FN Archimer Export Format
PT J
TI Hafnium isotope evidence for enhanced weatherability at high southern latitudes during Oceanic Anoxic Event 2
BT 
AF Chen, Hongjin
   Bayon, Germain
   Xu, Zhaokai
   Li, Tiegang
AS 1:1,2,6;2:2;3:1,3,4,5;4:6;
FF 1:;2:PDG-REM-GEOOCEAN-ASTRE;3:;4:;
C1 CAS Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
   Univ. Brest, CNRS, Ifremer, Geo-Ocean, F-29280 Plouzané, France
   Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266061, China
   CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China
   Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China
   Key Laboratory of Marine Mineral Resources, Ministry of Natural Resources, Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 510075, China
   Key Laboratory of Marine Sedimentology and Metallogeny, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
C2 CHINESE ACAD SCI, CHINA
   IFREMER, FRANCE
   QNLM, CHINA
   CHINESE ACAD SCI, CHINA
   CHINESE ACAD SCI, CHINA
   CHINA GEOL SURVEY, CHINA
   FIO, CHINA
SI BREST
SE PDG-REM-GEOOCEAN-ASTRE
UM GEO-OCEAN
IN WOS Ifremer UMR
   copubli-int-hors-europe
   copubli-sud
IF 5.3
TC 2
UR https://archimer.ifremer.fr/doc/00805/91715/97762.pdf
LA English
DT Article
DE ;OAE 2;IODP expedition 369;Mentelle Basin;hafnium-neodymium isotopes;silicate weathering;reverse weathering
AB The Oceanic Anoxic Event 2 (OAE 2; ca. ∼94 Ma) represents one of the most extreme carbon cycle perturbations of the Phanerozoic, which coincided with major environmental and climate reorganization in both terrestrial and marine realms. Chemical weathering of continental silicate rocks is thought to have played a crucial role during OAE 2, through enhanced release of bio-essential nutrients to the ocean, promoting high rates of marine primary production and organic carbon burial, but also due to its effect on atmospheric CO2 drawdown, which altogether possibly drove the OAE 2 termination. Yet, the evolution of continental chemical weathering during OAE 2 remains poorly defined, especially in high-latitude regions. In this study, we present a combined hafnium-neodymium isotope investigation of the clay-size detrital fraction (△εHfclay) of late Cenomanian to early Turonian sediments from the southwest Australian margin, at a site (International Ocean Discovery Program U1516) located in the southern high latitudes (∼62°S) during the late Cretaceous. The reliability of △εHfclay as a proxy for continental chemical weathering in ancient anoxic marine sediments was assessed by analyzing a suite of samples retrieved from methanogenic sediments experiencing marine silicate weathering at ocean margins, suggesting negligible effect of reverse weathering on hafnium-neodymium isotope compositions. At Site U1516, the early stage of OAE 2 was characterized by relatively low △εHfclay values (−5.9 ± 2), typical of reduced chemical weathering in nearby continental regions. At the onset of the most prominent carbon isotope excursion, an abrupt decrease in △εHfclay points towards accelerated export of poorly weathered sediments resulting from the abrupt reactivation of river systems in southwest Australia. This period was followed by a pronounced △εHfclay shift towards positive values, indicative of intensifying chemical weathering conditions during the OAE 2 interval showing the highest C anomaly. Based on these results, we posit that enhanced hydrological cycle, most likely caused by a southward shift of the westerlies, led to a large increase in weatherability at southern high latitudes during peak OAE 2 warmth. This finding provides empirical support for the potential role played by high-latitude weathering systems in driving the termination of OAE 2, via weathering-driven consumption of atmospheric CO2 and accelerated riverine fluxes of nutrients leading to enhanced organic carbon burial in marine sediments. 
PY 2023
PD JAN
SO Earth And Planetary Science Letters
SN 0012-821X
PU Elsevier BV
VL 601
UT 000895742800001
DI 10.1016/j.epsl.2022.117910
ID 91715
ER

EF