Record of climatic change in neritic carbonates: turnover in biogenic associations and depositional modes (Late Miocene, southern Spain)
Record of climatic change in neritic carbonates: turnover in biogenic associations and depositional modes (Late Miocene, southern Spain)
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浅海碳酸盐的气候变化记录：生物成因组合和沉积模式的更替（晚中新世，西班牙南部）
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
J. M. Martín
中科院分区：
文献类型：
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作者：
T. Brachert;C. Betzler;J. Braga;J. M. Martín
为了评估浅海碳酸盐岩气候变化的地质记录，我们研究了西班牙南部晚中新世岩石露头。六个事件的珊瑚礁生长记录（Burdigalian到Messinian）在新近纪盆地的Betic Cordillera，这是位于靠近全球礁带的边缘。珊瑚礁的特点是各种虫黄藻珊瑚的多样性随着时间的推移而减少，Halimeda;最新的Messinian最年轻的珊瑚礁的特点是占主导地位的属Porites。晚中新世珊瑚礁和礁缘台地随着时间的推移与非礁碳酸盐斜坡交替，其特征是骨骼钙质砾质岩或石膏，如在墨西拿盐度危机期间形成的。钙质砾屑岩缺乏礁珊瑚、钙化绿色藻类和大量的海洋胶结物，但显示出现代和化石非热带碳酸盐的骨骼成分。这些包括苔藓虫、软体动物、有孔虫、棘皮动物和小藤壶，以及苔藓虫协会的珊瑚藻。一些较大的有孔虫的存在表明高温，接近礁组合的温度下限。海平面低位和高位记录的楔形苔藓碳酸盐和绿藻斑礁或覆盖平台。因此，温带气候沉积模式对应于相对较低的海平面，而暖水模式对应于较高的海平面。Agua Amarga和Sorbas盆地的新近纪充填记录了其中两个旋回。其他气候/海平面周期（包括冷水沉积模式中的墨西拿石膏）在西班牙南部邻近的新近纪盆地中得到了很好的建立。这种类型的复合序列似乎只发生沿着全球礁带的边缘，并表明边缘的振荡纬向运动，这是与全球气候变化。因此，分析浅海沉积碳酸盐体系的周转率可以被认为是从化石记录重建气候变化的敏感工具。然而，碳酸盐沉积和成岩作用的暖水模式和温水模式有显著差异。因此，用层序地层学解释复合体系层序需要扩展概念。这种特殊类型的混合苔藓虫沉积序列也具有一定的溺水潜力，因为海平面上升可能比温带碳酸盐系统的净生产率更快。
In order to evaluate the geological record of climatic change in neritic carbonates, we studied Late Miocene rock outcrops in southern Spain. Six episodes of reef growth are documented (Burdigalian to Messinian) in Neogene basins of the Betic Cordillera, which were located close to the margin of the global reef belt. The reefs are characterized by various zooxanthellate corals which decrease in diversity with time, andHalimeda; the youngest reefs of the latest Messinian are characterized by the dominance of the genusPorites. Late Miocene coral reefs and reef-rimmed platforms alternate over time with non-reefal carbonate ramps characterized by skeletal calcirudites or with gypsum such as that formed during the Messinian salinity crisis. The calcirudites lack reef corals, calcified green algae and extensive marine cement, but exhibit skeletal components described from both modern and fossil nontropical carbonates. These include bryozoans, mollusks, foraminifers, echinoderms and minor balanids, as well as coralline algae of a bryomol association. The presence of some larger foraminifers indicates high temperatures, close to the lower temperature threshold of the reef assemblage. Sea level lowstands and highstands are documented by wedges of bryomol carbonate and chlorozoan patch reefs or prograding platforms. Thus, temperate climate depositional modes correspond to relatively low sea levels, and warm-water modes to high sea levels. The Neogene infill of the Agua Amarga and Sorbas basins documents two of these cycles. Other climate/sea-level cycles (including Messinian gypsum in the cool water depositional mode) are well established in adjacent Neogene basins in southern Spain. This type of composite sequence seems to occur only along the margin of the global reef belt and indicates an oscillatory latitudinal movement of the margin, which is associated with global climatic change. The analysis of turnover in neritic depositional carbonate systems may therefore be considered a sensitive tool for reconstructing climatic change from the fossil record. However, warm-water modes and temperate-water modes of carbonate sedimentation and diagenesis differ significantly. For this reason the interpretation of composite system sequences by sequence stratigraphy requires an extended concept. The particular type of mixed bryomolchlorozoan depositional sequence also bears some potential for drowning, because sea level rise may be faster than the net production rate of temperate carbonate systems.