A numerical simulation based on a finite/discrete element approach is used to study the deformation and failure process of standard rock mechanics tests on Opalinus clay samples, when subjected to static loading conditions. The layered structure of the Opalinus clay is considered and the resultant anisotropic behaviour is modelled. Rock heterogeneity is also taken into account, with the main pu...

Sandstone formations are ubiquitous in both aquifers and petroleum reservoirs, of which clay is a major constituent. The release of clay particles from pore surfaces as a result of reduced injection fluid salinity can greatly modify the recovery of hydrocarbons from subsurface formations by shifting the wettability properties of the rock. In this paper we demonstrate a microfluidic approach whe...

Clay minerals may be si<j'nifieant indieatoi's of earth processes. They form throufrh a range which involves at one extreme the action of compressed water vapor at a temperature of several hundred degrees centigrade, and at the other extreme, the action of atmospheric agencies at an ordinary temperature. Not recognized as original products of magmatic crystallization, clay minerals are prima fa...

We have performed preliminary mapping of the manganese and iron present in a cross-section of a rock varnish from the Cima volcanic flows in the Mojave Desert, California. Rock varnish is a nanostratigraphic deposit found on typically fine-grained rocks in hyper-arid to semi-arid deserts (Figure 1a) [1]. Rock varnish is defined as consisting of about 70% clay particles held together by about 30...

In argillaceous rocks, which are considered as a potential host rock for nuclear waste repositories, sorption and diffusion processes govern the migration behaviour of actinides like neptunium. For the safety analysis of such a repository, a molecular-level understanding of the transport and retardation phenomena of radioactive contaminants in the host rock is mandatory. The speciation of Np du...

This article presents magnetic data of a 300-m-thick Mio-Pliocene red clay and Quaternary loess-paleosol sequence near Chaona town in the Central Chinese Loess Plateau. Detailed magnetostratigraphy shows that the aeolian red clay began to accumulate at ca. 8.1 Ma. Here, we presented a high-resolution rock magnetic data at 20-40 cm intervals within 4.5-8 ka span per sample of this section, which...

The Mars Science Laboratory rover Curiosity found host rocks of basaltic composition and alteration assemblages containing clay minerals at Yellowknife Bay, Gale Crater. On the basis of the observed host rock and alteration minerals, we present results of equilibrium thermochemical modeling of the Sheepbed mudstones of Yellowknife Bay in order to constrain the formation conditions of its second...

Introduction: Clay minerals are the most common alteration products of water-rock-gas interactions on Earth. Because these hydrous alteration minerals are thermodynamically stable over a wide range of P-T-x conditions [1], significant amounts of clay may have also formed in Martian environments where liquid water or water vapor was present. It has been speculated that liquid water or vapor may ...