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Changing of the guards: detrital zircon provenance tracking sedimentological reorganization of a post‐Gondwanan rift margin
Basin Research ( IF 2.8 ) Pub Date : 2019-09-06 , DOI: 10.1111/bre.12403
Milo Barham 1 , Christopher L. Kirkland 1
Affiliation  

[Abstract Understanding the development of sedimentary systems during continental rifting is important for tracking environmental change and lithospheric processes. Conceptual models have been developed for the sourcing, routing and facies architecture of sediments in rift‐settings, driven in part by quantitative sediment tracking. Here, we present laser ablation split‐stream detrital zircon U/Pb geochronology and Hf‐isotopes for post‐rift (Cretaceous‐Paleogene) clastic sediments from Ocean Drilling Program (ODP) wells and Plio‐Pleistocene palaeoshoreline material, from the southern margin of Australia. Provenance results are contextualized through comparison with well‐characterized source regions and regional pre‐ and syn‐rift sediment reservoirs to track changes associated with Australia‐Antarctica separation during East Gondwana break‐up. The provenance character of the post‐rift sediments studied are distinct from pre‐existing sediment reservoirs and demonstrate termination of previously stable sediment routing systems and a dominance of local basement of the Proterozoic Madura and Coompana provinces (~1.2 Ga and CHUR‐like Hf‐signatures; Moodini Supersuite) in offshore ODP wells. A composite post‐rift Cretaceous?‐Eocene sample in the easternmost well expresses characteristic Phanerozoic zircon age signatures associated with source regions in eastern Australia that are interpreted to reflect inversion in the Ceduna Sub‐basin to the east. Detrital zircon signatures in Plio‐Pleistocene palaeoshoreline sediment are also relatively distinct, indicating derivation from coastal erosion in the Leeuwin Complex (~0.5 and 0.7 Ga subchondritic grains) and Albany–Fraser Orogen (~1.2 Ga subchondritic grains) several hundred, to over a thousand kilometers to the west. Collectively, results highlight the fundamental geological processes associated with rifting that dramatically change the character of sediment provenance via (a) isolation of pre‐existing primary and secondary sources of detritus, (b) development of new source regions in basin compartmentalized highs and localized fault scarps, and (c) establishment of marine and coastal currents that redefine clastic sediment transport., Detrital zircon U/Pb age and Hf‐isotopes facilitate a robust understanding of sediment source to sink relationships on the southern margin of Australia. Provenance analysis tracks complete reorganisation of sediment systems associated with the rifting of Australia and Antarctica during Gondwana break‐up. ]

中文翻译:

