Search Results (17)

Understanding Holocene high sea levels in the South China Sea (SCS) is critical for understanding climate change and assessing future sea-level rise risks. We provide a comprehensive review of the Holocene highstand in the SCS, focusing on its age, height, and mechanisms. Records reveal a wide range for this highstand: ages span 3480–7500 cal yr BP, while elevations range from −7.40 to 7.53 m relative to the present. Positive elevations dominate (80.5% of records), with the most frequent range being 2–3 m. Regionally averaged formation times suggest a broadly synchronous mid-Holocene high-sea-level event across the SCS, potentially reflecting a global background. The observed variability is attributed to the interplay of multiple factors: global processes like glacial meltwater input and seawater thermal expansion, particularly during the Holocene warm period, and regional neotectonic movements (uplift/subsidence), which are the primary cause of spatial differences in reconstructed elevations. Significant debate persists regarding precise timing, height, and dominant mechanisms due to limitations in data coverage, dating precision, and challenges in quantifying tectonic influences. Future research priorities include obtaining high-resolution data from stable marine sediments, employing diverse dating techniques and modern crustal deformation monitoring, quantifying tectonic impacts, developing regional sea-level models, and enhancing international collaboration to refine understanding and improve predictions of future sea-level rise impacts. Full article

The strong multi-stage tectonic movement caused the northwest of the North China Plain to rise and the southeast to fall. The covering layer in the plain area was several kilometers thick. In addition to expensive drilling, it is difficult to obtain deep geological information through traditional geological exploration. In this study, gravity, magnetotelluric (MT) sounding and shallow seismic methods are used to explore the basement relief and stratigraphic structure of the alluvial proluvial area in front of Taihang Mount in the North China Plain so as to understand the geological structure and sedimentary evolution of the area. The gravity anomaly map reveals the basement uplift, depression shape and faults distribution on the horizontal plane in the whole area. The MT profile reflects the geoelectric characteristics of the three-layer distribution in the Cenozoic. The seismic profile deployed on the Daxing Uplift depicts the structural style of the uplift area. The well-to-seismic calibration establishes the relationship between the lithostratigraphic and the wave impedance interface so that we can accurately obtain the shape and depth of the bedrock surface and further subdivide Cenozoic strata. Finally, we have improved the accuracy of interface inversion by using a variable density model based on density logging parameter statistics to constrain the depth of geological interfaces determined through drilling and multi-geophysical methods. Through the combination of geology and comprehensive geophysics, we have obtained the undulating patterns of Paleogene and Quaternary bottom interfaces, the structural styles of the basement and the distribution of faults in the survey area, which provide strong support for the study of neotectonic movement and sedimentary environment evolution since the Cenozoic. The successful application of this pattern proves that geophysical surveys based on prior geological information are an important supplementary tool for geological research in thick coverage areas. Full article

This article is devoted to the study of the Quaternary aeolian sands of the boreal zone of north Asia. Using the example of the study reference sections of the Selenga Dauria (Western Transbaikalia), it was established that the activation of aeolian processes is determined by the complex interaction of natural and anthropogenic factors. Natural factors include neotectonic movements; wide distribution of alluvial and lacustrine-alluvial deposits; a sharply continental semi-arid climate; and forest-steppe and steppe vegetation. Among the anthropogenic factors, the leading ones are deforestation, plowing of land and construction of new settlements, roads and other line structures. The obtained radiocarbon dating of buried soils and coal from ancient fire pits indicates the activation of aeolian processes during the Holocene. The main sources for aeolian transport (winnowing) are sands located in the areas of river and lake beaches, floodplains and river terraces. Almost all aeolian sands of the boreal zone were formed as a result of short-range wind transport. They form mini-deserts unfixed by vegetation, with active aeolian processes, dunes, barkhans and deflationary basins. Aeolian swells and blowout basins characterize aeolian landscapes weakly fixed by vegetation. It is noted that aeolian deposits of the boreal zone of north Asia, in contrast to similar sands of the subtropical and tropic zones, consist of coarser-grained material. Medium- and fine-grained sands dominate their composition, which is polymineral and well-sorted. In subtropical and tropical deserts, they are predominantly monomineral, fine and fine-grained. At the same time, mainly minerals that are unstable to weathering (feldspars, plagioclases, pyroxenes and amphiboles) represent the mineralogical composition of the studied aeolian sands. Weathering-resistant minerals dominate the sands of classical deserts: quartz, leucoxene, ilmenite, epidote, zircon, garnets, tourmaline, rutile and others. Modern aeolian landscapes are a unique natural formation for the boreal zone of north Asia and can be successfully used for the development of ecotourism. Full article

