1)从构造磁学和同位素年代学角度,提出阿拉善地块在晚古生代很可能不是华北地块的组成部分
在深部探测技术与实验研究专项(SinoProbe)经费资助下,杨振宇研究员团队对河西走廊带-阿拉善地块中晚泥盆世-早中三叠世沉积地层进行了碎屑锆石U-Pb同位素测年、Hf同位素分析和古地磁研究,发现牛首山地区中-晚泥盆统碎屑锆石U-Pb年龄谱及Hf同位素特征与华北地块同时代碎屑锆石存在显著差异,阿拉善地块中-晚泥盆世、晚石炭世、晚二叠世、早中三叠世古地磁极与华北地块也存在明显差别,指示阿拉善地块在晚古生代很可能不是华北地块的组成部分。古地磁资料还显示,中三叠世后印支运动使阿拉善地块相对于华北发生约30度逆时针旋转,导致阿拉善地块最终与华北地块拼合。该项成果对华北地块构造格局传统认识提出了挑战。
其研究成果发表了7篇科学论文,其中4篇为SCI收录论文。
1) Yuan, W., Yang, Z. Late Devonian closure of the North Qilian Ocean: evidence from detrital zircon U–Pb geochronology and Hf isotopes in the eastern North Qilian Orogenic belt. International Geology Review, 2015, 57(2), 182-198.
2)青藏高原形成和演化的古地磁制约方面,探讨了印度与亚洲大陆碰撞过程、班公湖-怒江中特提斯洋中生代演化过程,以及青藏高原东南侧向挤出变形模式
孙知明研究员研究团队通过古地磁方法,重建了印度-亚洲大陆碰撞拼合过程,认为印度-欧亚大陆的初始碰撞时间为 47 - 54 Ma,提出印度与亚洲大陆碰撞所造成的亚洲大陆内部南北向构造缩短主要集中在拉萨地块以北的区域。重建了班公湖-怒江中特提斯洋中生代演化过程,指出班公湖-怒江特提斯洋自早三叠世至晚三叠世期间逐渐扩张,至晚三叠世时期达到最大宽度,然后逐渐缩小直至闭合。。
仝亚博副研究员团队在充分参考最新构造磁学研究成果基础之上,对已有的古地磁数据进行筛选,以期望对印亚碰撞时限进行更合理的约束。本研究结果显示,拉萨地块早白垩世时处于13.2º ± 8.6ºN的古维度位置,晚白垩世和古近纪时期分别处于10.8º ±6.7ºN和15.2º ± 5.0ºN的古续度位置。而拉萨地块晚白垩世时期的古纬度则代表了印亚碰撞前欧亚大陆的稳定南缘。对比特提斯-喜马拉雅地块晚白垩世和古近纪古地磁数据可以确定印度板块与欧亚大陆在57.5 ± 1.5Ma时期在10.8º ±6.7ºN古维度位置发生了初始碰撞。印亚板块碰撞后欧亚大陆南缘发生了约2100 ± 780km的纬向地壳收敛量,其主要是由青藏高原内部地壳褶皱变形,逆冲推服断裂以青藏高原周边区域地壳物质的侧向挤出运动所吸收。
为了印证从青藏高原东南缘保山地体内部获得的关于青藏高原东部新生代隆升过程的信息,在青藏高原东缘羌塘地块古新统-始新统贡觉组红层中进行了磁性地层学和构造磁学研究。研究结果显示,拉萨地块和羌塘地块在54-43 Ma之前就开始经历大规模的纬向地壳缩短变形,表明藏南-藏中的拉萨地块和羌塘地块在始新世早期就开始经历了地壳增厚和构造抬升。随后,自35.4 ± 2.4 Ma左右,羌塘地块以北区域开始发生纬向地壳缩短,并最终累积了~ 1300 ± 410 km的地壳缩短量。而这一时期,羌塘地块和拉萨地块则没有发生进一步的地壳缩短变变形。表明自~35.4 Ma之前青藏高原南缘已隆升至相当的海拔高度,而自~35.4 Ma开始,青藏高原北部地区才开始发生构造抬升。自渐新世-中新世开始,腾冲地块和缅泰地块开始经历顺时针运动,在这一过程中由于其青藏原东南缘位于拉萨地块和羌塘地块之间的区域不再进一步发生地壳纬向缩短运动,因而其不能为腾冲地块和缅泰地块的顺时针旋转挤出运动提供充足的地壳物质来源,以保证二者地壳块体的侧向挤出逃逸运动。因此,自渐新世以来,腾冲地块和缅泰地块主要以东南向溃缩式韧性构造变形为其主要地壳变形方式,地壳的侧向挤出运动仅占次要地位。
其研究成果发表了23篇科学论文,其中20篇为SCI收录论文。
1) Cao Yong, Sun Zhiming*, Li Haibing, Pei Junling, Xue Wei, Pan Jiawei, Zhang Lei, Ye Xiaozhou, Huang Baochun, Wang Zongxiu. New Early and Late Carboniferous paleomagnetic results from the Qaidam Block, NW China: Implications for the paleogeography of Central Asia. Tectonophysics, 2017, 717: 242–252.
