摘要
苏北东海－赣榆地区出露的东海杂岩是苏胶杂岩的重要组成部分，它代表苏胶造山带的古老中下地壳，是研究中下地壳物质组成、流变行为和苏胶Ｂ型俯冲、碰撞、多期Ａ型俯冲、伸展塌陷造山带早期演化历史的重要地区。本文通过恢复和研究东海镁铁—超镁铁岩中的蛇绿岩，追溯苏胶造山带早期演化历史，为寻找金红石、蓝晶石、金刚石、榴石宝石、石榴石、蛇纹岩等与镁铁—超镁铁岩有成因联系的矿产资源提供背景资料。
Through careful study or the metamorphic ultramafic-mafic rocks in Doughai Complex of north Jiangsu,it can be determined that most of the metamorphic ultramafite belong to metamorphic beridotite and accumulative ultramafite while the protoliths of the eclogite and amphibolite are partly accumulative mafic rock, mafie lava (spilite,keratophyre and basalt), plagiogranite, dike etc. They belong to the opbiolites that were disintegrated by tectonic movements. The Wulian-Rongcheug deep-great fault on the boundary line of Jiaobei and Subei-Jiaonan terranes approximately inclined southeast and to the south there lies the ophiolite melange belt,island -arc granite belt of Jinning episode and volcanic -sedimentary formation of back- arc basin in order. Isotopic age of eclogites demonstrates that they formed mainly in Neoproterozoic, Paleozoic and Early Mesozoic. They came not only from oceanic crust but also from continental crust. According to mentioned analyses,the Pre-Yanshanian episode evolution of Su-Jiao orogenic belt can be divided into four stages: 1. Stage of paleo- ocean forming: In Calymmian, the Su -Jiao paleo - ocean formed and on the passive margin deposited the magnesium carbonate rock-elastic rock-silicalite formation of Jinping fm. 2. Stage of B- type subduction: In Ectasian and Tonian,the paleo-oceanic crust subducted southward along trench,and consequently,on the active margin formed island -are,on the back-arc basin deposited volcanic sedimenta ry formation of Yuntai fm, along the trench formed the ophiolite complex of Doughai. 3. Stage of terranes colliding: In Cryogenian, Su - Jiao and Jiaobei terrains collided and matched together. The collision. granite belt formed and on the north margin deposited molasse and flysch formations of Shiqiao Group and Penglai Group. 4. Stage of A - type subduction: In Paleozoic and Early Mesozoic, because of multiphase intracontin.nental orogenic movements, there formed eclogite derived from continental crust and glaucophane- greenschist zone etc.
出处
《江苏地质》
1996年第1期1-8,共8页
Jiangsu Geology
关键词
蛇绿岩
苏胶造山带
晋宁运动
江苏
东海
Ophiolite Orogenic belt Jinning movement Doughai Jiangsu
