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The geological record of the lowermost tectonic unit of the Cretan nappe pile in the Talea Ori, Crete, Greece - the deformation history during burial and exhumation

希腊克里特岛 Talea Ori 克里特岛推覆堆最低构造单元的地质记录 - 埋藏和挖掘过程中的变形历史

基本信息

批准号：
280061993
负责人：
Professorin Dr. Claudia Trepmann
金额：
--
依托单位：
Department für Geo- und Umweltwissenschaften
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/280061993?language=en
关键词：
geological record lowermost tectonic unit

项目摘要

The study proposes to decipher the geological record of HP-LT metasediments at the base of the Talea Ori unit, i.e., the oldest and lowermost known structural level of the Cretan nappe pile. The aim is to obtain information on the long-time deformation and stress history during burial and exhumation. In the chosen study areas around the village Bali and west to the village Fodele, low-strain metapelites and conglomerates grade continuously into high-strain zones. The mineral association and microstructure of gneiss and schist components in low-strain conglomerates will be used to obtain information on the unknown pre-Alpine basement. The high-strain zones provide information on at least two different deformation stages: a scaly foliation, lineation and cm-scale folds are crosscut by shear bands and related quartz veins at a high angle. The spatial arrangement of the inferred deformation structures (foliation, lineation, folds, shear band, veins) will be investigated and interpreted in relation to the large-scale fold structure in the Talea Ori and to the northern bordering tectonic contact. The structural, chemical and crystallographic characteristics of the microfabrics related to the various mesoscopic structures will be analyzed to infer the deformation mechanisms and deformation conditions (temperature, stress, strain rate). Preliminary observations on high-strain zones reveal that the microfabrics related to shear bands and sheared quartz veins indicate high-stress crystal plastic deformation of quartz. The correlation of the field observations with the microfabric analyses will allow characterizing and separating the different deformation stages. Reconciling the contrasting rock records of low-stress/low-strain on the one hand and high-strain and locally high-stress on the other within one tectono-stratigraphic unit will be used to extract the rheological properties during the subduction history. Finally, the comparison of the inferred geological record of the base of the Talea Ori unit to the mesoscopic deformation structures and microfabrics of the unit in northern contact, where the structural position is debated controversially, will be used to elucidate the regional geology of the Talea Ori.

该研究建议破译Talea Ori单元底部的HP-LT变质沉积物的地质记录，即，最古老和最低的已知结构层面的拉克伦推覆体桩。其目的是获得有关埋藏和折返过程中的长期变形和应力历史的信息。在巴厘村周围和Fodele村以西的选定研究区域，低应变变岩和砾岩不断渐变为高应变区。低应变砾岩中的片麻岩和片岩成分的矿物组合和显微结构将用于获得关于未知的前阿尔卑斯基底的信息。高应变带提供了至少两个不同变形阶段的信息：鳞片状叶理、线理和厘米级褶皱被剪切带和相关石英脉以高角度横切。推断的变形结构（叶理，线理，褶皱，剪切带，静脉）的空间排列将进行调查和解释有关的大型褶皱结构在Talea Ori和北方接壤的构造接触。将分析与各种介观结构相关的微组构的结构、化学和晶体学特征，以推断变形机制和变形条件（温度、应力、应变速率）。对高应变带的初步观察表明，与剪切带和剪切石英脉有关的显微组构表明石英发生了高应力晶体塑性变形。现场观测与微组构分析的相关性将允许表征和分离不同的变形阶段。将低应力/低应变与高应变和局部高应力的对比岩石记录在一个构造地层单元内进行对比，将用于提取俯冲历史期间的流变学性质。最后，将Talea Ori单元基底的推断地质记录与北方接触面单元的中观变形结构和微组构进行比较，以阐明Talea Ori的区域地质。