Gaivoron—Zavallia section of the Middle Pobuzhzhіa is the most representative part of the granulite complex of the Ukrainian Shield (structural-tectonophysical results and magnetometric studies)

In the article according to the geological and geophysical data of the well-exposed areas of development of Archean rocks of the Ukrainian Shield, two alternative approaches to establishing the structure and stratigraphy of the oldest granulite complexes are discuss. The outcrops of the enderbite-gneiss complex up to 3.6—3.8 billion years old are located along the Southern Bug River between the Gaivoron town and the Zavallia village. The first, «stratigenic-metamorphogenic» approach assumes that the main features of the composition and structure of the Lower Archean complexes are inherited from the original stratotypic strata. These strata are transformed in the conditions of quasi-isochemical metamorphism with preservation of the sequence of formation in section and the primary constitution in the form of stratification, rhythmicity, direction of change of their composition vertically and laterally. On the structural-formation map and geological section of the Gaivoron—Zavallia section, the Archean granulite complex is shown in the form of a synclinorium composed of four adjacent formations, which are equated to the world of metamorphosed volcanic-sedimentary rocks. The second, «deformation-metamorphogenic» approach, which is supported by the authors of this article, is based on the idea that the granulite complex of Pobuzhzhіa is a subvertically layered medium formed by tangential tectonic forces. The latter lead to shear deformations and displacement of matter at the atomic-molecular (with mineral transformation of rocks) and rock masses at the regional level. This creates structural and textural elements that are superimposed on the primary structure of rocks and often erase it. Field structural-tectonophysical, tectonofacial and magnetometric studies, its results are presented in the article. It was performed specifically to compare these two concepts. Magnetometric studies have shown that the enderbite-gneiss complex of the district by its magnetic characteristics belongs to the middle and lower crust of the Ukrainian Shield.

Results of land subsidence measurement using GPS method in the Jakarta groundwater basin in 2015-2019

The development of population and development activities in big cities in Indonesia, especially in the city of Jakarta and surrounding areas is very rapid. From several land subsidence studies, several factors have been identified that cause land subsidence, namely: excessive groundwater extraction, reduction due to building/infrastructure loads, subsidence due to natural consolidation of soft soil layers, and subsidence due to tectonic forces. At present the exploitation of ground water for industrial and residential needs is at a level that needs attention. Excessive pumping of groundwater will cause a decrease in the quantity of ground water, entry of seawater into the land (sea water intrusion) and land subsidence. Symptoms of the negative impact of land subsidence have been felt in several areas, especially in industrial areas located in the northern part of Jakarta. This land subsidence can be measured by GPS or satellite geodetic method, which have begun to develop in Indonesia in the past two decades. Measurements were made using the radial method at 53 GPS points in 2015 up to 100 measurement points in 2019 in Jakarta Groundwater Basin. The result of these campaign GPS surveys that is northern part of Jakarta relatively had higher subsidence rate than the southern. The largest subsidence almost reached 6.2 cm/year in Muara Baru in northern area which is southern area only suffered an average rate of 1.16 cm/year.

The role of surface processes in basin inversion and breakup unconformity

At divergent plate boundaries, extensional tectonics lead to subsidence, continental rifting and the formation of continental margins. Yet, within this extensional context, transient compressional structures (stress inversion) and phases of uplift (depth inversion) are frequently recorded with no corresponding change in plate motion. Changes in gravitational potential energy during the rifting process have been invoked as a possible source of compressional stresses, but their magnitude, timing and relationship with depth inversions remain unclear. Using high-resolution 2D numerical experiments of the full rifting process, we track the dynamic interplay between the far-field tectonic forces, loading and unloading of the surface via surface processes, and gravitational body forces. Our results show that rift basins tend to localize compressive stresses, they record transient phases of compressional stresses up to 30 MPa and experience a profound depth inversion, 2 km in magnitude, when sediment supply ceases, providing a novel explanation for the breakup unconformity, a well-documented phase of regional uplift typically associated to continental breakup.

