oai:archiv.ub.uni-heidelberg.de:5562
type: CreativeWork
name: Clay mineral formation and fluid-rock interaction in fractured crystalline rocks of the Rhine rift system : case studies from the Soultz-sous-Forêts granite (France) and the Schauenburg Fault (Germany)
description: The following study deals with the fluid-alteration history of fractured and faulted crystalline granitic basement in the Rhine rift system, based on the analytical investigation of clay mineral assemblages. It evaluates the argillite mineralizations along faults and fracture zones at key tectonic positions in relation to the upper Rhine graben rift structure and assesses the timing and episodic nature of clay mineral formation that occurred within both the buried basement rocks and similar exhumed units exposed in the uplifted rift shoulders. The rock alteration history is established largely on the basis of combined X-ray diffraction, X-ray textural goniometry, electron microscopy (SEM, HRTEM) and isotopic (K-Ar) techniques. One chapter presents results from the granitic basement rocks of the 2230m deep EPS-1 drilling site at Soultz-sous-Forêts, situated in the western part of the Upper Rhine graben basin (France). Pure illite without any sign of mixed-layerings could be distinguished in the different hydrothermal altered and fractured granite and argillite veins. The morphology of these illites varies clearly in the different rock types, with pseudo-hexagonal, platy 2M1 illite polytypes dominating the veins and thin and fibrous to lath shaped 1M trans-vacant illite polytypes common in pores of the granite matrix. The separated grain size fractions (> 63µm, 10-63µm, 4-10µm, 2-4µm, 1-2µm, 0.4-1µm, 0.2-0.4µm, < 0.2µm) indicate mixtures of both illite shapes and polytypes to characterize all samples, which based on K-Ar isotope results, occurred during three main crystallization episodes spanning over 200 Ma in time. The oldest illite crystallization recognized is of Permian age, which is most evident in the argillite veins (2176m) and samples of hydrothermally altered granite (e.g. 1570m). In contrast, a mixture of Jurassic and Cretaceous (or younger) illite was recorded in fractured rocks at 2167m, but Tertiary K-Ar values were not encounted in the limited amount o…
abstract: The following study deals with the fluid-alteration history of fractured and faulted crystalline granitic basement in the Rhine rift system, based on the analytical investigation of clay mineral assemblages. It evaluates the argillite mineralizations along faults and fracture zones at key tectonic positions in relation to the upper Rhine graben rift structure and assesses the timing and episodic nature of clay mineral formation that occurred within both the buried basement rocks and similar exhumed units exposed in the uplifted rift shoulders. The rock alteration history is established largely on the basis of combined X-ray diffraction, X-ray textural goniometry, electron microscopy (SEM, HRTEM) and isotopic (K-Ar) techniques. One chapter presents results from the granitic basement rocks of the 2230m deep EPS-1 drilling site at Soultz-sous-Forêts, situated in the western part of the Upper Rhine graben basin (France). Pure illite without any sign of mixed-layerings could be distinguished in the different hydrothermal altered and fractured granite and argillite veins. The morphology of these illites varies clearly in the different rock types, with pseudo-hexagonal, platy 2M1 illite polytypes dominating the veins and thin and fibrous to lath shaped 1M trans-vacant illite polytypes common in pores of the granite matrix. The separated grain size fractions (> 63µm, 10-63µm, 4-10µm, 2-4µm, 1-2µm, 0.4-1µm, 0.2-0.4µm, < 0.2µm) indicate mixtures of both illite shapes and polytypes to characterize all samples, which based on K-Ar isotope results, occurred during three main crystallization episodes spanning over 200 Ma in time. The oldest illite crystallization recognized is of Permian age, which is most evident in the argillite veins (2176m) and samples of hydrothermally altered granite (e.g. 1570m). In contrast, a mixture of Jurassic and Cretaceous (or younger) illite was recorded in fractured rocks at 2167m, but Tertiary K-Ar values were not encounted in the limited amount o…
author: Schleicher, Anja
date published: 2005-05-25
date modified: 2026-07-24T02:30:12Z
provider: Universität Heidelberg
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Universität Heidelberg