论文摘要
The Tibetan Plateau, sandwiched among the Tarim, North China, South China, and India blocks, is a collage of microcontinents rifted and drifted from the northern margin of Gondwanaland toward Eurasia from the Late Paleozoic period. As one of the crucial tectonic components in Tibetan Plateau, the kinematic process of the northern Qiangtang Block is still unclear. One of the main reasons is that the quantitative paleomagnetic dataset to determine the paleoposition is sparse. To add more available paleomagnetic data into dataset, in these years, we carried out systematic paleomagnetic work on the Paleozoic to Mesozoic strata of the northern Qiangtang Block（Table 1）. We obtained the Early-Middle Silurian paleomagnetic dataset from northern Longmucuo-Shuanghu suture. The dataset, based on 49 limestone specimens（6 sites）, passed the reversal test（C class） with 95% confidence level. The paleopole was calculated to be at 43.2°N, 352.8°E with A95 = 5.7°（N = 6）, and correspond to the paleolatitude of 25.1°S± 8.7° for the reference site. In the following context, a common reference point located at 33.7°N, 86.9°E is used for all paleolatitude comparisons. For the Early Devonian Period, characteristic remanent magnetizations（ChRM） derived from 33 limestone specimens（5 sites） which were sampled from the Mayigangri area of the hinterland of Qiangtang. The dataset passed the reversal test which corresponds to the paleopole at 44.5 °N, 243.4°E with A95 = 4.0° and paleolatitude of 9.0°S± 4.0°. For the Permian, the dataset derived from 10 sites of Changshehu and Xueyuanhe formations that passed bake, fold and reversal tests. The paleopole and paleolatitude are at 31.7°N, 226.8°E with A95 = 9.3°and 15.4°S± 9.3°, correspondingly（Cheng et al., 2012 a）. For the Late Permian, the Ch RM was obtained from the 253 volcanic samples（30 sites） of Nayixiong formation which were sampled from the Nuoribanabao area. The primary remanence was testified by the fold tests. The paleopole and paleolatitude located at 10.6°N, 189.4°E with A95 = 4.0°（N = 30） and 12.1°S± 4.0°. For the Triassic period, the datasets for the Early and Late Triassic Period were obtained from the eight sites（74 samples） and eight sites（62 samples）, respectively. Both the Early and Late Triassic datasets passed the fold tests. The Paleopoles were calculated to be at 24.9°N, 216.5°E with A95 = 8.2°（N = 8） for the Early Triassic dataset, and 80.4°N, 185.2°E with A95 = 7.5°（N = 7） for the Late Triassic. These paleopoles correspond to the paleolatitudes of 14.3°S± 8.2° and 31.8°N± 7.5°, respectively. For the Middle-Late Jurassic, the datasets were based on the 342 sedimentary rocks samples（29 sites） of Yanshiping group at the Yanshiping and Shuangquanhe areas. The result indicates that the northern Qiangtang Block located at（20-24） °N during that period（Cheng et al., 2012 b）. Our data combined with previously published results, a three-stage northward drift process of the northern Qiangtang Block was reconstruct
论文目录
文章来源
类型: 国际会议
作者: ZHOU Yanan,WU Hanning,CHENG Xin,YANG Xingfeng,JIANG Nan,SHAO Ruiqi
来源: 第九届世界华人地质科学研讨会 2019-06-01
年度: 2019
分类: 基础科学
专业: 地质学,地球物理学
单位: Department of Geology & State Key Laboratory of Continental Dynamics, Northwest UniversityInstitute of science and technology strategy of Jiangxi academy of sciences
分类号: P542;P318.44
DOI: 10.26914/c.cnkihy.2019.028422
页码: 256-257
总页数: 2
文件大小: 112k
下载量: 5