Levels of changes in the genus Pinus Linné in the composition of Mesozoic and Cenozoic flora and vegetation as an additional criterion for the division of sediments by the Mesozoic and Cenozoic of Ukraine

The article presents an analysis of a large array of results of palynological studies of Mesozoic and Cenozoic sediments of Ukraine and adjacent regions of Belarus and Russia. Numerous literature data on the palynological characteristics of Meso-Cenozoic sediments and the materials of the authors are summarized according to the results of spore-pollen analysis of Mesozoic and Cenozoic sediments within the main tectonic structures of Ukraine. It has been established that the genus Pinus (Pinaceae) is an integral part of the Meso-Cenozoic flora of Ukraine. Although, the participation in the flora and vegetation of the genus Pinus and its species diversity in different periods of geological time were different. Despite the long history and significant achievements of palynological research of Meso-Cenozoic sediments of Ukraine, no attention has been paid to the historical aspect of Pinus development in the Meso-Cenozoic flora. This work is presented as the first stem to fill this gap. The genus Pinus has a large stratigraphic range, but its species diversity and quantitative changes in the composition of Mesozoic and Cenozoic flora of different ages are markedly different. The analysis of these changes made it possible to trace the emergence and main levels at which the species composition was renewed and the role of Pinus in flora increased during the Mesozoic and Cenozoic. According to the results of the research, 5 levels of increasing the participation of the genus Pinus and changes in its species affiliation in the Mesozoic flora were established: Aalenian period of the Middle Jurassic (appearance of the first representatives of Pinus); Oxfordian time of the Late Jurassic; Valanginian – Early Barremian times of the Early Cretaceous; Albian time of the Early Cretaceous; Late Campanian time of the Late Cretaceous. 5 levels of increasing the role of Pinus and its species diversity for the flora and vegetation of the Cenozoic were also established: Oligocene time of the Paleogene, Konkian-early Sarmatian time of the Middle Miocene; early Pontian (Ivankov) time of the Late Miocene; early Kimmerian time (early Sevastopol) of the Early Pliocene and Martonosha time of the Early Neopleistocene. Certain levels have been traced for the similar age of Cenozoic flora of Belarus and Russia.

Stress-strain state of the earth’s crust of the Central Asian mountain belt: distant effect of the tectonic impact of the Indo-Eurasian collision

In recent decades, extensive geological, geophysical and geochronological data have been obtained that characterize in detail the results of the distant tectonic impact of the Indo-Eurasian collision on the lithosphere of Central Asia, which led to the formation of the mountain systems of the Pamirs, Tien Shan, Altai-Sayan region and Transbaikalia from the Late Paleogene (about 25 million years ago). It has been established that the formation of the structure of Central Asia occurred as a result of the transmission of deformations from the Indo-Eurasian collision over long distances according to the “domino principle” through the rigid structures of Precambrian microcontinents located among the Paleozoic-Mesozoic folded belts. The study of peneplain surfaces deformed into simple folds on high-mountain plateaus surrounded by rugged mountain ranges made it possible to reveal the parameters of the deformations of the earth’s crust, the interrelationship of the formation of relief and sedimentary basins. Apatite track dating data, structural and stratigraphic analyses of Late Cenozoic sediments in the basins prove a period of intense tectonic activation the entire lithosphere of Central Asia from the Indian continent to the Siberian platform starting from the Pliocene (about 3.5 million years). As a result of reactivation of the heterogeneous basement of Central Asia, high seismicity was manifested, which is concentrated mainly along the border of the microcontinents (Central Tianshan, Junggar and Tuva-Mongolian) and the Siberian craton, as well as in the zones of articulation of regional faults.

Paleogeographic and litho-facial conditions of meso-cenozoic sediment formation of the Anadyr depression

Background. The Anadyr depression has a marginal structure. It comprises four sub-regional elements. Disjunctive dislocations are widely developed within the area.Aim. To reconstruct the paleogeographic and litho-facies conditions of the formation of the Meso-Cenozoic sediments of the Anadyr depression. The reconstruction was performed by evaluating the initial data and developing paleogeographic and litho-facies maps. Data on the conditions of sediment formation in the study area, rich in hydrocarbon and mineral deposits, is essential from a practical standpoint.Materials and methods. Paleogeographic reconstructions of the Anadyr depression were performed based on an analysis of the sediment thickness and litho-facies composition of the relevant age. To build litho-facies maps, we used the data on the material composition of the Bering Sea sedimentary cover and adjacent areas, including well-drilling data, outcropping descriptions, thickness gradient analysis, seismic study results, etc.Results. In the course of the work, sedimentary environment maps were created. Litho-facies maps were developed for all four main sedimentary complexes of the Anadyr depression. Based on the generalised geological data and paleoreconstructions, we constructed forecasting schemes of the distribution of barrier formations in the study area.Conclusions. It was found that the formation of the sedimentary cover of the Anadyr depression took place mainly in shallow-water sedimentary environments. In addition, the depths of paleobasins did not overpass the internal relatively shallow marine shelf. Based on the analysis, two most probable reservoirs were selected. Regional fluid and potential seals were characterised.

