Lithofacies Analysis of the Tista River Deposits, Rangpur, Bangladesh

Eight (8) distinct lithofacies within the fluviatile reach of the Tista River have been recognized by the detailed study of the sediments as exposed along the river bank and river bars. Genetically, the matrix-supported conglomerate (Gms), massive sand (Sm), Trough cross stratified sand (St), planar cross stratified sand (Sp), ripple laminated sand (Sr) comprise the channel deposits whereas, the ripple laminated sand (Sr), parallel laminated sand (Sh), clay with silt (Fl) and massive Clay (Fm) represent overbank fine deposits. The channel deposits were laid down under relatively high energy conditions compared to the sediments of overbank fines. The stratigraphic succession is indicative of fining upward sequence. The dominance of coarser-grained sediments at the base of the lithostratigraphic unit, especially the matrix supported conglomerate (Gms) suggests that the deposition took place in the proximal part of the Tista Fan, which might be of glacial origin. Massive clay (Fm) is the final stage of vertical aggradations in the overbanks, possibly in the floodplains, flood basins, and back swamps when the velocity of the transporting medium was virtually lean that promotes the deposition of clay materials from suspension. The growth of cracks in the sedimentary succession is resulting from the compaction of the sediments and/or instant change in the paleoslope direction. The unimodal distribution of paleocurrent data with high mode value indicates mainly unidirectional sediment transport. The study of the lithofacies manifests that the deposits are produced by the braided river and debris flows. The modification of the depositional pattern from debris flow to overbank fines discloses the change of climatic condition in the Quaternary period.

Culture-Independent Survey of Thermophilic Microbial Communities of the North Caucasus

The Greater Caucasus is a part of seismically active Alpine–Himalayan orogenic belt and has been a center of significant volcanic activity during the Quaternary period. That led to the formation of the number of hydrothermal habitats, including subterranean thermal aquifers and surface hot springs. However, there are only a limited number of scientific works reporting on the microbial communities of these habitats. Moreover, all these reports concern only studies of specific microbial taxa, carried out using classical cultivation approaches. In this work, we present first culture-independent study of hydrotherms in the Republic of North Ossetia-Alania, located in the southern part of the North Caucasus. Using 16S metabarcoding, we analyzed the composition of the microbial communities of two subterranean thermal aquifers and terrestrial hot springs of the Karmadon valley. Analysis of correlations between the chemical composition of water and the representation of key taxa allowed us to identify the key factors determining the formation of microbial communities. In addition, we were able to identify a significant number of highly abundant deep phylogenetic lineages. Our study represents a first glance on the thermophilic microbial communities of the North Caucasus and may serve as a basis for further microbiological studies of the extreme habitats of this region.

PROBLEMS OF THE QUATERNARY STRATIGRAPHY OF THE SIBERIAN REGION

This special issue of the journal is devoted to modern controversial subjects arising during the research of the Siberian Quaternary system. The initiative to discuss these problems and new factual material that requires rethinking outdated stratigraphic constructions belonged to the section of the Quaternary system of SIBRMSK and was supported by leading experts actively working in the region. It should be noted that this issue does not cover all the unresolved issues on the geology, stratigraphy and paleogeography of the Quaternary period of Siberia.

Comparative Chloroplast Genome Analyses of the Winter-Blooming Eastern Asian Endemic Genus Chimonanthus (Calycanthaceae) With Implications For Its Phylogeny and Diversification

Chimonanthus of Calycanthaceae is a small endemic genus in China, with unusual winter-blooming sweet flowers widely cultivated for ornamentals and medicinal uses. The evolution of Chimonanthus plastomes and its phylogenetic relationships remain unresolved due to limited availability of genetic resources. Here, we report fully assembled and annotated chloroplast genomes of five Chimonanthus species. The chloroplast genomes of the genus (size range 153,010 – 153,299 bp) reveal high similarities in gene content, gene order, GC content, codon usage, amino acid frequency, simple sequence repeats, oligonucleotide repeats, synonymous and non-synonymous substitutions, and transition and transversion substitutions. Signatures of positive selection are detected in atpF and rpoB genes in C. campanulatus. The correlations among substitutions, InDels, and oligonucleotide repeats reveal weak to strong correlations in distantly related species at the intergeneric levels, and very weak to weak correlations among closely related Chimonanthus species. Chloroplast genomes are used to reconstruct a well-resolved phylogenetic tree, which supports the monophyly of Chimonanthus. Within Chimonanthus, C. praecox and C. campanulatus form one clade, while C. grammatus, C. salicifolius, C. zhejiangensis, and C. nitens constitute another clade. Chimonanthus nitens appears paraphyletic and is closely related to C. salicifolius and C. zhejiangensis, suggesting the need to reevaluate the species delimitation of C. nitens. Chimonanthus and Calycanthus diverged in mid-Oligocene; the radiation of extant Chimonanthus species was dated to the mid-Miocene, while C. grammatus diverged from other Chimonanthus species in the late Miocene. C. salicifolius, C. nitens(a), and C. zhejiangensis are inferred to have diverged in the Pleistocene of the Quaternary period, suggesting recent speciation of a relict lineage in the subtropical forest regions in eastern China. This study provides important insights into the chloroplast genome features and evolutionary history of Chimonanthus and family Calycanthaceae.