换岗:碎屑锆石物源追踪后冈瓦纳裂谷边缘的沉积学重组

[摘要 了解大陆裂谷期间沉积系统的发展对于跟踪环境变化和岩石圈过程很重要。已经为裂谷环境中沉积物的来源、路径和相结构开发了概念模型,部分由定量沉积物跟踪驱动。在这里,我们展示了来自大洋钻探计划 (ODP) 井和上新世古海岸线材料的裂谷后(白垩纪-古近纪)碎屑沉积物的激光烧蚀分流碎屑锆石 U/Pb 年代学和 Hf 同位素,来自南缘澳大利亚。通过与特征良好的源区和区域前和同裂谷沉积物储层进行比较,对物源结果进行背景化,以跟踪与东冈瓦纳大陆分裂期间澳大利亚-南极分离相关的变化。所研究的裂谷后沉积物的来源特征与先前存在的沉积物储层不同,并证明了先前稳定的沉积物路径系统的终止以及元古代马杜拉省和库姆帕纳省(~1.2 Ga 和 CHUR 样 Hf-签名;Moodini Supersuite)在海上 ODP 井中。最东口井中的裂谷后白垩纪-始新世复合样品表达了与澳大利亚东部源区相关的显生宙锆石年龄特征,这些特征被解释为反映了东部塞杜纳盆地的反演。上新世-更新世古海岸线沉积物中的碎屑锆石特征也相对不同,表明源自鲁文杂岩(~0.5 和 0.7 Ga 亚球粒陨石颗粒)和奥尔巴尼-弗雷泽造山带(~1. 2 Ga 球粒下颗粒)几百到一千多公里向西。总的来说,结果突出了与裂谷相关的基本地质过程,这些过程通过 (a) 分离先前存在的初级和次级碎屑源,(b) 在盆地分隔的高地和局部断层中开发新的源区,从而显着改变沉积物来源的特征(c) 建立了重新定义碎屑沉积物运输的海洋和沿海流。碎屑锆石 U/Pb 年龄和 Hf 同位素促进了对澳大利亚南缘沉积物源汇关系的深入了解。物源分析追踪与冈瓦纳大陆分裂期间澳大利亚和南极洲裂谷相关的沉积物系统的完全重组。] 向西一千多公里。总的来说,结果突出了与裂谷相关的基本地质过程,这些过程通过 (a) 分离先前存在的初级和次级碎屑源,(b) 在盆地分隔的高地和局部断层中开发新的源区,从而显着改变沉积物来源的特征(c) 建立了重新定义碎屑沉积物运输的海洋和沿海流。碎屑锆石 U/Pb 年龄和 Hf 同位素促进了对澳大利亚南缘沉积物源汇关系的深入了解。物源分析追踪与冈瓦纳大陆分裂期间澳大利亚和南极洲裂谷相关的沉积物系统的完全重组。] 向西一千多公里。总的来说,结果突出了与裂谷相关的基本地质过程,这些过程通过 (a) 分离先前存在的初级和次级碎屑源,(b) 在盆地分隔的高地和局部断层中开发新的源区,从而显着改变沉积物来源的特征(c) 建立了重新定义碎屑沉积物运输的海洋和沿海流。碎屑锆石 U/Pb 年龄和 Hf 同位素促进了对澳大利亚南缘沉积物源汇关系的深入了解。来源分析追踪与冈瓦纳大陆分裂期间澳大利亚和南极洲的裂谷相关的沉积物系统的完全重组。] 结果突出了与裂谷相关的基本地质过程,这些过程通过 (a) 分离预先存在的初级和次级碎屑来源,(b) 在盆地分隔的高地和局部断层陡坡中开发新的源区,显着改变沉积物来源的特征, (c) 建立了重新定义碎屑沉积物迁移的海洋和沿海流。碎屑锆石 U/Pb 年龄和 Hf 同位素促进了对澳大利亚南缘沉积物源汇关系的深入了解。物源分析追踪与冈瓦纳大陆分裂期间澳大利亚和南极洲裂谷相关的沉积物系统的完全重组。] 结果突出了与裂谷相关的基本地质过程,这些过程通过 (a) 分离先前存在的初级和次级碎屑来源,(b) 在盆地分隔的高地和局部断层陡坡中开发新的源区,从而显着改变沉积物来源的特征, (c) 建立了重新定义碎屑沉积物迁移的海洋和沿海流。碎屑锆石 U/Pb 年龄和 Hf 同位素促进了对澳大利亚南缘沉积物源汇关系的深入了解。物源分析追踪与冈瓦纳大陆分裂期间澳大利亚和南极洲裂谷相关的沉积物系统的完全重组。] (c) 建立了重新定义碎屑沉积物迁移的海洋和沿海流。碎屑锆石 U/Pb 年龄和 Hf 同位素促进了对澳大利亚南缘沉积物源汇关系的深入了解。物源分析追踪与冈瓦纳大陆分裂期间澳大利亚和南极洲裂谷相关的沉积物系统的完全重组。] (c) 建立了重新定义碎屑沉积物迁移的海洋和沿海流。碎屑锆石 U/Pb 年龄和 Hf 同位素促进了对澳大利亚南缘沉积物源汇关系的深入了解。物源分析追踪与冈瓦纳大陆分裂期间澳大利亚和南极洲裂谷相关的沉积物系统的完全重组。]
更新日期:2019-09-06
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