The establishment and significance of the Upper Permian-Lower Triassic Tianquanshan Formation in central Qiangtang, northern Tibet: The constraint on the tectonic evolution of Lungmu Co-Shuanghu-Lancang River area
-
摘要:
藏北羌塘中部改则县以北天泉山、屏风岭等地区大面积分布一套浅变质岩系,岩性以变质杂砂岩、千枚岩为主,夹变质玄武岩、变质安山岩等火山岩夹层,因缺乏化石依据时代不明。通过LA-ICP-MS锆石U-Pb同位素定年测得安山岩的206Pb/238U年龄为251.4 ҙ2.4Ma,同时结合该地区已测得的254Ma的206Pb/238U年龄,证实这套浅变质岩系的时代应属于晚二叠世-早三叠世,并非传统意义的展金组。在剖面测制和区域对比的基础上,将天泉山、屏风岭一带的浅变质岩系重新厘定为上二叠统-下三叠统天泉山组。天泉山组的发现和建立不仅进一步完善了该区的地层系统,而且是龙木错-双湖-澜沧江洋首次发现的晚二叠世-早三叠世洋盆地层记录,为进一步丰富和研究龙木错-双湖-澜沧江洋的演化提供了重要的地层证据。
-
关键词:
- 羌塘中部 /
- 龙木错-双湖-澜沧江缝合带 /
- 天泉山组 /
- 晚二叠世-早三叠世 /
- LA-ICP-MS锆石U-Pb年龄
Abstract:There exist extensive epimetamorphic rocks in Tianquanshan and Pingfengling of Gaize County. These rocks are mainly metamorphic complex sandstone, phyllite and some interlayered volcanic rocks which are metamorphic basalt and andesite. Due to the lack of fossils, their formation epoch is unknown. There exists interlayered andesite, and the authors obtained the 206Pb/238U age of andesite (251.4±2.4Ma) by LA-ICP-MS zircon U-Pb isotope dating. Combined with the 254Ma 206Pb/238U age obtained by Fan Jianjun in the region, it is confirmed that the epimetamorphic rocks in the region should belong to the Late Permian-Early Triassic rather than to the Zhangjin Formation held by the traditional opnion. Based on the profile measurement and regional correlation, the strata of Tianquanshan and Pingfengling along the shallow metamorphic rocks are redefined as the Upper Permian-Lower Triassic Tianquanshan Formation (P3T1t). The discovery and establishment of Tianquanshan Formation (P3T1t) not only further improve the regional stratigraphic system but also provide the first oceanic basin record for Late Permian-Early Triassic strata in Lungmu Co-Shuanghu-Lancang River area. The results obtained by the authors provide important evidence for furthe study of the evolution of Lungmu Co-Shuanghu-Lancang River suture zone.
-
致谢: 在此由衷感谢吉林大学徐锋老师，吴浩博士、许伟硕士、李兴奎硕士等师兄在论文过程中的帮助。
-
![]()
图 1 藏北改则县察布乡天泉山地区地质图
1—冰海杂砾岩夹层；2—安山岩夹层；3—玄武岩夹层；4—样品采样点；5—走滑断层；6—逆断层；7—地层剖面。Cz—新生界；C2P1z—展金组；P3T1t—天泉山组；O2-3d—达瓦山组
Figure 1. Geological map of the Tianquanshan area in Chabu Town of Gaize County, northern Tibet
![]()
图 2 改则县察布乡天泉山组实测剖面
（地层代号同图 1）
Figure 2. Geological section of Tianquanshan Formation in Chabu Town，Gaize County
![]()
图版Ⅰ A.变质杂砂岩野外露头；B.变质杂砂岩镜下特征；C.硅质岩野外层状露头D.变质杂砂岩与千枚岩互层；E.印模构造；F.变质砾岩野外露头；G.玄武岩和灰岩互层；F.安山岩镜下特征
![]()
图 3 安山岩（R14T2）锆石阴极发光图像、测点编号及206Pb/238U 年龄
Figure 3. CL images,measuring point serial number and 206Pb/238U ages ofthe zircons separated from the andesite（R14T2）
![]()
图 4 安山岩（R14T2）锆石U-Pb 谐和图
Figure 4. U-Pb concordia diagram of the zircons in the andesite（R14T2）
表 1 安山岩样品（R14T2）LA-ICP-MS 锆石U-Th-Pb 同位素测年数据
Table 1 LA-ICP-MS zircon U-Th-Pb isotopic data of andesite sample（R14T2）
