Open Access. Powered by Scholars. Published by Universities.®

Earth Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 5 of 5

Full-Text Articles in Earth Sciences

Energy-Constrained Recharge, Assimilation, And Fractional Crystallization (Ec-Raxfc): A Visual Basic Computer Code For Calculating Trace Element And Isotope Variations Of Opensystem Magmatic Systems, Wendy A. Bohrson, Frank J. Spera Nov 2007

Energy-Constrained Recharge, Assimilation, And Fractional Crystallization (Ec-Raxfc): A Visual Basic Computer Code For Calculating Trace Element And Isotope Variations Of Opensystem Magmatic Systems, Wendy A. Bohrson, Frank J. Spera

All Faculty Scholarship for the College of the Sciences

Volcanic and plutonic rocks provide abundant evidence for complex processes that occur in magma storage and transport systems. The fingerprint of these processes, which include fractional crystallization, assimilation, and magma recharge, is captured in petrologic and geochemical characteristics of suites of cogenetic rocks. Quantitatively evaluating the relative contributions of each process requires integration of mass, species, and energy constraints, applied in a self-consistent way. The energy-constrained model Energy-Constrained Recharge, Assimilation, and Fractional Crystallization (EC-RaxFC) tracks the trace element and isotopic evolution of a magmatic system (melt + solids) undergoing simultaneous fractional crystallization, recharge, and assimilation. Mass, thermal, and compositional (trace …


Contact Metamorphism In The Malashan Dome, North Himalayan Gneiss Domes, Southern Tibet: An Example Of Shallow Extensional Tectonics In The Tethys Himalaya, Tetsuo Kawakami, Mutsuki Aoya, Simon Wallis, Jeffrey Lee, Kentaro Terada, Yu Wang, Matt Heizler Sep 2007

Contact Metamorphism In The Malashan Dome, North Himalayan Gneiss Domes, Southern Tibet: An Example Of Shallow Extensional Tectonics In The Tethys Himalaya, Tetsuo Kawakami, Mutsuki Aoya, Simon Wallis, Jeffrey Lee, Kentaro Terada, Yu Wang, Matt Heizler

All Faculty Scholarship for the College of the Sciences

Combined petrographic, structural and geochronological study of the Malashan dome, one of the North Himalayan gneiss domes, reveals that it is cored by a Miocene granite, the Malashan granite, that intruded into the Jurassic sedimentary rocks of Tethys Himalaya. Two other granites in the area are referred to as the Paiku and Cuobu granites. New zircon SHRIMP U-Pb and muscovite and biotite 40Ar-39Ar dating show that the Paiku granite was emplaced during 22.2–16.2 Ma (average 19.3 ± 3.9 Ma) and cooled rapidly to 350–400 °C at around 15.9 Ma. Whole-rock granite chemistry suggests the original granitic magma …


Evidence For Prehistoric Coseismic Folding Along The Tsaotun Segment Of The Chelungpu Fault Near Nan-Tou, Taiwan, Ashley R. Streig, Charles M. Rubin, Wen-Shan Chen, Long-Shen Lee, Stephen C. Thompson, Chris Madden, Shih-Ting Lu Mar 2007

Evidence For Prehistoric Coseismic Folding Along The Tsaotun Segment Of The Chelungpu Fault Near Nan-Tou, Taiwan, Ashley R. Streig, Charles M. Rubin, Wen-Shan Chen, Long-Shen Lee, Stephen C. Thompson, Chris Madden, Shih-Ting Lu

All Faculty Scholarship for the College of the Sciences

Taiwan's 1999 Mw 7.6 earthquake generated over 85 km surface rupture along the Chelungpu thrust fault. Paleoseismic studies at the Shi‐Jia site near Nantou city, reveal folding as the predominant form of deformation. Stratigraphic relations across the 1999 fold scarp show the style and degree of deformation caused by the penultimate event is similar to observed 1999 deformation. A boring transect across the fold scarp provides additional evidence of an earlier earthquake. Investigations at the Shi‐Jia site revealed three prehistoric events; accelerator mass spectrometry (AMS) radiocarbon ages indicate that the penultimate earthquake occurred between 1160 and 1440 A.D. Paleoseismic …


Late Cretaceous To Paleocene Metamorphism And Magmatism In The Funeral Mountains Metamorphic Core Complex, Death Valley, California, Chris G. Mattinson, Joseph P. Colgan, James R. Metcalf, Elizabeth L. Miller, Joseph L. Wooden Jan 2007

Late Cretaceous To Paleocene Metamorphism And Magmatism In The Funeral Mountains Metamorphic Core Complex, Death Valley, California, Chris G. Mattinson, Joseph P. Colgan, James R. Metcalf, Elizabeth L. Miller, Joseph L. Wooden

All Faculty Scholarship for the College of the Sciences

Amphibolite-facies Proterozoic metasedimentary rocks below the low-angle Cenozoic Boundary Canyon Detachment record deep crustal processes related to Mesozoic crustal thickening and subsequent extension. A 91.5 ± 1.4 Ma Th-Pb SHRIMP-RG (sensitive high-resolution ion microprobe–reverse geometry) monazite age from garnet-kyanite-staurolite schist constrains the age of prograde metamorphism in the lower plate. Between the Boundary Canyon Detachment and the structurally deeper, subparallel Monarch Spring fault, prograde metamorphic fabrics are overprinted by a pervasive greenschist-facies retrogression, high-strain subhorizontal mylonitic foliation, and a prominent WNW-ESE stretching lineation parallel to corrugations on the Boundary Canyon Detachment. Granitic pegmatite dikes are deformed, rotated into parallelism, and …


High- And Ultrahigh-Pressure Metamorphism In The North Qaidam And South Altyn Terranes, Western China, Chris G. Mattinson, C. A. Menold, Jian-Xin Zhang, D. K. Bird Jan 2007

High- And Ultrahigh-Pressure Metamorphism In The North Qaidam And South Altyn Terranes, Western China, Chris G. Mattinson, C. A. Menold, Jian-Xin Zhang, D. K. Bird

All Faculty Scholarship for the College of the Sciences

The North Qaidam and South Altyn terranes extend approximately 1000 km across the northern Tibetan Plateau, and five localities preserve evidence of Early Paleozoic high-pressure (HP) or ultrahigh-pressure (UHP) metamorphism, including the presence of coesite, coesite pseudomorphs, and diamond. A review of the geology, petrology, and geochronology collected over the past 10 years since these localities were discovered supports a correlation of the North Qaidam and South Altyn terranes, offset 350-400 km across the Altyn Tagh fault. Geochronology interpreted to reflect eclogite-facies metamorphism yields ages between 500 and 420 Ma; detailed geochronology from one locality supports a protracted (tens of …