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The parameter b (commonly referred to as the b-value) is one of the most significant seismic parameters to describe the seismicity of an investigated region. In this study, the structural framework of the Sarigol- Buldan region located in the intersection area of the western Anatolian graben system in Turkey was investigated by using seismicity and gravity data. As known, western Anatolia is one of the most seismically active regions of the Anatolian plate. Therefore, seismic activity in this region is very high. Analysis of the Bouguer gravity data enabled to define the shallow subsurface structure of the study area. Results from the gravity analysis indicated that the sediment basement depth varied from 0.1 km and 2.1 km. We also detected many NW-SE, E-W, and NE-SW trending lineaments that may be faults or fractures, and the NW-SE trending the Denizli basin lies to the east of the Alasehir basin. We observed that the findings from this analysis seem compatible with the regional geological trend. In addition to this, the seismicity of the region was analyzed by using the frequency-magnitude distribution to find out the seismic hazard risk. The most useful way in the analysis of the seismic hazard studies is to reveal the location of the earthquake boundary, which produces devastating big seismic events because such studies make it possible to forecast the location of possible future earthquakes and improve seismic hazard maps. The b-value for this study region was estimated by using the maximum likelihood method. Variations in the b-value were observed, which range from approximate to 0.2 to 2. A higher b-value was detected in the Buldan horst and surrounding area. In contrast to this, lower b-values were observed in the northeast part of the interaction region between the Denizli and the Alasehir grabens. The positive Bouguer anomaly values as high as +10 mGal and low b-values in the north-eastern part of the study region were interpreted as indicating a thinner crustal root. In comparison, negative Bouguer anomaly values were observed in the Alasehir and the Denizli grabens. Also, in these grabens, intermediate to high b-values were found. This suggests that there is a relation between gravity anomaly and b-value. This relation is strongly related to the normal faulting mechanism existing in the region.

Carlin-type gold deposits in northern Nevada are inferred to overlie concealed late Eocene plutons, which are increasingly thought to have provided magmatic input to the meteoric water-dominated fluids from which the gold was precipitated. The Larderello, Monte Amiata, and Latera geothermal systems in the Northern Apennines of southern Tuscany and northern Latium, central Italy, may represent Pliocene to present-day analogues because of their demonstrated association with subsurface plutons and jasperoid-hosted antimony-gold mineralization. The plutons, which at depths of >5–7 km remain at least partially molten, continue to supply heat and magmatic fluids to the meteoric water-dominated geothermal systems. Formerly mined antimony deposits of Pliocene or younger age are exposed on the peripheries of the CO2 ± H2S-emitting geothermal systems, and antimony sulfides are still actively precipitating. Stibnite and submicroscopic gold in disseminated pyrite, along with Au/Ag of

The Apuseni Mts. is a key area to study the interplay between intra-continental extensional tectonics, sedimentation, and magmatism. These events occurred from ~14.5 to 7 Ma, covering the collision...

Geologic mapping in southern Death Valley, California, demonstrates Mesozoic contractional structures overprinted by two phases of Neogene extension and contemporaneous strike-slip deformation. The Mesozoic folding is most evident in the middle unit of the Noonday Formation, and these folds are cut by a complex array of Neogene faults. The oldest identified Neogene faults primarily displace Neoproterozoic units as young as the Johnnie Formation. However, in the northernmost portion of the map area, they displace rocks as young as the Stirling Quartzite. Such faults are seen in the northern Ibex Hills and consist of currently low- to moderate-angle, E-NE–dipping normal faults, which are folded about a SW-NE–trending axis. We interpret these low-angle faults as the product of an early, NE-SW extension related to kinematically similar deformation recognized to the south of the study area. The folding of the faults postdates at least some of the extension, indicating a component of syn-extensional shortening that is probably strike-slip related. Approximately EW-striking sinistral faults are mapped in the northern Saddlepeak Hills. However, these faults are kinematically incompatible with the folding of the low-angle faults, suggesting that folding is related to the younger, NW-SE extension seen in the Death Valley region. Other faults in the map area include NW- and NE-striking, high-angle normal faults that crosscut the currently low-angle faults. Also, a major N-S–striking, oblique-slip fault bounds the eastern flank of the Ibex Hills with slickenlines showing rakes of The exact timing of the normal faulting in the map area is hampered by the lack of geochronology in the region. However, based on the map relationships, we find that the older extensional phase predates an angular unconformity between a volcanic and/or sedimentary succession assumed to be 12–14 Ma based on correlations to dated rocks in the Owlshead Mountains and overlying rock-avalanche deposits with associated sedimentary rocks that we correlate to deposits in the Amargosa Chaos to the north, dated at 11–10 Ma. The mechanism behind the folding of the northern Ibex Hills, including the low-angle faults, is not entirely clear. However, transcurrent systems have been proposed to explain extension-parallel folding in many extensional terranes, and the geometry of the Ibex Hills is consistent with these models. Collectively, the field data support an old hypothesis by Troxel et al. (1992) that an early period of SW-NE extension is prominent in the southern Death Valley region. The younger NW-SE extension has been well documented just to the north in the Black Mountains, but the potential role of this earlier extension is unknown given the complexity of the younger deformation. In any case, the recognition of earlier SW-NE extension in the up-dip position of the Black Mountains detachment system indicates important questions remain on how that system should be reconstructed. Collectively, our observations provide insight into the stratigraphy of the Ibex Pass basin and its relationship to the extensional history of the region. It also highlights the role of transcurrent deformation in an area that has transitioned from extension to transtension.

