Sedimentary facies analysis and paleogeographic significance of the latest Silurian to Early Devonian Winduck Interval in the Darling Basin, western New South Wales, Australia

Abstract

This work presents the first detailed sedimentary facies analysis of the subsurface latest Silurian to Early Devonian Winduck Interval, based on four wells in the Blantyre and western Neckarboo sub-basins in the central part of the Darling Basin. The study integrates wireline logs, cores, cuttings and limited biostratigraphic data to determine the sedimentary sequence subdivision in the study area. Sedimentological analysis was applied, using characteristic wireline-log responses, and core and cuttings descriptions, to aid in the development of a depositional environment model for the Winduck Interval. Twenty-nine sedimentary facies are defined, forming five facies associations. These associations are characterised as distributary channel sandstone complex, distributary mouth bar, tidal channel sand, proximal delta front associated with mouth bars complex, and distal delta front to prodelta sediments. Tectonism influenced the paleogeography, although fault zones (a complex of normal and reverse faults) were important in determining sedimentary sequence thicknesses obtained from the wells. Tectonic subsidence was moderate, and accumulation rates were low. The results of sedimentary facies analysis of the Winduck Interval have implications for evaluating the hydrocarbon potential, and may assist extensive exploration efforts that are currently occurring in the Darling Basin within western New South Wales.

这项工作提出了首次志留纪末至早泥盆纪地下Winduck地层段的详细的沉积相分析。该分析基于达令盆地中部Blantyre和Neckarboo子盆地西部的四口测井。该研究综合了电缆测井、岩心、岩屑和有限生物地层数据，以确定研究区的沉积层序细分。我们运用了沉积学分析，使用特性有线测井反应，以及​​岩心和钻屑描述，以帮助建立Winduck层段的沉积环境模式。二十九个沉积相被确定，形成五个相组合。这些组合的特征是分流河道砂岩复合体、河口坝、潮汐河道砂、与河口坝复合体相关的近三角洲前缘以及远三角洲前缘至前三角洲的沉积物。构造运动影响了古地理，虽然断层带（一个正、逆断层的复合体）在确定从测井中得到的沉积层序厚度方面很重要。构造沉降幅度中度，沉积速率低。Winduck层段的沉积相分析结果对评价油气潜力有意义，并可能有助于那些目前发生在新南威尔士西部达令盆地的广泛勘探活动。

KEY WORDS:

• Blantyre Sub-basin
• Neckarboo Sub-basin
• latest Silurian to Early Devonian
• wireline log data
• core descriptions
• facies association
• Winduck Interval
• paleogeography

ACKNOWLEDGEMENTS

The authors wish to thank Geological Survey of NSW, NSW Trade & Investment (Petroleum Geoscience) for the release of the dataset and giving permission to publish this article. Special thanks to Jola Jaworska (Acting Manager—Petroleum Geoscience) and Michelle Kounnas (Technical Assistant—Petroleum) for providing all of the data and reports for this research. Thanks also to Dr Ralph Leonard Kugler (University of Malaya) for raising some useful issues in his review of this article. We are grateful to the editor and referees for their constructive criticism to an early version of the article, discussions, and helpful comments, which were of great assistance.

Disclosure statement

No potential conflict of interest was reported by the author.