TY - JOUR

T1 - Carbon isotopic signature and organic matter composition of cenomanian high-latitude paleosols of southern patagonia

AU - Varela, Augusto Nicolás

AU - Raigemborn, María Sol

AU - Santamarina, Patricio Emmanuel

AU - Lizzoli, Sabrina

AU - Adatte, Thierry

AU - Heimhofer, Ulrich

N1 - Funding Information: Agencia Nacional de Promoci?n Cient?fica y Tecnol?gica (PICT 2012-0828 awarded to A.N. Varela), Subsidio J?venes Investigadores de la UNLP 2013 (La Plata University Exp. Cod.100 N?19333/2/13 awarded to A.N. Varela), PIP 0259, PIP 0388, and PIP 0866 CONICET grants. The authors would like to thank P. Garc?a, A. Iglesias, V. Barreda, the Secretar?a de Cultura de la Provincia de Santa Cruz, Comisi?n de Fomento Tres Lagos, and Waring, Piccinini and Nacer families for their field work permission and priceless help both on and out the field. The authors would also like to thank C. Wenske (LUH) for support with the stable isotope analyses and Sebasti?n Mirabelli, Carlos Jaramillo, and Orlando C?rdenas for their technical assistance with the palynological sample processing. Constructive comments by two expert reviewers improved this manuscript and are gratefully acknowledged.

PY - 2021/9/8

Y1 - 2021/9/8

N2 - The Cenomanian Mata Amarilla Formation (MAF) in southern Patagonia (⁓55° S paleolatitude, Austral-Magallanes Basin, Argentina) is composed mainly of stacked fluvial deposits with intercalated paleosols, which document Cenomanian environments at high-paleolatitudes in the Southern Hemisphere. We performed a multiproxy study of the paleosols and sediments of the MAF in order to (1) understand the composition of the soil-and sediment-derived organic matter (OM), (2) apply carbon isotope stratigraphy as a tool to correlate patterns obtained from the MAF with existing marine and non-marine δ13Corg records worldwide, and (3) investigate the relationship between variations in spore-pollen assemblages of the MAF and the climatic conditions prevailing in the Cenomanian Southern Hemisphere. An integrated dataset was generated, including total organic carbon content, Rock-Eval pyrolysis data, stable isotope (δ13Corg) composition, and palynological data, combined with published paleosol-derived mean annual temperatures and mean annual precipitations. The results indicated that the OM preserved in the MAF paleosols allowed its use as a chemostratigraphic tool. The MAF δ13Corg curve showed the rather stable pattern characteristic for the Early to Late Cenomanian interval. The absence of the major positive carbon isotope excursion associated with oceanic anoxic event 2 provided an upper limit for the stratigraphic range of the MAF. The palynological data suggested the development of fern prairies during warmer and moister periods at the expense of the background gymnosperm-dominated forests. Overall, the multiproxy record provided new insights into the long-term environmental conditions during the Cenomanian in the high latitudes of the Southern Hemisphere.

AB - The Cenomanian Mata Amarilla Formation (MAF) in southern Patagonia (⁓55° S paleolatitude, Austral-Magallanes Basin, Argentina) is composed mainly of stacked fluvial deposits with intercalated paleosols, which document Cenomanian environments at high-paleolatitudes in the Southern Hemisphere. We performed a multiproxy study of the paleosols and sediments of the MAF in order to (1) understand the composition of the soil-and sediment-derived organic matter (OM), (2) apply carbon isotope stratigraphy as a tool to correlate patterns obtained from the MAF with existing marine and non-marine δ13Corg records worldwide, and (3) investigate the relationship between variations in spore-pollen assemblages of the MAF and the climatic conditions prevailing in the Cenomanian Southern Hemisphere. An integrated dataset was generated, including total organic carbon content, Rock-Eval pyrolysis data, stable isotope (δ13Corg) composition, and palynological data, combined with published paleosol-derived mean annual temperatures and mean annual precipitations. The results indicated that the OM preserved in the MAF paleosols allowed its use as a chemostratigraphic tool. The MAF δ13Corg curve showed the rather stable pattern characteristic for the Early to Late Cenomanian interval. The absence of the major positive carbon isotope excursion associated with oceanic anoxic event 2 provided an upper limit for the stratigraphic range of the MAF. The palynological data suggested the development of fern prairies during warmer and moister periods at the expense of the background gymnosperm-dominated forests. Overall, the multiproxy record provided new insights into the long-term environmental conditions during the Cenomanian in the high latitudes of the Southern Hemisphere.

KW - Carbon cycle

KW - Carbon isotopes

KW - Mid-cretaceous

KW - Palynology

KW - Southern Gondwana

KW - Terrestrial deposits

UR - http://www.scopus.com/inward/record.url?scp=85114894622&partnerID=8YFLogxK

U2 - 10.3390/geosciences11090378

DO - 10.3390/geosciences11090378

M3 - Article

AN - SCOPUS:85114894622

VL - 11

JO - Geosciences (Switzerland)

JF - Geosciences (Switzerland)

IS - 9

M1 - 378

ER -