Understanding Abrupt Climate Change in the Late Quaternary

During the late Quaternary period, a series of abrupt climate changes in the tropics and sub-tropics driven by changes in ocean circulation were both dramatic and disruptive.

Glacial Landforms as Geodiversity Resources for Geotourism in Tierra del Fuego, Argentina

The southern extreme location and the natural landscapes, highly modelled by glaciers during the Quaternary period, give Tierra del Fuego a unique opportunity to attract visitors worldwide. Its glacial landforms are geodiversity resources that are witness to global climate changes as natural processes. Therefore, this study aims to highlight different glacial landforms considering their geodidactic potential for educational information in terms of geographical study. Sixteen georesources connected by routes are analysed, using bibliographic research, fieldwork and a datasheet designed ad-hoc. Four of them were formed during middle Pleistocene glaciations and the other twelve during the Last Glacial Maximum (LGM), out of which two also represent the Holocene, which happens to be the youngest glaciation.

Quaternary geomorphological and climatic changes associated with the diversification of Iberian freshwater fishes: the case of the genus Cobitis (Cypriniformes, Cobitidae)

We studied the population genetic structure of Cobitis vettonica, an endangered freshwater fish species endemic to the Iberian Peninsula in order to propose a biogeographic model of the responses of species to the multiple changes that occurred in the Iberian hydrological system during the Quaternary period. We also deciphered the relationship of C. vettonica with its sister species C. paludica, particularly in sympatric areas and provide genetic information for conservation purposes. To achieve this end, we analysed both mitochondrial and nuclear data (the cytochrome b and the nuclear recombination activating 1 genes) and a battery of single nucleotide polymorphisms (SNPs) of 248 individuals of C. vettonica or C. paludica from 38 localities, including some sympatric ones, covering the entire distribution area of C. vettonica. We highlight the important role played by the hydrogeomorphological processes and climatic changes that occurred in the Iberian Peninsula during the Quaternary on both the population structure of C. vettonica and its relationship with its sister species C. paludica. Our results support the genetic introgression of populations at the eastern limit of the distribution of C. vettonica. Furthermore, we postulate genetic introgression in sympatric areas. Finally, we propose the establishment or expansion of four OCUs for C. vettonica, and highlight the threat faced by its populations due to the low level of genetic diversity detected for some of its populations and genetic introgression with C. paludica, which could eventually displace C. vettonica, resulting in a loss of diversity in this species.

Oil Production Enhancement by EOR Candidates Optimization

The study field is located in the Nizhnevartovsk district of the Khanty-Mansi autonomous region. The deposit is located in the Nizhnevartovsk crest zone. The geological section of this deposit features a thick layer (2740-2870 meters) of Meso-Cenozoic era sedimentary rocks starting from the Jurassic period up to and including the Quaternary period, and rests unconformably on the surface of the deposits of the folded Paleozoic basement. The pay zones of study oil and gas fields features mainly sandstone-siltstone reservoirs. The study formation XX11-2 features interleaved rocks with a high clay content. In the west and south-west of the field, the oil-saturated thicknesses vary on average from 5-10 m, and in the north, the thickness increases to 10-20 m. This field has a long-lasting production history as a result of drilling vertical and horizontal wells but is currently at production decline stage. The existing reservoir pressure support system assumes that the water-cut trend at the wells will increase. In recent years, there has been advanced flooding in some areas, resulting in a drop in oil production, while the reasons for the advanced flooding are not always clear. This is often due to the progressing spontaneous fracturing in the injector wells (Aslanyan, Akimov et al., 2020).

Issues related to velocity structure estimation in small coastal sedimentary plains - Case of Tottori plain facing the Sea of Japan

Issues of predominant period of ground motion and derived underground velocity structure model were investigated in the coastal plains affected by the soft sedimentary layer after the last ice age. Specifically, it is found that two predominant periods due to the shallow soft sediments and deep sedimentary layers over the seismic bedrock created by the tectonic movement after the quaternary period are close in a small plain such as the Tottori Plain, Japan as an example. It was shown by the analysis of underground velocity structure derived from H/V spectrum ratio of earthquake ground motions with the diffuse wave field theory. It is feared that the interaction of close predominant periods due to the different layer boundaries with high contrast may amplify the seismic motion in the period range that affects building structures in the small plains in coastal area.