Cretaceous Crust in the Scotia Sea: Missing Pieces in a Geological Puzzle?

IF 3.3 1区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS
Tectonics Pub Date : 2024-06-21 DOI:10.1029/2023tc008079
J. H. Oldenhage, W. P. Schellart, A. Beniest
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引用次数: 0

Abstract

The interplay between regional tectonics and the development of a major ocean gateway between the Pacific and the Atlantic Ocean has resulted in numerous paleogeographic reconstruction studies that describe the Cenozoic tectonic history of the Scotia Sea region. Despite the multitude of published tectonic reconstructions and the variety of geological and geophysical data available from the Scotia Sea, the geological history remains ambiguous. We present a comparative paleogeographic analysis of previously published tectonic reconstructions to identify agreements and conflicts between these reconstructions. We propose an alternative model to explain the Cenozoic evolution of the Scotia Sea region. The paleogeographic comparison shows that most reconstructions agree on the tectonic evolution of the South Scotia Ridge and the East Scotia Ridge. Major differences between the reconstructions are the role of the westward subducting plate below the South Sandwich plate, and the age and origin of the Central Scotia Sea. Tectonic reconstructions assume that the Central Scotia Sea is either part of a Cenozoic back-arc basin, or a captured piece of Cretaceous oceanic crust. We propose a new alternative tectonic reconstruction that brings these two prevailing hypotheses elegantly together. Here, we identified new geographical blocks consisting of thinned continental or Cretaceous oceanic fragments that originate from the Paleo-Pacific Weddell Sea gateway from high-resolution bathymetry. These fragments are now part of the Central Scotia Sea and have been affected by early back-arc tectonic activity of the South Sandwich subduction zone, leading locally to the formation of Cenozoic-aged crust in the Central Scotia Sea.
斯科舍海的白垩纪地壳:地质拼图中缺失的部分?
区域构造与太平洋和大西洋之间主要海洋门户的发展之间的相互作用,导致了许多描述斯科舍海区域新生代构造历史的古地理重建研究。尽管已发表的构造重建研究很多,斯科舍海的地质和地球物理数据也多种多样,但地质历史仍然模糊不清。我们对以前公布的构造重建进行了古地理比较分析,以确定这些重建之间的一致与冲突。我们提出了一个替代模型来解释斯科舍海地区新生代的演变。古地理对比结果表明,大多数重建都认同南斯科舍海脊和东斯科舍海脊的构造演化。重建之间的主要差异在于南桑威奇板块下方向西俯冲板块的作用以及中斯科舍海的年龄和起源。构造重建假定中斯科舍海要么是新生代弧后盆地的一部分,要么是白垩纪大洋地壳的一块俘虏。我们提出了一种新的构造重建方案,将这两种流行的假说巧妙地结合在一起。在这里,我们从高分辨率水深测量中发现了由变薄的大陆或白垩纪大洋碎片组成的新地理区块,这些碎片源自古太平洋威德尔海门户。这些碎块现在是中斯科舍海的一部分,受到南桑威奇俯冲带早期弧后构造活动的影响,在中斯科舍海局部形成了新生代地壳。
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来源期刊
Tectonics
Tectonics 地学-地球化学与地球物理
CiteScore
7.70
自引率
9.50%
发文量
151
审稿时长
3 months
期刊介绍: Tectonics (TECT) presents original scientific contributions that describe and explain the evolution, structure, and deformation of Earth¹s lithosphere. Contributions are welcome from any relevant area of research, including field, laboratory, petrological, geochemical, geochronological, geophysical, remote-sensing, and modeling studies. Multidisciplinary studies are particularly encouraged. Tectonics welcomes studies across the range of geologic time.
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