俄罗斯北极地区前寒武纪岩相古地理特征

Sedimentary facies and palaeogeography of the Arctic area in Russia during the Precambrian

关键词:  俄罗斯北极  前寒武纪  岩相  古地理

Key words:  Arctic area in Russia  Precambrian  sedimentary facies  palaeogeography

摘要:

本文基于大量文献资料,系统研究俄罗斯北极地区前寒武纪的岩相古地理。俄罗斯北极地区前寒武纪共识别出半深海-深海区、浅海区、滨海区、冲积区和隆起剥蚀区5种古地理单元,其中,隆起剥蚀区沉积记录缺失;冲积区以砾岩+砂岩+泥岩和变质碎屑岩+碳酸盐岩为主;滨浅海区沉积则以变质碎屑岩+碳酸盐岩、蒸发岩+碳酸盐岩、砂岩+泥岩+碳酸盐岩3种岩性组合为主,局部有蒸发岩、砾岩+砂岩+泥岩发育;而半深海-深海区为大洋。俄罗斯北极地区前寒武纪古地理以滨浅海区为主,主要分布在东西伯利亚台地、西西伯利亚盆地、鄂霍茨克地块、楚科奇板块和巴伦支海北部地区;半深海-深海区的分布仅次于滨浅海区,此时西西伯利亚盆地尚未完全形成,其东侧为半深海-深海区;隆起剥蚀区分布范围小于半深海-深海区,主要分布在波罗的地盾及其周缘地区,以及东西伯利亚台地的阿纳巴尔地块和阿尔丹地盾地区;冲积区分布范围最为局限,仅在蒂曼-柏朝拉盆地中部发育。研究表明,俄罗斯北极地区广泛发育前寒武纪地层,岩性以碳酸盐岩和变质碎屑岩为主,部分构造单元中的前寒武纪地层已成为陆壳基底,前寒武纪岩相古地理特征研究可为前寒武纪地质研究提供依据,为其余地质时期的岩相古地理研究奠定基础。

Abstract:

Five palaeogeographic units have been distinguished for the Arctic area in Russia during the Precambrian, including bathyal-abyssal, shallow sea, littoral, alluvial and uplift areas. The sedimentary records are absent in the uplift areas. The conglomerate + sandstone + mudstone and metamorphic clastic rocks + carbonate rocks associations prevail over the alluvial areas. In the littoral to shallow sea areas, the deposits consist dominantly of metamorphic clastic rocks + carbonate rocks associations, evaporate + carbonate rocks associations and sandstone + mudstone + carbonate rocks associations, with locally evaporate and conglomerate + sandstone + mudstone associations. In the bathyal-abyssal areas, oceans are widespread. During the Precambrian, the littoral to shallow sea areas once predominated, and occupied the East Siberian Platform, West Siberian Basin, Ochotsk block, Chukchi block and northern Barents Sea block. The bathyal-abyssal areas appeared only in the areas east of the West Siberian Basin. The uplifted areas appeared in the Baltic Shield and its adjacent areas, Anabar block and Aldan Shield within the East Siberian Platform, The alluvial areas were restricted to the central part of the Timan-Pechora Basin. It follows that the Precambrian strata occur on a wide range of scales in the Arctic area in Russia, and lithologically consist of carbonate rocks and metamorphic clastic rocks. The approaches to the sedimentary facies and palaeogeography of the Arctic area in Russia during the Precambrian may provide useful information for the studies of the sedimentary facies and palaeogeography in other geological times.