当前位置: X-MOL 学术Palaeogeogr. Palaeoclimatol. Palaeoecol. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Upper Triassic carbonate-platform facies, Timor-Leste: Foraminiferal indices and regional tectonostratigraphic association
Palaeogeography, Palaeoclimatology, Palaeoecology ( IF 2.6 ) Pub Date : 2021-03-18 , DOI: 10.1016/j.palaeo.2021.110362
David W. Haig , Sylvain Rigaud , Eujay McCartain , Rossana Martini , Isaias Santos Barros , Lucy Brisbout , Jacinto Soares , Jose Nano

Timor is part of the non-volcanic Outer Banda Arc with chaotic geology in the late Neogene collision zone between Sundaland (Southeast Eurasia) and the Australian continent. Confusion in the distinction between Triassic, Jurassic and Cenozoic shallow-marine carbonate units has led to a lack of appreciation of the widespread extent of Triassic carbonate-platform facies, at least in Timor-Leste. It also resulted in misunderstanding the different tectonostratigraphic/palaeogeographic affinities of the shallow-water limestones. Foraminiferal assemblages are critical in stratigraphic discrimination of these units. This study records for the first time the foraminiferal microfauna of Upper Triassic shallow-water carbonate deposits in Timor. Many of the foraminiferal species are known from North Africa and Europe and date these units to the Carnian–Rhaetian. The Upper Triassic Bandeira Group represents extensive sheet-like carbonate-platform deposits (possibly on horst plateaus as well as shelf areas adjacent land in the intracratonic sea). Contacts between the hard limestone, forming fatus (limestone peaks) and ridges, and friable mud-dominated surrounding units are often obscured under deep tropical soil cover. At all localities the Bandeira Group is closely associated in outcrop with coeval basinal mud-dominated deposits (Babulu and Aitutu groups). With these it forms part of the East Gondwana Interior Rift Association (EGIRA), similar to the classical Dachstein Platform–Hallstatt Basin facies associations found in the European Alps. The basinal units contain turbiditic and debris-slide deposits that include clasts derived from the carbonate platform. Shallow-water carbonate facies attributed to EGIRA, are present throughout the East Gondwana Interior Rift from the Papuan Basin in the north to Exmouth Plateau, part of the Northern Carnarvon Basin, in the south. These were deposited before Gondwanan breakup along this rift system. The Triassic carbonate-platform deposits have a different dominant biogenic mineralogy (aragonite rather than calcite) and a different architecture to the bryozoan-crinoidal carbonate mounds present in the Permian of EGIRA in Timor-Leste. No Lower and Middle Triassic shallow-water carbonate-platform deposits have been recognized in Timor-Leste. The Bandeira Group, confined to the Upper Triassic, belongs to a stratigraphic association (EGIRA; autochthonous) different both in constituent units and outcrop coverage from that of the allochthonous Overthrust Terrane Association to which the Lower Jurassic carbonate-platform deposits (viz. Perdido Group) belong. The Bandeira Group has been confused not only with the Perdido Group but also with other shallow-water limestone units of the Permian and Miocene in some former studies of Timor. The distinction between these units solves a major tectonostratigraphic problem in Timor, and may apply elsewhere along the Outer Banda Arc.



中文翻译:

东三叠纪上三叠统碳酸盐台地相:有孔虫指数和区域构造地层学关联

帝汶是桑达兰州(东南欧亚大陆)和澳大利亚大陆之间新近纪晚期碰撞带中非火山性外班达弧的一部分,地质混乱。三叠纪,侏罗纪和新生代浅海碳酸盐岩单元之间的区分混乱,导致人们至少在东帝汶对三叠纪碳酸盐岩台地相的广泛范围缺乏认识。这也导致了对浅水灰岩不同构造地层/古地理亲和力的误解。有孔虫组合对于这些单元的地层判别至关重要。这项研究首次记录了帝汶上三叠统浅水碳酸盐沉积物的有孔虫微动物区系。从北非和欧洲已知许多有孔虫物种,并将这些单元的年代追溯到卡尼期-拉脱期。上三叠纪班迪拉群代表广泛的片状碳酸盐台地沉积物(可能在霍斯特高原以及克拉通海附近陆架地区)。坚硬的石灰石之间的接触,形成了脂肪(石灰岩峰)和山脊,以及易碎的以泥浆为主的周围环境,常常被深热带土壤覆盖物所掩盖。在所有地方,班德拉(Bandeira)组露头与同时代的盆地性泥浆为主的沉积物(Babulu和Aitutu组)紧密相关。它们与东贡多瓦内陆裂谷协会(EGIRA)一样,类似于在欧洲阿尔卑斯山发现的经典达赫斯坦平台-哈尔施塔特盆地相协会。这些盆地单元包含湍流和泥石流沉积物,其中包括源自碳酸盐岩台地的碎屑。从北部的Papuan盆地到南部的Carnarvon盆地的一部分的埃克斯茅斯高原,整个冈多纳大陆东部裂谷都存在着属于EGIRA的浅水碳酸盐岩相。这些是在冈瓦纳解体之前沿着这个裂谷系统沉积的。三叠纪碳酸盐台地的沉积物具有与东帝汶EGIRA二叠纪中存在的苔藓类孢子-海藻酸盐碳酸盐土丘不同的主要生物成矿作用(文石而非方解石),并且具有不同的构造。东帝汶没有发现下中三叠世浅水碳酸盐岩台地。班迪拉群仅限于上三叠纪,属于地层学协会(EGIRA;下侏罗统碳酸盐台地沉积物(即Perdido组)所属的外推覆地层协会的组成单元和露头覆盖范围都不同。在帝汶的一些以前的研究中,班德拉(Bandeira)小组不仅与Perdido小组相混淆,而且与二叠纪和中新世的其他浅水石灰岩单元相混淆。这些单位之间的区别解决了帝汶一个主要的构造地层问题,并可能在外班达弧外的其他地方使用。在帝汶的一些以前的研究中,班德拉(Bandeira)小组不仅与Perdido小组相混淆,而且与二叠纪和中新世的其他浅水石灰岩单元相混淆。这些单位之间的区别解决了帝汶一个主要的构造地层问题,并可能在外班达弧外的其他地方使用。在帝汶的一些以前的研究中,班德拉(Bandeira)小组不仅与Perdido小组相混淆,而且与二叠纪和中新世的其他浅水石灰岩单元相混淆。这些单位之间的区别解决了帝汶一个主要的构造地层问题,并可能在外班达弧外的其他地方使用。

更新日期:2021-03-27
down
wechat
bug