On the Stability of Carbon Shale Slope under Rainfall Infiltration

Carbonaceous shale is a sedimentary rock containing a large amount of dispersed carbonaceous organic material.It is easy to crack and soften when exposed to water.In the present work,the stability of such a rock and its sensitivity to the formation of infiltrations due to rainfall are analyzed numerically using the GeoStudio software.The slope stability coefficient is calculated and verified using the landslide thrust calculation method.The results show that under the action of heavy rainfall,water infiltrates into the slope layer by layer,and,accordingly,the soil volume water content is different with respect to that typical of a homogeneous soil.It is also shown that,although in an initial stage,rainfall infiltration leads to the decline of the slope stability coefficient,with the progress of rainfall,this coefficient can temporarily increase,that is,these phenomena can display a lag phase.

First Occurrence of M andarinoite in China

This report describes the first occurrence of the rare mineral mandarinoite (Fe3+2 Se3Og · 6H2O) in China. It occurs in the Lower Permian Maokou Formation carbonaceous shale in Yutangba Village east of Enshi City in southwestern Hubei Province. The shale is selenium-rich and contains native selenium, V-Mo-Cr-bearing iron oxide, clay and quartz. Weathering of the selenium in the bedrock under moderate to high redox conditions in the presence of ferric iron has formed mandarinoite.

Geochemical characterization of shales of the Eocene Disang Group,Kohima Syncline,India:Inferences to hydrocarbon potential and depositional environment

The Kohima Syncline exposes the Eocene Upper Disang Formation in an extensive region that is composed of grey shales with subordinate sandstone and siltstone alterations.The shales contain low to fair amount of organic matters represented by Type IV/Type III terrestrial kerogens.The Biomarkers indicate presence of terrestrial angiosperms and microbially reworked organic matters with some marine phytoplankton.Rock-Eval maturity parameters indicate maturity within a wide range between immature to post mature wet gas window,while the biomarkers show maturity between immature to mid mature.The biomarkers indicate that the Disang shales deposited in an oxic deltaic-terrigenous environment.The trace elements characterize an oxic to suboxic warm and humid depositional environment.Few trace elements point to deposition in a low salinity continental rather than a marine environment.Thus,several biomarker and trace element parameters show that a continental milieu was already established during the deposition of the Upper Disang sediments.It indicates that either the Disang basin,that evolved as a marine basin,suffered rapid shallowing during the deposition of the Upper Disang sediments,or the Lower and Upper Disangs were coeval and Lower Disangs represented deep marine facies while the Upper Disangs represented peripheral shallow marine deltaic facies.Maturity parameters like Tmax and,sterane and hopane isomerization ratios indicate that the organic matters of the Disang Group were affected by sudden short duration thermal events followed by cooling.This is possible in an active tectonic region like the Kohima Syncline that bears many evidences of thrusting and folding.