Journal of Earth Science
Papers 1160
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Retrograde eclogite and garnet amphibolite of the Luliangshan unit of the Shenglikou area, North Qaidam, were studied with emphasis on rutile and titanite. A special focus is on the formation of rutile and its corona of titanite (Ttn1) in retrograde eclogite and on coarse-grained titanite (Ttn2) from the garnet amphibolite. Using zirconium (Zr)-in-rutile and Zr-in-titanite thermometers, the temperatures estimated for the formation of an early generation of rutile are 823–884 °C at 2.5–2.8 GPa, w...
The geological toolbox for the analysis of orogenic processes has seen substantial additions over the recent decades. Major advances have been made in the ability to simulate geological conditions and processes by computer modeling, we have a much improved knowledge of geochemical processes (trace elements and isotopes in particular), and, last but not least, the range and versatility of micro-analytical methods and instrumentation available to us has been expanded dramatically. The latter aspec...
This paper presents whole-rock Hf isotopic data for a suite of eclogite and garnet clinopyroxenite xenoliths hosted in the Early Cretaceous dioritic intrusions from the Xuzhou-Suzhou area along the southeastern margin of the Eastern Block of the North China Craton (NCC). Six of the eight studied xenolith samples plot significantly above the terrestrial Hf-Nd isotopic array and have eHf(0) value up to +60. All the samples define a well correlated 147Sm/144Nd-143Nd/144Nd age of 2 081 Ma, which is ...
Yushugou granulite-peridotite complex, located at the east part of the northern margin of South Tianshan, may represent an ophiolitic slice subducted to 40–50 km depth with high-pressure granulite facies metamorphism. Although a lot of studies have been conducted on rocks in this belt, the rock association and tectonic background of the ophiolitic slice are still in dispute. A detailed study on petrology, phase equilibrium modeling and U-Pb zircon ages have been performed on the metagabbro vein ...
The studied mafic granulites are located at Xiwangshan, Xuanhua region in the north of the Trans-North China Orogen (TNCO), occurring as lens within tonalite-trondhjemite-granodiorite (TTG) gneisses in the eastern part of the Xiwangshan area. The rocks contain the representative granulite-facies minerals such as garnet, clinopyroxene, orthopyroxene, plagioclase, amphibolite, rutile and quartz, and also well-developed melt pseudomorph and antiperthite. Although the prograde metamorphic stage (M1)...
Sagvandite is an enstatite+magnesite rock formed from dunite or harzburgite bodies occurring as tectonically emplaced fragments from the upper mantle in many orogenic belts by interaction with CO2-bearing crustal fluids at upper amphibolite facies P-T conditions. Sagvandite bodies occur widespread in distinct nappes in the Scandinavian Caledonides in Norway. Common to all of the many sagvandite outcrops is their general structure of radial bundles of very coarse cm-sized enstatite crystals and i...
The Sulu Orogen preserves the Neoproterozoic tectonic-magmatic events, corresponding to the breaking up of the Rodinia supercontinent. The ages and petrogenesis of meta-igneous rocks in the Liansandao area in the northern Sulu Orogen are not well-constrained. This study reports zircon U-Pb ages and Hf isotopes of these rocks from the Liansandao area. Three meta-igneous rock samples give similar weighted mean 206Pb/238U ages of 744±11, 767±12, and 762±15 Ma, respectively, indicating the Neoproter...
Global mean surface air temperature (SAT) has remained relative stagnant since the late 1990s, a phenomenon known as global warming hiatus. Despite widespread concern and discussion, there is still an open question about whether this hiatus exists, partly due to the biases in observations. The stable isotopic composition of precipitation in mid- and high-latitude continents closely tracks change of the air temperature, providing an alternative to evaluate global warming hiatus. Here we use the l...
This study reconstructed the annual mass balance (MB) of Laohugou Glacier No. 12 in the western Qilian Mountains during 1961–2015. The annual MB was calculated based on a temperature-index and an accumulation model with inputs of daily air temperature and precipitation recorded by surrounding meteorological stations. The model was calibrated by in-situ MB measurements conducted on the glacier during 2010–2015. Change in constructed annual MB had three phases. During Phase I (1961-1984), glacier-...
The magnetic fabric and petrofabric are often used as tectonic indicators of geological and geodynamic processes that a rock has experienced such as growth, deformation and metamorphism. This study presents the low field anisotropy of magnetic susceptibility (AMS) and the crystallographic preferred orientation (CPO) of constituent minerals in amphibolites from the Namcha Barwa Complex in the eastern Himalayan Syntaxis, Tibet. The bulk magnetic susceptibility varies significantly from 7.29×10−4 t...
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