Two episodes of subduction and collision events at the northern foot of Dabie Mountains: Evidence from petrology and structural geology of granitoid rocks |
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Authors: | Yang Kunguang MA Changqian Yang Weiran JIAN Ping |
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Institution: | 1. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China 2. Yichang Institute of Geology and Mineral Resources, Yichang 443003, China |
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Abstract: | The intrusive bodies studied include Mafan diorites ((462.7±1.5) Ma,40Ar/39Ar amphibole plateau age), Duhudian granites ((293±12) Ma, U-Ph zircon age) and Suxianshi granites ((146.2±0.9) Ma) in Beihuaiyang
area at the northern foot of Dabie Mountains, central China. Petrological studies indicate that all of them belong to I-type
granitoid rocks. Among them, the Mafan and Duhudian stocks were formed by arc magmatism, while the Suxianshi pluton is a post-collisional
granitic body. Three intrusive bodies have distinctive characteristics of structural deformation. The Mafan stock has a rather
complicated structure pattern resulting from polyphase deformation during the Caledonian and Mesozoic, the Duhudian stock
has been pronouncedly deformed during the Hercynian-Yanshanian events, while regional foliation is not pronounced within the
Yanshanian Suxianshi stock. Combination of regional stratigraphic, regional structural and geochronological data shows that
the Yangtze plate has experienced two episodes of subduction northward beneath the North China plate during the Paleozoic
and following collisional events. The first phase of collision at about 400 Ma resulted in the formation of the Beihuaiyang
crystalline basement and the Caledonian high-pressure metamorphism in Dabie orogenic zone, and a late phase of continent-continent
collision (~230 Ma) is responsible for the Triassic ultrahigh- and high-pressure metamorphism in Dabie Mountains and for orogenic
uplift of the Dabie Mountains. It is suggested that the Beihuaiyang tectonic belt at the northern foot of the Dabie Mountains
is a multicyclic suture. |
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Keywords: | Dabie Mountains Beihuaiyang tectonic belt granitoids polyphase collision |
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