2) Cao, Y., Sun, Z.M*, Li, H., Pei, J., Liu, D., Zhang, L., Ye, X., Zheng, Y., He, X., Ge, C., Jiang, W. New paleomagnetic results from Middle Jurassic limestones of the Qiangtang terrane, Tibet: Constraints on the evolution of the Bangong-Nujiang Ocean. Tectonics. 2019, 38: 315-232.
3) Cao, Y., Zhiming Sun*, Haibing Li, Junling Pei, Wan Jiang, Wei Xu, Laishi Zhao, Leizhen Wang, Chenglong Li, Xiaozhou Ye, Lei Zhang, New Late Cretaceous paleomagnetic data from volcanic rocks and red beds from the Lhasa terrane and its implications for the paleolatitude of the southern margin of Asia prior to the collision with India. Gondwana Research, 2017, 41: 337-351.
4) Gao. L., Yang, Z. Y., Tong, Y. B., et al., New paleomagnetic studies of Cretaceous and Miocene rocks from Jinggu, western Yunnan, China: Evidence for internal deformation of the Lanping-Simao Terrane. Journal of Geodynamics, 2015, 89, 39-59.
5) Sun Z., Pei,J., Li, H., Xu, W., Jiang, W., Zhu, Z., Wang, X., Yang, Z., Palaeomagnetism of late Cretaceous sediments from southern Tibet: Evidence for the consistent palaeolatitudes of the southern margin of Eurasia prior to the collision with India. Gondwana Research. 2012, 21:53-63.
6) Tong Y, Yang Z, Mao C, et al. Paleomagnetism of Eocene red-beds in the eastern part of the Qiangtang Terrane and its implications for uplift and southward crustal extrusion in the southeastern edge of the Tibetan Plateau[J]. Earth and Planetary Science Letters, 2017, 475, 1-14.
7) Tong Y, Yang Z, Pei J, et al. Paleomagnetism of the Upper Cretaceous red-beds from the eastern edge of the Lhasa Terrane: New constraints on the onset of the India-Eurasia collision and latitudinal crustal shortening in southern Eurasia[J]. Gondwana Research, 2017, 48:86-100.
8) Tong Y, Zhao Y, Pu Z. New insights of the Cenozoic Rotational Deformation of Crustal Blocks on the Southeastern Margin of the Tibetan Plateau and its Tectonic Implications[J]. ACTA GEOLOGICA SINICA (English Edition), 2017, 91(2):735-736.
9) Tong YB, Sun YJ, Wu ZH, Mao CP, Pei JL, Yang ZY, Pu ZW, Zhao Y, Xu H. Passive crustal clockwise rotational deformation of the Sichuan Basin since the Miocene and its relationship with the tectonic evolution of the fault systems on the eastern edge of the Tibetan Plateau. GSA Bulletin, 2019, 131(1-2): 175-190.
10) Tong YB, Yang ZY, Li JF, Pei JL, Li JF. New insights into the collision process of India and Eurasia: Evidence from the syntectonic-sedimentation-induced inclinational divergence of Cretaceous paleomagnetic data of the Lhasa Terrane. Earth-Science Reviews, 2019, 190: 570-588.
