Application of Improved Stereographic Projection Method to Quantify Lithospheric Plate Motion Trajectory

The traditional method of studying plate motion still cannot be used to obtain plate motion trajectory quantitatively. In this paper, we proposed a new method to quantitative determine plate motion trajectory. Depending on the paleomagnetic data of lithosphere plate and the stereographic projection principle. We selected the Wulff net as the basic projection net, improved and transformed the traditional stereographic projection methods. Projecting the paleomagnetic data (magnetic declination, palaeolatitude and geomagnetic pole coordinate) of the lithosphere plate into the improved stereographic projection net, we can get the analysis results of lithosphere plate stereographic projection. In our study, we took the Indian plate as an example, projected the paleomagnetic data (from Cretaceous) into the stereographic projection net, got the analysis results of motion trajectory of the Indian plate from Cretaceous. This method can be applied to quantify lithospheric plate motion trajectory.

Lithospheric plate tectonics and mass extinctions of biological species

The merging of lithospheric plates and the formation of supercontinents are considered to be the main causes of global species extinctions within the Earth’s biosphere. Under those conditions, the factor of geographic isolation is diminished and interspecies competition is accelerated, allowing for the survival of the best-adapted species. The divergence of lithospheric plates triggers a new spurt of speciation that surpasses the previous one, as it involves the participation of the winning species.

COMPARISON OF MODERN GEODYNAMIC MODES OF FRAMING OF THE EUROASIAN LITHOSPHERIC PLATE

The purpose of the work is to analyze the modern geodynamic mode of framing of the Eurasian lithospheric plate to determine the types of deformations in the structures of spreading, subduction and rift genesis and favorable conditions for oil and gas formation at certain stages of structure development. The authors have analyzed the Arctic spreading zone, the Kamchatka subduction zone, the southwestern part of Eurasia and the Baikal rift system. The author's development of calculation of slip vectors of rock masses in foci of earthquakes and methods of tensor analysis of mechanics of fractured media were used in the work. Differences and similarities between the Arctic spreading zone, the Kamchatka subduction zone, the southwestern part of Eurasia and the Baikal rift system are shown. All of the above structures have a complex layered-block structure. That is, in a layered-block medium in layers, and in individual blocks and in time, the stress-strain state of the lithosphere changes, which directly depends on the direction of the axes of compressive stresses

Asthenospheric zircon below Galápagos dates plume activity

Mantle plumes are active for long periods of time1,2, however dating the onset of their activity is difficult. The magmatic products of the Galápagos plume, for example, have been subducted and fragmentarily accreted to the Caribbean and South American plates3,4. Based on submarine and terrestrial exposures it is inferred that the plume has been operating for ~90 Myrs5 or perhaps even longer (e.g., ~139 Myrs6). Here we show that the activity of the plume dates back to ~170 Ma. Evidence for this comes from 0 to 168 Ma zircon with isotopic plume signature (Galápagos Plume Array; GPA) recovered from lavas and sediments from ten islands of the archipelago. Given lithospheric plate motion, this result implies that GPA zircon predating the Galápagos lithosphere (i.e., >14 Ma) formed at asthenospheric depths. Thermo-mechanical numerical experiments of plume-lithosphere interaction show that old zircon grains can be stored within local astenospheric stable domains to be later captured by subsequent rising plume magmas. These results open new avenues for research on mantle plume dynamics in similar tectonic settings.

PROBABILISTIC-DETERMINISTIC GRAVITY MODELS OF THE CENTRAL TYPE STRUCTURES IN THE CRUST AND UPPER MANTLE

The author shows the possibilities of diagnostics and spatial parameterization of central type structures (SCT) by distributions of density contrast and singular points, modeled without aprioristic geologic-geophysical information. The author characterizes the intrusive-dome structures in the crust, formed during the introduction of intrusive bodies, and mantle SCT of plume nature, formed by extrusion of the asthenosphere under the bottom of the lithosphere in the zones of lithospheric plate subduction and in the regional stretching zones.