The Ahdeb oil field is located in the southwestern part of the Zagros fold deformation zone. The study of the model of the formation of the oil reservoir in this field will be helpful to deepen the pattern of hydrocarbon distribution in this zone. In this paper, we use the seismic data of the Ahdeb oil field to recover the tectonic evolution history of the field. Under neotectonic movement, the oil field formed in the early stage, migrated to the high point in the late stage, and finally entered the present formation. From here, for the oil-bearing inclusions within the reservoir, the photometric absorption values of the organic matter groups were measured by infrared spectroscopy. Their ratios were used to evaluate the maturity, thus discovering two phases of oil charging. Finally, using the hydrocarbon generation history and tectonic evolution history, combined with the oil and gas transportation periods in the reservoir, we deduce that the reservoir formation mode in the area is a two-phase gathering and final adjustment formation mode. This understanding of the hydrocarbon formation patterns will promote oil and gas exploration in this zone. Full article

Accurately identifying the Bottom Simulating Reflector (BSR) is a crucial and fundamental task in seismic exploration and the interpretation of gas hydrates in marine areas. During our seismic interpretation and inference work on a gas hydrate survey in the Qiongdongnan Sea area, we encountered a phenomenon that closely resembled the seismic reflection characteristics of BSR. By comparing and identifying various geological phenomena, we have determined that this unique seismic reflection phenomenon is, in fact, the reflection of the depositional bottom interface known as “mass transport deposits (MTDs)” as described by previous researchers. The physical properties of the MTDs developed on the shallow surface of the seafloor are similar to those of gas hydrate reservoirs in the seismic exploration of marine areas, particularly in the northern South China Sea’s Qiongdongnan Sea area. Due to the lack of active neotectonic movement in the area, most identified BSR reflection occurrences are parallel to the seafloor. Consequently, during the process of seismic interpretation of BSR in the Qiongdongnan Sea area, it may be confused with the bottom boundary reflection interface of MTDs. Accurately identifying MTDs’ sedimentary bodies in gas hydrate exploration activities in this area would greatly enhance the accurate identification of BSR and support the refined evaluation of gas hydrate resources. In this paper, the structural characteristics of MTDs are compared with the reflection characteristics of seismic profiles, the reflectors are identified as MTDs rather than BSR through analysis and interpretation, and the possible mechanism of hydrate accumulation in this region is discussed. Full article

Caves serve as time capsules, preserving significant markers of tectonic activity and offering insights into geological history. Fault geometries and past activations found in caves can be correlated with known deformational events in the broader area, temporally delimiting the speleogenesis. More specifically, cave passage formation is suggested to be affected by the regional stress-field. The Asprorema Cave in Northern Greece is a typical example of a fracture guided cave, with passage geometry influenced by relative sidewall movements, revealing these discontinuities as faults. This study constructs the timeframe and conceptual model of speleogenesis in relation to tectonic events, geomorphological evolution and hydrological zones, and verifies its relation to the stress-field. Active tectonics, mineralogy and cave geomorphology are investigated. Results suggest syntectonic speleogenesis under phreatic and epiphreatic conditions. The absence of corrosion on fault slip surfaces implies recent activations post cave’s shift to the vadose zone. Structural analysis identifies three main neotectonic phases: NNW-SSE striking faults (oldest group of structures), NE-SW striking faults with dextral strike-slip movement (post-middle Miocene), and NE-SW striking normal faults indicating extensional stress-regime (Quartenary). The last two phases affect cave passage shape causing wall displacement, highlighting passage formation along discontinuities perpendicular to the horizontal minimum stress axis. Full article

The central part of the Zhangjiakou area is occupied by the Yanshan orogenic basin. A large number of piedmont faults developed over time, controlling the exposure of geothermal anomalies. The fluid chemistry characteristics and their influence on the heat generation mechanism of the medium- and low-temperature convective geothermal field in the area are not fully understood. In this study, the geothermal fluid was sampled and tested, and the hydrogeological background conditions were analyzed. The results show that the sulfate in geothermal fluid originates from the dissolution of gypsum or H₂S oxidation in deep magma. The geothermal fluid in the faulted basin flows upward after deep circulation and interacts with shallow groundwater. The main source of geothermal fluid is atmospheric precipitation. The temperature of the hot reservoir is between 82 °C and 121 °C, and the depth of geothermal water circulation is more than 3200 m. It can be seen that the geothermal resources in this area are formed by the long-term contact of residual magma, geothermal heating and mechanical heating of neotectonic movement after atmospheric precipitation recharge. Full article