The craton is a long-lived stable geologic unit on the Earth’s surface. However, since the Mesozoic, the North China Craton (NCC) experienced large-scale lithospheric removal, the fundamental change of physical and chemical characteristics of the lithospheric mantle, widely distributed crustal deformation, and extensive magmatism. This complex evolution contrary to other cratons is called the NCC destruction. Widespread magmatism in the eastern NCC is an important response to the lithospheric removal at depth and crustal deformation on the surface. The plutons emplace under a tectonic context and therefore record the information of the tectonics; especially, the anisotropy magnetic susceptibility (AMS) pattern of the pluton was acquired with the influence of regional stress. In the past fifteen years, about 22 plutons intruding during the different periods from the Late Triassic to the late stage of the Early Cretaceous have been studied with AMS. The emplacement mechanisms of plutons and the contemporary tectonic setting were discussed to constrain their relationship with the NCC destruction in different stages of magmatism. As a result, the Late Triassic, Early Jurassic, and Late Jurassic plutons exhibit consistent N(E)-S(W) trending magnetic lineations. The early stage of Early Cretaceous plutons display NW-SE trending magnetic lineations, while the late stage of Early Cretaceous plutons show magnetic lineations with various orientations. Combined with previous studies, it is concluded that the emplacements of the plutons intruding in these three stages were controlled by weak N(E)-S(W) trending extension, regional NW-SE trending extension, and weak extension in the shallow crustal level, respectively. The transformation of regional extension from the N(E)-S(W) to the NW-SE direction was accompanied by a strain-increasing tendency. The extensional tectonics in the eastern NCC was interpreted to represent the interaction between Mongol-Okhotsk belt, Paleo-Pacific plate, and eastern Eurasian continent.

Magmatism in northern Colorado beginning in the late Eocene is associated with the formation of Pb-Zn-Ag carbonate-replacement and polymetallic vein deposits, the onset of caldera-forming magmatism, and eventually, the formation of rift-related, F-rich Mo porphyries (“Climax-type” intrusions). We use high-precision U/Pb zircon geochronology to better evaluate the temporal framework of magmatism and mineralization in the region. Our results demonstrate that mineralization in the Leadville area occurred between 43.5 and 39.7 Ma and was followed by mesothermal mineralization in the Montezuma area at approximately 38.7 Ma. Mineralization is associated with a suite of approximately 43 to 39 Ma intermediate magmatic centers that extended from Twin Lakes through Montezuma. The oldest porphyries associated with F-rich Mo prospects and deposits (Middle Mountain; 36.45 Ma) intruded 900 kyr after the start of the ignimbrite flare-up in the region. Spatiotemporal analyses reveal that the pattern of magmatism shifted in orientation between 40 and 35 Ma. We propose a model wherein magmatism before 39 Ma was the result of fluids evolved from the subducted Farallon slab being focused through weak zones in the lithospheric mantle and into the lower crust. This was followed by a more diffuse and higher power melting event that corresponds to a distinct change in the spatial patterns of magmatism. Our data suggest that low-grade Mo porphyry deposits can form close in time to calderas. We hypothesize that the transition from subduction to extensional tectonics in the region was responsible for this more widespread melting and a distinct shift in the style of magmatic-hydrothermal mineralization.

