赣北程浪超基性-基性杂岩特征及其Sm-Nd等时线年龄

扬子古地台板块东南前缘发育一系列晚前寒武纪移置地体。本文着重论述了彭庐地体与障公山地体间深断裂带内的铁质超基性－基性杂岩特征。主要岩石类型有纯橄榄岩、二辉橄榄岩、斜辉橄榄岩、含长橄榄辉石岩、角闪岩及辉长岩、辉绿岩。其全岩钐钕等时线年龄为８２８．６±２７．９Ｍａ，属晋宁运动产物。杂岩体产状与地体边界深断裂产状一致，与晚前寒武纪围岩地层产状斜交。杂岩体片理产状与围岩轴面流劈理产状一致，被后寒武纪地台沉积盖层不整合覆盖。推测，地体在拼贴挤压过程中，玄武岩浆从上地幔上升过程中携带了大量超基性岩块沿深断裂侵入上升就位。

CHARACTERISTICS OF THE CHENGLANG BASIC-ULTRABASIC COMPLEX IN NORTHERN JIANGXI AND ITS Sm-Nd ISOCHRON AGE

A number of Late Precambrian displaced terranes are daveloped at the southeast front of the Yangtze paleoplatform. This paper mainly discusses the features of the ferroginous ultrabasic basic complex in the deep seated fracture zone between the Penglu terrain and the Zhenggongshan terrain. The complex is composed of dunite, lherzolite, harzburgite, plagioclase bearing olivine pyroxenite, hornblendite, diabase and gabbro. It is the product of the Jinning movement with a whole rock Sm Nd isochron age of 828.6±27.9 Ma. The complex trends parallell to the deep seated boundary fracture between the terranes and obliquely to the Late Precambrian country rocks. Its schistosity is parallel to the axial plane flow cleayage of the country rocks. It is overlain unconformably by the post Cambrian platform cover. It is inferred that during the collage and compression of the terranes, the basaltic magma which carried a large number of ultrabasic blocks during its ascent from the mantle was emplaced along the deep seated fracture.