Deciphering the fragmentary nature of Cretaceous shallow-water limestone archives: A case study from the subtropical Apennine carbonate platform
Deciphering the fragmentary nature of Cretaceous shallow-water limestone archives: A case study from the subtropical Apennine carbonate platform
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破译白垩纪浅水石灰岩档案的碎片性质：以亚热带亚平宁碳酸盐台地为例
DOI：
10.1127/nos/2019/0551
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发表时间：
2020
影响因子：
2.2
通讯作者：
Di Lucia
中科院分区：
文献类型：
--
作者：
Schmitt;Heimhofer;Frijia;Di Lucia
浅水碳酸盐台地剖面是重建深部环境和气候条件的宝贵档案，但与频繁的沉积间断相关的生物地层图的低分辨率常常妨碍其精确的年代地层分配。此外，浅水剖面与远洋层序的化学地层对比是众所周知的困难，并且与很大的不确定性相关，因为浅水块状碳酸盐档案特别容易受到成岩作用的影响。这项研究考察了暴露在亚平宁山脉中部（意大利）的特提斯中部白垩纪碳酸盐台地沉积物，这些沉积物经历了几个浮现阶段，导致了不同持续时间的沉积间隙。调查的部分（圣卢西亚、蒙特拉科斯塔）代表了穿过亚平宁碳酸盐台地的横断面，范围从泻湖内部碳酸盐台地区域到台地边缘。尽管底栖有孔虫有时很稀少，而且碳酸盐明显遭受了成岩蚀变，但高分辨率碳同位素地层学与（裸壳和软骨齿动物壳）锶同位素地层学相结合，能够将研究剖面与远洋复合参考曲线相关联。提出了所研究的浅水剖面的详细有孔虫-藻类生物地层记录及其与高分辨率碳和锶同位素地层学的整合。这种方法可以精确估计主要沉积间断所损失的时间，其中三个是在圣卢西亚地区发现的。在那里，长期的间断覆盖了早期阿普第阶（3.2 Myr）、晚阿普第阶（3.3 Myr）和晚阿尔布阶到塞诺曼阶（14.3 Myr）的部分区域，后者与喀斯特填充铝土矿的形成有关。这里介绍的亚平宁碳酸盐台地段沉积间断的记录和年代测定对于关联在近地中海地区观察到的浮现阶段至关重要，特别是在其起源机制方面。
Shallow-water carbonate platform sections are valuable archives for the reconstruction of deeptime environmental and climatic conditions, but the low resolution of biostratigraphic schemes associated with frequent sedimentary hiatuses often hampers their precise chronostratigraphic assignment. Moreover, chemostratigraphic correlation of shallow-water sections with well-dated pelagic successions is notoriously difficult and associated with large uncertainties, as shallow-water bulk carbonate archives are particularly prone to the impact of diagenesis. This study examines central Tethyan mid-Cretaceous carbonate platform deposits exposed in the Central Apennines (Italy) suffering several emersion phases, which cause sedimentary gaps of variable duration. The investigated sections (Santa Lucia, Monte La Costa) represent a transect through the Apennine Carbonate Platform, ranging from the lagoonal inner carbonate platform realm towards the platform margin. Although benthic foraminifera are at times scarce and the carbonates evidently suffered diagenetic alteration, high-resolution carbon isotope stratigraphy combined with (rudist and chondrodont shell) strontium isotope stratigraphy enables a correlation of the studied sections with pelagic composite reference curves. A detailed foraminiferal-algal biostratigraphic record of the studied shallow-water sections and their integration into high-resolution carbon and strontium isotope stratigraphy is presented. This approach allows precise estimates of the time lost in major sedimentary hiatuses, three of which were identified at the Santa Lucia locality. There, long-lasting hiatuses cover parts of the Early Aptian (3.2 Myr), the Late Aptian (3.3 Myr) and the Late Albian to Cenomanian (14.3 Myr), the latter being associated with formation of karst-filling bauxite. The documentation and dating of sedimentary hiatuses in the Apennine Carbonate Platform sector presented here is essential to correlate emersion phases observed in the perimediterranean region, in particular with respect to the mechanisms of their origin.