New data on eruptions of mud volcanoes in Azerbaijan

Статья посвящена новым извержениям самых активных грязевых вулканов Шамахи-Гобустанского региона Восточного Азербайджана – Шихзарли и Гушчу, характеризующихся частыми проявлениями. Так, начиная с 1844 г. зарегистрировано 26 извержений грязевого вулкана Шихзарли, одно из которых, наиболее интенсивное произошло в феврале 1902 г. после катастрофического Шамахинского землетрясения. Цель исследования. Рассмотрены геологическая позиция грязевых вулканов, сейсмологические данные, определившие глубину очага и энергию извержения, дан краткий исторический обзор извержений. Методы исследования. Геологическое строение площадей расположения грязевых вулканов изложено на основе новых данных, полученных в последние годы о тектонике грязевулканических районов Азербайджана, в частности Гобустана, с выделением разломных структур и расположенных между ними микроблоков, а также тектонических единиц – аллохтон, паравтохтон и автохтон. В одном их таких микроблоков (Баянатинский) расположен грязевой вулкан Шихзарли, относящийся к паравтохтону. Почти все извержения грязевых вулканов Шихзарли и Гушчу, а также последние их проявления спровоцированы землетрясениями, происшедшими в близкорасположенных к ним районах и отмечены 5–7 сейсмостанциями. Предыдущее извержение грязевого вулкана Гушчу в Шамахинском районе в январе 2020 года явилось следствием подземных толчков в соседнем Исмаиллинском районе. В историческом обзоре рассматриваемых грязевых вулканов отмечены характерные и отличительные особенности их проявлений. Последнее (16-е) извержение грязевого вулкана Гушчу произошло из нового эруптивного центра, на расстоянии 700 м к северу от основного действующего более ста лет кратера вулкана. Результаты работы. Приведены результаты геохимического анализа вулканической брекчии, особенно нефтеносных пород – песчаников и горючих сланцев эоцен-миоценовых отложений для оценки перспектив нефтегазоносности площадей расположения изученных грязевых вулканов. В пределах Баянатинского микроблока нефтегазовые скопления могут быть открыты под грязевулканическим очагом The article is devoted to new eruptions of the most active mud volcanoes Shikhzarli and Gushchu in the Shamakhi-Gobustan region of East Azerbaijan. These volcanoes are characterized by frequent manifestations. Thus, since 1844, 26 eruptions of the Shikhzarli mud volcano have been recorded. The most intense eruption occurred in February 1902 after the catastrophic Shamakhi earthquake. Aim. The geological position of mud volcanoes, seismological data that determined the depth of the source and the energy of the eruption are considered. A brief historical review of the eruptions is given. Methods.The geological structure of the areas where mud volcanoes are located is presented on the basis of new data obtained in recent years on the tectonics of mud volcanic regions of Azerbaijan. In particular for this reason was used Gobustan, with the identification of fault structures and microblocks located between them, as well as tectonic units - allochthon, parautochthon and autochthon. In one of these microblocks (Bayanata), there is the Shikhzarli mud volcano, which belongs to the parautochthon. Almost all the eruptions of the Shikhzarli and Gushchu mud volcanoes, as well as their last manifestations, are induced by earthquakes that have occurred in the regions close to them and are registered by 5–7 seismic stations. The previous eruption of the Gushchu mud volcano in the Shamakhi region in January 2020 was the result of tremors in the neighboring Ismayilli region. In the historical review of the considered mud volcanoes, characteristic and distinctive features of their manifestations are noted. The last (16th) eruption of the Gushchu mud volcano occurred from a new eruptive center, at a distance of 700 m to the north of the main crater of the volcano that has been active for more than a hundred years. Results. The results of geochemical analysis of volcanic breccias, especially oil-bearing rocks - sandstones and oil shales of Eocene-Miocene deposits are presented to assess the prospects for oil and gas content of the areas where the considered mud volcanoes are located. Within the Bayanata microblock, oil and gas accumulations can be discovered under a mud volcanic chamber

Linking exhumation, paleo-relief, and rift formation to magmatic processes in the Western Snake River Plain, Idaho

<p>Southwest Idaho has experienced substantial topographic changes over the Cenozoic that are reflections of complex tectonic and mantle processes. The western Snake River Plain (WSRP) in southwest Idaho has been characterized as an intracontinental rift basin but differs markedly in topography and style from other western Cordilleran extensional structures. It also differs in orientation and structural style from the down warped lava plain of the eastern Snake River Plain that follows the path of the Yellowstone hotspot (YHS). Potential magmatic drivers for WSRP formation include the ~12-10 Ma Bruneau-Jarbidge eruptive center of the YHS or the ~17-16 Ma Columbia River Basalt (CRB) large igneous province. To better constrain the timing and style of rifting in the region we sampled granitoid bedrock from Cretaceous and Eocene-aged plutons from the flanks of the WSRP to detail their exhumation history with apatite (U-Th)/He (AHe) thermochronometry. We present new AHe dates from seventeen samples, with cooling dates ranging range from 7 Ma to 55 Ma. The majority of cooling dates for the Cretaceous plutons are Eocene, and the Eocene intrusions yield Miocene dates. The AHe dates provide thermochronological evidence of rapid cooling and exhumation of the Idaho batholith during the Eocene. This supports the presence a high relief landscape in Idaho associated with regional uplift due to Farallon slab rollback and Challis magmatism. We also find evidence for a post-Eocene decrease in relief, seen in the negative slope on date-elevation relationships in the southwest flank of the WSRP. Our AHe dates indicate limited exhumation on the flanks of the WSRP during Miocene rift formation. We interpret this to be evidence of extension dominated by magmatic intrusions and intrabasin faults rather than basin-bounding faults. Miocene AHe dates show rapid exhumation along the Middle Fork Boise River that had begun by ~17 Ma. We take this to indicate focused incision along the river due to base level fall in the WSRP and the timing suggests that CRB activity was responsible for initiation of WSRP formation</p>

