Determination of 88Sr/86Sr mass-dependent isotopic fractionation and radiogenic isotope variation of 87Sr/86Sr in the Neoproterozoic Doushantuo Formation

Takeshi Ohno; Tsuyoshi Komiya; Yuichiro Ueno; Takafumi Hirata; Shigenori Maruyama

doi:10.1016/j.gr.2007.10.007

Determination of ⁸⁸Sr/⁸⁶Sr mass-dependent isotopic fractionation and radiogenic isotope variation of ⁸⁷Sr/⁸⁶Sr in the Neoproterozoic Doushantuo Formation

Takeshi Ohno, Tsuyoshi Komiya, Yuichiro Ueno, Takafumi Hirata, Shigenori Maruyama

Research output: Contribution to journal › Article › peer-review

63 Citations (Scopus)

Abstract

We measured both mass-dependent isotope fractionation of δ⁸⁸Sr (⁸⁸Sr/⁸⁶Sr) and radiogenic isotopic variation of Sr (⁸⁷Sr/⁸⁶Sr) for the Neoproterozoic Doushantuo Formation that deposited as a cap carbonate immediately above the Marinoan-related Nantuo Tillite. The δ⁸⁸Sr and ⁸⁷Sr/⁸⁶Sr compositions showed three remarkable characteristics: (1) high radiogenic ⁸⁷Sr/⁸⁶Sr values and gradual decrease in the ⁸⁷Sr/⁸⁶Sr ratios, (2) anomalously low δ⁸⁸Sr values at the lower part cap carbonate, and (3) a clear correlation between ⁸⁷Sr/⁸⁶Sr and δ⁸⁸Sr values. These isotopic signatures can be explained by assuming an extreme greenhouse condition after the Marinoan glaciation. Surface seawater, mixed with a large amount of freshwater from continental crusts with high ⁸⁷Sr/⁸⁶Sr and lighter δ⁸⁸Sr ratios, was formed during the extreme global warming after the glacial event. High atmospheric CO₂ content caused sudden precipitation of cap carbonate from the surface seawater with high ⁸⁷Sr/⁸⁶Sr and lighter δ⁸⁸Sr ratios. Subsequently, the mixing of the underlying seawater, with unradiogenic Sr isotope compositions and normal δ⁸⁸Sr ratios, probably caused gradual decrease of the ⁸⁷Sr/⁸⁶Sr ratios of the seawater and deposition of carbonate with normal δ⁸⁸Sr ratios. The combination of ⁸⁷Sr/⁸⁶Sr and δ⁸⁸Sr isotope systematics gives us new insights on the surface evolution after the Snowball Earth.

Original language	English
Pages (from-to)	126-133
Number of pages	8
Journal	Gondwana Research
Volume	14
Issue number	1-2
DOIs	https://doi.org/10.1016/j.gr.2007.10.007
Publication status	Published - Aug 2008
Externally published	Yes

Keywords

Chemostratigraphy
Neoproterozoic
Snowball Earth
South China

ASJC Scopus subject areas

Geology

Access to Document

10.1016/j.gr.2007.10.007

Cite this

@article{08858bc9b86a4b8fa1f899a474c62233,

title = "Determination of 88Sr/86Sr mass-dependent isotopic fractionation and radiogenic isotope variation of 87Sr/86Sr in the Neoproterozoic Doushantuo Formation",

abstract = "We measured both mass-dependent isotope fractionation of δ88Sr (88Sr/86Sr) and radiogenic isotopic variation of Sr (87Sr/86Sr) for the Neoproterozoic Doushantuo Formation that deposited as a cap carbonate immediately above the Marinoan-related Nantuo Tillite. The δ88Sr and 87Sr/86Sr compositions showed three remarkable characteristics: (1) high radiogenic 87Sr/86Sr values and gradual decrease in the 87Sr/86Sr ratios, (2) anomalously low δ88Sr values at the lower part cap carbonate, and (3) a clear correlation between 87Sr/86Sr and δ88Sr values. These isotopic signatures can be explained by assuming an extreme greenhouse condition after the Marinoan glaciation. Surface seawater, mixed with a large amount of freshwater from continental crusts with high 87Sr/86Sr and lighter δ88Sr ratios, was formed during the extreme global warming after the glacial event. High atmospheric CO2 content caused sudden precipitation of cap carbonate from the surface seawater with high 87Sr/86Sr and lighter δ88Sr ratios. Subsequently, the mixing of the underlying seawater, with unradiogenic Sr isotope compositions and normal δ88Sr ratios, probably caused gradual decrease of the 87Sr/86Sr ratios of the seawater and deposition of carbonate with normal δ88Sr ratios. The combination of 87Sr/86Sr and δ88Sr isotope systematics gives us new insights on the surface evolution after the Snowball Earth.",

keywords = "Chemostratigraphy, Neoproterozoic, Snowball Earth, South China",

author = "Takeshi Ohno and Tsuyoshi Komiya and Yuichiro Ueno and Takafumi Hirata and Shigenori Maruyama",

