摘要
北秦岭主要发育元古宙构造岩石地层单位，包括古元古代秦岭杂岩、中元古代峡河岩群、宽坪岩群和武关岩群、中元古代晚期松树沟蛇绿岩构造岩片、新元古代丹凤岩群和二郎坪岩群的下部地层单位等。北秦岭广泛存在晋宁期的强烈构造－岩浆－变质地质事件，且是新元古代主体形成的古老造山带。晋宁期的地质事件可能并不代表扬子地块和华北地块之间的直接碰撞拼合，而是具扬子地块基底特征的“中秦岭微地块”与北秦岭微地块或华北地块之间的俯冲碰撞拼合。震旦纪之后又逐渐开始发生大陆裂解，进入显生宙的构造演化阶段。新元古代晋宁期（１０００～８００Ｍａ）发生的主要地质事件和有限的俯冲—碰撞拼合及震旦纪之后又逐渐开始发生裂解与国外一些地质学家提出的新元古代时期Ｒｏｄｉｎｉａ超大陆的形成和７００～５７０Ｍａ期间Ｒｏｄｉｎｉａ超大陆的裂解不谋而合。
The Proterozoic tectono lithostratigraphic units in the North Qinling orogenic belt mainly include the Qinling complex of Paleo Proterozoic, the Xiahe Group, Kuanping Group and Wuguan Group of the Mesoproterozoic, Songshugou ophiolite tectonic slice of the Late Mesoproterozoic, the Danfeng Group and lower part lithostratigraphic units of the Neoproterozoic Erlangping Group The Qinling complex belongs to metamorphic crystalline basement( 2226 ～ 1984 Ma) of the North Qinling orogenic belt The Xiahe Group ( 1605 Ma), Kuanping Group ( 1827 ～ 1142Ma ) and Wuguan Group ( 1382 Ma) were respectively formed in the tectonic settings of the active continent margin, back arc small ocean basin and continent rift in the Mesoproterozoic The Songshugou ophiolite was formed in small ocean basin of the late Mesoproterozoic The Danfeng Group (973～825Ma) and lower part of the Erlangping Group (948～708Ma) were formed respectively in the tectonic settings of the island arc and back arc basin in the Neoproterozoic Strong tectono magmatic metamorphic geological events of the Jinning period ( 1000 ～800Ma) occurred widely in the North Qinling, which include island arc type basic intermediate basic and granitic magmatism, collisiontype granitic magmatism, tectonic emplacement of the Songshugou ophiolite, regional and high pressure metamorphism of the meta geological bodies during main metamorphic stage (996～744Ma), strong structural deformation and tectonic superimposition, as well as intensive crust accretion These geological events indicate that main body of the North Qinling was an ancient orogenic belt formed during the Neoproterozoic Although these events may not suggest a direct subduction collision integrating between the Yangtze block and North China block, they are evidences for a subduction collision integrating between “the Middle Qinling micro blocks” with characteristics of the Yangtze block basement and the North Qinling micro block or the North China block The continent breakup happened after the Sinian period in the Qinling region, which marked the beginning of the Phanerozoic tectonic evolution stages The major geological events of Jinning period( 1000 ～800Ma) and the tectonic history after the Sinian period in the Qinling orogenic belt are coincidence with the formation of the Rodinia supercontinent during the Neoproterozoic and breakup of the Rodinia supercontinent during 700～570Ma as suggested by some geologists
出处
《高校地质学报》
CAS
CSCD
1999年第2期137-147,共11页
Geological Journal of China Universities
基金
原地质矿产部区调填图项目
国家自然科学基金
关键词
秦岭造山带
北秦岭
晋宁期
地质事件
构造背景
Qinling orogen,North Qinling, Jinning period, geological events, subduction collision, tectonic settings
