Shallow lacustrine carbonate microfacies document orbitally paced lake‐level history in the Miocene Teruel Basin (North‐East Spain)
Shallow lacustrine carbonate microfacies document orbitally paced lake‐level history in the Miocene Teruel Basin (North‐East Spain)
复制标题
浅湖碳酸盐微相记录了中新世特鲁埃尔盆地（西班牙东北部）的轨道步调湖面历史
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
E. Tuenter
中科院分区：
文献类型：
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作者：
H. Abels;H. Abdul Aziz;J. Calvo;E. Tuenter
本文介绍了西班牙特鲁埃尔盆地上中新世湖相碳酸盐-硅质混合岩系的详细碳酸盐岩相学研究结果，旨在限制不同地层尺度下的湖平面变化。红色到绿色泥岩和湖相石灰岩的规则交替，称为“基本旋回”，反映了米级的湖平面变化。在早期的研究中，基本周期被证明是由气候岁差周期控制的。岩相学分析使得有可能区分两个主要的碳酸盐微相组的特点非常浅的瞬态和浅永久湖泊环境，分别。除了基本的旋回性，微相分析还揭示了更大规模的湖平面变化。由此，进一步探讨了卡斯坎特剖面旋回性的天文强迫假说。一项关于轨道极端情况的气候模拟研究表明，湖泊水位高可能与岁差极小期冬季净降水量和径流量增加有关，这与地中海的地质数据一致。利用这种相位关系，从磁反转边界的天文年龄出发，建立了周期的天文调谐。随后，连续的基本周期与岁差极小值相关。调谐显示卡斯坎特剖面中的基本旋回与Monte dei Corvi（意大利）深海序列中与岁差相关的腐泥旋回数量相同，证实了卡斯坎特基本旋回的岁差控制。通过微相分析确定的大规模周期中的湖平面高位与约100和405 kyr偏心率周期中的最大值有关，再次与地中海地质数据一致。 从卡斯坎特的古环境记录中减去已确定的天文学相关（湖平面）变化，表明该剖面上半部分向更深、更永久的湖泊环境转移。这种转变的原因尚不清楚，但可能与构造、非天文气候、长周期天文周期或自生过程有关。
Results are presented of a detailed carbonate petrographic study of an Upper Miocene lacustrine mixed carbonate–siliciclastic succession in the Teruel Basin (Spain) with the aim of constraining lake‐level variability at different stratigraphic scales. Regular alternations of red to green mudstone and lacustrine limestone, termed the ‘basic cycle’, reflect lake‐level variations at the metre‐scale. In an earlier study, the basic cycle was shown to be controlled by the climatic precession cycle. Petrographic analysis made it possible to distinguish two main carbonate microfacies groups characteristic of very shallow transient and shallow permanent lake environments, respectively. In addition to the basic cyclicity, the microfacies analysis reveals lake‐level variations on a larger scale. As a consequence, the astronomical forcing hypothesis of the cyclicity in the Cascante section is explored further. A climate modelling study of orbital extremes indicates that high lake levels could relate to enhanced net winter precipitation and runoff during precession minima, consistent with Mediterranean geological data. Using this phase relationship, an astronomical tuning of the cycles is established starting from astronomical ages of magnetic reversal boundaries. Subsequently, successive basic cycles are correlated to precession minima. The tuning reveals an identical number of basic cycles in the Cascante section as precession‐related sapropel cycles in the deep marine succession at Monte dei Corvi (Italy), corroborating the precessional control of the basic cycles at Cascante. Lake‐level highstands in the large‐scale cycle identified by the microfacies analysis relate to maxima in both the ca 100 and 405 kyr eccentricity cycles, again consistent with Mediterranean geological data. Subtraction of the identified astronomically related (lake‐level) variations from the palaeoenvironmental record at Cascante indicates a shift to deeper and more permanent lacustrine environments in the upper half of the section. The cause of this shift remains unclear, but it may be linked to tectonics, non‐astronomical climate, long‐period astronomical cycles or autogenic processes.