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Fig. 7 | Geothermal Energy

Fig. 7

From: Porosity–permeability relationship derived from Upper Jurassic carbonate rock cores to assess the regional hydraulic matrix properties of the Malm reservoir in the South German Molasse Basin

Fig. 7

Thin sections of Jurassic carbonate rocks from the Dingolfing FB rock core. a Fossiliferous grainstone of Malm ζ 4–5 section containing peloids and abundant fragments of green algae Clypeina jurassica (CJ) and Campbelliella striata (CS). Note interparticle porosity (blue staining) cumulating to \(\phi_{\text{eff}}^{\text{w}}\) of 13.0% for the whole sample. b Same rock type and strata than in a but pore space is reduced by sparitic cementation (arrows) between particles. (\(\phi_{\text{eff}}^{\text{w}} = 1.7 \% )\). c Euhedral dolomite crystals floating almost isolated in a microcrystalline calcite matrix of a dolomitic wackestone (Malm ζ 4–5). No porosity is visible in this thin section but \(\phi_{\text{eff}}^{\text{w}}\) of sample is 2.4%. d Idiotopic dolostone (medium crystalline) with abundant intercrystal porosity (Malm ζ 4–5) reaching \(\phi_{\text{eff}}^{\text{w}}\) of 16.3%. e Hypidiotopic dolostone (medium crystalline) showing some intercrystal and vuggy porosity (arrows) of dissolved fossil fragments. Fragment of a bryozoan (Br) is still preserved in one of the vugs (\(\phi_{\text{eff}}^{\text{w}}\) = 8.6%, Malm ζ 1). f Xenotopic (non-rhombic) dolostone with sutures along contacts of coarse dolomite crystals (Malm δ). Due to complete dolomitization and compaction, pore space is highly reduced in this sample (\(\phi_{\text{eff}}^{\text{w}}\) = 1.4%)

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