Thoroughly investigating the evolution of groundwater circulation and its controlling mechanism in the Aksu River Basin, where human activities are intensifying and the groundwater environment is increasingly deteriorating, is highly urgent and important for promoting the theory, development and implementation of groundwater flow systems (GFSs) and protecting groundwater resources. Based on a detailed analysis of the sediment grain size distribution, chronology, electrofacies, glacial sedimentary sequence, palaeoclimate indicators and existing groundwater age, this paper systematically reconstructs the palaeosedimentary environment of the basin-scale aquifer system in the study area and scientifically reveals the evolutionary pattern and formation mechanism of the GFS. The results showed that the later period of the late Pleistocene experienced a rapid downcutting erosional event caused by tectonic uplift, and the sedimentary environment transitioned from a dry–cold deep downcutting environment in the Last Glacial Maximum (LGM) to a coarse-grained fast-filling fluvial facies sedimentary environment in the Last Glacial Deglaciation (LDP) as the temperature rose; then, it shifted to an environment of fine-grained stable alternating accumulation of fluvial facies and lacustrine facies that was dominated by the warm and arid conditions of the Holocene megathermal period (HMP); this process changed the previous river base level via erosion, glacier elongation or shortening and river level, thus resulting in a complex coupling relationship between the palaeosedimentary environment, palaeoclimate and basin GFS. Furthermore, the existing GFS pattern in the basin exhibits a vertically unconformable groundwater age distribution, which indicates that it is the outcome of the complex superposition of groundwater flow controlled by the palaeosedimentary environment in different periods. Therefore, neotectonic movement and climate fluctuation have jointly acted on the variation in the river level, resulting in the “seesaw” effect, thereby fundamentally controlling the strength of the driving force of groundwater and resulting in the gradual evolution of the GFS from the fully developed regional GFS pattern during the LGM to the current multihierarchy nested GFS pattern. Full article

The construction of infrastructure projects such as the Sichuan–Tibet Railway and western cascade hydropower stations has led to the increasing development of ultra-long and deeply buried tunnels in an environment characterized by highly active neotectonic movement, which affects the sustainable development of ecological civilization in Tibet. However, the effects of faults resulting from tectonic activity on the distribution of geostress fields have not been systematically studied. This research focuses on the development characteristics and basic type of the Zhuka fault near the RM hydropower station, aiming to analyze the phenomenon of geostress concentration in the study area. Field investigations have revealed significant high-geostress damage on the downstream slope of the lower dam site, situated on the hanging wall of the Zhuka fault. The results indicate a correlation between these high-geostress phenomena and the Zhuka fault, suggesting the concentration of geostress within a certain range on the hanging wall and outside of the fault zone. Stress concentration primarily depends on the characteristics of fault thrusting and fault morphology. The left-lateral strike-slip and thrusting process of the Zhuka fault, combined with NNW-directed tectonic compression stress and sudden changes in fault strike, contribute to geostress concentration within a specific range of the fault hanging wall. The observed high-geostress damage to the hard rock on the valley slope results from the combined effect of construction stress concentration and fourth-order valley incision stress concentration, which influences site selection for the RM hydropower station, thereby highlighting the role of geostress concentration outside the fault zone in engineering practice. This study provides valuable insights into geostress concentration and its implications for sustainable development in the Sichuan–Tibet region. Full article

The Jiaju ancient landslide is a giant landslide located upstream of the Dadu River, eastern Tibetan Plateau, with a volume of approx. 7.04 × 10⁸ m³. The Jiaju ancient landslide is complex and comprises five secondary sliding bodies, e.g., the Jiaju landslide (H01), Niexiaping landslide (H02), Xiaobawang landslide (H03), Niela landslide (H04), and Mt.-peak landslide (H05). Affected by regional neotectonic movement, heavy rainfall, river erosion, and lithology, the secondary sliding bodies of the Jiaju ancient landslide are undergoing significantly different creep-sliding deformation, which will cause great damage to villages, roads, and rivers around the sliding bodies. Combined with the SBAS-InSAR method, Sentinel-1A data from June 2018 to August 2021, remote sensing and field surveys, this study obtained the Jiaju ancient landslide deformation characteristics and deformation rate in the line-of-sight direction (V_LOS), slope (V_Slope), and vertical (V_Vertical). It is concluded that the maximum deformation rate of the Jiaju ancient landslide is significant. The maximum of V_LOS, V_Slope, and V_Vertical are −179 mm/a, −211 mm/a, and −67 mm/a, respectively. The Niela landslide (H04), Jiaju landslide (H01), and Mt.-peak landslide (H05) are very large and suffer strong deformation. Among these, the Niela landslide (H04) is in the accelerative deformation stage and at the Warn warning level, and the Jiaju landslide (H01) is in the creep deformation and attention warning level, especially heavy rainfall, which will accelerate landslide deformation and trigger reactivation. Because the geological structure is very complex for the Jiaju ancient landslide and strong neotectonic movement, under heavy rainfall, the secondary landslide creep-sliding rate of the Jiaju ancient landslide is easily accelerated and finally slides in part or as a whole, resulting in river blocking. It is suggested to strengthen the landslide deformation monitoring of the Niela landslide and Jiaju landslide and provide disaster mitigation and prevention support to the government and residents along the Dadu River watershed. Full article

