Geochemical evidence for Proterozoic continental arc and continental-margin rift magmatism along the northern margin of the Yangtze Craton, South China

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doi: 10.1016/0301-9268(90)90039-S
Authors:Gao Shan; Zhang Benren; Li Zejiu
Author Affiliations:Primary:
China Univ. Geosci., Dep. Geochem., Wuhan, China
Other:
Tianjin Inst. Geol. and Miner. Resour., China
Volume Title:Geochemistry and mineralization of Proterozoic mobile belts
Volume Authors:Condie, Kent C., editor; Sun Dazhong
Source:Precambrian Research, 47(3-4), p.205-221; International symposium on the Geochemistry and mineralization of Proterozoic mobile belts, Tianjin, China, Sept. 6-10, 1988, edited by Kent C. Condie and Sun Dazhong. Publisher: Elsevier, Amsterdam, International. ISSN: 0301-9268
Publication Date:1990
Note:In English. 46 refs.; illus. incl. 5 tables, strat. cols., geol. sketch map
Summary:Middle to late Proterozoic volcanic-intrusive magmatism is well developed in this region. In the Xixiang area volcanism evolved from submarine low-K arc tholeiite through calc-alkaline to subaerial alkali or shoshonitic. This was accompanied by gradational enrichment of LREE and Zr, an increasing negative Eu anomaly and strong depletion of compatible elements Cr, Co, V and Sc. The Hannan intrusive complex evolved from gabbro through tonalite-trondhjemite-granodiorite to granite, the distribution of basic to felsic plutons suggesting arc polarity. There is a systematic lateral increase in K2O content, K2O/Na2O, and LaN/YbN towards the interior of the Yangtze craton in these rocks. The spatial framework and compositional variation resembles that found in circum-Pacific island arcs or active continental margins. In contrast the volcanic and intrusive rocks in the Beiba area are characterized by alkaline compositions and a bimodal habit; they consist of tholeiite and alkali rhyodacite-rhyolite and lack rocks of intermediate composition, and may have formed in a continental-margin rift setting. It seems that the Xixiang palaeo-arc was a mature continental arc built on older sialicbasement. The emplacement of voluminous tonalites and trondhjemites thickened the crust and may have marked an important continent-building event at the N margin of the Yangtze craton in the middle to late Proterozoic. [R.E.S.]
Subjects:Alkalic composition; Basalts; Basement; Chemical composition; Composition; Continental margin; Crustal shortening; Diorites; Gabbros; Geochemistry; Granites; Granodiorites; Igneous rocks; Intrusions; Magmas; Major elements; Mesoproterozoic; Metals; Neoproterozoic; Petrology; Plate tectonics; Plutonic rocks; Plutons; Precambrian; Proterozoic; Rare earths; Rift zones; Tectonophysics; Tholeiite; Tonalite; Trondhjemite; Upper Precambrian; Volcanic rocks; Volcanism; Asia; China; Far East; Beiba; Hannan Complex; Huodiya Group; Qinling Belt; Shensi; Southern China; Xixiang; Xixiang Group; Yangtze Craton
Abstract Numbers:91M/887
Record ID:1990043462
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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