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

Citation

Wainman, CC and Borissova, I and Harry, DL and Hobbs, RW and Mantle, DJ and Maritati, A and Lee, EY and the Expedition 369 Scientists, 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, 67, (1) pp. 89-105. ISSN 0812-0099 (2019) [Refereed Article]


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DOI: doi:10.1080/08120099.2019.1627581

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 369

  • Upper Jurassic–Lower Cretaceous non-marine strata below the Valanginian Unconformity

  • High TOC’s, high abundances of Botryococcus algae in a few horizons and a possible example of dinoturbation

  • Jurassic rifting not constrained to the western Mentelle Basin, but to depocentres in the east

Item Details

Item Type:Refereed Article
Keywords:Mentelle Basin, Jurassic, IODP, syn-rift, Lower Cretaceous, Valanginian unconformity, fluvio-lacustrine, eastern Gondwana, palynology, petroleum potential
Research Division:Earth Sciences
Research Group:Geology
Research Field:Tectonics
Objective Division:Environment
Objective Group:Environmental and Natural Resource Evaluation
Objective Field:Environmental Management Systems
UTAS Author:Maritati, A (Mr Alessandro Maritati)
ID Code:136750
Year Published:2019
Deposited By:Oceans and Cryosphere
Deposited On:2020-01-16
Last Modified:2020-02-05
Downloads:0

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