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首页> 外文期刊>Facies >Facies evolution and sequence chronostratigraphy of a “mid”-Cretaceous shallow-water carbonate succession of the Apulia Carbonate Platform from the northern Murge area (Apulia, southern Italy)
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Facies evolution and sequence chronostratigraphy of a “mid”-Cretaceous shallow-water carbonate succession of the Apulia Carbonate Platform from the northern Murge area (Apulia, southern Italy)

机译：北部Murge地区（Apulia，意大利南部）的Apulia碳酸盐岩台地“中”白垩纪浅水碳酸盐岩相的相演化和层序年代地层学

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The “mid”-Cretaceous carbonate succession of the Apulia Carbonate Platform cropping out in northern Murge area (Apulia, southern Italy) is composed of shallow- water carbonate rocks and is over 400 m in thickness. This paper focuses on the lithofacies analysis of this carbonate succession, its paleoenvironmental interpretation, and its sequence-chronostratigraphic architecture. Lithofacies analysis permitted to identify deposits which can be grouped into the following three facies belts: (1) terrestrial facies belt formed by: intraclast-supported paleosoils; solution- collapse breccias; (2) restricted facies belt made up of lithofacies deposited in protected peritidal environments; (3) normal-marine facies belt made up of lithofacies formed in moderate- to high-energy subtidal environments. The detailed study both in outcrops and in thin-sections revealed that, at the bed scale, lithofacies are cyclically arranged and form shallowing-upward small-scale depositional sequences comparable to parasequences and/or simple sequences. The following three small-scale sequence types have been distinguished: (1) subtidal sequences mostly made up of lithofacies formed in the normal-marine open subtidal domain; (2) peritidal sequences made up of lithofacies formed in the restricted peritidal domain; (3) peritidal sequences showing a cap formed by paleosoils. Small-scale sequences are not randomly arranged in the compiled succession but form discrete packages, or sets, that alternate in the sedimentary record. The repetition of such small-scale sequence packages in the succession has been the key to recognize large-scale sequences comparable to third-order depositional sequences. Although sedimentological data are often fragmentary due to late dolomitization, four large-scale sequences have been distinguished. The data support a generalized landward-backstepping of facies belts during transgression, which implies a gradual gain of accommodation culminating with the deposition of a package of small-scale sequences formed by normal-marine subtidal deposits. These mark periods of maximum accommodation space and form the maximum- Xooding zones of large-scale sequences. A gradual seaward progradation of facies belts is recorded during highstand conditions, which implies a gradual loss of accommodation culminating with the deposition of a package of peritidal small-scale sequences capped by paleosoils or by solutioncollapse breccias. The occurrence of terrestrial deposits marks periods of minimum accommodation on the platform and determines the sequence boundary of large-scale sequences. The large-scale sequences identiWed in this study Wt with the main transgressive/regressive cycles published in the sequence-chronostratigraphic chart of European basins. As a consequence, it is interpreted that changes of the sea level recorded at the scale of European basins played an important role in determining the sequence-stratigraphic architecture of the studied succession. In spite of this, the occurrence of solution-collapse breccias, which implies a signiWcant gap in carbonate sedimentation in between Early and Middle Cenomanian times, may also have an alternative interpretation. In particular, this deposit may represent the local Wngerprint of the wellknown tectonic phase which, during Late Albian-Early/ Middle Cenomanian times, determined the subaerial exposure of large parts of Periadriatic carbonate platforms producing a marked regional unconformity.
机译：在Murge北部地区（意大利南部Apulia）种植的Apulia碳酸盐平台的“中”白垩纪碳酸盐岩层由浅水碳酸盐岩组成，厚度超过400 m。本文重点研究了该碳酸盐岩演替的岩相分析，古环境解释及其层序-年代地层构造。岩相分析可以确定沉积物，这些沉积物可分为以下三个相带：（1）陆相相带，其形成方式为：碎屑内支撑的古土壤;解决方案-崩溃角砾岩; （2）由沉积在保护性围岩环境中的岩相构成的限制性相带; （3）由中至高能潮下环境形成的岩相组成的正常海洋相带。对露头和薄片的详细研究表明，在岩床规模上，岩相是周期性排列的，并形成了与副层序和/或简单层序相当的浅向上向上的小规模沉积层序。区分了以下三种小规模序列类型：（1）潮下序列，主要由正常海洋开放潮下域中形成的岩相组成; （2）围岩序列，由在围岩限定域形成的岩相组成; （3）围生层序显示由古土壤形成的盖。小规模的序列不是随机排列在已编排的序列中，而是形成离散的包裹或集合，在沉积记录中交替出现。连续重复这样的小规模序列包是识别与三阶沉积序列相当的大规模序列的关键。尽管由于后期白云石化作用，沉积学数据通常是零散的，但已区分出四个大规模序列。数据支持海相海侵期间海相带的普遍陆上后退，这意味着适应的逐步增加最终将沉积由正常海洋潮下沉积物形成的一整套小规模序列。这些标记最大容纳空间的周期，并形成大规模序列的最大Xooding区。在高水位条件下记录到了相带的逐渐向海发展，这意味着逐渐失去了适应性，最终沉积了一堆被古土壤或解体崩塌角砾岩覆盖的蠕变小尺度序列。地面沉积物的出现标志着平台上的最小适应期，并确定了大型序列的序列边界。在这项研究中确定了大范围的序列，并在欧洲盆地的时序地层图中公布了主要的海侵/回归旋回。因此，据解释，以欧洲盆地的规模记录的海平面变化在确定所研究演替的层序-地层构造方面起着重要作用。尽管如此，固溶倒塌角砾岩的发生，也暗示着在西诺曼尼亚早期和中期之间碳酸盐岩沉积存在明显的间隙，也可能有另一种解释。尤其是，该沉积物可能代表了著名的构造相的局部Wngerprint，在阿尔比晚期-早/中西诺曼尼亚时期，这确定了大部分古生碳酸盐台地的空中暴露，从而产生了明显的区域不整合。

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