Two episodes of subduction and collision events at the northern foot of Dabie Mountains: Evidence from petrology and structural geology of granitoid rocks  

作　　者：杨坤光 马昌前 杨巍然 简平 

出　　处：《Science China Earth Sciences》2001年第3期201-212,共12页中国科学（地球科学英文版）

基　　金：We thank Department of Geology and Mineral Resources, Regional Geology of Hubei Province for chemical analyses;We thank Qiu Yi and San Haiqing, Institute of Geology, Chinese Academy of Sciences for Ar-Ar method dating; We also thank our postgraduates a

摘　　要：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.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.

关 键 词：Dabie Mountains Beihuaiyang tectonic belt GRANITOIDS polyphase collision 

分 类 号：P597[天文地球—地球化学]