The Pb-Pb Isochron Age of the Kuangshishan Formation in Shennongjia Area on the Northern Margin of the Yangtze Craton and Its Geological Implications
-
摘要: 扬子克拉通北缘神农架地区出露了大量中元古代碳酸盐岩地层,但已有的同位素年代学资料有限,故对神农架群矿石山组白云岩开展了全岩Pb-Pb等时线测年.研究结果表明,矿石山组白云岩206Pb/204Pb变化范围相对较大,为18.753~23.106,而207Pb/204Pb和208Pb/204Pb则变化范围相对较小,分别为15.606~16.046和37.793~38.599.八件白云岩样品206Pb/204Pb和207Pb/204Pb之间呈良好的线性关系,构成Pb-Pb等时线年龄为1632±75Ma(MSWD=8.7),代表了矿石山组地层主体沉积时代,与已有的年代学结果可对应,表明Pb-Pb同位素体系可对古老的碳酸盐岩地层进行较为精确地定年.结合前人对于神农架群的年代学资料,确定神农架群的沉积时限应为1600~1100Ma的中元古代.Abstract: The Shennongjia Group, located on the northern margin of the Yangtze Craton, shows a series of well-preserved succession of the Mesoproterozoic carbonate strata. However, geochronological data collected from this area are limited. In this study, we report a Pb-Pb isochron age for the Kuangshishan Formation of the Shennongjia Group. The 206Pb/204Pb ratios of the dolostone of the Kuangshishan Formation show wide variations from 18.753 to 23.106. On the contrary, the 207Pb/204Pb ratios and the 208Pb/204Pb ratios have a limited range from 15.606 to 16.046 and 37.793 to 38.599, respectively. 8 dolostone samples data show an obvious linear relationship between 206Pb/204Pb and 207Pb/204Pb, yielding a Pb-Pb isochron age of 1632±75Ma (MSWD=8.7) which represent the depositional age for the Kuangshishan Formation. This age accords well with previous published data, indicating that a precise stratigraphic age of the ancient carbonate strata can be obtained through Pb-Pb dating technique. Combined with previous researches, we suggest that the age span of the Shennongjia Group is 1600 to 1100Ma of Mesoproterozoic.
-
Key words:
- Shennongjia Group /
- Kuangshishan Formation /
- Pb-Pb isochron /
- Mesoproterozoic /
- carbonate /
- petrology
-
图 2 神农架地区中元古代地层柱状图及采样点位
1.砾岩;2.砂砾岩;3.砂岩;4.粉砂岩;5.页岩/板岩;6.燧石;7.石灰岩;8.白云岩;9.角砾状白云岩;10.硅质条带白云岩;11.叠层石白云岩;12.火山岩;13.凝灰岩;14.整合接触关系;15.平行不整合接触关系;16.采样点;据李怀坤等(2013) 修改
Fig. 2. Mesoproterozoic stratigraphic histogram of the Shennongjia area and the sampling locations of the Kuangshishan Formation
表 1 神农架群矿石山组Pb同位素组成
Table 1. Pb isotope compositions of carbonate rocks from the Kuangshishan Formation, Shennongjia Group
序号 样号 岩性 206Pb/204Pb 2δ 207Pb/204Pb 2δ 208Pb/204Pb 2δ 1 12SNJ-72 块状白云岩 19.038 0.005 15.641 0.004 38.135 0.006 2 12SNJ-73 含黑色叠层石白云岩 19.774 0.005 15.707 0.004 37.897 0.008 3 12SNJ-75 块状白云岩 18.753 0.002 15.606 0.002 37.793 0.004 4 12SNJ-76 块状白云岩 20.322 0.007 15.740 0.006 38.341 0.009 5 12SNJ-77 含黑色叠层石白云岩 18.433 0.004 15.625 0.004 38.241 0.010 6 12SNJ-78 泥质条带白云岩 23.106 0.003 16.046 0.002 38.100 0.005 7 12SNJ-81 泥质条带白云岩 19.621 0.005 15.711 0.004 38.016 0.007 8 12SNJ-83 含叠层石白云岩 19.786 0.006 15.719 0.008 38.599 0.003 9 12SNJ-84 块状白云岩 21.076 0.005 15.830 0.004 38.114 0.001 -
[1] Abati, J., Aghzer, A.M., Gerdes, A., et al., 2010.Detrital Zircon Ages of Neoproterozoic Sequences of the Moroccan Anti-Atlas Belt.Precambrian Research, 181(1-4):115-128.doi: 10.1016/j.precamres.2010.05.018 [2] Chang, X.Y., Chen, L.Z., Hu, S.X., et al., 2004.Pb-Pb Isotope Dating of the Chengjiang Fauna-Bearing Beds.Acta Geoscientica Sinica, 25(2):181-184(in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-GSWX198703000.htm [3] Chen, J.H., Edwards, R.L., Wasserburg, G.J., 1986.238U, 234U and 232Th in Seawater.Earth and Planetary Science Letters, 80(3-4): 241-251.doi: 10.1016/0012-821X(86)90108-1 [4] Chen, D.F., Dong, W.Q., Zhu, B.Q., et al., 2004.Pb-Pb Ages of Neoproterozoic Doushantuo Phosphorites in South China: Constraints on Early Metazoan Evolution and Glaciation Events.Precambrian Research, 132(1-2):123-132.doi: 10.1016/j.precamres.2004.02.005 [5] Chen, Y.Q., Jiang, S.Y., Ling, H.F., et al., 2009.Pb-Pb Dating of Black Shales from the Lower Cambrian and Neoproterozoic Strata, South China.Chemie der Erde, 69(2):183-189.doi: 10.1016/j.chemer.2008.12.005 [6] Deng, Q., Wang, J., Wang, Z.J., et al., 2013.New Evidence for the Age of the Macaoyuan Group on the Northern Margin of the Yangtze Block, South China—Implications for Stratigraphic Correlation and Palaeogeographic Framework.Geological Bulletin of China, 32(4):631-638(in Chinese with English abstract). https://www.researchgate.net/profile/Zhengjiang_Wang/publications [7] Fölling, P.G., Zartman, R.E., Frimmel, H.E., 2000.A Novel Approach to Double-Spike Pb-Pb Dating of Carbonate Rocks: Examples from Neoproterozoic Sequences in Southern Africa.Chemical Geology, 171(1-2):97-122.doi: 10.1016/S0009-2541(00)00204-7 [8] Gao, F.H., Yang, Y., Wang, F., et al., 2014.Determination of the Early Paleozoic Strata in Eastern Heilongjiang Province: Evidence from Field Geology and Detrital Zircon U-Pb Geochronology.Earth Science, 39(5):499-508(in Chinese with English abstract). https://www.researchgate.net/publication/287618885_Determination_of_the_early_Paleozoic_strata_in_eastern_Heilongjiang_Province_Evidence_from_field_geology_and_detrital_zircon_U-Pb_geochronology [9] Gao, M., Qiao, X.F., Liu, D.Y., et al., 1995.Direct Determination of the Pb-Pb Age of Carbonate Rocks of the Sailinhudong Formation of Inner Mongolia.Regional Geology of China, 4:348-352(in Chinese with English abstract). https://www.researchgate.net/publication/232748704_PbPb_dating_of_young_marbles_from_Taiwan [10] Gao, M., Liu, D.Y., Li, Y.A., 1996.Direct Dating of Carboniferous Coral Fossils from Carbonate Using Pb-Pb Isotopic Method.Geological Review, 42(1):22-29 (in Chinese with English abstract). https://www.researchgate.net/publication/222193598_The_challenge_of_direct_dating_old_human_fossils [11] Gopalan, K., Kumar, A., Kumar, S., et al., 2013.Depositional History of the Upper Vindhyan Succession, Central India: Time Constraints from Pb-Pb Isochron Ages of Its Carbonate Components.Precambrian Research, 233:108-117.doi: 10.1016/j.precamres.2013.04.014 [12] Kuznetsov, A.B., Ovchinnikova, G.V., Gorokhov, I.M., et al., 2013.Age Constraints on the Neoproterozoic Baikal Group from Combined Sr Isotopes and Pb-Pb Dating of Carbonates from the Baikal Type Section, Southeastern Siberia.Journal of Asian Earth Sciences, 62:51-66.doi: 10.1016/j.jseaes.2011.06.003 [13] Li, H.K., Lu, S.N., Xiang, Z.Q., et al., 2007.SHRIMP U-Pb Geochronological Research on Detrital Zircons from Complex-Group in the Western Segment of the North Qilian Mountains, Northwest China.Geological Review, 53(1):133-140(in Chinese with English abstract). https://www.researchgate.net/publication/285751583_SHRIMP_U-Pb_geochronological_research_on_detrital_zircons_from_the_Beidahe_Complex_Group_in_the_western_segment_of_the_North_Qilian_Mountains_Northwest_China [14] Li, H.K., Zhang, C.L., Xiang, Z.Q., et al., 2013.Zircon and Baddeleyite U-Pb Geochronology of the Shennongjia Group in the Yangtze Craton and Its Tectonic Significance.Acta Petrologica Sinica, 29(2) :673-697 (in Chinese with English abstract). https://www.researchgate.net/publication/286123963_Zircon_and_baddeleyite_U-Pb_geochronology_of_the_Shennongjia_Group_in_the_Yangtze_Craton_and_its_tectonic_significance [15] Li, H.Y., Xu, Y.G., Huang, X.L., et al., 2009.Activation of Northern Margin of the North China Craton in Late Paleozoic:Evidence from U-Pb Dating and Hf Isotopes of Detrital Zircons from the Upper Carboniferous Taiyuan Formation in the Ningwu-Jingle Basin.Chinese Science Bulletin, 54(4):677-686.