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Basin-scale stratigraphic correlation of late Pleistocene-Holocene (MIS 5e-MIS 1) strata across the rapidly subsiding Po Basin (northern Italy)
Quaternary Science Reviews ( IF 4 ) Pub Date : 2020-06-01 , DOI: 10.1016/j.quascirev.2020.106300
B. Campo , L. Bruno , A. Amorosi

Abstract Eight stratigraphic transects, 40–140 km long reveal, for the first time on a regional scale, a comprehensive picture of facies architecture of the highly preserved Late Pleistocene-Holocene sedimentary succession from the rapidly subsiding Po Basin. Facies analysis and pollen-based correlation, supported by radiocarbon, electron-spin resonance and optically stimulated luminescence dates, enabled the attribution of distinct stratigraphic intervals to Marine Isotope Stages (MIS) 6 to 1. Basin-scale facies changes appear to have been driven mostly by glacio-eustatic oscillations falling in the Milankovitch band (∼100 ky). The MIS 5e coastal wedge was tracked continuously beneath the modern shoreline, for over 110 km along strike. Along-dip (west-east) stratigraphic correlation over 140 km revealed the characteristic landward transition from shallow-marine and coastal facies to lagoonal, swamp, and floodplain deposits. The MIS 5d-MIS 2 stratigraphic succession, up to 95-m-thick, records the stepped, basinward shift of facies related to the post-MIS 5e sea-level fall. In particular, lagoon and swamp facies mark minor transgressions (Substages 5c and 5a), whereas thick floodplain deposits and laterally extensive (>40 km) fluvial channel-belts, up to 30 m thick, characterized the glacial periods (MIS 4 and MIS 2). The Holocene (MIS 1) coastal wedge shares many similarities in terms of facies architecture and geometry with its MIS 5e counterpart, though maximum landward marine incursion during the MIS 5e transgression was 10 km farther inland (36 km inland of modern shoreline). Organic-rich (freshwater swamp) environments developed > 100 km landwards of the present-day coastline. The MIS 5e-MIS 1 succession of the Po Basin displays an exceptional thickness, up to 130 m. Minimum values (∼20 m) are recorded close to the Apennine margin and above the buried actively growing anticlines. The spatial distribution and geometry of the MIS 5e-MIS 1 strata, as well as rapidly varying subsidence rates (from 0.2 to 1.0 mm/y) reflect the strong influence of the structural setting (location of major thrust fronts) over the creation/destruction of accommodation.

中文翻译:

快速下沉的波盆地(意大利北部)晚更新世-全新世 (MIS 5e-MIS 1) 地层的盆地尺度地层对比

摘要 8 条长 40-140 公里的地层断面首次在区域尺度上全面展示了快速下沉的 Po 盆地高度保存的晚更新世-全新世沉积序列的相结构。相分析和基于花粉的相关性,在放射性碳、电子自旋共振和光受激发光日期的支持下,能够将不同的地层间隔归因于海洋同位素阶段 (MIS) 6 比 1。盆地尺度的相变化似乎已被驱动主要是由落在米兰科维奇带(~100 ky)中的冰川 - 静态振荡引起的。MIS 5e 海岸楔在现代海岸线下方连续追踪,沿走向超过 110 公里。超过 140 公里的沿倾(西-东)地层对比揭示了从浅海和沿海相到泻湖、沼泽和洪泛区沉积物的特征性陆上过渡。MIS 5d-MIS 2 地层序列,厚达 95 米,记录了与后 MIS 5e 海平面下降有关的相的阶梯式向盆地移动。特别是,泻湖和沼泽相标志着较小的海侵(子阶段 5c 和 5a),而厚的泛滥平原沉积物和横向广泛(> 40 公里)的河流河道带,厚达 30 m,表征了冰川期(MIS 4 和 MIS 2 )。全新世 (MIS 1) 海岸楔与其 MIS 5e 对应物在相结构和几何形状方面有许多相似之处,尽管在 MIS 5e 海侵期间最大的陆上海洋入侵是内陆 10 公里(现代海岸线内陆 36 公里)。富含有机物(淡水沼泽)的环境在现今海岸线向陆方向发展 > 100 公里。Po 盆地的 MIS 5e-MIS 1 序列显示出异常的厚度,高达 130 m。最小值 (~20 m) 记录在亚平宁边缘附近和埋藏的活跃生长背斜上方。MIS 5e-MIS 1 地层的空间分布和几何形状,以及快速变化的沉降速率(从 0.2 到 1.0 毫米/年)反映了构造背景(主要推力前沿的位置)对创建/破坏的强烈影响的住宿。Po 盆地的 MIS 5e-MIS 1 序列显示出异常的厚度,高达 130 m。最小值 (~20 m) 记录在亚平宁边缘附近和埋藏的活跃生长背斜上方。MIS 5e-MIS 1 地层的空间分布和几何形状,以及快速变化的沉降率(从 0.2 到 1.0 毫米/年)反映了构造背景(主要推力前沿的位置)对创建/破坏的强烈影响的住宿。Po 盆地的 MIS 5e-MIS 1 序列显示出异常的厚度,高达 130 m。最小值 (~20 m) 记录在亚平宁边缘附近和埋藏的活跃生长背斜上方。MIS 5e-MIS 1 地层的空间分布和几何形状,以及快速变化的沉降率(从 0.2 到 1.0 毫米/年)反映了构造背景(主要推力前沿的位置)对创建/破坏的强烈影响的住宿。
更新日期:2020-06-01
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