کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8908762 1636685 2018 33 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Growth of the lower continental crust via the relamination of arc magma
ترجمه فارسی عنوان
رشد پوسته قاره پایین تر از طریق تکه تکه شدن ماگما قوس
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
چکیده انگلیسی
How does continental crust transition from basaltic mantle-derived magmas into an andesitic composition? The relamination hypothesis has been presented as an alternative dynamical mechanism to classical delamination theory to explain new crust generation and has been supported by petrological and geochemical studies as well as by thermomechanical numerical modeling. However, direct evidence of this process from detailed seismic velocity structures is lacking. Here, we imaged the three-dimensional (3D) velocity structures of the crust and uppermost mantle beneath the geologically stable Ordos terrane of the North China Craton (NCC). We identify a region of continental crust that exhibits extreme growth using teleseismic data and an imaging technique that models the Common Conversion Point (CCP) stacking profiles. Our results show an approximately 400 × 400 km2 wide growth zone that underlies the primitive crust at depths of ~ 30-50 km and exhibits a gradual increase of velocity with depth. The upper layer of the growth zone has a shear wave velocity of 3.6-3.9 km/s (Vp = 6.2-6.8 km/s), indicating felsic material, and the lower layer has a shear wave velocity of 4.1-4.3 km/s (Vp = 7.2-7.5 km/s), which corresponds to mafic material. We suggest that this vertical evolution of the layered structure could be created by relamination and that the keel structure formed by relamination may be the root of the supernormal stability of the ancient Ordos terrane.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Tectonophysics - Volumes 724–725, 31 January 2018, Pages 42-50
نویسندگان
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