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Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Upper Plate Reverse Fault Reactivation And The Unclamping Of The Megathrust During The 2014 Northern Chile Earthquake Sequence, Gabriel González, Pablo Salazar, John P. Loveless, Richard W. Allmendinger, Felipe Aron, Mahesh Shrivastava
Upper Plate Reverse Fault Reactivation And The Unclamping Of The Megathrust During The 2014 Northern Chile Earthquake Sequence, Gabriel González, Pablo Salazar, John P. Loveless, Richard W. Allmendinger, Felipe Aron, Mahesh Shrivastava
Geosciences: Faculty Publications
After 137 years without a great earthquake, the Mw 8.1 Pisagua event of 1 April 2014 occurred in the central portion of the southern Peru–northern Chile subduction zone. This megathrust earthquake was preceded by more than 2 weeks of foreshock activity migrating ∼3.5 km/day toward the mainshock hypocenter. This foreshock sequence was triggered by an Mw 6.7 earthquake on a reverse fault in the upper plate that strikes at a high angle to the trench, similar to well-documented reverse faults onshore. These margin-oblique reverse faults accommodate north-south shortening resulting from subduction across a plate boundary that is curved in map …
Fossils Of Putative Marine Algae From The Cryogenian Glacial Interlude Of Mongolia, Phoebe A. Cohen, Francis A. Macdonald, Sara Pruss, Emily Matys, Tanja Bosak
Fossils Of Putative Marine Algae From The Cryogenian Glacial Interlude Of Mongolia, Phoebe A. Cohen, Francis A. Macdonald, Sara Pruss, Emily Matys, Tanja Bosak
Geosciences: Faculty Publications
Neoproterozoic carbonate successions provide a new taphonomic window into the diversification of eukaryotes. We report recently discovered macroscopic organic warty sheets (MOWS) in macerates of limestone from the ca. 662-635 Ma Taishir Formation (Tsagaan Olom Group, Mongolia). Sheets are applanate. One surface contains raised ridges and conspicuous, ∼ 100-μm-tall warty protuberances with depressed tops that enclose internal cavities containing cellular structures. The Taishir MOWS may be the remains of unusual bacterial, protistan, or fungal biofilms, or a previously undocumented, extinct taxon. However, multiple lines of evidence including the morphology of warty protuberances and the presence of cellular architecture within protuberances …
Total Variation Regularization Of Geodetically And Geologically Constrained Block Models For The Western United States, Eileen L. Evans, John P. Loveless, Brendan J. Meade
Total Variation Regularization Of Geodetically And Geologically Constrained Block Models For The Western United States, Eileen L. Evans, John P. Loveless, Brendan J. Meade
Geosciences: Faculty Publications
Geodetic observations of interseismic deformation in the Western United States provide con- straints on microplate rotations, earthquake cycle processes, and slip partitioning across the Pacific–North America Plate boundary. These measurements may be interpreted using block models, in which the upper crust is divided into microplates bounded by faults that accumulate strain in a first-order approximation of earthquake cycle processes. The number and geometry of microplates are typically defined with boundaries representing a limited subset of the large number of potentially seismogenic faults. An alternative approach is to include a large number of potentially active faults bounding a dense array of …
Kinematic Barrier Constraints On The Magnitudes Of Additional Great Earthquakes Off The East Coast Of Japan, John P. Loveless, Brendan J. Meade
Kinematic Barrier Constraints On The Magnitudes Of Additional Great Earthquakes Off The East Coast Of Japan, John P. Loveless, Brendan J. Meade
Geosciences: Faculty Publications
No abstract provided.
Taphonomic Bias Of Selective Silicification Revealed By Paired Petrographic And Insoluble Residue Analysis, Sara B. Pruss, Jonathan L. Payne, Sophie Westacott
Taphonomic Bias Of Selective Silicification Revealed By Paired Petrographic And Insoluble Residue Analysis, Sara B. Pruss, Jonathan L. Payne, Sophie Westacott
Geosciences: Faculty Publications
Silicification is an important mode of fossil preservation but the extent to which silicified material represents an unbiased sampling of the total fossil assemblage within a given rock sample remains poorly quantified. Here, we use paired analyses of thin sections and acid-extracted silicified specimens from the same samples to examine the biases introduced during silicification of Lower Triassic Virgin Limestone carbonates preserved in the Muddy Mountains of southern Nevada. Bivalves dominate most thin sections in the point count data, but rarely silicify completely enough to be recognized in residue. Echinoderms and gastropods are less abundant in thin section but dominate …
Sinuous Rhizoliths Mimic Invertebrate Trace Fossils On Upper Pleistocene Caliche Surfaces, San Salvador Island, Bahamas, H. Allen Curran
Sinuous Rhizoliths Mimic Invertebrate Trace Fossils On Upper Pleistocene Caliche Surfaces, San Salvador Island, Bahamas, H. Allen Curran
Geosciences: Faculty Publications
The Pleistocene–Holocene boundary on islands of the Bahama Archipelago is typically marked by a calichified paleosol horizon that formed on exposed limestone surfaces during lowered sea level of the Last Glacial. On the north coast of San Salvador, an extensive laminar caliche surface is present west of Singer Bar Point. Formed on Upper Pleistocene (Eemian) carbonate eolianite and overlain by Holocene eolianite, this surface bears numerous and distinctive large, sinuous structures typically preserved in half relief, and with sharp, parallel ridge-like edges that slope inward to form a smooth, medial ‘trough’ having widths mostly between 1 and 3 cm. Individual …