SUMMARY The Davie Fracture Zone (DFZ) evolved during the Jurassic and Cretaceous breakup and subsequent drift of Gondwana off East Africa. This old weak zone has been reactivated during the evolution of the East African Rift System. Recent faulting of Cenozoic sediments in the Kerimbas Basin off northern Mozambique shows that they are affected by the neotectonics. The question is if and how the crustal fabric in our research area has been modified by the rifting process. We present two seismic refraction profiles acquired offshore northern Mozambique to investigate its regional crustal structure and tectonic history. The profiles show a continent–ocean transition zone that widens from around 40 km at 13°S to more than 100 km at 11°S. In the west the transitional crust is up to 12 km thick. To the east, around 150 km off the Mozambique coast lies oceanic crust whose thickness varies from 4.9 to 6.5 km along the northern line and from 6.5 to 7.5 km along the southern one. The latter presents an unusual high-velocity lower crustal body (7.0–7.2 km s−1), about 40 km wide and 3.8 km thick, underlying the oceanic crust. The body may consist of underplated melt with the same source as the nearby Paisley Seamount, which has not yet reached its isostatic equilibrium. Despite well documented recent seismicity along the margin, neither of the profiles reveal significant crustal modifications or reduced crustal seismic velocities that might be related to ongoing extensional tectonics as part of of the East African Rift System. Neither profile reveals seismic evidence for the presence of a major fracture zone or sheared continental margin parallel to the margin. Instead, the profiles’ broad continent–ocean transitions are consistent with their formation during an early Jurassic stage of plate divergence oblique to the margin. Later, after 157 Ma, the azimuth of relative plate motion between East and West Gondwana changed to be parallel to the margin, and parts of the continent–ocean transitions may have been locally reactivated in a strike-slip sense. However, details on the plate movements during the directional change of the seafloor spreading between 157 and 144 Ma are not available. The oceanic crust formed by the initial divergent oblique extension became faulted/modified by the strike-slip movements between both plates. Instead of a narrow deformation zone, the DFZ is charcaterized by a broad, diffuse zone of transtensional deformation.

The recently developed fluorite (U–Th)/He thermochronology (FHe) technique was applied to date fluorite mineralization and elucidate the exhumation history of the Mazandaran Fluorspar Mining District (MFMD) located in the east Central Alborz Mountains, Iran. A total of 32 fluorite single-crystal samples from four Middle Triassic carbonate-hosted fluorite deposits were dated. The presented FHe ages range between c. 85 Ma (age of fluorite mineralization) and c. 20 Ma (erosional cooling during the exhumation of the Alborz Mountains). The Late Cretaceous FHe ages (i.e. 84.5 ± 3.6, 78.8 ± 4.4 and 72.3 ± 3.5 Ma) are interpreted as the age of mineralization and confirm an epigenetic origin for ore mineralization in the MFMD, likely a result of prolonged hydrothermal circulation of basinal brines through potential source rocks. Most FHe ages scatter around the Eocene Epoch (55.4 ± 3.9 to 33.1 ± 1.7 Ma), recording an important cooling event after heating by regional magmatism in an extensional tectonic regime. Cooling of the heated fluorites, as a result of thermal relaxation in response to geothermal gradient re-equilibration after the end of magmatism, or exhumation cooling during extensional tectonics characterized by lower amount of erosion are most probably the causes of the recorded Eocene FHe cooling ages. Oligocene–Miocene FHe ages (i.e. 27.6 ± 1.4 to 19.5 ± 1.1 Ma) are related to the accelerated uplift of the whole Alborz Mountains, possibly as a result of the initial collision between the Afro-Arabian and Eurasian plates further to the south.

Late Mesozoic igneous intrusions and extensional structures in Carboniferous to Permian sequences in the SW Fujian region acted as important controls on the localisation of Fe-polymetallic deposits. Here we document the identification of extensional deformation at shallow crustal levels and syn-tectonic granites related to normal faults. Based on spatial distribution and structural features, the extensional deformation can be divided into cover-only and basement-intersecting styles. A series of syn-tectonic plutons were emplaced into the footwall of normal faults. Representative samples of the Tangquan Granite have high SiO2 (66.4 wt.%–73.9 wt.%) assays and Mg# values (37–59). The samples also have relatively homogenous initial 87Sr/86Sr (0.708 3–0.708 9) and eNd (−9.2–−10.2) values. Geochemical and isotopic evidences indicate that the Tangquan granite originates from a hybrid source including lower crustal-derived felsic and lithospheric mantle-derived mafic magmas. Zircon U-Pb dating indicates that the granodiorite phase from the pluton crystallised at 161±4 Ma and the monzogranite phase crystallised at 159±1 Ma. Combined with the granitic rocks in a wider region of SE China, the widespread granitic magmatism and polymetallic mineralisation have been synchronous during the Late Mesozoic, probably resulting from extensional tectonics related to the lithospheric thinning.

