Boulder, Colo., USA: GSA s dynamic online journal,
Geosphere, posts articles online regularly. Locations and topics studied this month include the Central Anatolian Plateau; the Southern Rocky Mountain Volcanic Field; petrogenesis in the Grand Canyon; and the evolution of the Portland and Tualatin forearc basins, Oregon.
A physical and chemical sedimentary record of Laramide tectonic shifts in the Cretaceous-Paleogene San Juan Basin, New Mexico, USA
Kevin M. Hobbs; Peter J. Fawcett
Abstract: Fluvial siliciclastic rocks bracketing the Cretaceous-Paleogene (K-Pg) boundary in the San Juan Basin, New Mexico (USA), provide records of regional fluvial and tectonic evolution during the Laramide orogeny. Petrographic analyses of sandstones from the Upper Cretaceous Fruitland Formation and Kirtland Formation and the Paleocene Ojo Alamo Sandstone and Nacimiento Formation show that the rivers depositing these sediments were sourced in areas where unroofing of crystalline basement rocks
reconstructed from sub-ice shelf and offshore sediments
J.A. Smith; C.-D. Hillenbrand; C. Subt; B.E. Rosenheim; T. Frederichs .
Abstract:
Because ice shelves respond to climatic forcing over a range of time
scales, from years to millennia, an understanding of their long-term
history is critically needed for predicting their future evolution. We
present the first detailed reconstruction of the Larsen C Ice Shelf (LCIS),
eastern Antarctic Peninsula (AP), based on data from sediment cores
recovered from below and in front of the ice shelf. Sedimentologic and
chronologic information reveals that the grounding line (GL) of an expanded
AP ice sheet had started its retreat from the midshelf prior to 17.7 ± 0.53
Credit: Shane Rooyakkers.
Boulder, Colo., USA: Volcanologists ability to estimate eruption risks is largely reliant on knowing where pools of magma are stored, deep in the Earth s crust. But what happens if the magma can t be spotted?
Shane Rooyakkers, a postdoctoral scholar at GNS Science in New Zealand, grew up in the shadow of Mount Taranaki on the country s North Island, hiking on the island s many volcanoes. Today, his research is revealing hidden dangers that may have been beneath his feet all along.
A new study, published yesterday in
Geology, explores a threat volcanologists discovered only recently: surprisingly shallow magma pools that are too small to be detected with common volcano monitoring equipment. Such a magma body was discovered in Iceland in 2009, when scientists with the Iceland Deep Drilling Project accidentally drilled directly into the molten rock two kilometers shallower than the depths where magma had been detected before. Magma began to creep up the d
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IMAGE: View of Mount Sharp, Mars, with buttes showing main stratigraphy of the sulfate-bearing unit to be explored by the Curiosity rover, and expected ancient environments based on observed sedimentary structures.. view more
Credit: Rapin et al., Geology
Boulder, Colo., USA: Gale Crater s central sedimentary mound (Aeolis Mons or, informally, Mount Sharp) is a 5.5-km-tall remnant of the infilling and erosion of this ancient impact crater. Given its thickness and age, Mount Sharp preserves one of the best records of early Martian climatic, hydrological, and sedimentary history.
In this paper, published today in
Geology, William Rapin and colleagues present the first description of key facies in the sulfate-bearing unit, recently observed in the distance by the rover, and propose a model for changes in depositional environments.
Boulder, Colo., USA: GSA s dynamic online journal,
Geosphere,
posts articles online regularly. Locations studied this month include the
western Himalaya, the boundary between the southern Coast Ranges and
western Transverse Ranges in California, the northern Sierra Nevada, and
northwest Nepal.
Marine sedimentary records of chemical weathering evolution in the
western Himalaya since 17 Ma
Peng Zhou; Thomas Ireland; Richard W. Murray; Peter D. Clift
Abstract:
The Indus Fan derives sediment from the western Himalaya and Karakoram.
Sediment from International Ocean Discovery Program drill sites in the
eastern part of the fan coupled with data from an industrial well near the
river mouth allow the weathering history of the region since ca. 16 Ma to