New C isotope stratigraphy from southwest China: Implications for the placement of the Precambrian-Cambrian boundary on the Yangtze Platform and global correlations

Shen, Yanan; Schidlowski, Manfred

doi:10.1130/0091-7613(2000)28<623:ncisfs>2.0.co;2

Cited by 118 publications

(44 citation statements)

References 27 publications

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“…This observation tends to confirm a relatively low burial diagenesis. Secondly, diagenetic alteration of the δ 13 C signal by burial diagenesis can be detected by a strong correlation between δ 13 C and δ 18 O values (correlation coefficient = 1; Brasier et al 1996;Shen & Schidlowski 2000). The correlation coefficient for two sets of data has been defined as:…”

Section: Evaluation Of the Datamentioning

confidence: 99%

C and O isotope stratigraphy in shallow-marine carbonate: a tool for sequence stratigraphy (example from the Lodève region, peritethian domain)

Hamon

Merzeraud

2007

Swiss j geosci

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Carbon and Oxygen isotope profiles from a well-dated carbonate section spanning the Sinemurian time on the Caussenard High (southeast France) are compared to sedimentological data and the results from sequence stratigraphy analysis, in order to discuss the origin of isotopic variations in a shallow-marine carbonate succession. The sedimentological study has enabled the identification of four types of depositional environments (peritidal, lagoonal, sand shoal, outer-shelf) that formed meter-scale cycles. The latter are arranged in two third-order cycles whose boundaries correspond to distinct δ 13 C and δ 18 O negative peaks (at the end of the Hettangian time and during Middle Sinemurian). The origin of the isotopic signals is discussed and several hypothesis are envisaged: sea water ageing, early meteoric diagenesis. Isotopic curves observed here seems to be related to early meteoric diagenesis linked to variations of third-order sea-level cycles rather than environmental factors (temperature, salinity). RESUME Sur la coupe du Perthus, située sur le Seuil Caussenard (Sud-Est de la France), quarante échantillons couvrant l'intervalle Sinémurien ont été prélevés pour des analyses d'isotopes stables (C et O) et comparer aux données sédimento-logiques dans le but de discuter l'origine du signal isotopique dans une série carbonatée d'environnement peu profond. L'étude sédimentologique a permis l'identification de quatre grands types de faciès sédimentaires (péritidal, lagunaire, dunes sous-marines, plate-forme externe) qui forment des cycles d'échelles métriques. Ces derniers s'arrangent verticalement en deux cycles de troisième ordre dont les limites correspondent aux tendances négatives en δ 13 C et δ 18 O (deux tendances négatives ont été observées, la première à la fin de l'Hettangien, la seconde au Sinémurien Moyen). L'origine des variations du signal isotopique est discutée et plusieurs hypothèses sont examinées: «vieillissement» des masses d'eau, diagenèse précoce. Dans le cas étudié, les variations observées semblent être contrôlées par les phénomènes de diagenèse précoce liés aux variations eustatiques moyen terme (troisième ordre), plutôt que par les paramètres environnementaux (température, salinité). This paper shows that δ 13 C and δ 18 O signals in shallowwater carbonate can be related to the relative sea-level variations, rather than environmental factors (temperature, salinity) and that isotopic signals in shallow-water carbonates have the potential for providing an excellent complementary tool to sequence stratigraphy. Two distinct approaches have therefore been used in order to investigate the relation between sequence and isotope stratigraphy: firstly, a sedimentological and sequential analysis; secondly a chemostratigraphic study. Geological and palaeogeographic setting

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Section: Evaluation Of the Datamentioning

confidence: 99%

C and O isotope stratigraphy in shallow-marine carbonate: a tool for sequence stratigraphy (example from the Lodève region, peritethian domain)

Hamon

Merzeraud

2007

Swiss j geosci

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“…2 The positive  13 C excursion at the base of the Stage 2 and Terreneuvian Series: "ZHUCE" event A distinct  13 C positive excursion from the uppermost of Fortunian Stage to Stage 2 is well recorded in sections from South China (such as the Maidiping section in Sichuan Province [5], the Meishucun [5], Laolin [40] and Xiaotan [41] sections in Yunnan Province, Yangtze Gorges section in Hubei Province [42]) (Figure 3), Iran [5], Mongolia [7], Canada [23], England [23], Morocco [34], India [43] and Siberia Platform [44,45] (Figure 1). It peaks at 3‰-7‰, with the magnitude over 5‰ (Figure 2).…”

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Significant carbon isotope excursions in the Cambrian and their implications for global correlations

Fan

Deng

Zhang

2011

Sci. China Earth Sci.

