Blog Profile / GeoScienceWorld


URL :http://geoscienceworld.org/
Filed Under:Academics / Geology
Posts on Regator:265
Posts / Week:5.8
Archived Since:September 5, 2016

Blog Post Archive

Fluid-rock interaction is decisive for the formation of tungsten deposits

Tungsten mineralization is typically associated with reduced granitic magmas of crustal origin. While this type of magmatism is widespread, economic tungsten deposits are highly localized, with ~90% produced from only three countries worldwide. Show More Summary

10Be dating of late Pleistocene megafloods and Cordilleran Ice Sheet retreat in the northwestern United States

During the late Pleistocene, multiple floods from drainage of glacial Lake Missoula further eroded a vast anastomosing network of bedrock channels, coulees, and cataracts, forming the Channeled Scabland of eastern Washington State (United States). Show More Summary

The onset of the Dead Sea transform based on calcite age-strain analyses

The onset and evolution of the Dead Sea transform are re-evaluated based on new in situ U-Pb dating and strain analyses of mechanically twinned calcites. Direct dating of 30 syn-faulting calcites from 10 different inactive fault strands...Show More Summary

Did Paleo-Tethyan anoxia kill arc magma fertility for porphyry copper formation?

The Tethyan orogen is host to numerous porphyry Cu ± Mo ± Au deposits, but the majority formed during subduction of the Neo-Tethyan ocean basin in the late Mesozoic–Cenozoic; very few deposits have been found associated with Paleo-Tethyan subduction. Show More Summary

Biological memory of the first Pleistocene glaciation in New Zealand

Living species retain memories of their evolutionary history in their DNA, and that evolutionary history commonly reflects distinct geological events, such as mountain building and glaciation. We synthesize previously documented genetic...Show More Summary

Magma sheets defined with magnetic susceptibility in the Maiden Creek sill, Henry Mountains, Utah, USA

In the ~20-m-thick Maiden Creek sill of the Henry Mountains (Utah, USA) intrusive complex, 2 magma sheets are locally separated by a 1.5-m-thick lens of sandstone. We studied the boundary between these sheets at the termination of this...Show More Summary

A triple S-shaped compositional profile in a Karoo dolerite sill--Evidence of concurrent multiple fractionation processes

Thick dolerite sills show a range of vertical geochemical variation trends attributable to various processes during slow crystallization. We have identified chemical parameters in a 169-m-thick sill from the Karoo igneous province in...Show More Summary

Precarious ephemeral refugia during the earliest Triassic

The term refuge describes, in both ecology and paleoecology, an ecosystem that acts as a sanctuary during times of environmental stress. This study tests the concept by examining the fate of a single community that lived ~50 k.y. after the end-Permian mass extinction (EPME). Show More Summary

Biotic effects on oxygen consumption during weathering: Implications for the second rise of oxygen

The oxygen concentration of the atmosphere likely increased substantially in the late Neoproterozoic. Although several studies have presented compelling geochemical evidence for this stepwise oxygenation, few have addressed the mechanisms behind it. Show More Summary

Persistence of a freshwater surface ocean after a snowball Earth

Geochemical data from cap carbonates deposited above Cryogenian glacial deposits have been widely used to infer the conditions that prevailed in the aftermath of snowball Earth. However, the time scale over which these carbonates were...Show More Summary

Middle Eocene CO2 and climate reconstructed from the sediment fill of a subarctic kimberlite maar

Eocene paleoclimate reconstructions are rarely accompanied by parallel estimates of CO 2 from the same locality, complicating assessment of the equilibrium climate response to elevated CO 2. We reconstruct temperature, precipitation, and CO 2 from latest middle Eocene (ca. Show More Summary

Zircon petrochronological evidence for a plutonic-volcanic connection in porphyry copper deposits

Bridging the gap between the plutonic and volcanic realms is essential for understanding a variety of magmatic processes from caldera-forming eruptions to the formation of magmatic-hydrothermal ore deposits. Porphyry copper depositsShow More Summary

Small profile concavity of a fine-bed alluvial channel

Although most natural streams have concave-upward longitudinal profiles, there are conflicting perspectives about whether an alluvial channel is less concave than a bedrock channel. Alluvial channels can be classified as coarse-bed and fine-bed channels, depending on the bed grain size. Show More Summary

A volcanic trigger for the Late Ordovician mass extinction? Mercury data from south China and Laurentia

The Late Ordovician mass extinction (LOME), one of the five largest Phanerozoic biodiversity depletions, occurred in two pulses associated with the expansion and contraction of ice sheets on Gondwana during the Hirnantian Age. It isShow More Summary

Recognizing seamount-forearc collisions at accretionary margins: Insights from discrete numerical simulations

We conducted discrete numerical simulations to examine the effects of seamount collisions with forearcs along actively accreting subduction margins. Modeled seamount interactions leave behind distinctive structures in overriding forearcs that differ from those found at non-accreting margins. Show More Summary

Xenoconformities and the stratigraphic record of paleoenvironmental change

Most interpretations of the stratigraphic record are founded on the premise that the depositional environments that produced it either have not changed appreciably through time, or else have changed very slowly. Paradoxically, some of...Show More Summary

El Nino-Southern Oscillation-like variability in a late Miocene Caribbean coral

Reconstructions of Pliocene sea-surface temperature (SST) gradients and thermocline depths suggest that the zonal temperature gradient of the tropical Pacific was distinct from the modern. However, the nature of any El Niño–Southern Oscillation (ENSO) variability superimposed on this mean state is difficult to determine. Show More Summary

Plateau subduction, intraslab seismicity, and the Denali (Alaska) volcanic gap

Tectonic tremors in Alaska (USA) are associated with subduction of the Yakutat plateau, but their origins are unclear due to lack of depth constraints. We have processed tremor recordings to extract low-frequency earthquakes (LFEs), and generated a set of six LFE waveform templates via iterative network matched filtering and stacking. Show More Summary

Copyright © 2015 Regator, LLC