This study compares several geochemical factors (major and minor rare earth elements, Ti/Al ratios, and chemical index of alteration, CIA, values) in the Early Triassic Canizar Formation (Fm) (Buntsandtein facies) of E Iberia with those of adjacent Middle Permian and Middle Triassic units (Alcotas and Eslida fms, respectively). According to significant differences detected, it seems that most geochemical perturbation occurred during the Early Triassic. Variations in Ti/Al ratios suggest changes in source areas between the studied units and even within the Canizar Fm. These provenance changes correlate with successive tectonic pulses during the opening and development of the Iberian Basin, as they can be linked to major sedimentary surfaces and unconformities, as well as major sedimentological variations. Ti enrichment in the lower and middle part of the Canizar Fm, together with high Sr and P concentrations, may be indicative of environmental alterations related to acid meteoric waters. Moreover, this acid alteration took place under arid conditions as reflected by CIA values, indicating that during the deposition of the Canizar Fm, variable but predominantly physical weathering prevailed in contrast to the chemical weathering that took place when the Alcotas and Eslida formations were deposited. Our data along with the known fossil record of the study area indicate that during the Middle–Late Permian and Early Triassic, conditions in this tectonically active area changed from humid to arid-acid, hampering biotic recovery. Then, during late Early–Middle Triassic times, the return of more humid and less acid environments promoted biotic development. Geochemical markers emerged as useful tools complementary to sedimentological, paleontological, and tectonic data for unveiling paleoenvironmental events, especially in a setting of significant regional change.

中文翻译：

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二叠纪-三叠纪陆相沉积物中古环境、风化和物源的地球化学标志

本研究比较了 E Iberia 的早三叠世 Canizar 组 (Fm)（Buntsandtein 相）中的几个地球化学因素（主要和次要稀土元素、Ti/Al 比和化学蚀变指数、CIA、值）与相邻的中二叠纪和中三叠纪单元（分别为 Alcotas 和 Eslida fms）。根据检测到的显着差异，大多数地球化学扰动似乎发生在早三叠世。Ti/Al 比率的变化表明所研究单元之间甚至 Canizar Fm 内源区的变化。这些物源变化与伊比利亚盆地开放和发展过程中的连续构造脉冲相关，因为它们可能与主要沉积表面和不整合面以及主要沉积学变化有关。Canizar Fm 下部和中部的 Ti 富集，以及高 Sr 和 P 浓度，可能表明与酸性大气水相关的环境改变。此外，这种酸蚀发生在 CIA 值反映的干旱条件下，这表明在 Canizar Fm 沉积期间，与 Alcotas 和 Eslida 地层沉积时发生的化学风化相比，主要是物理风化变化。我们的数据以及研究区已知的化石记录表明，在中-晚二叠世和早三叠世期间，这个构造活动区的条件从潮湿变为干旱酸性，阻碍了生物恢复。然后，在早三叠世晚期 - 中三叠世时期，更多潮湿和更少酸性环境的回归促进了生物的发展。地球化学标记作为对沉积学、古生物学和构造数据的补充，成为揭示古环境事件的有用工具，尤其是在区域发生重大变化的情况下。