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“…The intra-basinal stratigraphic correlation also implies that the absolute age of the Chengjiang biota should be younger than 518±5 Ma. Our new result, together with the SHRIMP U-Pb zircon age for the K-bentonite in the Zhongyicun member of the Zhujiaqing Formation at the Meishucun section, Yunnan Province, provides a temporal constraint for the Lower Cambrian of the Yangtze Platform in South China.Lower Cambrian, Niutitang Formation, tuff, SHRIMP, zircon, Chengjiang biota, polymetallic Ni-Mo-PGE-rich layerThe wide-spread outcrops of the early-Cambrian sequences over the Yangtze Platform in South China represent an important window for studying the Cambrian bio-radiation, the secular paleo-seawater isotope variations, the ore-forming events of terminal Neoproterozoic-Cambrian times, and in particular, for investigating the Cambrian subdivision and global correlation [1][2][3][4][5][6][7][8][9] . Since the last century, these sequences have been studied from a number of different aspects, and paleontological studies have acquired many unique findings [10][11][12][13][14][15][16][17][18][19] .…”

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SHRIMP U-Pb zircon age of tuff at the bottom of the Lower Cambrian Niutitang Formation, Zunyi, South China

Zhou

Luo

et al. 2008

Chin. Sci. Bull.

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A SHRIMP U-Pb zircon geochronology study of the tuff at the bottom of the Lower Cambrian NiutitangFormation at Songlin, Zunyi, South China yielded a mean 206 Pb/ 238 U age of 518±5 Ma. It is significantly younger than the Re-Os ages of 537-542 Ma for the overlying polymetallic Ni-Mo-PGE-rich layer in the basal Niutitang Formation at Songlin, suggesting that the Re-Os ages might represent that of the original magma chamber for the Ni-Mo-PGE-rich layer rather than the formation age of the strata. The intra-basinal stratigraphic correlation also implies that the absolute age of the Chengjiang biota should be younger than 518±5 Ma. Our new result, together with the SHRIMP U-Pb zircon age for the K-bentonite in the Zhongyicun member of the Zhujiaqing Formation at the Meishucun section, Yunnan Province, provides a temporal constraint for the Lower Cambrian of the Yangtze Platform in South China.Lower Cambrian, Niutitang Formation, tuff, SHRIMP, zircon, Chengjiang biota, polymetallic Ni-Mo-PGE-rich layerThe wide-spread outcrops of the early-Cambrian sequences over the Yangtze Platform in South China represent an important window for studying the Cambrian bio-radiation, the secular paleo-seawater isotope variations, the ore-forming events of terminal Neoproterozoic-Cambrian times, and in particular, for investigating the Cambrian subdivision and global correlation [1][2][3][4][5][6][7][8][9] . Since the last century, these sequences have been studied from a number of different aspects, and paleontological studies have acquired many unique findings [10][11][12][13][14][15][16][17][18][19] . The geochronological research, on the other hand, is still lagging behind. Up to now, there is only one high-precision, reliable U-Pb zircon age for the early Cambrian strata at the Meishucun section, Yunan Province, South China [20][21][22] . Global correlations for the Lower Cambrian strata and biological events have thus been hampered by the lack of good geochronological constraints.The existence of two biogeographic realms during early Cambrian [23] and the lithofacies change made stratigraphic correlations over long distances even harder. Therefore, high-precision ages are urgently needed for the Lower Cambrian of the Yangtze Platform, South China.The extensive occurrences of a polymetallic Ni-Mo-PGE-rich layer [24,25] in the Lower Cambrian black shale series (the basal Niutitang Formation in Guizhou and Hunan Provinces and its lateral equivalents) within the Yangtze Platform apparently represents one of the major ore-forming events in early Cambrian. Previous study [26] suggested that the Chengjiang biota [10][11][12][13][14][15][16][17][18][19] in the Kun-

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New C isotope stratigraphy from southwest China: Implications for the placement of the Precambrian-Cambrian boundary on the Yangtze Platform and global correlations

Cited by 118 publications

References 27 publications

C and O isotope stratigraphy in shallow-marine carbonate: a tool for sequence stratigraphy (example from the Lodève region, peritethian domain)

C and O isotope stratigraphy in shallow-marine carbonate: a tool for sequence stratigraphy (example from the Lodève region, peritethian domain)

Significant carbon isotope excursions in the Cambrian and their implications for global correlations

SHRIMP U-Pb zircon age of tuff at the bottom of the Lower Cambrian Niutitang Formation, Zunyi, South China

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