The Anisian depositional history in the Western Tethys realm provides the possibility to study the stepwise opening of the Neo-Tethys, and is well preserved in the sedimentary record of the Northern Calcareous Alps. Whereas the depositional characteristic in the Early (to early Middle) Anisian is characterized by shallow-water carbonates, formed in a semi-restricted environment, the situation changed in the Middle Anisian. A rapid increase of subsidence resulted in an abrupt deepening event with deposition of deeper-water limestones, in some cases even with chert nodules, sometimes with resedimented shallow-water debris intercalated in radiolaria-filament wackestones, or with clayey or marly intercalations. This abrupt deepening, termed the Annaberg Event, is followed by a shallow-water carbonate evolution. The deeper-water limestones can be dated by conodonts and shallow-water organisms like calcareous algae or foraminifera from the resedimented intercalations as Late Bithynian to Early Pelsonian. In contrast to the Early Anisian microbial carbonates, formed under semi-restricted conditions, the Middle Anisian (Pelsonian) shallow-water carbonates were formed under fully marine influence and a diverse fauna and flora was, therefore, able to counterbalance the rapid subsidence by increasing carbonate production. During Middle Anisian times, the newly tectonically created accommodation space became rapidly filled by shallow-water carbonates. At the end of the Middle Anisian (Late Pelsonian), the final break-up of the Neo-Tethys led to a rapid decrease of carbonate production and widespread deposition of deep-marine and condensed limestones. This drowning event (Reifling Event) was accompanied by the formation of a horst-and-graben morphology, dated by conodonts and ammonoids as late Middle Anisian from overlying condensed limestones. In contrast to the well-known drowning event in the late Middle Anisian, precursor events to the final oceanic break-up of the Neo-Tethys have not yet been described, but play an important role in the reconstruction of the opening history of the Neo-Tethys. This knowledge gap is filled by the analysis of exactly datable sedimentary successions in the central Northern Calcareous Alps.

Many oases (wet interdunes) are sedimentary systems characterized by high-frequency water-level oscillations, marked changes in salinity and intense biological activity at their margins. They are considered to be one of the most challenging environments on Earth for ecosystem development. These dynamic, depositional settings are usually unfavourable for fossilization and subsequent preservation of vegetal remains. This paper describes bryophyte (liverwort) assemblages occurring in three successive horizons interpreted to represent (i) recurrent early successional phases of biological soil crust colonization of wet interdune margins or (ii) exceptional preservation of floating or riparian liverworts in oasis pond waters associated with a progressive fall of the interdune water level. The record of in situ colonization surfaces characterized by delicate (e.g. lignin-free) three-dimensional structures represents an exceptional type of preservation herein associated with a rapid variation in phreatic interdune water level and the subsequent establishment of anoxic and reducing conditions. The occurrence of exceptionally preserved liverwort colonies coincides with the sedimentary record of, at least, three seismite levels in the oasis. Data gathered from the site suggests that the water table of the oasis was controlled by a combination of (i) a positive creation of accommodation space due to subsidence associated with movement on syn-sedimentary extensional faults, and (ii) the rise and fall of the oasis water table controlled by the oscillations of the groundwater system due to orbital changes which appear to drive the variability of the climate system. Rising groundwater levels flooded the oasis soil crusts and lead to the exceptional recurrent preservation of liverwort colonies at the oasis margins. Alternatively, considering the hypothesis of floating or riparian liverworts in the oasis pond waters, the fall in the level of the oasis water table placed the floating liverworts in contact with the oasis bottom sediments. This fall in the level of the oasis water table could indicate a cessation of accommodation space by syn-sedimentary extensional faults and/or a regional lowering of the groundwater system level associated with drought periods. Preliminary results indicate that oasis lamination between liverwort colonies records decadal and sub-decadal cyclicity, related with 11-year Schwabe sunspot and sub-decadal NAO cyclicities, conferring for every sedimentary cycle between liverwort colonies a duration of approximately 200 years, that otherwise matches the expected recurrence period for the De Vries cycle of solar activity.

The sandstone relics of probable Cretaceous age found around Tohoun show an extensional tectonics imprint associated with the Atlantic opening. This imprint consists of normal fault networks well expressed on two sites of outcrop and corresponds to three fracturing episodes materialized by families of conjugated planes striking E-W, NW-SE, and NE-SW. Striated plane data analysis shows three extensional axes successively N-S, NE-SW and NNW-SSE. The reconstructed paleostress tensors can be attributed to pre- to syn-rift phases responsible for the development of primary basin structures in the Gulf of Guinea. This preliminary analysis, concerning only fractures in the basal sequence relics, remains to be extended to the entire Togolese coastal basin to a better definition of the Atlantic dynamic.

Ground-penetrating radar (GPR) survey was performed at ten potential sites to delineate the blind surface ruptures, structural discontinuities/shallow subsurface active faults and palaeoseismic deformation in the dynamic range front environment of Pir Panjal. A total of 20 GPR profiles were recorded in four districts with the unshielded 100 MHz rough terrain antenna system and 250 MHz shielded antenna, and out of them, 10 profiles were processed and correlated with detailed structural and lithological map of the area. Several tectonic landforms such as strath surfaces, uplifted fluvial terraces, fault scarps, structural discontinuities, offset ridges, meanders, linear valleys and liquefaction structures mapped during field exercises were meticulously examined by GPR prospecting. Steeply dipping hyperbolas, warped and inclined radar reflections that sharply cut or offset stratigraphic reflections correspond to thrust fault strands. The processed data unearth normal and reverse faults, as well as liquefaction structures covered by recent deposits. However, their correlation with geological and structural data gave a more precise insight into the structural settings of the studied area. The different discontinuity relations specified in the Karewa deposits are mainly due to the regional compressional stress regimes and gradual anisotropic lithology prevailing in the area. The GPR data in agreement with the exposed geological units and structural models suggest that bulk of the landscapes have been evolved/sculptured under the influence of compressional and extensional tectonics along the concomitant active faults. The structural discontinuities (Faults) and the mechanical properties of Karewa deposits will be useful to infer the neotectonic activity prevailing in the area. The whole study would be helpful for the seismic hazard assessment of parts of the Kashmir Valley, NW Himalaya.