Insights into the structure and surface geology of balanced and retrodeformed geological cross sections from the Nizampur basin, Khyber Pakhtunkhwa, Pakistan

The current research work is an attempt to apply the basic geological procedures, methods of geological mapping, surface and subsurface interpretation and restoration of balanced and retrodeformed cross sections from the Nizampur basin, Khyber Pakhtunkhwa, Pakistan. The work also includes the documentation of several surface structural features, i.e., anticlines, synclines and different types of folds and faults exposed in the vicinity of study area. Four central thrust faults were recognized named as Kahi Thrusts along the cross sections. These thrust faults carried the older sequences of rocks over the younger sequences in different portion along the measured cross section. The folded and faulted rocks in the area show that stratigraphic framework comprises of Eocene, Paleocene, Cretaceous and Jurassic succession of rocks. There are Eocene rocks existing in the extreme South of the mapped area with addition of older Cretaceous and Jurassic succession and contains simple and large-scale folds, faults and back thrust. Two structural transect were mapped which encounter different folds and faults, i.e., X-sections AB oriented NS and CD oriented NE-SW. Restoration of the structural transects was calculated and assumed that at the formation of Main Boundary Thrust, the study area was exposed to the tectonic forces which prognosticated 19.5% shortening in rock sequences from Jurassic to Eocene succession along the measured cross section A_B.

Geomorphology and geochemistry of the late Cenozoic volcanoes in the Halaha River-Chaoer River volcanic fields, western Greater Hinggan Mountain Range, NE China

The Halaha River-Chaoer River (HC) volcanic field in the Greater Hinggan Mountain Range (NE China) consists of at least 41 monogenetic basaltic volcanoes. Strombolian, violent Strombolian, and phreatomagmatic eruptions, as well as the transitional eruptions, generated simple volcanic cone (single vent) and composite volcanic cone (multiple vents). Simple elongated cone is the most abundant geomorphology type. By analyzing the elongated crater and coalescent aligned circular crater, cone breaching and depression, and aligned vents, we identified a number of magma-feeding fissures. The majority of these fissures strike NE-ENE. Accordingly, we infer that the regional stress field affected volcanism in the HC field. The lavas in this field are alkali basalts that are enriched in light rare earth elements (La/YbN = 7.9 to 24.5). Their OIB-like REE and spider-diagram patterns, high Nb/U ratios, and high TiO2 contents (> 2 wt. %) indicate that the basalts were derived from the asthenosphere mantle. Both the asthenosphere upwelling and the tectonic forces are the key controlling factors of the volcanism in the HC field.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5355233

Three Dimensional Terrain Modeling for Tectonic Geomorphology of Chinara Anticline, Northern Iraq

Analysis of the terrain using three-dimensional models offers a deep insight view of ground surface topography and terrain representation. The Chinara anticline is one of the main structures of NW-SE trends for the highly folded zone in northeastern Iraq. The objective of this study is to understand the interrelationship between topography and morphotectonic features using three-dimensional models. This research employed fourth generates principal raster derivative products from the DEM using ArcGIS. To understand the undulating of this anticline with the morphotectonic style, the adaptive equation has been suggested to determine the direction and amount of the main tectonic forces, which can be applied to other undulated anticlines. The values of northeastern and southwestern limbs undulating index UI are 11.7 and 7.8 respectively that indicates the strong tectonic force towards the northeast. Two listric faults have been conducted via the field survey that confirmed by remotely sensed interpretation and DEM products. These listric faults had an intensive impact in comparison with concluded strike-slip faults, and then the Chinara anticline would be less structural undulating in a region of vicinity syncline to Perat undulation. The morphotectonic landscapes reveal that the listric fault has branched into two parts, the first one extending to form the anticline and the other comprises the structural dilemma.

Time Distribution of Strong Seismic Events in the Fore-Sudetic Monocline in Context of Signals Registered by Water-Tube Gauges in Książ Geodynamic Laboratory

Changes in the stress field in Świebodzice Depression (ŚU) unit area are the reason of complex kinematics of the rock blocks consisting of rotations and horizontal/vertical displacements. The measurement system of the Geodynamic Laboratory in Książ, associated with rock blocks which are separated by faults, is a natural detector of tectonic activity. Installed in laboratory long water-tube gauges allowing to determine the functions of tectonic activity—TAF, and their derivatives. A comparison of the TAF with the seismic activity of the Fore-Sudetic Monocline showed that the strong seismic shocks (magnitude ≥3.6) occur in the Monocline only during defined and repeatable phases of the kinematic activity of the ŚU. Observed concordance proves the thesis of the existence of a large-scale, and largely homogeneous field of tectonic forces which, at the same time, cover the ŚU and the Fore-Sudetic Monocline units. The results of comparison between seismic events temporal distribution and phases of tectonic activity of the ŚU orogen indicate existence of the time relation between function of derivative of the tectonic activity (TAF) and seismic events.

