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‘Isolated base-of-slope aprons’: An oxymoron for shallow-marine fan-shaped, temperate-water, carbonate bodies along the south-east Salento escarpment (Pleistocene, Apulia, southern Italy)
Sedimentology ( IF 2.6 ) Pub Date : 2021-09-07 , DOI: 10.1111/sed.12941
Marcello Tropeano 1 , Luigi Spalluto 1 , Demetrio Meloni 1 , Massimo Moretti 1 , Luisa Sabato 1
Affiliation  

This paper regards the lower Pleistocene temperate-water carbonate deposits disconformably overlying an escarpment made up of faulted Cretaceous to Miocene limestones of the Apulia Foreland (southern Italy). Study deposits discontinuously crop out along the present-day eastern Salento sea cliff, and form isolated fan-shaped bodies, up to 1 km wide and up to 40 to 50 m thick, each of them covering an area of a few square kilometres. The internal arrangement of beds is represented by up to 25° to 30° lobate, seaward dipping clinobeds thinning and onlapping onto a rocky foreslope in the proximal sector and passing to gently inclined to sub-horizontal strata in the distal sector. Seven facies were distinguished, mainly composed of coarse-grained skeletal carbonates made up of a heterozoan association including coralline algae, large and small benthic foraminifera, echinoids, molluscs, bryozoans and serpulids. Since clinobeds were formed thanks to hyperconcentrated density flows (grain flows) bypassing the upper part of the inherited escarpment, these skeletal grains represent ex situ deposits whose shallow-marine factory was located upward (landward) with respect to the bypassed zone, likely in the almost flat area on top of the Salento Peninsula. Clinobeds are often affected by tens of metres wide and long channel-like structures interpreted as landslide scars. Inside these gullies, contorted beds (slumps) or matrix-supported intra-bioclastic floatstone/rudstone (massive deposits) are present. The occurrence of supercritical-flow structures (for example, backset-bedded beds) indicates the development of hydraulic jumps along the steep slope of gullies. Since these clinostratified, fan-shaped carbonate bodies represent carbonate slopes, and that the latter are known as aprons, normally related to linear sourced sediments, an acceptable oxymoron for studied fan-shaped carbonate bodies is suggested: ‘isolated base-of-slope aprons’.

中文翻译:

'孤立的坡底围裙':萨伦托东南部悬崖(更新世,普利亚,意大利南部)沿岸浅海扇形、温带水、碳酸盐岩体的矛盾

本文研究了位于阿普利亚前陆(意大利南部)的断层白垩纪至中新世石灰岩上的下更新世温带水碳酸盐沉积物不整合地覆盖在悬崖上。研究矿床沿今东萨伦托海崖不连续地出现,形成孤立的扇形体,宽达 1 km,厚达 40 至 50 m,每个体面积达几平方公里。床层的内部排列表现为高达 25° 至 30° 的裂片,向海倾斜的斜切层变薄并重叠到近端部分的岩石前坡上,并传递到远端部分的平缓倾斜的亚水平地层。区分了七种相,主要由粗粒骨骼碳酸盐组成,由包括珊瑚藻在内的杂种动物组合组成,大型和小型底栖有孔虫、海胆类、软体动物、苔藓动物和蛇类。由于斜层是由于绕过继承悬崖上部的超浓密度流(颗粒流)形成的,这些骨骼颗粒代表异地浅海工厂位于绕过区域上方(向陆地)的沉积物,可能位于萨伦托半岛顶部几乎平坦的区域。斜床经常受到数十米宽和长通道状结构的影响,这些结构被解释为滑坡疤痕。在这些沟渠内,存在扭曲床层(坍塌)或基质支持的生物碎屑内浮石/粉砂岩(大块沉积物)。超临界流构造(例如,倒置层)的出现表明沿沟壑陡坡的水跃发展。由于这些斜向分层的扇形碳酸盐体代表碳酸盐斜坡,后者被称为围裙,通常与线性来源的沉积物有关,因此建议对所研究的扇形碳酸盐体采用可接受的矛盾:
更新日期:2021-09-07
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