西秦岭若尔盖—迭部地区志留系研究的新进展

本文对西秦岭若尔盖—迭部地区的志留系研究取得较大进展,建立了6个岩石地层单位,即下统的羊肠沟组、塔尔组、拉垅组、下地组,中统的马尔组和上统的卓乌阔组。并对各组的生物群特征及时代进行了讨论。首次在该区发现早志留世珊瑚动物群,主要属种有Amplexoides,Kodonophyllum cf.leijiatunense,Ceriaster,Mesofavositesshiqianensis,Fletcheria cf. sinanensis等,可与扬子区石牛栏期珊瑚群对比。对该区志留纪沉积、生态环境特征、白龙江裂陷槽演变也进行了初步讨论,并对志留系的铀、金来源、成矿带及富集期作了说明。

ADVANCE ON STUDY OF SILURIAN IN ZOIGE AND TEWO REGIONS,WEST QINLING MOUNTAINS,CHINA

The Silurian strata are well developed in Zoige Tewo regions (West Qinling) and abound with various fossils, especially in the upper part of Lower Sil. and Upper Sil. Bilscd on lithologic association features and lithostratigraphic classification the West Qinlillg Silurian may be divided into six lithostratigraphic units in ascending order as follows; Yangchanggou Formation, Tar Formation, Lalong Formation, Xiade Formation, Mar Formation and Zhuowukuo Formation (see Table 1). The present paper deals with the fauna assemblage characters for some formations as mentioned above. It is noteworthy that many rugose corals such as Amplexlides,Aphyllum, Palaeophyllum, Ceriaster, Kodonophyllum and tabulate corals Catenipora, Favosites, Mesofavosites, Syringopora, Fletcheria have been discovered for the first time in the Lower Silurian Strata from these two regions. Particularly, the Lalong Formation is rich in corals, In addition, the present paper has discussed the sedimentary and ecological environ- ment relating to palaeotectonic framework and Beilongjiang aulacogen evolution. the paper has also mentioned the source of sedimentary deposit (uranium), metal ore (gold) and their mineral belt, mineral concentration age in Zoige--Tewo regions.