点号 元素含量/10-6 Th/U 同位素比值 年龄/Ma Pb 232Th 238U 207Pb/206Pb 1σ 207Pb/235U 1σ 206Pb/238U 1σ 207Pb/206Pb ratio 207Pb/235U 1σ 206Pb/238U 1σ 01 2.93 61.4 59.6 1.03 0.051 0.0085 0.28 0.046 0.039 0.0015 243 283 247 36 247 9 02 3.63 110.6 64.8 1.71 0.051 0.010 0.28 0.056 0.040 0.0016 261 329 254 44 254 10 03 2.35 51.2 44.1 1.16 0.051 0.019 0.29 0.10 0.041 0.0017 261 575 260 84 260 11 04 3.02 97.7 53.5 1.82 0.051 0.0099 0.28 0.055 0.040 0.0015 249 326 253 43 254 9 05 2.59 64.7 48.8 1.33 0.051 0.012 0.28 0.062 0.039 0.0016 238 360 248 50 249 10 06 3.34 82.4 61.9 1.33 0.052 0.0086 0.28 0.045 0.039 0.0016 265 288 251 37 250 10 07 1.97 43.1 36.6 1.18 0.051 0.017 0.28 0.091 0.040 0.0020 247 498 252 72 252 13 08 2.36 48.7 47.3 1.03 0.051 0.011 0.28 0.062 0.040 0.0016 250 357 250 49 250 10 09 2.81 56.6 54.1 1.05 0.051 0.013 0.29 0.071 0.041 0.0017 239 398 256 56 257 10 10 4.42 119.7 79.2 1.51 0.051 0.0099 0.28 0.054 0.040 0.0015 260 324 252 43 252 9 11 2.16 46.2 45.8 1.01 0.051 0.011 0.27 0.060 0.039 0.0016 244 351 245 48 245 10 12 3.47 79.7 60.3 1.32 0.051 0.0095 0.28 0.052 0.040 0.0015 257 310 252 41 252 9 13 3.13 88.8 54.1 1.64 0.052 0.012 0.28 0.065 0.040 0.0014 266 371 253 51 252 9 14 2.97 73.2 54.0 1.35 0.051 0.0064 0.28 0.036 0.040 0.0014 243 222 254 28 255 9 15 2.89 79.3 51.3 1.55 0.051 0.0082 0.27 0.044 0.039 0.0014 243 281 245 35 246 9 
下载: 导出CSV
-
李才. 青藏高原龙木错-双湖-澜沧江板块缝合带研究二十年[J]. 地质论评, 2008, 1:105-119. 李才. 龙木错-双湖-澜沧江板块缝合带与石炭-二叠纪冈瓦纳北界[J]. 长春地质学院学报, 1987, 17(2):155-166. 范建军, 李才, 彭虎, 等. 藏北龙木错-双湖-澜沧江板块缝合带发现晚石炭世-早二叠世养道姓岩石组合[J]. 地质通报, 2014, 33(11):1690-1695. 李才, 翟庆国, 陈文, 等. 青藏高原龙木错-双湖板块缝合带闭合的年代学证据——来自果干加年山蛇绿岩与流纹岩Ar-Ar和SHRIMP年龄制约[J]. 岩石学报, 2007, 23(5):911-918. 解超明, 李才, 范建军, 等. 青藏高原羌塘中部中-上奥陶统达瓦山组的建立及意义[J]. 地质通报, 2015, 34(10):1812-1820. 胡培元, 李才, 吴彦旺, 等. 龙木错-双湖-澜沧江洋的打开时限:来自斜长花岗岩的制约[J]. 科学通报, 2014, 59(20):1992-2003. 李才, 翟庆国, 董永胜, 等. 青藏高原龙木错-双湖板块缝合带与羌塘古特提斯洋演化记录[J]. 地质通报, 2007, 26(1):13-21. 李才, 谢尧武, 蒋光武等. 藏东吉塘地区冈瓦纳相冰海杂砾岩的特征及其意义[J]. 地质通报, 2008, 27(10):1654-1658. 李才, 程立人, 胡克, 等. 西藏羌塘南部地区的冰海杂砾岩及其成因[J]. 长春地质学院学报, 1995, 25(4):368-374. 范建军, 李才, 王明, 等. 青藏高原羌塘南部冰海杂砾岩的成因与物源-以冈玛错地区为例[J]. 地质通报, 2012, 31(9):1451-1460. 梁定益. 西藏阿里喀喇昆仑南部的冈瓦纳-特提斯相石炭-二叠系[J]. 武汉地质学院学报, 1983, 1:19-27. 范建军, 李才, 王明, 等. 青藏高原羌塘南部冈玛错地区展金组的沉积环境分析及碎屑锆石U-Pb定年[J]. 地质通报, 2014, 88(10):1003-1008. 李才. 羌塘基底质疑[J]. 地质评论, 2003, 16(1):4-9. 王权, 续世朝, 魏荣珠, 等. 青藏高原羌塘北部托和平错一带二叠系展金组火山岩的特征及构造环境[J]. 地质通报, 2006, 25(1/2):146-155. 王明, 李才, 解超明, 等. 藏北羌塘南部冈玛错地区展金组玄武岩的成因及其构造意义[J]. 地质通报, 2014, 33(11):1768-1777. 杨式溥, 宋志敏, 梁定益. 西藏阿里地区晚石炭世-早二叠世复理石相遗迹化石[J]. 武汉地质学院学报, 1983, 1:93-105. 李才, 翟庆国, 董永胜, 等. 青藏高原羌塘中部果干加年山上三叠统忘湖岭组的建立及意义[J]. 地质通报, 2007, 26(8):1820-1831. 许伟, 李才, 江庆源, 等. 藏北羌塘中部冈玛错-日湾茶卡地区下石炭统望果山组的建立及其地质意义[J]. 地质通报, 2014, 33(11):1697-1701. Fan J J, Li C, Xie C M, et al. Depositional environment and provenance of the Upper Permian-Lower Triassic Tianquanshan Formation, northern Tibet:implications for the Paleozoic evolution of the Southern Qiangtang, Lhasa and Himalayan terranes in the Tibetan Plateau[J]. International Geology Review, 2015, doi: 10.1080/00206814.2015.1070108. Fan J J, Li C, Xie C M, et al. Depositional environment and provenance of the Upper Permian-Lower Triassic Tianquanshan Formation, northern Tibet:implications for the Paleozoic evolution of the Southern Qiangtang, Lhasa and Himalayan terranes in the Tibetan Plateau[J]. International Geology Review, 2015, doi: 10.1080/00206814.2015.1070108.
