Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published October 1, 2020 | Supplemental Material
Journal Article Open

Coniacian-Campanian magnetostratigraphy of the Marambio Group: The Santonian-Campanian boundary in the Antarctic Peninsula and the complete Upper Cretaceous – Lowermost Paleogene chronostratigraphical framework for the James Ross Basin


Recent magnetostratigraphic works from different areas of the James Ross Basin have expanded on chronostratigraphic studies previously based on ammonite, palynomorph and nanoplankton biostratigraphy, and strontium isotope stratigraphy. Here we present a new magnetostratigraphy of Coniacian through Campanian marine sedimentary rocks from Hidden Lake, Santa Marta and Snow Hill Island Formations, on northwest James Ross Island. A total of 189 paleomagnetic directions were obtained along more than 1500 m of stratigraphic thickness from Brandy Bay to Santa Marta Cove areas, identifying three polarity chrons of the global polarity time scale. The local magnetostratigraphic column starts in the upper part of the Cretaceous Normal Superchron C34N (Coniacian) and ends in Chron C33N (middle Campanian). The correlation between the magnetostratigraphy and the age framework given by ammonite biostratigraphy allowed the assignment of precise ages to particular horizons of the Santa Marta Formation. The newly identified geomagnetic polarity reversals are the earliest identified in the James Ross Basin and include: a) C34N/C33R (84.2 Ma, late Santonian – early Campanian) in the Alpha Member of the Santa Marta Formation and b) C33R/C33N (79.9 Ma, middle Campanian) in the upper Beta Member (Santa Marta Formation). By integrating this new data with previous work, we present a complete Upper Cretaceous – lowermost Paleogene chronostratigraphical framework for the basin, spanning both proximal to distal sedimentary facies of the Marambio Group.

Additional Information

© 2020 Published by Elsevier. Received 21 January 2020, Revised 11 May 2020, Accepted 11 June 2020, Available online 16 June 2020. To the Instituto Antártico Argentino and the NSF Office of Polar Programs (Grants OPP-0739541 to J. Kirschvink and OPP-0739432 to P. Ward and E. Steig) for the logistic support during the Antarctic field seasons, and the NSF Office of Polar Programs for support of the laboratory work at Caltech (Grant #1341729 to JLK). Grants from ANPCyT (PICTO 2010-0114) and UNTdF PID-A1 to E. Olivero, and Universidad de Buenos Aires (UBACyT 20020130100465BA) to A. Rapalini provided additional support for this research. To Matías Nasselli for the rock magnetics analyses. Special thanks are due to Matías Vaca, Alvar Sobral, Hang Yu, Lewis Ward, Peter Ward, Eric Steig, Nick Swanson-Hysell, David J. Smith, Tomás Wagener, Tomaso Bontognali, Magalia Bonifacie, Lauren Edgar, Shane Schoepher, and Kelly Hillbun for their help during field work. By last, we would like to thank to Elisabet Beamud and to an anonymous reviewer, whose comments and suggestions helped us to improve the first version of this manuscript. Declaration of Competing Interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Attached Files

Supplemental Material - 1-s2.0-S0031018220303163-mmc1.docx


Files (3.2 MB)
Name Size Download all
3.2 MB Download

Additional details

August 22, 2023
October 20, 2023