note = "Funding Information: We are grateful to Prof. D. Shu, Prof. Y. Li, Dr. J. Han and Dr. J. Guo for helping with the fieldwork in South China. We thank Ms. T. Ishikawa, Mr. Y. Sawaki, Mr. K. Irisawa, Mr. Y. Fukushi and Mr. T. Wakabayashi for providing helpful suggestions for the sample preparation techniques. This work was partly supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan.",

year = "2008",

month = aug,

doi = "10.1016/j.gr.2007.10.007",

language = "English",

volume = "14",

pages = "126--133",

journal = "Gondwana Research",

issn = "1342-937X",

publisher = "Elsevier Inc.",

number = "1-2",

}

TY - JOUR

T1 - Determination of 88Sr/86Sr mass-dependent isotopic fractionation and radiogenic isotope variation of 87Sr/86Sr in the Neoproterozoic Doushantuo Formation

AU - Ohno, Takeshi

AU - Komiya, Tsuyoshi

AU - Ueno, Yuichiro

AU - Hirata, Takafumi

AU - Maruyama, Shigenori

N1 - Funding Information: We are grateful to Prof. D. Shu, Prof. Y. Li, Dr. J. Han and Dr. J. Guo for helping with the fieldwork in South China. We thank Ms. T. Ishikawa, Mr. Y. Sawaki, Mr. K. Irisawa, Mr. Y. Fukushi and Mr. T. Wakabayashi for providing helpful suggestions for the sample preparation techniques. This work was partly supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

PY - 2008/8

Y1 - 2008/8

N2 - We measured both mass-dependent isotope fractionation of δ88Sr (88Sr/86Sr) and radiogenic isotopic variation of Sr (87Sr/86Sr) for the Neoproterozoic Doushantuo Formation that deposited as a cap carbonate immediately above the Marinoan-related Nantuo Tillite. The δ88Sr and 87Sr/86Sr compositions showed three remarkable characteristics: (1) high radiogenic 87Sr/86Sr values and gradual decrease in the 87Sr/86Sr ratios, (2) anomalously low δ88Sr values at the lower part cap carbonate, and (3) a clear correlation between 87Sr/86Sr and δ88Sr values. These isotopic signatures can be explained by assuming an extreme greenhouse condition after the Marinoan glaciation. Surface seawater, mixed with a large amount of freshwater from continental crusts with high 87Sr/86Sr and lighter δ88Sr ratios, was formed during the extreme global warming after the glacial event. High atmospheric CO2 content caused sudden precipitation of cap carbonate from the surface seawater with high 87Sr/86Sr and lighter δ88Sr ratios. Subsequently, the mixing of the underlying seawater, with unradiogenic Sr isotope compositions and normal δ88Sr ratios, probably caused gradual decrease of the 87Sr/86Sr ratios of the seawater and deposition of carbonate with normal δ88Sr ratios. The combination of 87Sr/86Sr and δ88Sr isotope systematics gives us new insights on the surface evolution after the Snowball Earth.

AB - We measured both mass-dependent isotope fractionation of δ88Sr (88Sr/86Sr) and radiogenic isotopic variation of Sr (87Sr/86Sr) for the Neoproterozoic Doushantuo Formation that deposited as a cap carbonate immediately above the Marinoan-related Nantuo Tillite. The δ88Sr and 87Sr/86Sr compositions showed three remarkable characteristics: (1) high radiogenic 87Sr/86Sr values and gradual decrease in the 87Sr/86Sr ratios, (2) anomalously low δ88Sr values at the lower part cap carbonate, and (3) a clear correlation between 87Sr/86Sr and δ88Sr values. These isotopic signatures can be explained by assuming an extreme greenhouse condition after the Marinoan glaciation. Surface seawater, mixed with a large amount of freshwater from continental crusts with high 87Sr/86Sr and lighter δ88Sr ratios, was formed during the extreme global warming after the glacial event. High atmospheric CO2 content caused sudden precipitation of cap carbonate from the surface seawater with high 87Sr/86Sr and lighter δ88Sr ratios. Subsequently, the mixing of the underlying seawater, with unradiogenic Sr isotope compositions and normal δ88Sr ratios, probably caused gradual decrease of the 87Sr/86Sr ratios of the seawater and deposition of carbonate with normal δ88Sr ratios. The combination of 87Sr/86Sr and δ88Sr isotope systematics gives us new insights on the surface evolution after the Snowball Earth.

KW - Chemostratigraphy

KW - Neoproterozoic

KW - Snowball Earth

KW - South China

UR - http://www.scopus.com/inward/record.url?scp=46149100088&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=46149100088&partnerID=8YFLogxK

U2 - 10.1016/j.gr.2007.10.007

DO - 10.1016/j.gr.2007.10.007

M3 - Article

AN - SCOPUS:46149100088

SN - 1342-937X

VL - 14

SP - 126

EP - 133

JO - Gondwana Research

JF - Gondwana Research

IS - 1-2

ER -