The review of recent bathymetric and geophysical data collected in the framework of several research and cartographic projects have allowed a detailed reconstruction of the morpho-structural setting and the (neo)tectonic evolution for both the Alpine and Apennine margins of the Ligurian Sea (Italy). The widespread occurrence of erosional processes and sediment mass movements along the steep continental slope and within the system of submarine canyons reflect the close correlation between the active tectonics and the recent morpho-dynamic evolution of the Ligurian Margin. This relation is better constrained in the western sector (Alpine) of the Ligurian Sea, where the recent uplift of the continental margin is associated to a well-developed system of inherited structures reactivated under a compressive/transpressive regime and widespread seismicity. In the eastern sector, where the seismicity is lower or absent, the mass movements are limited to few areas (e.g., the Portofino slope) coinciding with seismic clusters. Additionally, this sector is characterized by moderate and episodic fault reactivations under a compressive regime. The evidence of compressive deformation along the inherited fault systems has been revealed in some areas of the Ligurian Sea where the post-drifting extensional tectonics is interrupted by episodic tectonic inversion (at least) during the Middle–Upper Miocene and the Plio–Pleistocene until present. Full article

From the geomorphological cartography, the geometric and spatial distribution of the quaternary forms and deposits are analyzed, with special relevance to the fluvial terraces that allow obtaining the chronology of the successive landscape changes of the course of the Tagus River attributed to the activity of the Fault of Alentejo-Plasencia (APF). The “Appalachian” relief of Monfragüe National Park, constituting a series of quartzitic combs with direction NW, between which they find slopes, hills and valleys following the same direction, for the dismantlement of the Cenozoic cover that was covering the substratum (still present in the central sector) and encasement of the Rivers Tagus and Tiétar. The remains of fluvial terraces inside and outside the Park stand out at different heights and so they originate from different times and show different landscapes along the routes of the Tagus river and its movement over time. In the north end (basin of the Campo Arañuelo), there are remains of ten fluvial terraces of relative importance attributed to the River Tagus (with heights relative to the thalweg between 120 and 20 m). In the south edge, there are eight levels attributed to a former fluvial drainage network, which assimilates to the River Tagus, with the more recent level reaching over 280 m on the current river. Neotectonics readjustments that rejuvenated the relief produced the elevation of the socle and cover, at the time of diversions in the path of the fluvial network, up to the structure and encasement (for supertax and/or antecedence). During the Quaternary, the activity of the Alentejo-Plasencia Fault (APF) has given rise to palaeogeographic changes in the fluvial valley of the Tagus River. During the ancient Lower Pleistocene, its course passed south of the current one (Talaván-Torrejón el Rubio basin); at the end of the Lower Pleistocene, it came out crossing the syncline through the Boquerón porthole, and the meander that bordered the town of Almaraz was abandoned; at the beginning of the Middle Pleistocene, it changes its direction, from NE–SW to SE–NW, leaving the porthole and joining the Tiétar river within the Park; later it moves somewhat to the south. These changes in the route and the anomalous fitting of the course of the Tagus River into the Paleozoic substrate, have been attributed to the APF, which, through impulses, has had a great activity from the Lower Pleistocene to the Middle Pleistocene. Full article

