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Tectonostratigraphic evolution of the Cretaceous Western South Atlantic
Marine and Petroleum Geology ( IF 3.7 ) Pub Date : 2021-06-26 , DOI: 10.1016/j.marpetgeo.2021.105197
Pedro Kress , Octavian Catuneanu , Ricardo Gerster , Nestor Bolatti

The Cretaceous evolution of the Argentine margin between the Agulhas Malvinas (Falkland) Fracture Zone and the Rio de la Plata Fracture Zone is key in understanding the development of a volcanic divergent margin. In order to outline the evolution, more than 50000 km of 2D Seismic data were the foundation of the identification of the tectonic events and the sequence stratigraphic interpretation of the margin. However, ages of these events remain uncertain, as well data is limited to continental and shallow marine sequences with few biostratigraphic records.

Rifting during late Jurassic-early Cretaceous times preserved under the current shelf seems not to be mechanically linked to the crustal thinning, breakup and subsequent generation of oceanic crust, as rifts entered into sag stage before the onset of crustal breakup.

Four main turning points in the evolution of the passive margin have been identified: (i) crustal breakup associated with the SDRs emplaced during the late fault-extensional stage of the margin (ii) top of the first marine ingression creating accommodation for shallow marine carbonate and clastic deposits by Late Aptian times, followed by the development of a stratigraphic shelfbreak in overall shallow marine (300m) paleowater depth during Albian times; (iii) a regional unconformity after which deep marine conditions with a structurally enhanced shelfbreak and thermohaline currents came into being (Late Cenomanian – Turonian), likely to be associated to final split off between SW Africa and the Malvinas (Falkland) plateau; (iv) a regional unconformity followed by a widespread transgression which marks the end of the Cretaceous (Maastrichtian-Danian) and a margin-wide reorganization of the sediment dispersal systems.



中文翻译:

白垩纪西南大西洋构造地层演化

Agulhas Malvinas(福克兰)断裂带和Rio de la Plata 断裂带之间阿根廷边缘的白垩纪演化是了解火山发散边缘发育的关键。为了勾画演化,50000多公里的二维地震资料是构造事件识别和边缘层序地层解释的基础。然而,这些事件的年龄仍然不确定,因为数据仅限于大陆和浅海序列,生物地层记录很少。

现今陆架下保存的晚侏罗世-早白垩世的裂谷似乎与地壳变薄、破裂和随后的洋壳生成没有机械联系,因为裂谷在地壳破裂开始之前进入凹陷阶段。

已经确定了被动边缘演化的四个主要转折点:(i) 与在边缘断层延伸晚期阶段发生的 SDR 相关的地壳破裂 (ii) 第一次海侵的顶部为浅海相碳酸盐岩创造了容纳空间和碎屑沉积物到晚 Aptian 时代,随后在整个浅海 (300m) 古水深在 Albian 时代发展了地层陆架断裂;(iii) 区域性不整合,在此之后形成具有结构性增强的陆架断裂和温盐流的深海条件(晚塞诺曼阶 - 图伦阶),可能与非洲西南部和马尔维纳斯(福克兰)高原之间的最终分裂有关;

更新日期:2021-06-28
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