Revealing the Mineralogical and Petrographic Signs of Fluid-Related Processes in the Kelebia Basement Area (Szeged Basin, S Hungary): A Case Study of Alpine Prograde Metamorphism in a Permo-Triassic Succession

Figure 10

Thin-section photomicrographs of the Triassic sandstone clasts separated from the Lower Miocene conglomerate ((a–d, f) well Ás–É–4 core #3; (e) well Ás–É–9 core #2). (a, b) Sets of parallel transgranular microcracks marked by fluid inclusion plains together with tiny quartz veinlets (see volcanic lithic grain). (c–f) Rounded framework grains with syntaxial quartz overgrowths. Notice that the yellow arrows show the original grain boundary. Marginal parts of the detrital quartz grains and/or overgrowth cement are partially replaced by microcrystalline silica. Note: deformation lamellae in both the original quartz grain and its overgrowth (red arrow), reflecting that the lamellae developed after cementation. Abbreviations: PPL: plane-polarized light; XPL: cross-polarized light; FIP: fluid inclusion plain; Lv: volcanic lithic fragment; Qm: monocrystalline quartz; Qp: polycrystalline quartz.

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