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Revised chrono and lithostratigraphy for the Oligocene-Miocene Patagoniense marine deposits in Patagonia: Implications for stratigraphic cycles, paleogeography, and major drivers
Journal of South American Earth Sciences ( IF 1.8 ) Pub Date : 2021-04-10 , DOI: 10.1016/j.jsames.2021.103327
Ana Parras , José I. Cuitiño

Richly fossiliferous upper Oligocene to lower Miocene Patagoniense marine deposits constitute a conspicuous feature of the sedimentary record of most basins in Patagonia. Patagoniense meaning and subdivisions have been confusing, and correlation and elucidation of factors controlling sedimentation in a region as extensive as Patagonia are still highly debated. Our revision of the distribution, correlation, stratigraphic arrangement, and timing of deposition, allows redefining the Patagoniense as a succession of widely distributed marine sediments accumulated in Patagonia from ~25 to 15 Ma, showing different timing of accumulation for each basin. It can also be conceived as a higher rank stratigraphic cycle of relative sea-level fluctuation, which comprises two medium rank stratigraphic cycles spanning 2–4 Myr each, in turn enclosing several lower rank cycles of less than 1 Myr. The late Oligocene (~25-23 Ma) medium rank cycle shows deposits restricted mostly to the coastal area of Tierra del Fuego and Santa Cruz provinces in the Austral-Magallanes Basin, which respond to a combination of global sea-level fluctuations and flexural subsidence. The overlying early Miocene (~22-15 Ma) medium rank cycle comprises sediments deposited over extensive areas of Patagonia with a maximum flooding at 20-19 Ma suggesting, in addition to tectonic subsidence in the Austral-Magallanes Basin, regional long-wavelength subsidence and a global sea level component for this episode. The timing and thickness of the regressive part of this cycle show differences for each basin, suggesting the action of local sedimentary controls such as differential rates of sediment supply. Further geochronological and stratigraphic studies are necessary, especially for the northern exposures, which will allow improving time-constrained paleogeographic reconstructions.



中文翻译:

修订后的巴塔哥尼亚中新世-中新世巴塔哥尼ense海相沉积物的年代学和岩相地层学:对地层循环,古地理和主要驱动因素的影响

化石丰富的上渐新世至下中新世巴塔哥尼亚人海相沉积物构成了巴塔哥尼亚大多数盆地沉积记录的显着特征。巴塔哥尼亚语的含义和细分一直令人困惑,而且在像巴塔哥尼亚这样广泛的地区,控制沉积的因素之间的相关性和阐明仍然存在争议。我们对分布,相关性,地层排列和沉积时间的修订允许重新定义Patagoniense分布在巴塔哥尼亚约25至15 Ma的一系列广泛分布的海洋沉积物,显示每个盆地的沉积时间不同。它也可以被认为是相对海平面波动的较高等级地层循环,它包括两个跨度为2-4 Myr的中等等级地层循环,进而包含了几个小于1 Myr的较低等级循环。渐新世晚期(〜25-23 Ma)中阶周期显示,沉积物主要限于Austral-Magallanes盆地的Tierra del Fuego和Santa Cruz省的沿海地区,这些地区对全球海平面波动和挠曲沉降的共同反应。上新世中期(〜22-15 Ma)中层周期包括沉积在巴塔哥尼亚广大地区的沉积物,最大洪水发生在20-19 Ma,这表明,除了南极-马加拉尼盆地的构造沉降以外,该事件还包括区域长波沉降和全球海平面分量。该周期回归部分的时间和厚度显示每个盆地的差异,这表明了局部沉积控制的作用,例如不同的沉积物供应速率。进一步的地质和地层研究是必要的,特别是对于北部地区而言,这将有助于改善受时间限制的古地理重建。

更新日期:2021-04-21
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