大别山黄石-六安反射地震剖面新的地质解释  

New geological interpretation of the seismic reflection profile from Huangshi to Liu′an across the Dabie Mountains, China.

作　　者：徐树桐[1] 袁学诚[2] 吴维平[1] 刘贻灿[3] 

机构地区：[1]安徽省地质调查院,安徽合肥230001 [2]中国地质调查局发展研究中心,北京100083 [3]中国科学技术大学地球和空间科学系,安徽合肥230026

出　　处：《地质通报》2008年第1期19-26,共8页Geological Bulletin of China

基　　金：国家“973”专项(编号:2003CB716500);国家自然科学基金重大项目(编号:40399104);国家自然科学基金项目(编号:40542012)资助

摘　　要：在大别山黄石至六安反射地震剖面上有很多近水平的反射体,表明大别山中心部位的中、下地壳内也有近水平的分层性,反映有流变性和动力学方面的差异,与大型薄皮构造理论对岩石圈性质的认识一致,因而在其运动过程中应服从薄皮构造的运动规律。结合以往对大别山区划分的岩石-构造组合,在前人对此反射地震剖面所作的地质解释的基础上,对反射地震剖面作了较为详细的地质解释,并建立了大别山造山带在此剖面上的两维几何结构。剖面南部为造山过程中形成的背斜构造,地表15km深度内为由碰撞混杂岩组成的扬子与中-朝大陆之间的主滑脱带。剖面中部为造山期后的侵入体。剖面北部为主滑脱带的根带(通常认为的缝合带),根带被中生代形成的晓天磨子潭断裂带切割。剖面最北端为变质复理石中略晚于主滑脱带的反向冲断带。推测下地壳的断开距离在扬子大陆俯冲时(三叠纪前)规模较大,然后逐渐缩小,直至保留到今天的规模。There are many subhorizontal reflectors in the Huangshi-Liu＇an migrated seismic reflection profile across the Dabie Mountains, which suggests that subhorizontal stratification also occurs in the middle and lower crust below the central part of the Dabie Mountains and shows the difference in rheology and kinematics. This agrees with the understanding of the nature of the lithosphere based on the concept of ＂thin skin tectonics＂. On the basis of the previous geological interpretation of this seismic reflection profile, combined with the classification of the petrologic-tectonic associations of the Dabie Mountains, a more detailed geological interpretation of this profile is made and a 2D geometric architecture of the Dabie orogen along the profile is established in the present paper. In the southern part of the profile, an antiform was formed in the orogenic process, and within 15 km below the surface there occurs the main detachment between the Yangtze block and Sino-Korean block, composed of collisional meanges. The middle part of the profile is occupied by a post-orogenic intrusion. The northern part is the root zone of the main detachment, cut by the Xiaotian-Mozitan fault formed in the Mesozoic; it is commonly regarded as a suture between the two blocks. The northernmost part is the back thrust belt formed slightly later than the main detachment. It is inferred that the offset of the lower crust and Moho was large during the subduction of the Yangtze block before the Triassic and then was reduced to the present magnitude.

关 键 词：大别山 反射地震剖面 地质解释 

分 类 号：P631.425[天文地球—地质矿产勘探]