T241 Late Jurassic through Early Cretaceous Geologic Time Scale

Wednesday, 7 November 2018
8:00 AM - 12:00 PM
Sagamore Ballroom 7

MAGNETOSTRATIGRAPHY ACROSS U-PB-DATED HORIZONS IN SVALBARD BOREHOLES TO PARTLY RESOLVE THE DEBATED AGE OF BARREMIAN/APTIAN BOUNDARY

Paper number: T241-12
Program: Technical Sessions
Time: 11:00 AM – 11:15 AM

Authors

Abstract

Bentonites associated with the High Arctic Large Igneous Province (HALIP) (Corfu et al., 2013) occur within clastic-shelf deposits that have been cored near Svalbard and have a possible late Barremian or early Aptian biostratigraphic age based on sparse palynomorphs. These have yielded zircons that are dated using U-Pb TIMS as 123.1 +/-0.3 Ma (Midtkandal et al., 2016). Several meters higher are organic-rich deposits that have been interpreted as coeval with the earliest Aptian Oceanic Anoxic Event 1a (OAE1a or (Selli Event) based upon their carbon-isotope excursion pattern. If this OAE1a interpretation is correct, then the Barremian/Aptian boundary might be ca. 121-122 Ma (Midtkandal et al., 2016). This date is nearly 4-myr younger than the 125-126 Ma age for the base-Aptian in Geologic TimeScale 2012/2016(Gradstein et al., 2012; Ogg et al., 2016), which was based on the agreement of a astronomical cycle-scaled duration of the Aptian stage relative to U-Pb dating of the Aptian/Albian boundary with Ar-Ar dating of the Ontong Java Plateau, which is a proposed trigger for the OAE1a.

Magnetostratigraphy enables a test of the proposed Svalbard geologic age assignments and the implied boundary dating, because polarity Chron M0r spans much of the interval between the base-Aptian and the beginning of OAE1a. Therefore, we did a paleomagnetic sampling of the clastic sediments in these Svalbard boreholes; and report the pilot results in this presentation.

Corfu, F., Polteau, S., Planke, S., Faleide, J. I., Svensen, H., Zayoncheck, A., Stolbov, N., 2013. U-Pb geochronology of Cretaceous magmatism on Svalbard and Franz Josef Land, Barents Sea large igneous province. Geological Magazine, 150(6): 1127-1135.

Gradstein, F.M., Ogg, J.G., Schmitz, M.D., Ogg, G.M. (Eds.) 2012. Geologic Time Scale 2012. Elsevier Publ., 2 volumes, 1176 pp.

Midtkandal, I., et al., 2016. The Aptian (Early Cretaceous) oceanic anoxic event (OAE1a) in Svalbard, Barents Sea, and the absolute age of the Barremian-Aptian boundary. Palaeogeography, Palaeoclimatology, Palaeoecology463: 126-135.

Ogg, J.G., Ogg, G.M., Gradstein, F.M., 2016. A Concise Geologic Time Scale 2016. Elsevier Publ., 234 pp.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-323068

© Copyright 2018 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.