Stratigraphic Evolution of the Haslingden Group in the Leichhardt River Fault Trough, Mount Isa Orogen, Australia: Implications for Rift Tectonics

哈斯灵登群是地球上最古老的覆盖层层序。 伊萨山Orogen;它是CA。厚达18公里， 1800 ~ 1710 Ma Leichhardt River Fault Trough（LRFT） 在CA之前。1860年--大陆地壳。 火山- 沉积的Haslingden群以前被解释为 一个单期裂谷序列和一个上覆沉积 包，Quillestan形成，作为凹陷相关联， 伴随着岩石圈的热收缩。 我们 对哈斯灵登集团的初步研究表明， 复杂的演化涉及至少两个阶段的裂谷作用。 该假设将通过以下方式进行评估：i）约束 哈斯灵登群的地层演化 详细的沉积学/古地理分析，包括 可能的浅海沉积物定量分析 潮汐成因; ii）对比地层演化 哈斯灵登群在地质上有记录的裂谷序列 记录;以及iii）对沉降进行定量建模 在地层约束下的LRFT历史 分析和地质年代学框架。 的理解 哈斯灵登群的地层演化 加强对暴露较少的裂缝的了解， 北海和基韦纳湾裂谷以及一般的裂谷。 这项研究是多学科的一部分。 对伊萨山造山带的调查，包括一个结构 矿产资源局对LRFT的分析， 澳大利亚 作为该项目的一部分，我们将能够评估 LRFT在其自身构造背景下的演化， 以及周围构造过程的框架内。 哈斯灵登小组的分析结果将是 与正在进行的构造变质地质年代学 地球化学和沉积学研究， 伊萨山造山带的综合构造模式。 沉降建模和各种学科的整合， 建立伊萨山造山带的构造模型 在PI在BMR学习休假期间进行， 1988年的时间。

The Haslingden Group is the oldest cover sequence in the Mount Isa Orogen; it is ca. 18 km thick and accumulated in the Leichhardt River Fault Trough (LRFT) between 1800 and 1710 Ma ago on ca. 1860 Ma-old continental crust. The volcano- sedimentary Haslingden Group has previously been interpreted as a single-stage rift sequence and an overlying sedimentary package, the Quilalar Formation, as the sag phase associated with subsequent thermal contraction of the lithosphere. Our preliminary work on the Haslingden Group suggests a more complex evolution involving at least two stages of rifting. This hypothesis will be evaluated by: i) constraining the stratigraphic evolution of the Haslingden Group through a detailed sedimentological/paleogeographical analysis including quantitative analysis of shallow marine sediments of probable tidal origin; ii) contrasting the stratigraphic evolution of the Haslingden Group with documented rift sequences in the geologic record; and iii) quantitatively modelling the subsidence history of the LRFT within the constraints of the stratigraphic analysis and the geochronological framework. An understanding of the stratigraphic evolution of the Haslingden Group will enhance the understanding of less well-exposed rifts such as the North Sea and Keweenawan Rifts and of rifts in general. The proposed study is part of a multidisciplinary investigation of the Mount Isa Orogen, including a structural analysis of the LRFT, by the Bureau of Mineral Resources, Australia. As part of this project we will be able to evaluate the evolution of the LRFT within its own tectonic context as well as within the framework of surrounding tectonic processes. The results of the analysis of the Haslingden Group will be integrated with ongoing structural-metamorphic, geochronologic, geochemical and sedimentological studies to formulate a comprehensive tectonic model for the Mount Isa Orogen. Subsidence modelling and integration of various disciplines in developing a tectonic model for the Mount Isa Orogen will be undertaken while the PI is on study leave at the BMR for the duration of 1988.