]
Constraints on the numerical age of the Paleocene‐Eocene boundary
Published: 2017-11-05
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Stratigraphy
Here we present combined radioisotopic dating (U-Pb zircon) and cyclostratigraphic analysis of the carbon isotope excursion at the Paleocene-Eocene (P-E) boundary in Spitsbergen to determine the numerical age of the boundary. Incorporating the total uncertainty from both radioisotopic and cyclostratigraphic data sets gives an age ranging from 55.728 to 55.964 Ma, within error of a recently [...]
Multiple Palaeoproterozoic carbon burial episodes and excursions
Published: 2017-11-05
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Stratigraphy
Organic-rich rocks (averaging 2–5% total organic carbon) and positive carbonate-carbon isotope excursions ( ‰ δC13>+5‰ and locally much higher, i.e. the Lomagundi-Jatuli Event) are hallmark features of Palaeoproterozoic successions and are assumed to archive a global event of unique environmental conditions following the c. 2.3 Ga Great Oxidation Event. Here we combine new and published [...]
Dating the termination of the Palaeoproterozoic Lomagundi-Jatuli carbon isotopic event in the North Transfennoscandian Greenstone Belt
Published: 2017-11-05
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Stratigraphy
Existing radio-isotopic age constraints indicate that the global Palaeoproterozoic Lomagundi-Jatuli large, positive carbonate carbon isotopic excursion, with δ13C values >+5‰, occurred between 2.2 and 2.06 Ga. In the North Transfennoscandian Greenstone Belt of the Kola Peninsula, NW Russia, northern Norway and Finland, the Lomagundi-Jatuli Event is recorded in the carbonate rocks of the Umba [...]
A users guide to Neoproterozoic geochronology
Published: 2017-11-05
Subjects: Earth Sciences, Geochemistry, Geology, Paleontology, Physical Sciences and Mathematics, Stratigraphy
Geochronology is essential for understanding Neoproterozoic Earth history. Here we review the types of rocks and minerals that are used to date geologic events and the analytical protocols for the different radio-isotopic decay systems employed. We discuss the limitations and potential of these methodologies for dating Neoproterozoic stratigraphy, highlighting the major sources and magnitudes of [...]
U-Pb geochronology and global context of the Charnian Supergroup, UK: Constraints on the age of key Ediacaran fossil assemblages
Published: 2017-11-05
Subjects: Earth Sciences, Geology, Paleontology, Physical Sciences and Mathematics, Stratigraphy
U-Pb (zircon) ages for key stratigraphic volcanic horizons within the ~3200-m-thick Ediacaran-age Charnian Supergroup provide an improved age model for the included Avalonian assemblage macrofossils and, hence, temporal constraints essential for intercomparisons of the Charnian fossils with other Ediacaran fossil assemblages globally. The Ives Head Formation (Blackbrook Group), the oldest exposed [...]
Duration and nature of the end-Cryogenian (Marinoan) glaciation
Published: 2017-11-05
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Stratigraphy
The end-Cryogenian glaciation (Marinoan) is portrayed commonly as the archetype of snowball Earth, yet its duration and character remain uncertain. Here we report U-Pb zircon ages for two ash beds from widely separated localities of the Marinoan-equivalent Ghaub Formation in Namibia: 639.29 ± 0.26 Ma and 635.21 ± 0.59 Ma. These findings verify, for the first time, the key prediction of the [...]
Precision and Accuracy in Geochronology
Published: 2017-11-05
Subjects: Earth Sciences, Geochemistry, Geology, Paleontology, Physical Sciences and Mathematics, Stratigraphy, Tectonics and Structure, Volcanology
Geochronology in Earth and Solar System science is increasingly in demand, and this demand is not only for more results, but for more precise, more accurate, and more easily interpreted temporal constraints. Because modern research often requires multiple dating methods, scrupulous inter- and intramethod calibration in absolute time is required. However, improved precision has highlighted [...]
Synchronizing terrestrial and marine records of environmental change across the Eocene–Oligocene transition
Published: 2017-11-05
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Stratigraphy
Synchronizing terrestrial and marine records of environmental change across the Eocene–Oligocene transition
Geological applications of digital terrain analysis
Published: 2017-11-01
Subjects: Earth Sciences, Geochemistry, Geographic Information Sciences, Geography, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Remote Sensing, Social and Behavioral Sciences, Spatial Science, Tectonics and Structure, Volcanology
Editorial to the IJGIS Special Issue on "Geological applications of digital terrain analysis". In this volume, the modern advances in the field of geological terrain analysis are presented, while emphasis is given to the quantitative analysis of modern datasets.
Reactivation of intrabasement structures during rifting - A case study from offshore southern Norway
Published: 2017-11-01
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Pre-existing structures within crystalline basement may exert a significant influence over the evolution of rifts. However, the exact manner in which these structures reactivate and thus their degree of influence over the overlying rift is poorly understood. Using borehole-constrained 2D and 3D seismic reflection data from offshore southern Norway we identify and constrain the three-dimensional [...]
A general model for the helical structure of geophysical flows in channel bends
Published: 2017-10-31
Subjects: Civil and Environmental Engineering, Earth Sciences, Engineering, Environmental Engineering, Environmental Sciences, Fluid Dynamics, Geology, Geomorphology, Geophysics and Seismology, Hydrology, Life Sciences, Natural Resources and Conservation, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Oil, Gas, and Energy, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics, Physics, Risk Analysis, Sedimentology
Meandering channels host geophysical flows that form the most extensive sediment transport systems on Earth (i.e. rivers and submarine channels). Measurements of helical flow structures in bends have been key to understanding sediment transport in rivers. Turbidity currents differ from rivers in both density and velocity profiles. These differences, and the lack of field measurements of turbidity [...]
Nature, origin and evolution of a Late Pleistocene incised valley-fill, Sunda Shelf, Southeast Asia
Published: 2017-10-31
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Understanding the stratigraphic fill and reconstructing the palaeo-hydrology of incised valleys can help to constrain those factors that controlled their origin, evolution and regional significance. This condition is addressed through the analysis of a large (up to 18 km wide by 80 m deep) and exceptionally well-imaged Late Pleistocene incised valley from the Sunda Shelf (South China Sea) based [...]
Development of cutoff-related knickpoints during early evolution of submarine channels
Published: 2017-10-30
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics
Submarine channels are often thought of as having relatively simple geometries, with significant along-channel morphologic and stratigraphic continuity. Using high-resolution seismic reflection data from offshore Angola and a kinematic model of channel evolution, we present evidence that channels on the seafloor can develop slope variability as a result of meander cutoff events. When cutoffs [...]
Seismic Interpretation of Sill-Complexes in Sedimentary Basins: The ‘Sub-Sill Imaging Problem’
Published: 2017-10-30
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Application of 3D-seismic reflection-data to igneous systems in sedimentary basins has led to a revolution in the understanding of mafic sill-complexes. However, there is considerable uncertainty on how geometries and architecture of sill complexes within the subsurface relates those imaged in seismic reflection-data. To provide constraints on how sill complexes in seismic data should be [...]