摘要
重点论述了秦岭—大巴山及邻区构造研究方面取得的主要新进展和新认识:(1)从地质、地球物理和区域成矿规律等方面论证了本区没有真正的古大洋,而是“洋盆化”的多期次裂陷海槽;扬子陆块与华北陆块是同一个岩石圈板块。(2)对本区重新划分构造(成矿)区,划分出11个板内裂陷—增生带和5个裂陷边缘过渡带。其中最重要的古秦岭裂陷—增生带等分别生成于元古代和早古生代。(3)秦岭构造带在不同地史阶段有不同的板内俯冲碰撞带,从早元古代到早中生代共有7条。其中商丹断裂带只是晚加里东期碰撞带,而礼县—麻沿河—山阳断裂带则是扬子陆块与华北陆块在早—中三叠纪最后一次碰撞的碰撞带。因此秦岭带是板内多旋回裂陷—增生一拼合碰撞的重叠造山带。
The paper mainly discusses the new progress and new recognition in the tsctonic study of the Qinling-Daba Mountains and their adjacent areas. (1) From many aspects, the paper demonstrates that there was no real ancient ocean in the study region but a polyphase rift sea trough and that the Yangtze and North China continental blocks belong to the same lithospheric plate. (2) A new tectonic (metallogenic) area division of the region has been made; of these areas, the most important Paleo-Qinling rift-accretion belt and others were formed in the Proterozoic and Early Paleozoic respectively. (3) Different intraplate subduction-collision zones were formed in different geological stages within the Qinling tectonic belt, of which the Shangdan fracture zone is only a late Caledonian collision zone, while the Lixian-Mayanhe-Shanyang fracture zone is a collision zone formed during the last event of collision (in the Early-Middle Triassic) of the Yangtze and North China continental blocks. Therefore, the Qinling belt is a superposed orogenic belt formed by ifntraplate polycyclic rifting-accretion-coalescence and collision.
出处
《中国区域地质》
CSCD
1993年第4期289-301,共13页
Regional Geology of China
