东阿拉善地块诺尔公群石英岩的碎屑锆石年龄特征——物源区制约及其地质意义

发布时间：2018-05-04 17:50

本文选题：阿拉善地块 + 中元古代　；参考：《岩石矿物学杂志》2017年01期

【摘要】：传统上将阿拉善地块东部变质基底"阿拉善岩群"之上的一套以石英岩、浅粒岩、碳酸盐岩及碎屑岩为主的浅变质地层称为诺尔公群,并根据区域地层对比及叠层石化石将其归为"长城纪"。为进一步限定地层时代,对诺尔公群底部3件石英岩进行LA-MC-ICP-MS锆石U-Pb测年,获得的年龄主要集中在2 530~2 500 Ma和1 950~1 850 Ma两个年龄段内,另外还获得少量年龄为~1.69 Ga、~2.0 Ga、~2.15 Ga、~2.35 Ga、~2.7 Ga和~3.4 Ga的锆石。其中,最年轻的碎屑锆石年龄限定了诺尔公群底部石英岩的沉积时代晚于1.69 Ga,结合上覆地层的年龄数据将诺尔公群的沉积时代大致限定为1.69~1.29 Ga,肯定了阿拉善地块存在中元古代地层。石英岩中~2.5 Ga和~1.95 Ga两个显著的碎屑锆石年龄峰符合典型的华北克拉通物源区特征,因此认为,阿拉善地块在太古代-中元古代具有与华北克拉通相似的构造环境,是华北克拉通的一部分。
[Abstract]:Traditionally, a set of shallow metamorphic strata based on quartzite, shallow-grained rock, carbonate rock and clastic rock in the metamorphic basement "Alashan Group" in the eastern part of the Alashan Block is called the Norgong Group. According to regional stratigraphic correlation and stromatolite fossils, it is classified as "the Great Wall period". In order to further define the stratigraphic age, the LA-MC-ICP-MS zircon U-Pb dating of the three quartz rocks at the bottom of the Normand Group was carried out. The ages obtained are mainly within the ages of 2 530 Ma 2 500 Ma and 1 950 Ma 1 850 Ma. In addition, a small amount of zircon with an age of 1.69 Ga ~ (2. 0) ~ (2. 15) Ga ~ (2. 15) ~ (2. 35) Ga ~ (2. 35) Ga and ~ (3. 4) Ga zircon has been obtained. Of which, The youngest detrital zircon age limits the sedimentary age of the quartz rock at the bottom of the Norton group later than 1.69Ga. combined with the age data of the overlying strata, the sedimentary age of the Norgong group is roughly limited to 1.69- 1.29Ga, which confirms the existence of the Mesoproterozoic strata in the Alashan massif. Two significant zircon age peaks of 2.5 Ga and 1.95 Ga in quartzite accord with the typical North China craton provenance. Therefore, it is suggested that the Alashan block has a tectonic environment similar to that of the North China Craton in Archean and Mesoproterozoic. Is part of the North China Craton.
【作者单位】：中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室;中国地质科学院地质研究所;
【基金】：基本科研业务费专项基金(K1403)~~
【分类号】：P588.341;P597.3

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