西南极纳尔逊岛Stansbury半岛火山岩地质特征初论

纳尔逊岛Stansbury半岛被玄武质、玄武安山质熔岩和火山碎屑岩以及沉积火山碎屑岩所覆盖。区域火山岩地层对比证明其是在形成长城站地区火山岩的同一火山作用下发育起来的。据地质接触关系和岩石组合特点,初步认为该半岛火山岩地层可以进一步划分为三个岩性段,分别形成于两期火山作用。该半岛的主要构造线方向平行于菲尔德斯海峡,这在地貌特征及次火山岩的分布上得到了证实。

FIRST REPORT ON THE VOLCANIC GEOLOGY OF STANSBURY PENINSULA, NELSON ISLAND, WEST ANTARCTICA

The Stansbury Peninsula, Nelson Island, a neighbor of Fildes Peninsula, on which the Chinese Great Wall Station is located, is covered with basaltic, basalt-andesitic lavas and breccias' as well as fossiliferous volcanic-sedimentary clastic rocks. Based on the stratigra-phical relationship and the petrological characteristics the author considers that the strati-gsaphical division of volcanic rocks on Stansbury Peninsula is much similar to that in Fildes Peninsula.The volcanic rocks and volcanic-sedimentary clastic rocks are the products of two stages of volcanism and can be stratigraphically subdivided into three members. At the first stage agglomerates and breccias, interbedding basaltic, basalt-andesitic lavas and breccias formed successively, which are comparable with that of Jasper Hill plus Agate Beach Members in Fildes Peninsula. Before the end of this stage some subvolcanic intrusives appeared. The flora-bearing volcanic sedimentary clastic rocks belonging to Fossil Hill Member as found on Fildes Peninsula represent a long time break of volcanic activities on the peninsula. A lots of agglomeratic lavas and breccia on the volcanic sediments near the east coast of peninsula showes that the centre of volcanic activities of the second stage had migrated eastwards.The similar development of volcanic strata and the discovery of plant fossils provided an evidence for such a suggestion that the volcanic rocks on Stansbury Peninsula and on Fildes Peninsula resulted from the same regional volcanism in the Early Tertiary.The faults on the peninsula parallel to the Fildes Strait Fault are the main structure and control the distribution of subvolcanic intrusives in the Peninsula.