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Orbital cycles, differential subsidence and internal factors controlling the high-frequency sequence architecture in a sinemurian shallow carbonate platform (Mallorca Island, Spain)
Sedimentary Geology ( IF 2.8 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.sedgeo.2020.105729
Ana Sevillano , Beatriz Bádenas , Idoia Rosales , Antonio Barnolas , José María López-García

Abstract The ~125 m thick lower to lowermost upper Sinemurian peritidal to shallow subtidal platform carbonates in the Llevant Mountains of Mallorca (Spain) have been analysed from four stratigraphic sections, to provide new data on the hierarchical stacking pattern of high-frequency depositional sequences. Due to the fact that in shallow water environments the stacking of carbonate facies can be controlled by external (allocyclic) and internal (autocyclic) processes, deciphering the dominant controls on the high-frequency sequence architecture of these platforms is a challenge. The studied carbonates encompass a high variety of facies representative of open lagoon, internal bars, restricted lagoon and tidal flats with local beach sands. Based on a detailed analysis of vertical facies trends and bounding surfaces, large-, medium- and small-scale sequences have been identified within the long-term transgressive-regressive facies cycle defined by the entire succession. Large-scale sequences (~10–30 m thick) and medium-scale sequences (~1–10 m thick) are generally shallowing-upward sequences bounded by sharp facies changes to relatively deeper facies, and have been related to sea-level variations driven by long- (~400 kyr) and short- (~100 kyr) eccentricity cycles respectively. The overprinting of differential subsidence (probably related to extensional tectonic) and carbonate production and accumulation processes varied throughout time, controlling the lateral continuity and preservation potential of the ~100 kyr medium-scale sequences. Shallowing-upward, locally aggradational, small-scale sequences (~0.3 to 5 m thick) are very variable in number and thickness and cannot be correlated between sections, pointing out that their most important controlling factor was the internal processes (hiatuses and erosion related to subaerial exposure at the peritidal caps, lateral migration of internal bars, local wave and currents patterns, depositional and erosional processes related to spring tides and storms) in the frame of a complex mosaic of facies within the studied platform.

中文翻译:

控制sinemurian浅碳酸盐台地(西班牙马略卡岛)高频层序结构的轨道周期、差异沉降和内部因素

摘要 已从四个地层剖面分析了马略卡岛(西班牙)Llevant 山脉从下到最下层 Sinemurian 潮间带至浅潮下台地台碳酸盐约 125 m 厚,以提供有关高频沉积序列分层叠加模式的新数据。由于在浅水环境中,碳酸盐岩相的堆积可以由外部(异环)和内部(自循环)过程控制,因此破译这些平台高频序列结构的主要控制是一个挑战。所研究的碳酸盐岩包括代表开放泻湖、内部酒吧、限制泻湖和具有当地海滩沙子的潮滩的多种相。基于对垂直相趋势和边界面的详细分析,大、在由整个序列定义的长期海进-海退相循环中,已经确定了中小尺度层序。大尺度层序(~10~30 m 厚)和中尺度层序(~1~10 m 厚)一般是上浅层序,以急剧的相变到相对较深的相为界,并与海平面变化有关分别由长(~400 kyr)和短(~100 kyr)偏心率循环驱动。差异沉降的叠加(可能与伸展构造有关)和碳酸盐生产和聚集过程随时间变化,控制了~100 kyr 中等尺度序列的横向连续性和保存潜力。浅向上、局部累加、小尺度序列(~0.
更新日期:2020-09-01
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