https://scholars.lib.ntu.edu.tw/handle/123456789/37585
Title: | Evidence against subduction-related magmatism for the Jiaoziyan Gabbro, northern Dabie Shan, China | Authors: | Tsai, Chin-Ho Lo, Ching-Hua Liou, Juhn G. Jahn, Bor-ming |
Keywords: | Cretaceous; Dabie Mountains; Extension tectonics; Gabbros; Petrogenesis | Issue Date: | 2000 | Journal Volume: | 28 | Journal Issue: | 10 | Start page/Pages: | 943-946 | Source: | Geology | Abstract: | The largest gabbroic intrusion, Jiaoziyan, in the Northern Orthogneiss of the Dabie Shan was investigated to test whether such intrusions represent arc-related or collision-related magma, as postulated in recent regional tectonic models. The Jiaoziyan intrusions comprise a gabbro-monzogabbro suite and are locally characterized by cumulus textured anhydrous silicates. Petrologic indications against arc magmatism include (1) coexisting olivine-plagioclase compositions beyond the documented range of arc gabbros, and (2) a compositional trend of Al/Ti ratios in the gabbroic clinopyroxenes that is significantly different from subduction-related gabbros worldwide. In contrast, the Jiaoziyan rocks are mineralogically similar to rift gabbros. Geochronologic and geometric arguments against collision-related magmatism (i.e., as a consequence of slab break off) include the following: (1) crystallization of the Jiaoziyan mafic intrusion postdated the Triassic (245-240 Ma) subduction and peak orogenic metamorphism by ~100 m.y. and (2) the rocks of the Dabie Cretaceous magmatic suite, including Jiaoziyan, are on the footwall plate, rather than on the hanging wall, of the Triassic subduction-zone framework and do not show a linear distribution. These observations argue that the voluminous Early Cretaceous magmatism in the Northern Orthogneiss is geodynamically unrelated to the Qinling-Dabie orogeny, but was caused by extensional tectonism related to regional magmatic under-plating beneath the thinned Dabie crust. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/172288 http://ntur.lib.ntu.edu.tw/bitstream/246246/172288/1/14.pdf https://www.scopus.com/inward/record.uri?eid=2-s2.0-84879883516&doi=10.1130%2f0091-7613%282000%2928%3c943%3aEASMFT%3e2.0.CO%3b2&partnerID=40&md5=4d0be26765ee2f1ba6ec4fabc16d8af0 |
DOI: | 10.1130/0091-7613(2000)028<0943:EASRMF>2.3.CO;2 |
Appears in Collections: | 地質科學系 |
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