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Evidence for non-marine Jurassic to earliest Cretaceous sediments in the pre-breakup section of the Mentelle Basin, southwestern Australia

Wainman, CC, Borissova, I, Harry, DL, Hobbs, RW, Mantle, DJ, Maritati, A ORCID: 0000-0003-0587-8237 and Lee, EY 2019 , 'Evidence for non-marine Jurassic to earliest Cretaceous sediments in the pre-breakup section of the Mentelle Basin, southwestern Australia' , Australian Journal of Earth Sciences, vol. 67, no. 1 , pp. 89-105 , doi: 10.1080/08120099.2019.1627581.

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Abstract

The Mentelle Basin, located off the southwestern continental Australian margin, is an under-explored deep-water basin that developed during the breakup of eastern Gondwana in the Middle Jurassic through to the Early Cretaceous. There is a high degree of uncertainty in stratigraphic interpretations of the basin owing to the lack of well and seismic data in the region. As a consequence, there has been a heavy reliance on data from the neighbouring Perth Basin to infer the geological history of the Mentelle Basin. During Expedition 369 of the International Ocean Discovery Program, a single hole was drilled with a rotary core bit to 517.10 m below seafloor at Site U1515 on the continental slope in the eastern Mentelle Basin. The aim was to sample and date the inferred Permian to Jurassic pre-breakup strata. The presence of palynomorphs including Murospora florida and Retitriletes watherooensis in the fluvio-lacustrine succession below the Valanginian breakup unconformity indicates a Jurassic to earliest Cretaceous age for the upper part of the pre-rift sedimentary succession. Notable characteristics of this succession include intervals with high percentages of total organic carbon (up to 44 wt%) and high hydrogen index values (Type I source rocks) associated with an increase in Botryococcus and other freshwater algae that accumulated in shallow lakes and waterlogged floodplains. A possible example of dinoturbation was also noted in this core. The discovery of Jurassic to earliest Cretaceous pre-breakup strata at Site U1515 suggests that Jurassic rifting was not constrained to the western depocentre of the Mentelle Basin, but also extended to a number of depocentres in the eastern Mentelle Basin. This has significant implications for the understanding of the regional tectonic history and the Mentelle Basin’s petroleum potential.Pre-breakup strata sampled in the eastern Mentelle Basin for the first time by IODP Expedition 369Upper Jurassic–Lower Cretaceous non-marine strata below the Valanginian UnconformityHigh TOC’s, high abundances of Botryococcus algae in a few horizons and a possible example of dinoturbationJurassic rifting not constrained to the western Mentelle Basin, but to depocentres in the east

Item Type: Article
Authors/Creators:Wainman, CC and Borissova, I and Harry, DL and Hobbs, RW and Mantle, DJ and Maritati, A and Lee, EY
Keywords: Mentelle Basin, Jurassic, IODP, syn-rift, Lower Cretaceous, Valanginian unconformity, fluvio-lacustrine, eastern Gondwana, palynology, petroleum potential
Journal or Publication Title: Australian Journal of Earth Sciences
Publisher: Blackwell Publishing Asia
ISSN: 0812-0099
DOI / ID Number: 10.1080/08120099.2019.1627581
Copyright Information:

© The Australian Association for Research in Education, Inc. 2020

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