کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4691322 1636725 2016 18 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Quartz veining in slates and Variscan deformation: Insights from the Luarca sector (NW Spain)
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
Quartz veining in slates and Variscan deformation: Insights from the Luarca sector (NW Spain)
چکیده انگلیسی


• Quartz veins as tools to understand the brittle deformation in a compressional regime
• An interesting structural history undergone by the veins during the Variscan orogeny
• Variety of microstructures due to plastic deformation, pressure solution and fracturing
• Using fluid inclusion to determine the role of fluids in the vein development

A structural and geochemical analysis of quartz veins is made in order to determine their evolution and the physical–chemical conditions that enabled their development. In this sector of the Variscan belt (Westasturian-Leonese Zone), three phases of deformation have been described. However, only the first and third phases are represented in the study sections. The first phase (D1) resulted in tight or closed folds (F1) verging towards the foreland and associated slaty cleavage (S1). The third phase (D3) resulted in approximately upright asymmetric folds (F3) with associated crenulation cleavage (S3). The veins are hosted in slates and approximately follow the slaty cleavage (S1). The veins started their development at the beginning of the deformation phase D3 as a result of S1 near parallel shortening. Through a process of progressive deformation, this compression gave rise to the folding of the cleavage and, eventually, of the veins. The F3 folds have associated crenulation cleavage parallel to the axial planes. In some cases, the location of the veins was controlled by irregularities in the bedding due to sedimentary structures. The quartz of the veins underwent notable intracrystalline plastic deformation, and the contact zone between the veins and the host rock was affected by pressure solution. The microstructures produced by the latter mechanism indicate the greatest compressive stress forming a high angle with the vein walls at a time post-dating vein generation.Quartz precipitated from an aqueous-carbonic fluid at temperatures between 350 °C and 375 °C under fluid pressure fluctuations of up to 140 MPa at constant depth. Maximum values of fluid pressure of 220 MPa and minimum values of 75 MPa were recorded by fluid inclusion assemblages in quartz of the veins under study. Pressure fluctuation from lithostatic to infralithostatic at constant depth was caused by the opening and sealing of the dilatant fractures.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Tectonophysics - Volume 671, 7 March 2016, Pages 24–41
نویسندگان
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