The formation of large, economic borate deposits requires a boron-rich source, the means of transporting and concentrating the boron in a restricted environment, and mechanisms for the preservation of the deposit. There are several Miocene basins in western Turkey containing world-class borate reserves, with mineralization present as stratabound deposits in volcano-sedimentary successions. Although it is well-documented that the conditions required to form and preserve large borate deposits are most common in post-collisional tectonic settings (of which western Anatolia is a prime example), recent advances in the understanding of extensional tectonics and volcanism in this region, make it possible to gain fresh insights into their formation. Here, we suggest that formation of one of the largest borate deposits in the world was intimately related to the recently recognized Kırka-Phrigian caldera that lies in the northernmost part of the Miocene Eskişehir–Afyon volcanic field. Following caldera collapse, the basin filled with lacustrine sediments and volcaniclastic deposits with the boron mineralization concentrated in two main sub-basins: Sarıkaya and Göcenoluk. The close spatial and temporal relationship between borate deposition and the vast Early Miocene ignimbrite deposits that surround the caldera (and contain high levels of elements associated with mineralization) strongly suggest that the ignimbrites were the major source of boron. The boron was transported by geothermal fluids and post-volcanic gases that vented into warm water at the base of the caldera-paleolake system and was then concentrated during cycles of sedimentation and evaporation, with most of the mineralization concentrated along a N-S striking fault system.

The Huaishuping gold deposit is located in the Xiong’ershan Mountains of the Qinling-Dabie Orogen of central China. The mineralisation is structurally controlled and hosted by faulted rhyolite, quartz andesite, volcaniclastic rocks and volcanic breccia assigned to the Jidanping Formation towards the top the Palaeoproterozoic Xiong’er Group. The deposit has a resource of around 32 t with an average grade of 5.5 g/t Au. Alteration at the deposit progressed from an early K-feldspar–quartz–pyrite assemblage through quartz–pyrite–gold, quartz–base-metal sulfides, to a late-stage assemblage of quartz–carbonate. The δ34S (V-CDT) values for pyrite in the ore range from − 13.3 to + 1.6‰. The calcite has C-isotopes ranging from − 6.1 to + 2.5‰ (V-PDB) and O-isotopes from + 10.6 to + 15.8‰ (V-SMOW). The δ18O quartz ranges from 10.5 to 15.1‰, and the δD values for fluid inclusions in quartz range from − 93 to − 76‰. The δ56Fe value for the mineralisation varies between 0.1 and 0.5‰ with corresponding δ57Fe values between 0.2 and 0.7‰. The isotope systematics indicates that the hydrothermal fluids were derived from metamorphic fluid, but the source of gold remains uncertain. Re–Os dating of molybdenite yields a date of 202 ± 8 Ma interpreted as the age of the gold mineralisation. This age is consistent with the Triassic onset of extensional tectonics following the collision between North and South China.

Bu çalışmada, 22 Ocak 2020 Akhisar-Manisa (Mw 5.5) depremi ve artçılarının odak mekanizması çözümleri dalga şekli ters çözümü ile elde edilmiş ve buna göre sismotektonik yorum yapılmıştır. Bu amaçla, ana şok ve 35 artçı depremin odak mekanizması çözümleri ISOLA algoritması ile elde edilmiştir. Depremlerin odak mekanizması çözümlerinin çoğunluğu, bölgenin genişleme tektoniği ile uyumlu olup, normal faylanma ve az miktarda doğrultu atım bileşeni olan normal faylanma veya normal faylanma bileşeni olan doğrultu atımlı faylanma özelliğine sahiptir. Analizi yapılan depremlerin odak derinlikleri 4-15 km arasında değişmektedir. Gerilme tensörü ters çözümüne göre; bölge açılma rejiminin (R’=0.75) etkisi altındadır ve KD-BG yönünde açılmaktadır. Açılma hızı 1.3 mm/yıl olarak hesaplanmıştır. Bölgede minimum basınç ekseni (σ3), K21oD olarak yönlenmiştir. Asal gerilme eksenlerinin bölgedeki konumları sırasıyla σ_1, σ_2, ve σ_3 olmak üzere 74o /111o, 16o/291o ve 0o/201o (eğim/azimut) olarak hesaplanmıştır. Bu stres dağılımlarına göre depremlerin üzerlerinde meydana geldiği fay düzlemleri, gerilmeli tektonik kabuk deformasyonunu işaret etmektedir.