11) Tong, Y.B., Yang, Z.Y, Zheng, L.D., Xu, Y.L., Wang, H. Gao, L., Hu, X.Z., Internal crustal deformation in the northern part of Shan-Thai Block:New evidence from paleomagnetic results of Cretaceous and Paleogene redbeds. Tectonophysics, 2013, 608:1138-1158.
12) Tong, Y.B., Yang, Z.Y., Gao, L., Wang, H., Zhang, X.D., An, C.Z., Xu, Y.C., Paleomagnetism of Upper Cretaceous red-beds from the eastern Qiangtang Block:clockiwse rotations and latitudinal translation during the India-Asia collision. Journal of Asian Earth Sciences, 2015 114: 732-749.
13) Tong, Y.B., Yang, Z.Y., Jing, X.Q, Zhao, Y., Li, C.H, Huang, D.G, Zhang, X.D., New insights into the Cenozoic lateral extrusion of crustal blocks on the southeastern edge of Tibetan Plateau: Evidence from paleomagnetic results from Paleogene sedimentary strata of the Baoshan Terrane. Tectonic, 2016,35, doi:10.1002/2016TC004221
14) Tong, Y.B., Yang, Z.Y., Wang, H., Gao L., An, C.Z., Zhang, X.D, Xu ,Y.C., The Cenozoic rotational extrusion of the Chuan Dian Fragment: New paleomagnetic results from Paleogene red-beds on the southeastern edge of the Tibetan Plateau. Tectonophysics,2015, 658, 46-60.
15) Xu, Y. C., Yang, Z. Y., Tong, Y. B.. et al., Further paleomagnetic results for lower Permian basalts of the Baoshan Terrane, southwestern China, and paleogeographic implications. Journal of Asian Earth Sciences, 2015, 104, 99-114.
16) 仝亚博,杨振宇等. 中国西南思茅地体中部白垩纪古地磁结果及陆内地壳变形特征. 地球物理学报, 2014, 57(1): 179-198.
17) 仝亚博,杨振宇等. 青藏高原东南缘晚新生代川滇地体旋扭构造体系地壳变形特征的古地磁学分析. 地质学报. 20014, 88(11):2057-2070.
18) 孙知明, 曹勇, 李海兵, 裴军令, 仝亚博, 叶小舟, 吴百灵, 曹新文, 刘晨光. 青藏高原形成和演化的古地磁研究进展综述. 地球学报, 2019, 40(1): 17-36.
19) 孙知明,李海兵,裴军令,许伟, 潘家伟,司家亮, 刘栋梁.帕米尔-西昆仑地区新生代古地磁结果及其构造意义. 岩石学报, 2013,29(9): 3183-3191。
20) 孙知明,李海兵,裴军令,许伟,潘家伟,司家亮,赵来时,赵越.阿尔金断裂走滑作用对青藏高原东北缘山脉形成的古地磁证据. 岩石学报, 2012, 28(6): 1928-1936.
21) 曹勇,孙知明,刘栋梁,等. 拉萨地块北缘尼玛地区晚白垩世古地磁结果及其构造意义. 岩石学报, 2017, 33(12): 3989-3998.
22) 王恒,仝亚博等. 青藏高原东南缘川滇地块古近纪沉积地层古地磁分析及其构造意义. 地质通报,2015, 34(1):45-57.
23) 高亮,仝亚博等. 川滇地块古新统宁蒗组磁组构特征及构造意义. 地球物理学报. 2014, 57(1): 199-213.
3)获得了柴达木地块石炭纪可靠的古地磁结果,为晚古生代中亚块体重建提供可靠的古地磁依据
孙知明研究员研究团队通过对柴达木地块石炭系地层系统古地磁研究,获得了柴达木地块早石炭世和晚石炭世可靠的古地磁数据。结果显示柴达木地块在石炭纪期间处于北纬~27°的稳定古纬度位置,并未发生明显的南北向运动。但是柴达木地块在早石炭世至晚石炭世期间经历了约21°的逆时针旋转作用。综合中亚诸块体古地磁结果显示,柴达木地块在晚二叠世后经历了相对快速的北向飘移运动才与塔里木地块碰撞拼合。另外,根据中亚诸块体的古地磁数据重建了柴达木地块及其周边地体在石炭纪的古地理位置。(相关成果已经发表在国际SCI期刊《Tectonophysics》上)