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On the Problem of Global Ordovician Lower Boundary “Golden Spike” and Tremadocian Subdivision and Correlation in China |
WANG Xiao-feng1, STOUGE Svend2, MALETZ Jorg3, WANG Chuan-shan1, YAN Chun-bo1 |
1. Wuhan Center of China Geological Survey, Wuhan, Hubei 430205, China;
2. Natural History Museum of Denmark, University of Copenhagen University, Copenhagen, Denmark;
3. Institute of Geology, Free University of Berlin, Germany |
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Abstract Correlative studies of the Cambrian and Ordovician global boundary stratotype section and point (GSSP)-western Newfoundland Green Point section with the former GSSP candidate for the Cambrian and Ordovician boundary, Xiaoyangqiao section in Dayangcha, Baishan (formerly Hunjiang), Jilin, China indicate that the conodont species Iapetognathus fluctivagus is not present in the specified boundary layer and point at Green Point section (i.e. Bed 23),and it is a disputed species both in distribution and taxonomy. The most of the conodont and graptolite specimens as well as carbon and oxygen isotopic data submitted in the original proposal, unfortunately, are not from the "Golden Spike" section. This is totally incompatible with the principles and requirement for selecting GSSP and necessary for reassessment. The Xiaoyangqiao Cambrian-Ordovician boundary section is easy accessibility and well-exposed along beautiful rivulet. The Cambrian-Ordovician boundary interval is comprised of unmetamorphic deep water black, grey and green shale intercalated with thin-bedded gray nodular limestone, bearing complete and well represented conodont and graptolite succession from uppermost Cambrian to lowest Ordovician. In 34 m interval, 5 conodont biozones can be recognized in ascending order: the Cambrostodus, Codylodus proavus, C. intermedius, C. lindstromi and C. angulatus and in turn three graptolite-bearing beds, referred to 2 graptolite biozones, the Rhabdinopora parabola biozone with R. “praeparabola” and the Anisograptus matanensis biozone from the upper C. intermedius to C. angulatus conodont biozones. There are also a plenty of trilobite coexisting with ostracoda fossils. Combining high-resolution carbon and oxygen isotope studies the present authors suggest that the Cambrian-Ordovician boundary would be better to be defined by the first appearance (FAD) of widespread conodont C. intermedius, instead of the FAD of the controversial and rare Iapetognathus fluctivagus as boundary biomarker for the base of the Ordovician System. This boundary proposed, however, is close-if not identical-to the level specified at the GSSP section and easily recognized and correlated anywhere in the world. The maximum carbon isotopic excursion recorded above the boundary layer and appearance of the earliest planktonic graptolites—R. parabola (including R. “praeparabola”, can be make as an auxiliary signs for determination of the boundary.
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Received: 23 February 2015
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[1] Webby B D. Steps toward a global standard for Ordovician stratigraphy [J].Newsletter on Stratigraphy, 1998,1: 1-33.
[2] Wang X F, Svend S, Bernd D.E, et al. A proposed GSSP for the base of the Middle Ordovician Series: the Huanghuachang section, Yichang, China[J]. Episodes, 2005, 28(2): 105-117.
[3] Wang X F, Svend S, Chen X H, et al. Dapingian Stage: standard name for the lowermost global stage of the Middle Ordovician Series[J]. Lethaia, 2009, 42 (3): 377-380.
[4] Wang X F, Svend S, Chen X H,et al.The Global Stratotype Section and Point for the base of the Middle Ordovician Series and the Third Stage (Dapingian)[J]. Episodes, 2009, 32 (2):96-113.
[5] Fortey R A, Harper D A, Ingham J K, et al. A revised correlation of Ordovician rocks in the British Isles[J]. The Geological Society Special Report, 2000, 24:1-83.
[6] 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:科学出版社,2001:1-59.
[7] Cohen K M, Finney S, Gibbard P L. Geological Time scale[J]. 地层学杂志,2013, 37(3):附表1-2.
[8] Finney S C. Global Series and Stages for the Ordovician System: a progress report[J]. Geologica Acta, 2005(3): 309-316.
[9] Bergstrm S M, Chen X, Guttierrez-Marco J C, et al. The new chronostratigraphic classification of the Ordovician System and its relations to major regional series and stages and δ13C chemostratigraphy[J]. Lethaia, 2008, 42(1):97-107.
[10] 陈旭,周志毅. 奥陶系全球界线层型剖面和点位(GSSP)的研究[J]. 地层学杂志, 2005,29(2):165-170.
[11] Zhan R B, Jin J S. Aspects of recent advances in the Ordovician stratigraphy and palaeontology of China[J]. Palaeoworld, 2008,17:1-11.
[12] Terfelt F, Bagnoli G, Stouge S. Re-evaluation of the conodont Iapetognathus and implications for the base of the Ordovician System GSSP [J]. Lethaia, 2012, 45:227-237.
[13] Cooper R A, Nowlan G S, Williams S H. Global Stratotype Section and Point for base of the Ordovician System [J]. Episodes, 2000, 24(1): 19-28.
[14] Miller J F, Repetski J, Nicoll R S, et al. The conodont Iapetognathus and its value for defining the base of the Ordovician System[M] // Lindskog A, Mehlqvist K. Proceedings of the 3rd IGCP 591 Annual Meeting. Lund, Sweden,2013: 215-216.
