华南地区地幔热源活动与陆块漂移

THE ACTIVITIES OF MANTLE HEAT SOURCE AND LANDMASS DRIFT IN THE SOUTH CHINA AREA

张用夏

Zhang Yongxia

地质矿产部, 航空物探总队

Headquaters of Airborne exploration geophysics, Ministry of Geology and Mineral Resources

在华南及相邻地区广泛出现有各种级别的环形构造,它们是中生代以来深部地幔热源对上部岩石圈,特别是对上地壳塑性基底作用而形成的一种构造型式。通过对环形构造及其有关的岩浆岩的分布规律及形成时间的研究,可以了解中生代时期地幔热源的活动情况,这对于研究华南陆块的构造发育、岩浆活动,陆块漂移都是很有意义的。

Ring structures of various grades spread widely in the South China area.It is an important intra-plate structure type resulted from the action of mantle heat source on lithosphere since Mesozoic.The second grade ring appeared as four NW-trend ring-chains.The formation time was successively later and later,as moving toward SE.The author tries to explain this phenomena by landmass drift on a fixed heat source settled in mantle.The idea is set up according to the relative movement of mantle heat source (thermal plume) towards SE as the lithosphere (landmass) drifts oppositely above it.It is inferred that South China Landmass drifted a distance of about 600km towards NW during middle-late stage of Mesozoic (190-90 m.y.B.C.) with a speed of 6 km per m.y.Based on the comprehensive analysis of paleomagnetism,paleontology,paleoclimate and track of the mantle heat source,it is indicated that South China Landmass have drifted toward NW in period of Ceno-Mesozic.At Late Permian period (240 m.y.B.C.),it was located in the vicinity Of equator,in the present ocean area between New Guinea and Garoling Islands of SW Pacific.In Late Mesozoic (about 110 m.y.B.C),South China Landmass drifted northwestwards to 14?-24皀orth latitude of the present Philippine Sea Basin.During 190-25 m.y.B.C.,the diift speeded up gradually,varying from 0.6 to 3.8 cm/yr.

https://doi.org/10.11781/sysydz198502124