Stratigraphy and Geological Correlation ( IF 1 ) Pub Date : 2020-11-27 , DOI: 10.1134/s0869593820060064 I. K. Kozakov , T. I. Kirnozova , V. P. Kovach , M. M. Fugzan , Yu. V. Plotkina , Ch. Erdenejargal
Abstract
The Dzabkhan terrane, represented by the basement of the Tsaganolom Formation carbonate sequences referring to the Ediacaran shelf cover, was considered as an ancient cratonic fragment in the structure of the Central Asian Fold Belt. It was assumed that its sequences marked the regional unconformity between the Early and Late Precambrian deposits. However, the occurrence of the Tsaganolom Formation rocks on high-temperature metamorphic rocks is established only in the Bogdoingol block (eastern part of the Dzabkhan terrane), where dolomites unconformably superimpose migmatized gneisses and intruding granitoids, for which the age of 717 ± 5 Ma was determined. Synmetamorphic quartz diorites with zircon age of 847 ± 3 Ma (U–Pb, ID-TIMS) are found in gneisses and migmatites of the Bogdoingol block. The tNd (DM-2st) values are 1.97 Ga in gneisses, while in quartz diorites tNd (DM-2st) = 2.0 Ga.
中文翻译:
Dzabkhan Terrane(中亚褶皱带)Bogdoingol块结晶基底的新元古代时代
摘要
由Tsaganolom组碳酸盐岩层序的基底所代表的Dzabkhan地层,指的是Ediacaran陆架覆盖层,被认为是中亚褶皱带结构中的一个古代克拉通碎片。假定其序列标志着早寒武世沉积晚期与晚寒武纪沉积之间的区域不整合。但是,仅在Bogdoingol区块(Dzabkhan地块的东部)中才建立了高温变质岩上Tsaganolom组岩石的存在,那里白云岩不整合地叠加了半球形的片麻岩和侵入的花岗岩,年龄为717±5 Ma被确定。在Bogdoingol块的片麻岩和辉锰矿中发现锆石年龄为847±3 Ma的同形变石英石英闪长岩(U–Pb,ID-TIMS)。t Nd(DM-2st)在片麻岩中,该值为1.97 Ga,而在石英闪石中,t Nd(DM-2st) = 2.0 Ga。