The March 25, 2020 MW 7.5 Paramushir earthquake

The strong earthquake with moment magnitude Mw = 7.5 occurred on March 25, 2020, in the North Kurils to the southeast of the Paramushir Island. The hypocenter of the earthquake was located under the oceanic rise of deep-sea trench in the subducting Pacific lithospheric plate. This earthquake has been the strongest seismic event since 1900 for an area about 800 km long of the outer rise of the trench. It also was the strongest earthquake for the 300-kilometer long area of the Kuril-Kamchatka subduction zone adjacent to the epicenter. The article summarizes the data on the Paramushir earthquake. Tectonic position of the earthquake, source parameters, features of the aftershock process development, as well as coseismic displacement of the nearest continuous GNSS station are considered. The performed analysis did not allow us to clearly determine the rupture plane in the source. Nevertheless, the study of the features of the outer-rise earthquake is a matter of scientific interest, since the stress state of the bending area of the subducting Pacific lithospheric plate reflects the interplate interaction in the subduction zone.

RECONSTRUCTION OF THE TECTONIC STRESS FIELD IN THE DEEP PARTS OF THE SOUTHERN KURIL-KAMCHATKA AND NORTHERN JAPAN SUBDUCTION ZONES

Earthquake focal mechanisms in the Southern Kuril-Kamchatka and Northern Japan subduction zones were analysed to investigate the features of the tectonic stress field inside the Pacific lithospheric plate subducting into the upper mantle. Earthquake focal mechanism (hypocenter depths of more than 200 km) were taken from the 1966– 2018 NIED, IMGiG FEB RAS and GlobalCMT catalogues. The tectonic stress field was reconstructed by the cataclastic analysis method, using a coordinate system related to the subducting plate. In most parts of the studied seismic focal zone, the axis of the principal compression stress approximately coincides with the direction of the Pacific lithospheric plate subduction beneath the Sea of Okhotsk. It slightly deviates towards the hinge zone separating the studied regions. The principal tension stress axis is most often perpendicular to the plate movement, but less stable in direction. This leads to compression relative to the slab in some parts of the studied regions, and causes shearing in others. The hinge zone is marked by the unstable position of the tension axis and high values of the Lode–Nadai coefficient, corresponding to the conditions of uniaxial compression, while the compression direction remains the same, towards the slab movement. Two more areas of uniaxial compression are located below the Sea of Japan at depths of 400–500 km.

Hot Times in Tectonophysics: Mantle Plume Dynamics and Magmatic Perturbances

Earth’s dynamic lithospheric (plate) motions often are not obvious when considered in relation to the temporal stability of the crust. Seismic radiology experiments confirm that the extreme pressures and temperatures in the mantle, and to a lesser extent the asthenosphere, result in a heterogeneously viscous rheology. Occasionally, magmatic fluid makes its way through the lithospheric plate to the surface, appearing typically as a volcano, fissure eruption, or lava flow. When occurring away from the edges of plate boundaries, these long-lasting suppliers of lava, present over millions of years, are called mantle plumes, or ‘hotspots.’ Conventional definitions of mantle plumes note that they are stationary with respect to each other and the motion of the plates, passively tracing historical plate motion in volcanic formations such as the Hawaiian-Emperor island arc – the Plate Model. In this model, mantle plumes primarily occur as a consequence of lithospheric extension.Recent empirical studies, however, have demonstrated that hotspots are not as geographically consistent as previously thought. They may move in relation to each other, as well as contribute actively toward lithospheric plate motions – the Plume Model. There is a lively, ongoing debate between the Plate and Plume hypotheses, essentially seeking to determine if mantle flow is merely a passive reaction to lithospheric plate motion (Plate Model), or whether plume activity in part drives this motion (Plume Model). More likely, it is a combination of passive and active mantle plume components that better describe the comprehensive behavior of these important and distinctive landscape forming features.

MOUNTAINS AS STABILIZERS FOR EARTH FROM THE QURANIC AND MODERN SCIENCE PERSPECTIVES

The main thought and foundation in Islamic civilization is based from the teaching and learning of Quran. There are many secrets and mysteries in Quran and the only way to uncover it is by reading, understanding and researching its content. Among the miracles stated in the Quran, there are 49 times mentioned about mountain in different form of words and sentence structure hence its meaning. Therefore, this study will discuss and uncover the scientific evidence related to the mountain that is mentioned in the Quran. The method of this study is qualitative approach which most of the data are collected from library and literary materials that related to the word ‘mountain’. In Quran, it has mentioned mountain as the pillar of earth which strengthen its ground and enable other being to inhabit it. Meanwhile, from the perspectives of scientific evidences claimed that when two continents collide, stronger plates will slip beneath the other plate and creating a platform that restrict the movement of the continent to avoid shaking. Then, the upper one folds and will form the mountain plate. This depicts that without mountains, the lithospheric plate movements will be eroded drastically. All this information has been mentioned in Quran as the word ‘rawasiya’ and will be discussed along in this paper accordingly Keywords: Mountain, Quran, stabilizer.

