Climate and sea-level perturbations during the Incipient Eocene Thermal Maximum: evidence from siliciclastic units in the Basque Basin (Ermua, Zumaia and Trabakua Pass), northern Spain
Climate and sea-level perturbations during the Incipient Eocene Thermal Maximum: evidence from siliciclastic units in the Basque Basin (Ermua, Zumaia and Trabakua Pass), northern Spain
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始新世初期热最大值期间的气候和海平面扰动：来自西班牙北部巴斯克盆地（埃尔穆阿、祖马亚和特拉巴库亚山口）硅质碎屑单元的证据
DOI：
10.1016/s0031-0182(00)00167-x
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
K. Núñez
中科院分区：
文献类型：
--
作者：
B. Schmitz;V. Pujalte;K. Núñez
基于碳同位素地层学和岩性，提出了一个修订后的高分辨率之间的相关性，在巴斯克地区，北方西班牙的始始新世热最大（IETM）的部分。在三个研究剖面中，IETM事件由一个显著的非-低钙质硅质岩单元（SU）代表，厚度为4-20.5m。在形成的SU，沉积速率为silicicitarian材料增加了2至5倍，而碎屑粒度显着下降。粘土组分中高岭石和绿泥石含量增加，水柱中方解石溶解加剧。SU反映了气候和水文状况的重大变化，气候变暖，季节性干燥。干旱导致常年植被崩溃，导致大陆侵蚀加剧，但也减少了流入海洋的淡水的水动力能量。同时代的相对海平面下降，可能与影响西欧主要地区的构造隆起或隆起有关，增加了陆海坡度，进一步提高了侵蚀速率。孢粉学研究支持在季节性降雨期间周期性的植被，而不是永久性的针叶林。西班牙北方同时代大陆沉积物中的显著钙质土也支持温暖的半干旱条件。在IETM事件期间，包括巴斯克地区在内的副热带高压单体下的净蒸发量增加，而更北的纬度变得更加潮湿。SU与先前在西欧其他地区被分配到旧第三纪早期所谓的“铁石器时代”排放的碎屑单位有着相似的起源。
Based on carbon isotope stratigraphy and lithology, a revised high-resolution correlation is proposed between sections spanning the Incipient Eocene Thermal Maximum (IETM) in the Basque region, northern Spain. In three studied sections, the IETM event is represented by a prominent non- to low-calcareous siliciclastic unit (SU), 4–20.5m thick. During formation of the SU, sedimentation rates for siliciclastic material increased by a factor of two to five, whereas detrital grain size decreased significantly. Kaolinite and chlorite became more abundant in the clay fraction and calcite dissolution in the water column intensified. The SU reflects a significant change in climate and hydrological regime towards a warmer and seasonally drier climate. The drying caused perennial vegetation cover to collapse and led to increased continental erosion but also to reduced hydrodynamic energy of freshwater debouching into the oceans. A coeval relative sea-level fall, probably related to tectonic uplift or doming affecting major parts of western Europe, increased the land–sea slope and further enhanced erosion rates. Palynological studies support periodic vegetation during seasonal rain instead of permanent conifer forests. Prominent caliche soils in coeval continental deposits in northern Spain also support warm semiarid conditions. During the IETM event, net evaporation increased under the subtropical high-pressure cells, including the Basque region, whereas more northerly latitudes became more wet. The SU has a similar origin as detrital units previously assigned to the early Palaeogene so-called ‘Siderolithic’ discharge in other parts of western Europe.