Preprints
Filtering by Subject: Stratigraphy
Temporal evolution of extensional fault-propagation folds
Published: 2017-11-23
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Stratigraphy, Tectonics and Structure
Integration of three-dimensional seismic and well data from the Upper Jurassic North Sea rift provides insights into the temporal evolution of fault-propagation folds in extensional settings. The hangingwall of the Oseberg fault zone is characterised by an asymmetric, fault-parallel syncline interpreted as the hangingwall portion of a breached monocline which formed in response to an [...]
Seismic and structural characterization of a pre-salt rifted section: the Lagoa Feia Group, Campos Basin, offshore Brazil
Published: 2017-11-17
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Stratigraphy
The exploration of pre-salt offshore SE Brazil presents a multifaceted deep-water scenario that is bringing new challenges to seismic interpretation in offshore Brazilian exploration and production. Reservoirs in this domain are complex, heterogeneous with layered carbonates which makes accurate reservoir characterization very challenging. Our study here deals with the seismic characterization of [...]
Punctuated Sediment Discharge During Early Pliocene Birth of the Colorado River: Evidence from Regional Stratigraphy, Sedimentology, and Paleontology
Published: 2017-11-14
Subjects: Earth Sciences, Physical Sciences and Mathematics, Stratigraphy
The Colorado River in the southwestern U.S. provides an excellent natural laboratory for studying the origins of a continent-scale river system, because deposits that formed prior to and during river initiation are well exposed in the lower river valley and nearby basinal sink. This paper presents a synthesis of regional stratigraphy, sedimentology, and micropaleontology from the southern Bouse [...]
Distribution of discontinuous mudstone beds within wave-dominated shallow-marine deposits: Star Point Sandstone and Blackhawk Formation, Eastern Utah, USA
Published: 2017-11-08
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Deposits of wave-dominated shorelines are typically considered to act as relatively simple hydrocarbon reservoirs and are commonly modeled as “tanks of sand”. However, important heterogeneities that can act as barriers to fluid flow occur at the parasequence, bedset and bed scales, especially in viscous oil or low permeability oil fields. Heterogeneities at the parasequence and bedset scale have [...]
Environmental signal propagation in sedimentary systems across timescales
Published: 2017-11-07
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Review of concepts of environmental signal (climate, tectonics, anthropogenic, etc.) propagation in sedimentary systems from source to sink.
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
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 [...]
Cenozoic contourites in the eastern Great Australian Bight, offshore southern Australia: implications for the onset of the Leeuwin Current
Published: 2017-10-24
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Volcanology
Thermohaline oceanic currents influence global heat transfer, controlling local and global variations in climate, biodiversity, and the terrestrial biosphere. Paleoceanographic studies typically use biostratigraphic and geochemical proxies to reconstruct the dynamics of these currents in Earth’s ancient oceans, although seismic reflection data have also been successfully employed, most commonly [...]