[15] Nicoll R S, Miller J F, Nowlan G S, et al. Iapetonudus (new genus) and Iapetognathus Landing, unusual earliest Ordovician multielement conodont taxa and their utility for biostratigraphy[J]. Brigham Young University Geology Studies, 1999,44: 27–101.
[16] Miller J F. Conodont as biostrtigraphic tools for redifinition and correlation of the Cambrian-Ordovician boundary[J]. Geological Magzine, 1988,125 (4):349-362.
[17] Erdtmann B D. Early Ordovician eustatic cycles and their bearing on punctuations in early nematophorid (planktic) graptolite evolution [M]// Walliser O H. Lecture Notes in Earth Sciences. Global Bioevents. 1986: 139-152.
[18] Erdtmann B D. The earliest Ordovician nematophorid graptolites: taxonomy and correlation[J].Geological Magzine, 1988, 125(4): 327-348.
[19] Wang X F, Wang C S. The Tremadoc (Ordovician) graptolite diversification events[J]. Alcheringa, 2001,25:155-168.
[20] Azmy K, Stouge S, Brand U, et al. High-resolution chemostratigraphy of the Cambrian-Ordovician GSSP: Enhanced global correlation[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2014, 409: 135–144.
[21] 穆恩之. 正笔石及正笔石式树形笔石的演化、分类和分布[J].中国科学,1974, 2:175-183.
[22] 汪啸风,刘义仁,周国强. 广东台山早奥陶世新厂组笔石[J].古生物学报,1979, 18(5):493-504.
[23] Li J J, Ge M Y, Chen X. Xinchangian( Early Ordovician ) anisograptid fauna from Taishan, Guangdong[J]. Palaeontologia Cathayana, 1985, 2: 103-135.
[24] Dong X P, Repetski J E, Bergstrm S M. Conodont biostratigraphy of the Middle Cambrian through lowermost Ordovician in Hunan, South China[J]. Acta Geolologic Sinica, 2004,78: 1185-1260.
[25] 金玉琴,汪啸风.湘中白水溪组笔石群的发现和桥亭子组的多枝笔石[M]//中国地质科学院地层古生物论文集编委会. 地层古生物论文辑. 第三辑.北京:地质出版社, 1977:74-85.
[26] 俞建华,刘怀宝,方一亭.江西修水流域新厂期(早奥陶世)反称笔石科[J].古生物学报,1984, 23(5):532-542.
[27] 曾庆銮,倪世钊,徐光洪,等.长江三峡东部地区奥陶系划分与对比[J].中国地质科学院宜昌地质矿产研究所所刊,1983, 6:1-68.
[28] Chen J Y. Aspect of Cambrian-Ordovician boundary in Dayangcha, China[M]. Beijing: China Prospect Publishing House,1986: 1-406.
[29] Chen J Y, Qian Y Y, Zhang J M, et al. The recommended Cambrian-Ordovician global boundary stratotype of Xiaoyangqiao section (Dayangcha,Jilin Province), China[J]. Geological Magzine,1988,135(4):415-444.
[30] Zhang Y D,Erdtmann B D. Tremadocian(Ordovician) biostratigraphy and graptolites at Dayangcha (Baishan, Jilin, NE China)[J]. Palontologische Zeitschrift,2004,78(2): 323-354.
[31] Wang X F, Erdtmann B D. Zonation and correlation of the earliest Ordovician graptolites from Hunjiang, Jilin Province, China[J]. Bulletin of Geological Society of Denmark, 1987, 35(3/4):237-245.
[32] Wang X F, Chen X H, Erdtmann B D. Ordovician chronostratigraphy—A Chinese approach [M]//Webby B D, Lauries J R. Global Perspectives on Ordovician Geology. Ratterdam: Balkema, 1992: 35-55.
[33] Zhou Z Y, Wang Z H, Zhang J M, et al. Cambrian-Ordovician boundary sections and the proposed candidate for stratotype in North and Northeast China [M]// Stratigraphy and Palaeontology of Systematic Boundaries.Cambrian-Ordovician boundary (2). Hefei: Anhui Science and Technology Publishing House, 1984: 1-62.
[34] 汪啸风,陈旭,陈孝红,等. 中国地层典——奥陶系[M].北京:地质出版社,1996:1-126.
[35] 周志毅,林焕令. 西北地区地层、古地理和板块构造[M].南京:南京大学出版社, 1995:1-299.
[36] 周志毅.塔里木盆地各纪地层[M].北京:科学出版社,2001:1-359.
[37] 陈旭,林焕令,许汉奎,等. 新疆西北部早古生代地层[J].地层学杂志,1998, 22(4):241-251.
[38] 张师本,高琴琴.塔里木盆地震旦纪至二叠纪地层古生物(II). 柯坪-巴楚分册[M]. 北京:石油工业出版社,1992: 1-115.
[39] 张师本. 塔里木盆地周缘地层考察指南[M].北京:石油工业出版社,2003:1-280.
[40] 赵祥麟,林尧坤,张舜新.吉林浑江地区奥陶纪新厂阶笔石序列[J].古生物学报,1988(2):188-204.
[41] 陈均远,张俊明, 尼柯尔 R S,等.中国大阳岔寒武-奥陶系界线地层碳酸盐岩碳、氧同位素及其与牙形石演化序列相关性[J].古生物学报,1995,14(4):392-409.
[42] Jing X C, Deng S H, Zhao Z J, et al. Carbon isotope composition and correlation across the Cambrian–Ordovician boundary in Kalpin Region of the Tarim Basin, China[J]. Sci China Earth Science, 2008,51:1317-1359. |
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