Syn- to late-orogenic quartz veins marking a retrograde deformation path in a slate belt: Examples from the High-Ardenne slate belt (Belgium)

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• 作者：Dominique Jacques ; Tine Derez ; Philippe Muchez ; Manuel Sintubin
• 关键词：Quartz veins ; P-T-X-t conditions ; Overpressured fluid reservoir ; Retrograde deformation path
• 刊名：Journal of Structural Geology
• 出版年：January, 2014
• 年：2014
• 卷：58
• 期：Complete
• 页码：43-58
• 全文大小：9240 K

文摘

An integrated structural, petrographic and microthermometric methodology has been applied on syn- to late-orogenic quartz veins from the High-Ardenne slate belt (Belgium) to define their relative timing. The quartz precipitates, which do not show any mutual cross-cutting relationships, represent the meso-scale brittle accommodation during fold initiation, amplification and locking. Crystal-plastic deformation structures and P-T trapping conditions indicate that the different processes accommodating folding occurred in a progressive manner along a retrograde deformation path, associated with the gradual exhumation of the slate belt from ca. 7.5 to 6聽km depth. Successive veining occurred from peak metamorphic conditions (ca. 300聽掳C and 190聽MPa), measured in extrados veins, to subsequent lower P-T conditions in the periphery of a lenticular vein (ca. 275聽掳C and 180聽MPa), late-orogenic saddle reef filling (ca. 245聽掳C and 160聽MPa), and the core of a lenticular vein (ca. 220聽掳C and 150聽MPa). Open-cavity growth and fluid-assisted brecciation indicate that veining occurred under overpressured fluid conditions. It is therefore fair to assume that the High-Ardenne slate belt acted - at least episodically - as a mid-crustal overpressured fluid reservoir, not only in the earliest and latest stages, but also during the main stage of orogeny.