On the occurrence of ichnogenera Planolites and Psilonichnus from the Jogira Formation (Lower to Middle Eocene), Bikaner Basin, Western India: Implications on depositional environment

The Cenozoic sediments of the Bikaner basin are lithostratigraphically classified into four formations in ascending order of deposition viz., Palana Formation, Marh Formation, Jogira Formation and Kolayat Formation. The present paper records ichnofossils viz., Planolites montanus, P. beverleyensis and Psilonichnus isp from Jogira Formation (Lower Middle Eocene) of Bikaner basin, Western India. The presence of these ichnofossils in a succession exposed in a quarry SE of Jogira Lake plays a significant role in deciphering the depositional environment of Jogira Formation. In the present section two ichnofossil horizons are marked, the lower horizon is dominated by Psilonichnus isp whereas upper horizon is conquered by Planolites montanus, and P. beverleyensis. The sedimentological characteristic features and associated ichnofossils from the studied succession infer that the deposition of the sediments of the Jogira Formation initiated with lagoonal to backshore environment with the formation of mudstone and sandy shale, later with rise in the bathymetry from onshore to shallow marine environment, fossiliferous limestones were formed.

Low-temperature thermochronology constraints on the evolution of the Eastern Kunlun Range, northern Tibetan Plateau

Signals of uplift and deformation across the Tibetan Plateau associated with the Cenozoic India-Asia collision can be used to test debated deformation mechanism(s) and the growth history of the plateau. The spatio-temporal evolution of the Eastern Kunlun Range in northern Tibet provides a window for understanding the intracontinental tectonic evolution of the region. The Eastern Kunlun Range exposes the Cenozoic Kunlun left-slip fault and kinematically linked thrust belts. In this contribution, integrated field observations and apatite fission-track thermochronology were conducted to constrain the initiation ages of localized thrust faults and the exhumation history of the Eastern Kunlun Range. Our analyses reveal four stages of cooling of the Eastern Kunlun Range. We relate these four stages to the following interpreted tectonic evolution: (1) an initial period of early Cretaceous cooling and slow exhumation over the early Cenozoic, which is associated with the formation of a regional unconformity observed between Cretaceous strata and early Cenozoic sediments; (2) rapid Oligocene cooling that occurred at the eastern domain of the Eastern Kunlun Range related to the southern Qaidam thrusts; (3) extensive rapid cooling since the early-middle Miocene in most of the eastern-central domains and significant uplift of the entire range; and (4) a final pulse of rapid late Miocene-to-present cooling associated with the initiation of the Kunlun left-slip fault and dip-slip shortening at the western and eastern termination of the left-slip fault. Early Cenozoic deformation was distributed along the northern extent of the Tibetan Plateau, and overprinting out-of-sequence deformation migrated back to the south with the initiation of Miocene-to-present deformation in the Eastern Kunlun Range.

Molecular Geochemistry of the Dispersed Organic Matter in the Late Cenozoic Sediments of the Laptev Sea Continental Margin and Adjacent Part of the Arctic Ocean

––The main factors controlling the bulk sedimentation in the Siberian segment of the Lomonosov Ridge (axial part and western slope) and the Laptev Sea continental margin during the late Cenozoic were studied using a complex of geomorphological, lithological, and organic geochemical data. Samples for the study were collected during the cruises of R/V Akademik Fedorov in 2005 and 2007 and nuclear icebreaker Rossiya in 2007. Analysis of the group and molecular composition of the dispersed organic matter (DOM) in bottom sediments has shown that the input of terrigenous sediments enriched in the products of abrasion of lithified rocks determines sedimentation process on the continental slope of the Laptev Sea and in the Amundsen Basin. The individual characteristics of the DOM of the late Cenozoic sediments from the Lomonosov Ridge reflect the wide diversity of sedimentary sources and depositional environments. Subaqueous erosion of edaphogenic products and pre-Holocene sediments plays an important part in sedimentation together with terrigenous flow and ice transport.

Earthquake-induced clastic dyke and fluid inflow at the Miguel Burnier manganese-ore deposit, Quadrilátero Ferrífero of Minas Gerais, Brazil

A clastic dyke has been recognised within manganese (Mn)-rich Cenozoic sediments near a historical Mn-ore deposit in the Miguel Burnier district, Quadrilátero Ferrífero, in the southern São Francisco craton, Brazil. Here, we describe the clastic dyke, a subvertical fissure that is filled with friable arenaceous fragments, and characterise it as seismite. An overprint by stockwork-like Mn-oxide veinlets and Mn-oxide dissemination, mineralogically expressed as birnessite, lithiophorite and jianshuiite, and geochemically represented by metalliferous enrichments, particularly mercury (Hg), occurs in the clastic dyke and its immediate vicinity. Such an overprint also contains illite, which forms a mineral association with birnessite, lithiophorite and jianshuiite, and constrains the temperature of hydrothermal alteration to less than 300 °C. The recognition of seismite and its Hg enrichment indicate that the Cenozoic history of the Quadrilátero Ferrífero cratonic terrane has been affected by seismic episodes, which were not only conducive to local enrichment in Mn at Miguel Burnier, but also to recent seismic-related phenomena such as a dam failure (Agurto-Detzel et al. in GRL 43: 4929–4936, 2016).