Palaeoenvironmental reconstruction based on non-geniculate coralline red algal assemblages in Miocene limestone of central Crete
Palaeoenvironmental reconstruction based on non-geniculate coralline red algal assemblages in Miocene limestone of central Crete
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基于克里特岛中部中新世石灰岩非膝状珊瑚红藻组合的古环境重建
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发表时间：
2006
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通讯作者：
T. Brachert
中科院分区：
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作者：
K. Kroeger;M. Reuter;T. Brachert
地中海新近系海岸沉积物为定量研究古环境参数及其对气候变化的响应提供了极好的实验室。为了研究克里特岛中南部托托尼期石灰岩沉积过程中环境参数的变化，我们采用了综合野外和生物相分析方法，并对有孔虫和非膝曲红藻进行了详细的研究。通过与现代非膝曲珊瑚红藻数据的比较和从所研究的沉积物中获得的额外信息，解释了非膝曲珊瑚红藻相对丰度的模式。基于这些综合数据集，确定了4个红藻组合：暖温带上光带的石藻占优势组合，暖温带下光带的石藻占优势组合，暖温带至热带环境下光带典型的海绵占优势组合，以及暖温带至热带环境下光带特有的中叶占优势组合。我们引入珊瑚红藻指数，以量化环境参数的变化。我们在克里特岛中南部的托尔顿期石灰岩序列中识别出四个温暖的间隔期。在最广泛的时间间隔内，在普遍的贫营养条件下形成了广泛的珊瑚地毯。对地层结构的分析表明，暖间隔与海平面高位有关，因此可能反映了全球气候过程。
Neogene coastal sediments of the Mediterranean provide an excellent laboratory for a quantitative study of palaeoenvironmental parameters and their response to climate change. In order to examine change in environmental parameters during deposition of Tortonian limestone of southern central Crete, we use integrated field and biofacies analysis together with a detailed study of foraminfera and non-geniculate red algae. Patterns in the relative abundance of non-geniculate coralline red algae are interpreted by comparison with data from modern non-geniculate coralline red algae and with additional information from the studied sediments. Based on these integrated datasets, four red algal associations are identified: a Lithophyllum-dominated association restricted to the upper photic zone in warm-temperate environments, a Lithothamnion-dominated association found in the lower photic zone in warm-temperate environments, a Spongites-dominated association typical for shallow warm-temperate to tropical environments and an association with dominant Mesophyllum which is characteristic for the lower photic zone in warm-temperate to tropical environments. We introduce coralline red algal indices in order to quantify changes in environmental parameters. We recognise four warm intervals within a succession of the Tortonian limestones in southern central Crete. During the most extensive interval, widespread coral carpets formed under prevalent oligotrophic conditions. Analysis of the stratigraphic architecture shows that warm intervals are related to sea-level highstands and therefore may reflect global climatic processes.