Classification and Disintegration Characteristics of the Carboniferous Rocks in Guangxi, China

To investigate the disintegration characteristics of the carbonaceous rocks in Guangxi Province, the typical carbonaceous rocks in the section exposed by the Hechi-Baise Expressway were investigated in this study. First, based on their mineral compositions and contents, the carbonaceous rocks were divided into four types: carbonate chert, carbonaceous argillaceous limestone, carbonaceous illite clay mudstone, and carbonaceous illite clay shale. Then, through indoor wet-dry cyclic disintegration test, the disintegration characteristics of the four types of rocks were studied. The test results showed the following: (1) the disintegration residues of the carbonate chert and the carbonaceous argillaceous limestone decrease linearly as the number of wetting-drying cycles increases. (2) The disintegration index of the carbonaceous illite clay mudstone and the carbonaceous illite clay shale decreases exponentially as the number of wetting-drying cycles increases. (3) As the number of wetting-drying cycles increases, the disintegration index curves of the carbonaceous illite clay mudstone and the carbonaceous illite clay shale samples gradually become stable until the disintegration of the samples is completed. (4) The disintegration of carbonaceous rocks is mainly affected by the clay content, followed by the structural form, but it cannot be ignored.

Investigation of the Centers of Endogenous Fires at the Rock Dumps of the Coal Enterprises

The formed rock dumps of sections, mines and washing plants are composed of carbonaceous rocks and are capable of spontaneous combustion when the required amount of air is supplied. The conducted studies evaluated the efficiency of detecting a center of spontaneous combustion at the rock dumps of sections by measuring the temperature of rocks in the wells with a depth of 2.5 m, drilled at the distance of 20 m from each other, according to the current normative documents. For the landfill, a dump site with a long-existing center of spontaneous combustion was selected. The experiment showed the impossibility of drilling wells on the slopes of the dumps, as well as the need for casing the wells with pipes along the entire length. The temperature of rocks in the wells at a depth of 2.5 m varied from 69 to 773 °C. It was found that in the heated zone there are sharp temperature drops in the rocks, which cannot be detected with an interval between the measurement points equal to 20 m. With such a distance between the control wells, the places with a diameter of 1–10 m may remain undetected at the initial stage of spontaneous combustion. Measurements showed that in all the wells the rock temperature increases with depth. At the same time, the recommended well depth of 2.5 m does not allow determining the size of the heated zone deep into the rock dump. The upper layer of rocks above the center of spontaneous combustion exceeds the ambient temperature, so remote temperature measuring devices can be used to detect endogenous fires in the rock dumps. The use of thermal imagers installed on the unmanned aerial vehicles will significantly reduce the cost of detecting spontaneous combustion centers on the rock dumps and increase the efficiency of detecting fire centers not only on the dump sites, but on the slopes of the dump side and in other hard-to-reach places. Moreover, with a decrease in the atmospheric air temperature, the efficiency of remote thermal photography does not decrease. To clarify the parameters of the center of endogenous fires, it is advisable to use the temperature measurement of rocks with a contact thermometer at a depth of 0.5 m.

THE STRUCTURE, COMPOSITION AND DEPOSITIONAL ENVIRONMENTS OF KUONAMKA FORMATION IN THE EAST OF ANABAR OIL-AND-GAS REGION

The structural features, lithological composition and sedimentation conditions of the Kuonamka Formation were identified in the analysis of core material uncovered by wells in the east of Anabar oil-and-gas region in the basin of the Kyulenke River. It was established that the studied highly carbonaceous rocks accumulated in deep-water conditions of the open sea in reducing, mainly euxinic environments.

Structure of the Golets Vysochaishy gold deposit (Northern Transbaikalia)

The article describes the fold-thrust structure of the Golets Vysochaishy deposit located at the Baikal-Patom Upland in the Marakan-Tunguska megasyncline. The latter is composed of terrigenous-carbonate carbonaceous rocks metamorphosed in greenschist facies conditions. The deposit is detected in the hanging wing of the asymmetric Kamenskaya anticline. In a cross section, the anticline is an S-shaped structure extending in the latitudinal direction. The main feature of the Golets Vysochaishy deposit is the development of interlayer sulfidization zones (pyrite, pyrrhotite), including gold-bearing ones. Its gold-ore zones tend to occur in layered areas of interlayer sliding in the rocks of the Khomolkhinskaya suite.Four structural markers revealed within the deposit area are indicative of repeated deformation processes: (1) sublatitudinal folding, cleavage of the axial surface and its subsequent transformation into schistosity; (2) crenulation cleavage; (3) interlayer sliding and rock breakdown with interlayer drag folds, parallel microfractures and polished slickensides; (4) large quartz veins and veinlets that cross cut the main structural elements in plan.

THE CARBONACEOUS ROCKS IN CRETACEOUS DEPOSITS OF THE KAMCHATSKY MYS PENINSULA: GEOCHEMISTRY, METAL ACCUMULATION AND SEDIMENTATION CONDITIONS

In the Cretaceous paleoceanic deposits of Eastern Kamchatka, carbonaceous beds have been studied, the origin of which relates to the oceanic anoxic events. In carbonaceous rocks, the contents of trace elements and noble metals: Ba, Cu, Ni, Zn, Mo, V, U, Y, Au, rare-earth elements and platinoids are increased in comparison with the hosted jaspers and limestones. In particular, the Au content in ash-laden carbonaceous rocks reaches 0.8 ppm, and Pt 2.1 ppm. The geochemical proxies Mo/Mn and V/(V + Ni) indicate the accumulation of carbonaceous deposits in euxinic conditions. The significant non-lithogenic excess Ba indicates a high bio-productivity in the upper part of the water column. High bio-productivity and euxinic conditions of sedimentation caused the enrichment of carbonaceous rocks with many trace elements. Phosphorus trapped into the sediments with bone detritus, which subsequently sorbed rare-earth elements and yttrium from sea water during its fossilization. Copper, zinc and vanadium are associated with the Fe-sulfide phase (framboidal pyrite). Noble metals accumulated during sedimentation and early diagenesis were deposited with organic matter and/or directly from seawater. In carbonaceous rocks, they appear to be in the form of organometallic compounds or enter into the composition of framboidal pyrite. The sedimentation occurred at the top of a seamount in the Pacific Ocean. The studied deposits are similar to the Cretaceous sediments that formed at the tops of seamounts in the northwestern Pacific, where carbonaceous beds are also present in the sections. Organic-rich sediments were deposited within the oxygen minimum zone during periods of maximum bio-productivity of plankton.

Mineralogical and geochemical specificity of carbonaceous rocks from the area of Ust'-Kara astrobleme (Pay-Khoy)

We studied Upper Paleozoic (P1pt-ng) carbonaceous shales and siltstones from the area of the Ust'-Kara astrobleme (PayKhoy). We analyzed mineralogical and geochemical features of carbonaceous rocks of the target in the vicinity of the Ust'-Kara astrobleme event using a complex of modern methods to identify possible mobilization, redeposition and concentration of ore substance under intensive post-impact hydrothermal activity. Geochemical features of carbon deposits, altered by post-impact hydrothermal processes in the vicinity of the Ust'-Kara impact structure, have been determined. We found anomalous contents of Ti, Mn, Cr, Zr, Ni, Li, Co, Sc and REE. Inherent rare metal and rare earth minerals (monazite, florensite), sulfides (pyrite, chalcopyrite, marcasite, sphalerite), apatite, barite, anatase, chrome spinels were diagnosed.