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Lead isotopic record of Barremian–Aptian marine sediments: Implications for large igneous provinces and the Aptian climatic crisis

Lead isotopic record of Barremian–Aptian marine sediments: Implications for large igneous provinces and the Aptian climatic crisis
Lead isotopic record of Barremian–Aptian marine sediments: Implications for large igneous provinces and the Aptian climatic crisis
We present initial isotopic ratios of lead for Early Cretaceous (Barremian–Aptian) sections from Shatsky Rise (Pacific) and Gorgo a Cerbara (Italy). Our Pb isotopic data track an interval representing Oceanic Anoxic Event (OAE)-1a, which is characterized by quasi-global deposition of organic carbon-rich black shale. Pb isotopic compositions of sediments from Shatsky Rise decrease at the end of Barremian time, from radiogenic continental values to unradiogenic values, and subsequently remained less radiogenic until the end of early Aptian time. We explain the isotopic shift by a significant increase in supply rate of unradiogenic Pb, most likely due to massive volcanism. In contrast, the Pb isotopic compositions from the Italian section, which was situated at the western end of Tethys, are mostly identical to those of upper continental crust, showing no significant change in supply rate of unradiogenic Pb. The discrepancy between two sites is attributed to quiescent deep-submarine eruptions of Pacific large igneous provinces (LIPs) such as the Ontong Java Plateau (OJP), which severely limited dispersion of Pb-carrying particles out of the Pacific Ocean. Published Os isotopic data from the Italian section indicate two episodes of massive eruptions of OJP or contemporaneous Manihiki and Hikurangi plateaus starting from earliest Aptian time, slightly later than that indicated by the sedimentary Pb isotopic record from Shatsky Rise. Differences in isotopic variations between Pb and Os likely reflect differences in their chemical behaviors in the oceans, i.e., Pb isotopic compositions would have varied in response to local or regional changes in sediment provenances, whereas large-scale changes in Os inputs are required to explain variations in seawater Os isotopic compositions. Our Pb isotopic data, together with the published Os isotopic record, provide new evidence for the eruptive history of OJP together with contemporaneous Pacific plateaus and its environmental consequences, starting from end-Barremian time and extending through early Aptian time.
Oceanic Anoxic Event (OAE)-1a, Large Igneous Province, Pb isotope
0012-821X
126-134
Kuroda, Junichiro
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Tanimizu, Masaharu
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Hori, Rie S.
0482e3ac-4b43-4c02-ac06-488d63248708
Suzuki, Katsuhiko
8102f9f2-354a-4eb4-a957-70f6be4e2be1
Ogawa, Nanako O.
38b45f0e-d332-476d-a7d5-2ad6ca24db38
Tejada, Maria L.G.
9b31f8b0-c9f4-4ea6-bf50-e7df2dc33b91
Coffin, Millard F.
69674f21-5f5a-4ef4-aac5-caa4d8c3b5e4
Coccioni, Rodolfo
ab9b9b8f-13b3-41a8-9fcd-b841f9ab55e1
Erba, Elisabetta
5d8f2006-9848-4450-95dd-1f4a1c47fbb5
Ohkouchi, Naohiko
8301159a-d979-4d80-8ff2-daf7b223b820
Kuroda, Junichiro
54ebf90e-fff1-4de6-921d-88c3eccf8d6a
Tanimizu, Masaharu
22125d7e-2d72-4c82-9077-74298d5670e3
Hori, Rie S.
0482e3ac-4b43-4c02-ac06-488d63248708
Suzuki, Katsuhiko
8102f9f2-354a-4eb4-a957-70f6be4e2be1
Ogawa, Nanako O.
38b45f0e-d332-476d-a7d5-2ad6ca24db38
Tejada, Maria L.G.
9b31f8b0-c9f4-4ea6-bf50-e7df2dc33b91
Coffin, Millard F.
69674f21-5f5a-4ef4-aac5-caa4d8c3b5e4
Coccioni, Rodolfo
ab9b9b8f-13b3-41a8-9fcd-b841f9ab55e1
Erba, Elisabetta
5d8f2006-9848-4450-95dd-1f4a1c47fbb5
Ohkouchi, Naohiko
8301159a-d979-4d80-8ff2-daf7b223b820

Kuroda, Junichiro, Tanimizu, Masaharu, Hori, Rie S., Suzuki, Katsuhiko, Ogawa, Nanako O., Tejada, Maria L.G., Coffin, Millard F., Coccioni, Rodolfo, Erba, Elisabetta and Ohkouchi, Naohiko (2011) Lead isotopic record of Barremian–Aptian marine sediments: Implications for large igneous provinces and the Aptian climatic crisis. Earth and Planetary Science Letters, 307 (1-2), 126-134. (doi:10.1016/j.epsl.2011.04.021).

Record type: Article

Abstract

We present initial isotopic ratios of lead for Early Cretaceous (Barremian–Aptian) sections from Shatsky Rise (Pacific) and Gorgo a Cerbara (Italy). Our Pb isotopic data track an interval representing Oceanic Anoxic Event (OAE)-1a, which is characterized by quasi-global deposition of organic carbon-rich black shale. Pb isotopic compositions of sediments from Shatsky Rise decrease at the end of Barremian time, from radiogenic continental values to unradiogenic values, and subsequently remained less radiogenic until the end of early Aptian time. We explain the isotopic shift by a significant increase in supply rate of unradiogenic Pb, most likely due to massive volcanism. In contrast, the Pb isotopic compositions from the Italian section, which was situated at the western end of Tethys, are mostly identical to those of upper continental crust, showing no significant change in supply rate of unradiogenic Pb. The discrepancy between two sites is attributed to quiescent deep-submarine eruptions of Pacific large igneous provinces (LIPs) such as the Ontong Java Plateau (OJP), which severely limited dispersion of Pb-carrying particles out of the Pacific Ocean. Published Os isotopic data from the Italian section indicate two episodes of massive eruptions of OJP or contemporaneous Manihiki and Hikurangi plateaus starting from earliest Aptian time, slightly later than that indicated by the sedimentary Pb isotopic record from Shatsky Rise. Differences in isotopic variations between Pb and Os likely reflect differences in their chemical behaviors in the oceans, i.e., Pb isotopic compositions would have varied in response to local or regional changes in sediment provenances, whereas large-scale changes in Os inputs are required to explain variations in seawater Os isotopic compositions. Our Pb isotopic data, together with the published Os isotopic record, provide new evidence for the eruptive history of OJP together with contemporaneous Pacific plateaus and its environmental consequences, starting from end-Barremian time and extending through early Aptian time.

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Published date: 1 July 2011
Keywords: Oceanic Anoxic Event (OAE)-1a, Large Igneous Province, Pb isotope
Organisations: Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 195579
URI: http://eprints.soton.ac.uk/id/eprint/195579
ISSN: 0012-821X
PURE UUID: 3c2e2633-f4c3-4418-b01c-895d735a56dd

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Date deposited: 23 Aug 2011 11:00
Last modified: 14 Mar 2024 04:05

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Contributors

Author: Junichiro Kuroda
Author: Masaharu Tanimizu
Author: Rie S. Hori
Author: Katsuhiko Suzuki
Author: Nanako O. Ogawa
Author: Maria L.G. Tejada
Author: Millard F. Coffin
Author: Rodolfo Coccioni
Author: Elisabetta Erba
Author: Naohiko Ohkouchi

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