全国地层委员会. 中国地层指南及中国地层指南说明书[M]. 北京:地质出版社, 2001. 张继淹. 广西中三叠统底模构造[J]. 广西地质, 1996, 9(4):9-12. 王起琮, 李文厚, 赵虹, 等. 鄂尔多斯盆地东南部三叠系延长组一段湖相浊积岩特征及意义[J]. 地质科学, 2006, 41(1):54-63. 李瑞保, 裴先志, 李佐臣, 等. 东昆仑南缘布青山构造混杂带哥日卓托洋岛玄武岩地球化学特征及构造意义[J]. 地学前缘, 2014, 21(1):183-195. 王忠恒, 王永胜, 谢元和, 等. 西藏班公湖-怒江缝合带中段塔仁本洋岛型玄武岩的发现及地质意义[J]. 沉积与特提斯地质, 2005, 25(1/2):155-162. Yuan H L, Gao S, Liu X M, et al. Accurate U-Pb age and trace element determinations of zircon by laser ablation-inductively coupled plasma mass spectrometry[J]. Geostandards and Geoanalytical Research, 2004, 28(3):353-370. Yuan H L, Gao S, Liu X M, et al. Accurate U-Pb age and trace element determinations of zircon by laser ablation-inductively coupled plasma mass spectrometry[J]. Geostandards and Geoanalytical Research, 2004, 28(3):353-370.
Anderson T. Correction of common lead in U-Pb analyses that do not report 204Pb[J]. Chemical Geology, 2002, 193(1/2):59-79. Anderson T. Correction of common lead in U-Pb analyses that do not report 204Pb[J]. Chemical Geology, 2002, 193(1/2):59-79.
Ludwig K R. Isoplot/Ex version 3. 00:A Geochronology Toolkit for Microsoft Excel[J]. Berkeley Geochronology Center Special Publication, 2003, 4:1-70. Ludwig K R. Isoplot/Ex version 3. 00:A Geochronology Toolkit for Microsoft Excel[J]. Berkeley Geochronology Center Special Publication, 2003, 4:1-70.
Wiedenbeck M, Alle P, Corfu F, et al. Three natural zircon standards for U-Th-Pb, Lu-Hf, trace element and REE analyses[J]. Geostandards Newsletter, 1995, 19(1):1-23. Wiedenbeck M, Alle P, Corfu F, et al. Three natural zircon standards for U-Th-Pb, Lu-Hf, trace element and REE analyses[J]. Geostandards Newsletter, 1995, 19(1):1-23.
于红. 陕西商南松树沟橄榄岩矿物地球化学特征及成因机理示踪[D]. 中国地质大学(北京)硕士学位论文, 2011. 李长民. 锆石成因矿物学与锆石微区定年综述[J]. 地质调查与研究, 2009, 33(3):161-174. 吴元保, 郑永飞. 锆石成因矿物学研究及其对U-Pb年龄解释的制约[J]. 科学通报, 2004, 49(16):1589-1604. 祝向平, 陈华安, 刘鸿飞, 等. 西藏多不杂斑岩铜矿斑岩锆石UPb年龄、岩石地球化学特征及其成矿意义[J]. 地质学报, 2015, 89(3):534-548. 祝向平, 陈华安, 刘鸿飞, 等. 西藏拿若斑岩铜金矿床成矿斑岩年代学、岩石化学特征及其成矿意义[J]. 地质学报, 2015, 89(1):109-128. 杨式溥, 宋志敏, 梁定益. 西藏阿里(狮泉河-多玛)地区中侏罗-早白垩世复理石相遗迹化石[J]. 地质学报, 1982, 4:302-315.
计量
- 文章访问数: 2053
- HTML全文浏览量: 302
- PDF下载量: 63