Message from the Winner

A volcanic eruption is a phenomenon in which ballistic bombs, lapilli, volcanic ash, lava, and gas are discharged. Volcanic ash and gas are carried by the wind, and pyroclastic flows and lava flows are carried away by the force of gravity. These cause disasters of various forms in the areas around volcanoes, sometimes far from eruptive center. Accordingly, volcanic countries, particularly Asian countries such as Japan, Indonesia, and the Philippines, have been the scenes of volcanic disasters. We conducted the research project “Integrated study on mitigation of multimodal disasters caused by the ejection of volcanic products” with the Center for Volcanology and Geological Hazard Mitigation and other institutes in Indonesia under the SATREPS project from FY2013 to 2018. The aim of the project was to advance volcanic hazard mitigation, and I served as the guest editor of “Special Issue on Integrated Study on Mitigation of Multimodal Disasters Caused by Ejection of Volcanic Products” (2016) and “Special Issue on Integrated Study on Mitigation of Multimodal Disasters Caused by Ejection of Volcanic Products: Part 2” (2019) of the Journal of Disaster Research. The articles in the Special Issues have been downloaded by many researchers. The Special Issues cover many topics related to volcanic disasters, but the main theme is how to forecast real-time volcanic hazards using data monitoring, since it is this monitoring that triggers the issuing of warnings. I have studied the volcanic activity of Sakurajima, the most active volcano in Japan, for 40 years, primarily to forecast its eruptions. Forecasting the eruptions is not as important as forecasting the hazards and risks posed by volcanic actions. Research done on the mitigation of the volcanic hazards of Sakurajima as well as Indonesian volcanoes has been enhanced by interaction. The cumulative volume of magma stored in the past 100 years indicates that Sakurajima has the potential for a large-scale eruption (VEI > 4). An eruption and its dispersal of volcanic ash in particular would cause a variety of disasters over a wide area, as described in the other issues of Journal of Disaster Research. I hope that the research results will be utilized for hazard mitigation in the event of future large-scale eruptions. The research could be advanced through collaboration with studies aimed at the enhancement of resilience and recovery.

Rhyolite ignimbrite boulders and cobbles in the Middle Jurassic Carmel Formation of Utah and Arizona—age, composition, transport, and stratigraphic setting

A stratigraphic layer containing rhyolite cobbles and boulders in the Middle Jurassic Carmel Formation of southern Utah represents a singular, unusual event in the otherwise low-energy sedimentation of this formation. A laser-fusion, single-crystal 40Ar/39Ar age of 171.73 ± 0.19 Ma obtained from sanidine in one of the clasts is about 8 m.y. older than a zircon U-Pb age obtained on a fallout tuff from the sediments surrounding the clasts (163.9 ± ~3.3 Ma). The volcanic clasts are poorly-welded rhyolite ignimbrites that may have been deposited as much as 200 km from the eruptive center, perhaps along pre-existing valleys. The tuff deposits then remained in place for several million years during which time they were subjected to weathering, alteration, and perhaps topographic inversion, creating mesas capped with tuff underlain by soft Middle Jurassic silt and mud. Triggered by unusual rainfall or earthquakes, debris flows carried the clasts a few 10s of kilometers from their outcrops to the depositional site. Earlier work proposed that the Middle Jurassic arc was a low-standing, arc-graben. If this was the case, then the tectonic setting was likely similar to the modern Central American arc in the vicinity of Nicaragua where tuffs erupted from a low-standing arc deposited onto an adjacent highland and were then eroded by streams flowing to the east onto a fluvial plain that is near the sea.

Conceptualization of the Dike Distribution Analysis Aiming at Identification of Eruptive Centers

Formation of dikes is typical for most of the volcanic centers. Different types of eruptive centers tend to create different patterns of dike distribution by strike. Looking at this distribution, one may suggest, by purely geometrical reasons, where the vent should be (if buried) or should have been (if removed by denudation or new eruptions). However, wide application of this technique raises the issue of interpretation of the results in the context of the geological history of a particular volcano. Impartial and universal interpretation may be possible in a framework of knowledge of eruptive center evolution that can be built by means of the event bush method. Such a framework, however, may have wide application in volcanology extending far from the initial task it has been developed for.

Vegetation cover at the Maguntan mud volcano (Sakhalin Island, Russia): species composition and spatial distribution

Mud volcano vegetation is not well-studied even in comparison with that of geothermal areas. Mud volcanoes provide opportunities to study the formation of the spatial and species structure of vegetation cover in distinct conditions, showing the trends in vegetation succession. The mud fields of the Maguntan mud volcano (Sakhalin, Russia) are cool, not warm, and their mud fluids have high salinity and alkalinity. In the 20th century some local endemic taxa were found at this place: Artemisia limosa, Gentianella sugawarae, Primula sachalinensis and Deschampsia tzvelevii. I identified nine plant communities and analyzed floristic richness, vegetation cover and endemism rate using data from 185 1 m × 1 m quadrats. The salinity decreases with distance from the volcano's main eruptive center. The total plant cover, number of plant species, and floristic richness increase with the distance from the volcano's center. Endemic taxa including the local endemic grass species Deschampsia tzvelevii are located in young mud substrates. Detrended correspondence analysis showed that the plant communities are arranged along a stress gradient. The spatial distribution of plant communities may be interpreted via succession dynamics.