(in Chinese with English abstract). doi: 10.1007/s11434-008-0444-9 [16] Li, Q., Leng, J., 1987.The Upper Precambrian in the Shennongjia Region.Tianjin Science and Technology Press, Tianjin (in Chinese). [17] Liu, C.X., Mao, X.W., Wei, Y.X., et al., 2004.A Preliminary Reseaech on Stratigraphic Sequence of Shengnong Group.Resources Environment & Engineering, 18(Suppl.):5-16 (in Chinese with English abstract). https://www.researchgate.net/publication/284964870_A_preliminary_research_on_stratigraphic_sequence_of_Shennongjia_Group [18] Liu, X.M., Ling, W.L., Gao, S., 2010.Proterozoic Crustal Evolution of Yangtze Craton Revealed by Detrital Zircons from Shennongjia Area, South China.In: 19th V.M.Goldschmidt Conference, Knoxville (United States).Geochimica et Cosmochimica Acta, 74(12):A621. doi: 10.1007/978-94-007-4444-8_4 [19] Moorbath, S., Taylor, P.N., Orpen, J.L., et al., 1987.First Direct Radiometric Dating of Archaean Stromatolitic Limestone.Nature, 326:865-867.doi: 10.1038/326865a0 [20] Qiao, X.F., Gao, M., 1997.Carbonate Pb-Pb Isotopic Dating of Qingbaikouan System in Northern China and Its Significance.Earth Science, 22(1):1-7(in Chinese with English abstract). [21] Qiu, X.F., Ling, W.L., Liu, X.M., et al., 2011.Recognition of Grenvillian Volcanic Suite in the Shennongjia Region and Its Tectonic Significance for the South China Craton.Precambrian Research, 191(3-4):101-119.doi: 10.1016/j.precamres.2011.09.011 [22] Toulkeridis, T., Goldstein, S.L., Clauer, N., et al., 1998.Sm-Nd, Rb-Sr and Pb-Pb Dating of Silicic Carbonates from the Early Archaean Barberton Greenstone Belt, South Africa:Evidence for Post-Depositional Isotopic Resetting at Low Temperature.Precambrian Research, 92(2):129-144.doi: 10.1016/S0301-9268(98)00071-0 [23] Tucker, R.T., Roberts, E.M., Hu, Y., et al., 2013.Detrital Zircon Age Constraints for the Winton Formation, Queensland:Contextualizing Australias Late Cretaceous Dinosaur Faunas.Gondwana Research, 24(2):767-779.doi: 10.1016/j.gr.2012.12.009 [24] Wan, Y.S., Miao, P.S., Liu, D.Y., et al., 2010.Formation Ages and Source Regins of the Palaeoproterozoic Gaofan, Hutuo and Dongjiao Groups in the Wutai and Dongjiao Areas of the North China Craton from SHRIMP U-Pb Dating of Detrital Zircons:Resolution of Debates over Their Stratigraphic Relationships.Chinese Science Bulletin, 55(7):572-578(in Chinese with English abstract). doi: 10.1007/s11434-009-0615-3 [25] Wang, J., Deng, Q., Wang, Z.J., et al., 2013.New Evidences for Sedimentary Attributes and Timing of the "Macaoyuan Conglomerates" on the Northern Margin of the Yangtze Block in Southern China.Precambrian Research, 235:58-70.doi: 10.1016/j.precamres.2013.06.003 [26] Westerhold, T., Rhl, U., Raffi, I., et al., 2008.Astronomical Calibration of the Paleocene Time.Palaeogeography, Palaeoclimatology, Palaeoecology, 257(4):377-403.doi: 10.1016/j.palaeo.2007.09.016 [27] Xiao, Z.B., 2012.Research of the Detrital Zircon from Mesoproterozoic Sedimentary Strata in the North Margin of Yangtze Craton, China(Dissertation).Northwest University, Xian, 28-39(in Chinese with English abstract). doi: 10.1007/s12583-017-0723-y [28] Yang, E.L., Lü, X.B., Shi, P., et al., 2014.Detrital Zircon Age of Stratigraphic Sinian-Cambrian in East Guizhouand Its Geological Significance.Earth Science, 39(4):387-398(in Chinese with English abstract). https://www.researchgate.net/publication/285996187_Detrital_zircon_age_of_stratigraphic_Sinian-Cambrian_in_East_Guizhou_and_its_geological_significance [29] Zhang, Q.D., Song, T.R., He, Z.J., et al., 2002.Pb-Pb Age Determination of Meso-to Neoproterozoic Carbonates in the Ming Tombs District, Beijing.Geological Review, 48(4):416-423(in Chinese with English abstract). https://www.researchgate.net/publication/264658746_The_Mesoproterozoic_%27seismite%27_at_Laiyuan_Hebei_Province_E_China_re-interpreted [30] Zhou, H.W., Li, X.H., Liu, Y., et al., 1998.Pb-Pb Dating of Marbles from Longxiu Area within Yunkai Complex and Its Geological Implication.Geoscience, 12(2):180-184(in Chinese with English abstract). https://www.researchgate.net/publication/240403528_Early_Permian_peak_metamorphism_recorded_in_U-Pb_system_of_black_slates_from_the_Ogcheon_metamorphic_belt_South_Korea_and_its_tectonic_implication [31] 常向阳, 陈良忠, 胡世学, 等, 2004.含澄江动物群地层的Pb-Pb同位素定年.地球学报, 25(2):181-184. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXB200402015.htm [32] 邓奇, 王剑, 汪正江, 等, 2013.扬子北缘元古宇马槽园群时代归属新证据——对地层对比和古地理格局的启示.地质通报, 32(4):631-638. http://www.cnki.com.cn/Article/CJFDTOTAL-ZQYD201304012.htm [33] 高福红, 杨扬, 王枫, 等, 2014.黑龙江省东部早古生代地层的确定:地质与碎屑锆石U-Pb年代学证据.地球科学, 39(5):499-508. http://www.earth-science.net/WebPage/Article.aspx?id=2859 [34] 高劢, 刘敦一, 李永安, 1996.用Pb-Pb同位素方法直接测定石炭系碳酸盐岩珊瑚化石年龄.地质论评, 42(1):22-29. http://www.cnki.com.cn/Article/CJFDTOTAL-DZLP199601003.htm [35] 高劢, 乔秀夫, 刘敦一, 等, 1995.直接测定内蒙古腮林忽洞组碳酸盐岩Pb-Pb同位素年龄.中国区域地质, 4:348-352. http://www.cnki.com.cn/Article/CJFDTOTAL-ZQYD504.010.htm [36] 李怀坤, 陆松年, 相振群, 等, 2007.北祁连山西段北大河岩群碎屑锆石SHRIMP U-Pb年代学研究.地质论评, 53(1):133-140. http://www.cnki.com.cn/Article/CJFDTOTAL-DZLP200701018.htm [37] 李怀坤, 张传林, 相振群, 等, 2013.扬子克拉通神农架群锆石和斜锆石U-Pb年代学及其构造意义.岩石学报, 29(2):673-697. http://www.cnki.com.cn/Article/CJFDTOTAL-YSXB201302023.htm [38] 李洪颜, 徐义刚, 黄小龙, 等, 2009.华北克拉通北缘晚古生代活化:山西宁武-静乐盆地上石炭统太原组碎屑锆石U-Pb测年及Hf同位素证据.科学通报, 54(5):632-640. http://www.cnki.com.cn/Article/CJFDTOTAL-KXTB200905017.htm [39] 李铨, 冷坚, 1987.前寒武纪地质研究:神农架上前寒武系.天津:天津科学技术出版社. [40] 刘成新, 毛新武, 魏运许, 等, 2004.神农架群地层层序初探.资源环境与工程, 18(增刊):5-16. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZGDJ200400005001.htm [41] 乔秀夫, 高劢, 1997.中国北方青白口系碳酸盐岩Pb-Pb同位素测年及意义.地球科学, 22(1):1-7 doi: 10.11764/j.issn.1672-1926.1997.01.1 [42] 万渝生, 苗培森, 刘敦一, 等, 2010.华北克拉通高凡群、滹沱群和东焦群的形成时代和物质来源:碎屑锆石SHRIMP U-Pb同位素年代学制约.科学通报, 55(7):572-578. http://www.cnki.com.cn/Article/CJFDTOTAL-KXTB201007007.htm [43] 肖志斌, 2012.中元古代扬子北缘神农架地区沉积岩碎屑锆石研究(硕士学位论文).西安:西北大学, 28-39. [44] 杨恩林, 吕新彪, 石平, 等, 2014.黔东震旦-寒武系转换期碎屑锆石年龄及其地质意义.地球科学, 39(4):387-398 http://www.earth-science.net/WebPage/Article.aspx?id=2848 [45] 张巧大, 宋天锐, 和政军, 等, 2002.北京十三陵地区中-新元古界碳酸盐岩Pb-Pb年龄研究.地质论评, 48(4):416-423. http://www.cnki.com.cn/Article/CJFDTOTAL-DZLP200204012.htm [46] 周汉文, 李献华, 刘颖, 等, 1998.粤西龙修地区大理岩的Pb-Pb年龄及其地质意义.现代地质, 12(2):180-184. http://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ802.004.htm