RECONSTRUCTION OF TECTONIC STRESSES ON THE SCHMIDT PENINSULA (SAKHALIN)

The article presents data on the stress state of the Schmidt Peninsula of Sakhalin Island, obtained as a result of field tectonophysical studies in 2020. The importance of studying the northern part of Sakhalin is due to the prospects of this region for the minerals search. The performed studies allowed us to establish differences in the geodynamic condition between the western and eastern coasts of the peninsula. In general, the conditions of horizontal shear (shear type of deformation) prevail among the types of stress state in the studied territory. On the east coast, there are many situations of horizontal extension, which are usually confined to the axial parts of anticlinal structures. The west coast is characterized by the stable orientation of the axis of maximum compression in the NW direction and its subhorizontal position. For the east coast, the direction of the reconstructed orientations of maximum compression is characterized by greater variability. According to the data of the reconstruction, the stress-and-strain state pattern of the Schmidt Peninsula has significant differences from the main territory of Sakhalin Island.

Geodynamic condition of formation of favorable structural positions for ore-grade gold placement in auminzatau-beltau ore area (the central kyzyl kum, western uzbekistan)

Work is directed on studying of a geodynamic condition under which the structural positions controlling process of endogenous ore formation were formed. It is shown that explosive region tectonics under the influence of regional tectonic efforts formed structural elements (positions) which controlled formation of gold deposits. It is recognized that structural positions are defined by variety of systems of disjunctive dislocation and their relationship among themselves. Formation of favorable positions depends as well on morphology of ore controlling structures, on degree of their tectonic activity and spatial situation in relation to the direction of tectonic (geodynamic) efforts.

The geological and geodynamic condition on the formation of the Dabashan thrust nappe structure: Based on FLAC numerical modelling

The Dabashan thrust nappe structure at the southern margin of the Qinling orogenic belt suffered at least two stages of evolution which are Late Triassic plate subduction collisional orogeny between North China block, Qinling micro-plate and Yangtze block followed by intracontinental orogeny since the Meso-Cenozoic. A prominent topography characteristic within the Dabashan area is a southwestward extrusive arc (Bashan Arc fault) that is one of key factors to understand the geodynamic condition of the Dabashan thrust nappe structure. In this work, two-dimensional plan-view models are constructed to simulate the collisional and intracontinental orogenic movements, and the factors that may control the formation of the Bashan Arc fault are analysed. The modelling results show that the compressive stress produced by the plates collision along both north and south boundaries is the main driving force. The dextral shearing derived from the inconsistent shape on the block margins is the main controller. Rigid tectonic units such as Bikou and Hanan-Micangshan terranes, Foping and Wudang domes, as well as Shennongjia-Huangling anticline also contribute as “anchor” effects. Additionally, the rheology properties of rock material in the Dabashan area affect the shape of the arc. Condición geológica y geodinámica para la formación estructural de la falla de cabalgamiento en las montañas Dabashan basada en el modelo numérico del software FLAC ResumenLa estructura de la falla de cabalgamiento de las montañas Dabashan en el margen sur del cinturón orogénico de Qinling sufrió por lo menos dos etapas de evolución, la colisión orogénica del Triásico Superior entre el bloque de la China del Norte, la microplaca de Qinling y el bloque Yangtze, y la orogénesis intracontinental desde el Meso-Cenozoico. Una característica topográfica prominente del área de Dabashan es un arco extrusivo (falla Arco de Bashan) hacia el suroeste, que es un factor determinante para entender la condición geodinámica de la falla de cabalgamiento en las montañas Dabashan. En este trabajo se construyeron modelos bidimensionales planos para simular los movimientos de colisión e intracontinental orogénicos y se analizaron los factores que podrían controlar la formación de la falla del Arco de Bashan. Los resultados del modelado muestran que el esfuerzo de compresión producido por las placas de colisión en los límites norte y sur es la principal fuerza impulsora de la falla. La principal controladora es la fuerza de cizallamiento dextral derivada de la forma inconsistente en los margenes del bloque. Las unidades tectónicas rígidas como los terrenos Bikou y Hanan- Micangshan, el domo Foping y Wudang, al igual que el anticlinal Shennongjia-Huangling tienen funciones de ancla. Adicionalmente, las propiedades reológicas del material rocoso en el área Dabashan afectan la forma del arco.