Pluto is thought to possess a present-day ocean beneath a thick ice shell. It has generally been assumed that Pluto accreted from cold material and then later developed its ocean due to warming from radioactive decay; in this ‘cold start’ scenario, the ice shell would have experienced early compression and more recent extension. Here we compare thermal model simulations with geological observations from the New Horizons mission to suggest that Pluto was instead relatively hot when it formed, with an early subsurface ocean. Such a ‘hot start’ Pluto produces an early, rapid phase of extension, followed by a more prolonged extensional phase, which totals ~0.5% linear strain over the last 3.5 Gyr. The amount of second-phase extension is consistent with that inferred from extensional faults on Pluto; we suggest that an enigmatic ridge–trough system recently identified on Pluto is indicative of early extensional tectonics. A hot initial start can be achieved with the gravitational energy released during accretion if the final stage of Pluto’s accretion is rapid (

The exhumation of the deep crustal rocks through brittle crust by extensional tectonics is recognized in orogens of all ages. Paleostress analysis are generally used to understand the brittle exhumation process. In this study, we reconstructed the paleostress of faults of the Neoproterozoic Ambaji Granulite, South Delhi Terrane of the Aravalli-Delhi Mobile Belt, NW India by analyzing the fault slip data in Win Tensor program. Several NE-SW and WNW-ESE faults have been mapped in the area and found to be normal faults with a few strike-slip faults. The strike-slip faults are pre-kinematic to normal faults. Tensor solutions for 237 fault slip data points estimate WNW-ESE extension for strike slip faults and NW-SE direction extension for normal faults. From these results, we interpret that the NE-SW striking, orogen-parallel normal faults were produced from a NW-SE directed extensional stress and are primarily responsible for brittle exhumation of the granulite through crustal extension and thinning at 764–650 Ma. This is comparable to earlier studies on brittle exhumation along the Southern Tibet detachment in the Higher Himalayas. On a more regional scale, our results are in agreement with the extensional tectonics that affected the entire Aravalli-Delhi Mobile Belt and adjoining continents of the Neoproterozoic-Cambrian Gondwanaland Supercontinent.

[A tectonic model for the evolution of the Zagros Orogenic Belt based on the different types of melanges in the Neyriz region. , Abstract Melanges are formed by sedimentary, tectonic and diapiric processes and are generally found in collisional belts. The Zagros Orogeny provides an intriguing geological laboratory for the study of melange‐forming processes during the progressive tectonic evolution of the Neotethys Ocean. Different types of tectonic and sedimentary melanges occur in specific structural positions within the Zagros orogenic belt in the Neyriz Region (Iran). Based on their block‐in‐matrix fabrics, and tectonostratigraphic positions, we differentiated 14 different melange types, which mark different episodes of the tectonic evolution of the Neyriz Region from the Cretaceous subduction to the Miocene collision. The Cretaceous subduction stage is recorded by volcanic‐sedimentary melanges (Mv). Sedimentary melanges characterized by megabreccia from the Cretaceous limestone (Ms1) and Eocene polymictic megabreccia (Ms2) represent epi‐nappe melanges formed during the Palaeocene–Eocene in wedge‐top basins. The ophiolite emplacement in the Oligocene resulted in local extensional tectonics in the upper part of the ophiolitic nappe, and deposition of a polymictic megabreccia (Ms3, Ms4). As the final production of the Neotethys Ocean closure and the Eurasian‐Arabian collision, the sedimentary melanges characterized by different types of chaotic rock units (Ms5, Ms6, Ms7 and Ms8 facies) were developed in front of the Cretaceous–Eocene nappes due to growth of the orogenic wedge in the Miocene. Our findings indicate that the recognition and distinction of different types of melange may provide additional constraints for a better understanding of the tectono‐sedimentary evolution of the Neotethyan region.]

We present a 130 km2 wide geological map for the NE side of the fault-bounded High Agri Valley Southern Italy, that formed in the Quaternary in response to extensional tectonics dissecting the folds and thrusts of the Lucanian Apennine. To prepare the map, at 1:25,000 scale, we integrated information obtained through field surveys and the review of pre-existing geological data. Our work describes a number of significant map-scale structures, which can be related to well-constrained tectonic episodes. The new geological map provides important constraints that can be used to distinguish ancient structures from those that were active during the Quaternary, allowing a more detailed reconstruction of the processes that operate during the development of a post-orogenic trough. We expect that the new map will be used for different types of geological investigations, including studies of inversion tectonics, active tectonics, geosite mapping, 3D modelling of geological structures.

