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A revised Permian–Triassic stratigraphic framework for the northeastern Galilee Basin, Queensland, Australia, and definition of a new Middle–Upper Triassic sedimentary unit
Australian Journal of Earth Sciences ( IF 1.2 ) Pub Date : 2021-06-17 , DOI: 10.1080/08120099.2021.1931962
C. N. Todd 1 , E. M. Roberts 1 , A. J. Charles 2
Affiliation  

Abstract

The upper Paleozoic–lower Mesozoic strata in the northeastern Galilee Basin are important for their hydrocarbon and groundwater potential; however, despite numerous previous investigations, the nature of this stratigraphic interval remains enigmatic. This study integrates lithostratigraphy, palynology and U–Pb zircon geochronology of well-exposed Permian and Triassic sedimentary rocks and nearby stratigraphic cores from the Hughenden district to determine their maximum depositional ages and then revises the stratigraphy where necessary. The newly defined Galah Tuff Bed was discovered at the top of the Betts Creek beds in Porcupine Gorge and was dated at 251.9 ± 3 Ma. This provides an important age constraint for the Betts Creek beds and is a tie-point for correlations with coeval units in the adjacent Bowen Basin and the Sydney and Gunnedah basins to the southeast. The Galah Tuff Bed is interpreted to correlate with the Yarrabee Tuff in the Bowen Basin. Unconformably overlying the Betts Creek beds is a newly recognised stratigraphic unit, defined herein as the Porcupine Gorge Formation. Detrital zircon maximum depositional ages and palynology indicate a significant depositional hiatus of up to 20 million years between the Betts Creek beds and Porcupine Gorge Formation. The hiatus indicates that the lower part of the Porcupine Gorge Formation is at least upper Middle Triassic, whereas the upper part of the unit extends into the Late Triassic. This age also constrains the overlying Warang Sandstone, which is considerably younger locally than previously reported and is likely diachronous across the northeastern Galilee Basin.

  1. KEY POINTS
  2. An integrated lithostratigraphy, palynology and U–Pb detrital zircon geochronology methodology is applied to the Permian–Triassic succession the northeastern Galilee Basin.

  3. Two new stratigraphic units were recognised: the upper Permian Galah Tuff Bed (251.9 ± 3 Ma) and the late Middle–Late Triassic Porcupine Gorge Formation (238.7 ± 3 Ma).

  4. The Galah Tuff Bed, correlative of the Yarrabee Tuff in the Bowen Basin, is evidence for widespread volcanism in the late Permian.

  5. The age of the Porcupine Gorge Formation indicates diachroneity of the Triassic succession in the Galilee Basin, warranting further examination.



中文翻译:

澳大利亚昆士兰加利利盆地东北部二叠纪-三叠纪地层格架的修订,以及新的中上三叠统沉积单元的定义

摘要

加利利盆地东北部的上古生界-下中生界地层对其油气和地下水潜力很重要;然而,尽管之前进行了许多调查,这个地层间隔的性质仍然是神秘的。本研究综合了 Hughenden 地区出露良好的二叠纪和三叠纪沉积岩和附近地层岩心的岩石地层学、孢粉学和 U-Pb 锆石年代学,以确定它们的最大沉积年龄,然后在必要时修改地层学。新定义的 Galah 凝灰岩床是在 Porcupine Gorge 的 Betts Creek 床层顶部发现的,其年代为 251.9 ± 3 Ma。这为 Betts Creek 河床提供了重要的年龄限制,并且是与邻近的 Bowen 盆地以及东南部的悉尼和 Gunnedah 盆地中的同时代单元相关的连接点。Galah凝灰岩床被解释为与Bowen盆地的Yarrabee凝灰岩相关。不整合地覆盖 Betts Creek 床层的是一个新发现的地层单元,在此定义为 Porcupine Gorge 组。碎屑锆石的最大沉积年龄和孢粉学表明 Betts Creek 床层和 Porcupine Gorge 组之间存在长达 2000 万年的显着沉积中断。断口表明,Porcupine Gorge 组下部至少为中三叠统上层,而单元上部延伸至晚三叠世。这个时代也限制了上覆的瓦朗砂岩,

  1. 关键点
  2. 一种综合的岩石地层学、孢粉学和 U-Pb 碎屑锆石年代学方法应用于加利利盆地东北部的二叠纪-三叠纪序列。

  3. 发现了两个新的地层单元:上二叠纪 Galah 凝灰岩层 (251.9 ± 3 Ma) 和晚中-晚三叠世 Porcupine Gorge 组 (238.7 ± 3 Ma)。

  4. 加拉凝灰岩床与鲍文盆地的亚拉比凝灰岩相关,是二叠纪晚期广泛火山活动的证据。

  5. Porcupine Gorge 组的年龄表明了加利利盆地三叠纪演替的历时性,值得进一步研究。

更新日期:2021-06-17
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