The Methana volcano in Greece belongs to the western part of the Hellenic Volcanic Arc, where the African and Eurasian tectonic plates converge at a rate of approximately 3 cm/year. While volcanic hazard in Methana is considered low, the neotectonic basin constituting the Saronic Gulf area is seismically active and there is evidence of local geothermal activity. Monitoring is therefore crucial to characterize any activity at the volcano that could impact the local population. This study aims to detect surface deformation in the whole Methana peninsula based on a long stack of 99 Sentinel-1 C-band Synthetic Aperture Radar (SAR) images in interferometric wide swath mode acquired in March 2015–August 2019. A Multi-Temporal Interferometric SAR (MT-InSAR) processing approach is exploited using the Interferometric Point Target Analysis (IPTA) method, involving the extraction of a network of targets including both Persistent Scatterers (PS) and Distributed Scatterers (DS) to augment the monitoring capability across the varied land cover of the peninsula. Satellite geodetic data from 2006–2019 Global Positioning System (GPS) benchmark surveying are used to calibrate and validate the MT-InSAR results. Deformation monitoring records from permanent Global Navigation Satellite System (GNSS) stations, two of which were installed within the peninsula in 2004 (METH) and 2019 (MTNA), are also exploited for interpretation of the regional deformation scenario. Geological, topographic, and 2006–2019 seismological data enable better understanding of the ground deformation observed. Line-of-sight displacement velocities of the over 4700 PS and 6200 DS within the peninsula are from −18.1 to +7.5 mm/year. The MT-InSAR data suggest a complex displacement pattern across the volcano edifice, including local-scale land surface processes. In Methana town, ground stability is found on volcanoclasts and limestone for the majority of the urban area footprint while some deformation is observed in the suburban zones. At the Mavri Petra andesitic dome, time series of the exceptionally dense PS/DS network across blocks of agglomerate and cinder reveal seasonal fluctuation (5 mm amplitude) overlapping the long-term stable trend. Given the steepness of the slopes along the eastern flank of the volcano, displacement patterns may indicate mass movements. The GNSS, seismological and MT-InSAR analyses lead to a first account of deformation processes and their temporal evolution over the last years for Methana, thus providing initial information to feed into the volcano baseline hazard assessment and monitoring system. Full article

The Vigan-Aggao Fault is a 140-km-long complex active fault system consisting of multiple traces in the westernmost part of the Philippine Fault Zone (PFZ) in northern Luzon, the Philippines. In this paper, its traces, segmentation, and oblique left-lateral strike-slip motion are determined from horizontal and vertical displacements measured from over a thousand piercing points pricked from displaced spurs and streams observed from Google Earth Pro satellite images. This work marks the first instance of the extensive use of Google Earth as a tool in mapping and determining the kinematics of active faults. Complete 3D image coverage of a major thoroughgoing active fault system is freely and easily accessible on the Google Earth Pro platform. It provides a great advantage to researchers collecting morphotectonic displacement data, especially where access to aerial photos covering the entire fault system is next to impossible. This tool has not been applied in the past due to apprehensions on the positional measurement accuracy (mainly of the vertical component). The new method outlined in this paper demonstrates the applicability of this tool in the detailed mapping of active fault traces through a neotectonic analysis of fault-zone features. From the sense of motion of the active faults in northern Luzon and of the major bounding faults in central Luzon, the nature of deformation in these regions can be inferred. An understanding of the kinematics is critical in appreciating the distribution and the preferred mode of accommodation of deformation by faulting in central and northern Luzon resulting from oblique convergence of the Sunda Plate and the Philippine Sea Plate. The location, extent, segmentation patterns, and sense of motion of active faults are critical in coming up with reasonable estimates of the hazards involved and identifying areas prone to these hazards. The magnitude of earthquakes is also partly dependent on the type and nature of fault movement. With a proper evaluation of these parameters, earthquake hazards and their effects in different tectonic settings worldwide can be estimated more accurately. Full article

This research investigates geohazards and preventative countermeasures for Lanzhou City, China. To investigate the factors related to the development of geohazards in Lanzhou, the regional geological conditions around Lanzhou were investigated. The geomorphology of the region is comprised of a loess landform underlying quaternary loess deposits. A large number of faults induced by strong neotectonic movements are present in the area. Therefore, earthquakes frequently occur around Lanzhou. Earthquakes cause numerous rock falls and landslides, with landslide masses found scattered on the upper middle level of the area’s mountains. When intense rainfall occurs, a lot of loose deposits are brought together along steep gullies, forming debris flows; hence, a disaster chain of earthquake–landslide–debris flow is formed. To evaluate the georisks around Lanzhou, the Analytic Hierarchy Process (AHP) was employed to assess geohazards. The spatial distribution of the evaluated georisk levels was mapped using a Geographic Information System (GIS). Based on the assessed results, about 55% of the urban area and 44% of Gaolan County have high or very high-risk levels. The ratio of relatively high disaster risk levels is up to 31% of the total area. To mitigate these geohazards, both strategic decision making and technical countermeasures should be implemented. Full article