The factors controlling the selective reactivation of pre-existing crustal structures and strain localization process in natural rifts have been studied for decades but remain poorly understood. We present the results of surface strain analysis of a series of analogue rifting experiments designed to test the influence of the size, orientation, depth, and geometry of pre-existing crustal weak zones on strain localization and partitioning. We apply distributed basal extension to crustal-scale models that consist of a silicone weak zone embedded in a quartz sand layer. We vary the size and orientation (θ-angle) of the weak zone with respect to the extension direction, reduce the thickness of the sand layer to simulate a shallow weak zone, and vary the geometry of the weak zone to reflect a range of anticlinal, either linear or curvilinear natural weak zone geometries. Our results show that at higher θ-angle (≤ 60o) both small- and large-scale weak zones localize strain into graben-bounding (oblique-) normal faults. At lower θ-angle (≤ 45o), small-scale weak zones do not localize strain effectively, unless they are shallow. We observe diffuse, second-order strike-slip internal graben structures, which are conjugate and antithetic under orthogonal and oblique extension, respectively. In general, the changing nature of the rift faults (from discrete fault planes to diffuse fault zones, from normal to oblique and strike-slip) highlights the sensitivity of rift architecture to the orientation, size, depth, and geometry of pre-existing weak zones. Our generic models are comparable to observations from many natural rift systems like the northern North Sea and East Africa, and thus have implications for understanding the role of structural inheritance in rift basins globally.

In our reply we demonstrate the inconsistency of the comment we received from Mazzarini et al. Our data, models and conclusions are solid and framed in the regional evolution of the Northern Apennines, typified by eastward migration of coeval extensional tectonics and magmatism since late Miocene. We show that understanding the natural processes recognizable in the Elba Island requires a scientific approach based on reproducible, reliable and high-quality datasets, independently of the scale of observation.

Western Anatolia is located at the boundary between the Aegean and Anatolian microplates. It is considered a type-location for marking a significant transition between compressional and extensional...

A new interpretation of the Middle Jurassic-Early Cretaceous paleogeographic evolution of the NW sector of the Latium-Abruzzi carbonate platform facing the Umbria-Marche Basin is proposed, based on Monte Giano area (central Apennines, Italy). During Late Triassic-early Bajocian time, the area was characterized by shallow water sedimentation. Inner and marginal carbonate platform deposits are overlain by pelagic deposits (Posidonia level), early Bajocian p.p. in age. This unconformity testifying the sudden drowning of the Monte Giano area, while shallow water sedimentation persisted in the remaining sectors of the carbonate platform. The Posidonia level is paraconformably overlain by distal slope deposits of the Velino Gorge limestones Formation, Kimmeridgian p.p.-Tithonian p.p. in age. Therefore, a 12Ma gap is recorded as in the Umbria-Marche Basin pelagic carbonate platforms. An extensional Bajocian tectonic phase, possibly related to the Piemont-Ligurian Ocean opening coupled with rheologic differences at the basin/platform boundary, drastically changed the regional paleogeography causing the breakup and the drowning of the NW sector of the Latium-Abruzzi carbonate platform and the creation of a large flat-topped pelagic carbonate platform. The estimate offset of the early Bajocian fault is around 300-350m. The Velino Gorge limestones fm. pass laterally and vertically to the Upper Tithonian platform-margin reef complex of the Ellipsactinia limestones fm.; these units constitute a shallowing and coarsening upward sequence and levelled the paleobathymetric gradient created by the Bajocian extension. The progradation of the Latium-Abruzzi carbonate platform continued during Early Cretaceous time. These results have strong implications on the tectonic and paleogeographic evolution of the major domains of the central Apennines.

The Aptian hydrocarbon-producing reservoirs, in the onshore Semmama and Douleb oil fields of west-central Tunisia are characterized by a heterogeneous flow with continuous decline. Petroleum exploration in this area requires detailed knowledge of the structural development of the basin and its relationship to the reservoir sequence and the source rock distribution. The structural configuration of west-central Tunisia is characterized by NE-SW, NW-SE and N-S deep-seated faults, which outline tectonic structures and it is influenced by Triassic salt intrusions. During the Aptian period, the basin was extensive and shallow at the center, though moderately deep to the North. The northeast-southwest dominated synsedimentary extensional tectonics induced high and subsiding zones and thus controlled sedimentary deposition. The Aptian reservoir is characterized by the lateral variation of sedimentary facies. The first zone, dominated by dolomitic lithofacies has been proven as a petroleum reservoir. The second zone corresponds to carbonate reef and para-reef facies. The third zone, trending north-south is characterized by shallow marine sedimentation, punctuated by episodes of detrital influx. The early Aptian is outlined by the emergence of Kairouan Island that took place in central Tunisia. This study facilitated mapping of the areas exhibiting hydrocarbon reservoir potential which resulted from the conjunction of extensional tectonics and salt ascension.

