نتایج جستجو برای: lower crust

تعداد نتایج: 699706  

Journal: :Geophysical Research Letters 2023

The outward growth of many orogens occurs through pulsed migration the strain front. During Cenozoic shortening central Andes, front abruptly migrated ∼400 km eastward across Altiplano, isolating plateau interior from major deformation. In contrast to traditional critical wedge model that focuses on shallow crust deformation, our lithosphere-scale numerical models show ductile lower plays a key...

2006
L. A. COOGAN

The mechanism of heat extraction from the lower oceanic crust near the ridge axis is poorly constrained despite its importance for understanding both the process of accretion of the plutonic complex and the mass fluxes associated with ridge hydrothermal systems. We have investigated the role of zones of focussed fluid flow in the plutonic complex of the Oman ophiolite in the near-axis cooling o...

2008
Pak Kin Wong Fuqu Yu Arash Shahangian Genhong Cheng Ren Sun Ming Ho

Continental crust rises higher than oceanic crust because it is less dense: It is rich in Si and poor in Mg. However, basalt, which is derived from magma, is denser and has a higher ratio of Mg to Si than the rock that makes up mature continental crust. Cin-Ty Lee et al. argue that chemical weathering alters the composition of continental crust as it ages and helps give it its more buoyant char...

2014
Sascha Brune Christian Heine Marta Pérez-Gussinyé Stephan V. Sobolev

When continents break apart, continental crust and lithosphere are thinned until break-up is achieved and an oceanic basin is formed. The most remarkable and least understood structures associated with this process are up to 200 km wide areas of hyper-extended continental crust, which are partitioned between conjugate margins with pronounced asymmetry. Here we show, using high-resolution thermo...

2010
Jean-Alix Barrat Akira Yamaguchi Brigitte Zanda Claire Bollinger Marcel Bohn

The eucrites and diogenites are meteorites that probably originate from asteroid 4-Vesta. The upper part of the crust of this body is certainly composed of eucrites which are basaltic or gabbroic rocks. Diogenites are ultramafic cumulates whose relationships with eucritic lithologies are unknown. Here, we show that the orthopyroxenes of some diogenites display very deep negative Eu anomalies (E...

2008
G. E. Hilley K. M. Johnson M. Wang Z. - K. Shen R. Bürgmann

Fault slip rate estimates along the Altyn Tagh and Kunlun strike-slip faults in northern Tibet vary considerably between short-term geodetic and long-term geologic studies. Here we reanalyze and model all global positioning system (GPS) data from northern Tibet to determine if these differences might be explained by previously unmodeled transient processes associated with the earthquake cycle, ...

2002
Inmaculada Serrano Dapeng Zhao José Morales

Three-dimensional P and S wave velocity models of the crust under the Granada Basin in Southern Spain are obtained with a spatial resolution of 5 km in the horizontal direction and 2 to 4 km in depth. We used a total of 15407 P and 13704 S wave highquality arrival times from 2889 local earthquakes recorded by both permanent seismic networks and portable stations deployed in the area. The comput...

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