郭家岭花岗闪长岩岩体中闪长质包体的成因研究

郭家岭花岗闪长岩是胶东金矿区的重要岩体，Rb－Sr全岩等时线年龄为200．6Ma［1］。岩体中常见一种闪长质包体，这些包体具有淬火结构、变余斑状结构及索列特扩散分带，表明它们是由来自地幔的高温玄武质岩浆快速冷凝结晶形成的。包体中存在由辉石→角闪石→黑云母→石英完整的交代系列，反映了包体岩浆受到壳源长英质主岩岩浆不同程度的交代改造。包体的常量元素、微量元素及稀土元素也支持壳幔岩浆相互作用的成因解释。     

Palinspastic reconstruction of the Grenville terrane in the Blue Ridge Geologic Province,southern and central Appalachians,U.S.A

Examinations of Grenville massifs in the Blue Ridge Geologic Province of Virginia and North Carolina indicate that the country rocks (∼ 1100–1450 Ma) are layered gneisses that were metamorphosed during Grenville orogenesis (∼ 1000–1100 Ma) to amphibolite to granulite facies and intruded by plutonic suites. Subsequently, the Grenville terrane was intruded by a suite of peralkaline granitic plutons (∼ 700 Ma) and progressively overlapped westward by Upper Precambrian to Cambrian sedimentary and volcanic rocks. Following deposition of Upper Precambrian and Palaeozoic rocks, the Blue Ridge Geologic Province was subjected to Taconic metamorphism (∼ 450–480 Ma) which generally increased in intensity southeastward from greenschist (chlorite grade) to upper amphibolite (sillimanite grade) facies. Large-scale late Devonian thrusting (∼ 350 Ma) along the Fries fault system and the Brevard zone-Yadkin fault system produced the present day distribution of juxtaposed Grenville massifs and Palaeozoic metamorphic zones in the Blue Ridge Geologic Province. Palinspastic restoration of the Taconic metamorphic zones to their pre-late Devonian relative positions yields an ∼ 50 km displacement on the Fries fault system near the Grandfather Mountain window and and an ∼ 80 km displacement on the Smith River allochthon farther east. Restoration of the Grenville massifs to this same palinspastic base shows that Grenville metamorphic grade decreased southeastward from the deeper granulite facies (opx + gar) to the shallower granulite facies (opx ± amp) to amphibolite facies.