Geological and geophysical system “tectonics-seismicity” of the unique Khailinsk center of high-magnet swarm. South-west of the Koryak seismic belt

Хаилинский центр уникальное явление в Корякском сейсмическом поясе, который обрамляет на севере литосферную плиту Берингию. Он создан роем Хаилинского и Олюторского землетрясений и афтершоков с М 5,07,6. Центр лежит в погруженной глыбе литосферы Олюторского залива, созданной межглыбовыми СЗ разломами на бортах трога с глубиной 82 км в рельефе литосферы. На трог надвинуты морские террейны с максимальным прогибом горизонтов литосферы в их килях, через которые проходит колонна с гипоцентрами землетрясений. Высокомагнитудный рой землетрясений Хаилинского Центра имеет взаимно ортогональные эллипсы афтершоков при общих эпицентрах главных толчков. Хаилинское землетрясение не проявило традиции связи эллипса релаксации афтершоков с известной геологией афтершоков в плане и разрезе. События столь мощные, не увязанные с очевидной геологической структурой представляются очевидной новинкой в мировой горнодобывающей практике. Анализ Хаилинского и Олюторского событий выявил коллизию двух фактов: совпадение эпицентров и полную ортогональность облаков обоих землетрясений. Их исследование как элементов одной системы тектоника-сейсмичность определило геологическое пространство положения гипоцентров. Интерес к сейсмичности Хаилинского высокомагнитудного центра рассматривается как обращение в геологии окраины к уникальной малой литосферной плите Берингия в сейсмологии СВ Азии. В основу исследования системы тектоника-сейсмичность положена концепция сейсмогенной тектоники территории активной окраины континента СВ Азии и места в ней Хаилинского Центра высокомагнитудного роя (ХВЦ). Основы такого понимания сейсмичности окраины территории тектоники определены авторской Концепцией глыбово-клавишной структуры литосферы на активной окраине континента . Эпицентральная область Хаилинского и Олюторского землетрясений локализуется на площади локальной Тылговаямской впадины, причленённой к Вывенской впадине с юга на её висячем ЮВ крыле зоны Вывенского разлома The Khailinsk Center is a unique phenomenon in the Koryak seismic belt, which frames the Beringia lithospheric plate in the north. It was created by a swarm of Khailinsk and Olyutorsk earthquakes and aftershocks with M 5.07.6. The center lies in a submerged block of the lithosphere of the Olyutor Bay, created by interblock northwestern faults on the sides of the trough with a depth of 82 km in the relief of the lithosphere. Sea terranes with a maximum deflection of the lithosphere horizons in their keels, through which a column with earthquake hypocenters passes, are thrust onto the trough. The high-magnitude swarm of earthquakes of the Khailinsk Center has mutually orthogonal ellipses of aftershocks at common epicenters of the main shocks. The Khaili earthquake did not show the tradition of connecting the aftershock relaxation ellipse with the known aftershock geology in plan and section. Such powerful events that are not tied to an obvious geological structure seem an obvious novelty in world mining practice. An analysis of the Khailinsk and Olyutor events revealed a collision of two facts: the coincidence of the epicenters and the complete orthogonality of the clouds of both earthquakes. Their study as elements of one system tectonics-seismicity determined the geological space of the hypocenters position. The interest in the seismicity of the Khailinsk high-magnitude center is considered as an appeal in the geology of the outskirts to the unique small lithospheric plate Beringia in the seismology of NE Asia. The research basis of the tectonics-seismicity system is the concept of seismogenic tectonics in the territory of the active margin of the North Asian continent and the place of the Khailinsk Center for High Magnitude Swarm (KHC). The basics of such understanding of the seismicity in the outskirts of the territory tectonics are determined by the authors Concept of the block-key structure of the lithosphere on the active outskirts of the continent. The epicentral region of the Khailinsk and Olyutorsk earthquakes is localized on the area of the local Tylgovyamsk Depression, connected to the Vyvensk Depression from the south on its hanging SE wing of the Vyvensk Fault zone