摘要
大别山高压、超高压变质期后构造格架的最显著特征是以罗田片麻岩穹隆为核部的多层伸展拆离滑脱带的发育，并由它们将超高压变质单元、高压变质单元和蓝闪－绿片岩单元分隔成垂向叠置的席状岩片，类似于变质核杂岩的基本结构样式．这种伸展构造格架制约了高压、超高压岩石的展布，而在较大榴辉岩体中保存的缩短或挤压组构则是以高压、超高压变质作用为标志的陆－陆碰撞事件的记录．正确地区分挤压组构与伸展组构是识别大别造山带内高压、超高压变质岩形成与折返动力学过程的关键之一．有迹象表明，在高压、超高压变质岩的折返和抬升过程中伴随有较大规模的部分熔融作用，它所反应的热状态的变化，是促使地壳由挤压体制向伸展体制转换的重要因素之一．大别山高压、超高压变质期后大规模地壳尺度的伸展和抬升，以及相伴的深熔或部分熔融作用很可能与地幔或下地壳的拆沉和岩浆的底侵作用有关．
The most prominent feature of the extension tectonic framework of post high and ultrahigh pressure metamorphism in Dabieshan is the development of the multi_layered extension detachment zones surrounding the core of the Luotian dome, and the separation of the UHP, HP and epidote blueschist units by the detachment zones, forming the vertically stacking sheet_like slices of the high and ultrahigh pressure metamorphic rocks, similar to the structural style of metamorphic core complex. The extension tectonics of post HP and UHP metamorphic event constrains the distribution and present configuration of the HP and UHP metamorphic rocks. However, the shortening and compression fabric preserved in the larger eclogite bodies is the record of continent_continent collision event marked by HP and UHP metamorphism. Correctly discriminating the compressional and the extensional fabrics is one of the key problems in the study of the geodynamic process of the formation and exhumation of HP and UHP metamorphic rocks. It is suggested that the partial melting happened in the DGC and UHP unit contemporaneous with the extrusion of UHP metamorphic rocks into the lower_middle crust, and the formation and emplacement of the migmatite and granites are the response to the change in thermal state, facilitating the transfer from the compressive regime to extension regime in the crust. The large_scale crustal extension and uplift and the accompanying anatexis in Dabieshan are probably related to the delamination and magmatic underplating in the mantle and the lower crust.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
1998年第3期225-229,共5页
Earth Science-Journal of China University of Geosciences
基金
国家自然科学基金
地质矿产部重点科技项目
关键词
变质岩
伸展构造
大别山
高压变质期
high and ultrahigh pressure metamorphic rock, post collision, extension tectonic, Dabieshan.
