Abstract
High precision Chemical abrasion-isotope dilution thermal ionisation mass spectrometry (CA-IDTIMS) U-Pb zircon results from tuff marker beds that are interstratified within the Upper Permian deposits of the northern Sydney Basin add constraints on the timing of sediment deposition, and afford a better understanding of the regional stratigraphy. The results indicate a magmatic influence during the deposition of the sediments, with episodic events spanning at least from 255.65 ± 0.08 to 255.08 ± 0.09 Ma. The zircon data suggest that the studied sedimentary rocks and tuffs have accumulated simultaneously over a short time interval, which contrasts with current stratigraphic models that suggest a much greater period of deposition and stratigraphic thickness. Therefore, an updated stratigraphic correlation of the basin is suggested, which combines the presently defined Lambton, Adamstown, and Boolaroo sub-groups into a single Lambton sub-group. This updated correlation framework is stratigraphically and geochronologically constrained and provides a more precise exploration model for the northern Sydney Basin. This case study highlights the valuable contribution of the CA-IDTIMS method in intrabasinal correlations of sedimentary successions, when integrated with a robust sedimentological framework, to minimize the stratigraphic uncertainties.
Highlights
Tuff beds interstratified in the sedimentary successions are common and are often employed as marker horizons to add tighter constraints on the stratigraphic evolution of sedimentary basins.Chemical abrasion-isotope dilution thermal ionisation mass spectrometry (CA-IDTIMS) data from such beds have been recently utilised as the most precise radio-isotopic dating data for zircon analysis [1,2].This method has the ability to provide dates with an accuracy of ~100,000 years [3], making it a useful tool for intrabasinal correlations [4,5]
The application of CA-IDTIMS method has been proven very useful in obtaining numerical constraints on biostratigraphic schemes [6], refining the temporal framework of mass extinction events and major climatic changes [7], and determining the initiation of major plate tectonics configurations [8,9]
The contribution of CA-IDTIMS method to link the isotopic dates to the palynostratigraphic schemes in sedimentary successions has been recognized previously [1,4,5,6]
Summary
Tuff beds interstratified in the sedimentary successions are common and are often employed as marker horizons to add tighter constraints on the stratigraphic evolution of sedimentary basins.Chemical abrasion-isotope dilution thermal ionisation mass spectrometry (CA-IDTIMS) data from such beds have been recently utilised as the most precise radio-isotopic dating data for zircon analysis [1,2].This method has the ability to provide dates with an accuracy of ~100,000 years [3], making it a useful tool for intrabasinal correlations [4,5]. The application of CA-IDTIMS method has been proven very useful in obtaining numerical constraints on biostratigraphic schemes [6], refining the temporal framework of mass extinction events and major climatic changes [7], and determining the initiation of major plate tectonics configurations [8,9]. Even though such models are critical exploration natural reserves, the research thatwithin utilizessedimentary
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