External signal preservation in halokinetic stratigraphy: A discrete element modeling approach

Subsurface salt movement in the absence of external tectonic forces can affect contemporaneous sediment deposition, mask allocyclic signals, and deform older strata. We used a discrete element model (DEM) to better understand salt-related modification of a sedimentary sequence with an increasing sedimentation rate. This permitted quantification of thinning rates and analysis of the lateral extent of synkinematic layers. Results show realistic evolution of salt-related faults, defining two salt-withdrawal basins, beyond which strata are undeformed. Thinning of stratigraphy is four times greater between the salt flank and crest than between the undeformed zone and flank, confirming an intense zone of halokinetic modulation adjacent to the diapir. Early, slowly aggrading layers are isolated within the salt-withdrawal basin and strongly influenced by salt growth, whereas later, quickly aggrading layers are more laterally extensive, matching inferences made from subsurface and outcrop data. Halokinetic modulation reduces up the stratigraphic section, mirroring observations around the Pierce diapirs, in the North Sea, offshore UK. Our DEM provides quantitative insights into the dynamic interplay between halokinetic and allocyclic controls on salt-stratigraphic relationships.

To the Problem of Safety of Tyrnyauz Deposit Combined Development

The results are presented related to the retrospective analysis of the stability of Tyrnyauz deposit massifs during combined open-cast and underground mining for the development of measures to improve occupational safety. The information about Russian reserves of the tungsten and molybdenum is given. The characteristics of Tyrnyauz tungsten-molybdenum deposit and technologies for its development in the historical cross-section are provided. The distinctive features of the development of high-altitude deposits are described on the example of the Caucasus. Brief information is given on the method of measuring the displacement deformations of the mined ore mass by geometric leveling using profile lines of the reference marks. The result of the experience of the deposit combined development and the idea of the rock mass as a heterogeneous medium of structural blocks limited by the fractures in the form of agitators with the glide planes and filling with the secondary material are formulated in the article. The methodology is given concerning identification of the regularities of the massif deformation based on the data of surveying measurements with the location of reference marks on the surface, at the bottom of the open-cast and in the underground horizons with graphical construction of hazardous zones. Information about the mechanism of destruction of the massif is generalized and systematized differentially for the composing elements: Blind deposit, Main scarn, Mukulansky open-cast It is shown that the deposit is located in the zone of tectonic forces effect, the stress state of its massif differs from geostatic in magnitude and direction of stresses, genesis and technogenic changes facilitated the transformation of the ore massif into a discrete medium, the formation of voids in the rock massifs was accompanied by the development of deformation with massif destruction. Studies of the history of the development of Tyrnyauz deposit testify the adequacy of massif behavior during technogenic intervention, which is a prerequisite for optimizing the technologies for industrial development of the deposit with an economic and environmental benefits.

New sequence stratigraphic framework on a ‘passive’ margin: Implications for post-breakup depositional environment and onset of glaciomarine conditions in Northeast Greenland

Detailed sequence stratigraphic frameworks have been produced for most of the Cenozoic deposits around the North Atlantic and Greenland Sea. However, the sequence stratigraphic evolution of the Northeast Greenland shelf, a significant part of the Atlantic Ocean margin, has so far never been interpreted. This study provides for the first time, a detailed sequence stratigraphic interpretation of the Northeast Greenland shelf since the late Eocene. Tectonic evolution, eustatic sea level change and the impact of glaciations are integrated into a consistent geological history. Based on the identification of pronounced unconformities and their correlative conformities, 10 stratigraphic sequences are identified. The onset of deposition is defined by a pronounced erosional event, where late Palaeocene tectonic activity caused mass wasting of the uplifted footwall of the Danmarkshavn Ridge along ca. 200 km section of the ridge. During the mid Miocene, a second pronounced unconformity developed across the margin, which caused forced regressive submarine fans to prograde across the margin. The following tectonic quiet period is overlain by glaciomarine deposits, with evidence of ice deformation reaching the present day shelf break. Finally, unknown superregional plate tectonic forces are suggested as a driver of sequence formation based on correlation with the Canadian Arctic.