Carbon isotopes in speleothems can vary in response to a number of complex processes active in cave systems that are both directly and indirectly related to climate. Progressing downward from the soil zone overlying the cave, these processes include soil respiration, fluid–rock interaction in the host limestone, degassing of CO2 and precipitation of calcite upflow from the speleothem drip site,...

Introduction: Secondary carbonate minerals produced by low temperature aqueous processes [1] in the martian meteorite ALH 84001 are evidence of an early active hydrosphere on Mars when they were formed ~3.9 Ga ago [2]. Further evidence for an early hydrosphere includes orbital and surface observations of diverse alteration mineral assemblages [e.g. 3-5] and fluvial geomorphology [6]. While carb...

Compaction of porous rocks can occur in two modes: uniform and localized. Recent experimental work has demonstrated that compaction can occur in tabular zones that expand with increasing applied deformation. The appearance of compaction bands and their growth has a strong influence on the measured permeability of the host rock. The rock behind the moving compaction front can be either uniformly...

During October 2003, a specimen of Amblyrhynchotes honckenii (Bloch, 1795) was captured at low tide, with a hand net, in a rock pool at Koppie Alleen, De Hoop Nature Reserve, South Africa. This fish was heavily parasitized by unidentified gnathiid praniza larvae, caligid copepods identified as Caligus tetrodontis Barnard, 1948, cymothoid isopods identified as Cinusa tetrodontis (Schioedte et Me...

Introduction: The Yaxcopoil borehole (Yax-1) penetrates below the suevitic units through 600 m of sediments (894.9 m – 1510.9 m). These rocks are most likely of Cretaceous age and are regarded as a displaced “megablock”. The stratified sequence was intruded by suevitic dikes (910 m, 916 m), one impact melt dike (1347 m) and several clastic, polymict dikes. The latter are the focus of this study...

The description of the geochemical properties of the bentonite backfill that serves as engineered barrier for nuclear repositories is a central issue for performance assessment since these play a large role in determining the fate of contaminants released from the waste. In this study the porewater chemistry of bentonite was assessed with a thermodynamic modelling approach that includes ion exc...

Biotite samples from different units of Boroujerd Granitoid Complex (BGC) of the Sanandaj-Sirjan Zone, western Iran, have beenanalyzed by electron microprobe for major elements. Biotite analyses from three units of quartzdiorite, granodiorite and monzograniteof BGC have their own distinct non-overlapping compositional fields in the annite – siderophyllite – phlogopite – eastonitequadrilateral (...

Chlorite flakes, as a product of alteration of biotite, the dominant ferromagnesian mineral in the Paleozoic granitic rocks of the Canadian Appalachians, have been analyzed by electron microprobe for major elements and by 57Fe M?ssbauer spectroscopy for the coordination and oxidation state of Fe. Comparison of M?ssbauer Fe3+/Fe ratios obtained from chlorite and its host biotite indicates that c...

Cyclic microfracturing and epitaxial crystal growth have long been recognized in crack-seal veins, but an understanding of a single cycle is still missing. Here we present phase-field model that includes both fracture mechanics crack propagation, on the walls, repeating this multiple times polycrystalline, microporous quartz rock. Our simulations two end members: If vein completely seals, it st...