Two microbial mound-shaped carbonate bodies buried below the slope deposits of the middle Triassic Latemar platform (Dolomites, Italy) have been studied. The two sedimentary bodies, after having reached different stages of evolution, drowned and were covered by the slopes of the Latemar carbonate platform. The estimation of the depth and time at which they were located when they were buried made it possible to infer the average rates of relative sea-level rise to which they were subjected, revealing that these latter exceeded the growth rate of the main Latemar buildup. Given the estimated rates of sea-level rise, the two satellite bodies reached a critical depth at which microbial carbonate production stops, or it is significantly reduced, before being buried. As extensional tectonics was active in the area of the Dolomites during the Anisian, subsidence is the more likely cause of sea level rise. It is therefore hypothesized that the cause of the ultimate drowning of the “mounds” were subsidence rates exceeding their aggradation potential and inducing a progressive deepening that brought them below the lower depth threshold of microbial carbonate production.

Mass-transport deposits (MTDs) intercalated in slope/basinal successions, produced by submarine collapses and mass flows, are generally constituted of allochthonous elements sourced from platform margins. Here we present a noticeable exception where Toarcian calciclastic deposits made of pelagic carbonate elements are embedded in other pelagic carbonates. Selected outcrops pertaining to the Rosso Ammonitico Fm of three different pelagic carbonate platform (PCP)-basin systems were studied. The pelagic successions of the study areas onlap Early Jurassic structural highs. These clastic bodies partially replace the typical Toarcian reddish marls and shales of the Umbria-Marche-Sabina palaeogeographic Domain at different stratigraphic levels. The clasts range from blocks to megablocks; extraclasts of Corniola facies (Pliensbachian) and, sporadically, of Calcare Massiccio peritidal carbonates (Hettangian) are associated with Rosso Ammonitico intraclasts.The internal architecture of the MTDs and their emplacement processes, as well as their source and accumulation areas, were identified. Three distinct lithofacies characterise the clastic bodies, each one corresponding to a different emplacement process or to a different portion of the flow. The occurrence of lithified megablocks (>20 m across) of Corniola Fm suggests the exhumation of the buried portion of the unit. Synsedimentary extensional tectonics is the most likely triggering mechanism.Sedimentological analysis, coupled with geological mapping of the study areas, reveals the key role played by PCPs in the genesis of these MTDs. The early Toarcian reactivation of Hettangian palaeofaults bounding the structural highs is inferred. These faults, characterised by moderate offsets, crosscut the onlap wedges of the hangingwall successions, exhuming the older and lithified portion of Corniola Fm. Once become inactive, the fault planes were then eroded producing palaeoescarpments. Their backstepping, coupled with seismic shocks, produced the accumulation of the study clastic bodies.

Extensional systems of back-arc basins have been widely recognized and studied in SE Asia, however the interactions between extensional tectonics and spatial-temporal distributions of tectonic subsidence in an active back-arc basin are poorly known. Using a backstripping technique, we analysed 33 multichannel seismic profiles to calculate the Neogene tectonic subsidence across the entire Okinawa Trough (OT) for the first time. Reconstruction of the tectonic subsidence shows that the OT can be roughly divided into four subsidence stages with variable rate. By comparing the temporal-spatial distribution of the intensive subsidence area, we confirmed that rifting events first occurred in the northern segment (NOT) and middle segment (MOT) from the Miocene to Late Pliocene, and then propagated to the southern segment (SOT) after the Late Pliocene. The factors controlling the rapid tectonic subsidence over the entire OT can be classified into two categories: 1) NE-to NNE-trending normal faulting, related to extension of the OT, and NW- to NWW-trending strike-slip faulting; i.e., the Tokara Fault and the Miyako Fault, related to subduction of the Philippine Sea Plate under the Eurasian Plate; 2) The anomalous rapid subsidence occurred in the southernmost part of the SOT is likely related to the subducted Gagua Ridge which caused magma intrusion resulting from partial melting. We suggest that magmatic bodies produced by partial melting of subducted materials intruded into the crust and created a dense lithosphere, causing this rapid tectonic subsidence.

We report U–Pb dating of zircon, as well as geochemical and Hf isotope data, in order to constrain the formation time, magma source, and tectonic setting of granite porphyry dykes in the Xicha gold–(silver) district in southern Jilin Province, Northeast China. The zircon grains are euhedral–subhedral, display oscillatory growth zoning and have Th/U ratios varying between 0.11 and 0.78, which together imply a magmatic origin. The dating results indicate the porphyry formed in the Early Cretaceous (122 ± 1 Ma), and it contains SiO2 = 70.64–72.31 wt%, Al2O3 = 13.99–14.64 wt%, K2O + Na2O = 6.96–7.81 wt%, K2O/Na2O = 1.24–2.10, and A/CNK = 1.11–1.41. Chemically, the porphyry belongs to a high-K calc-alkaline S-type granite. Chondrite-normalized rare earth elements (REE) patterns show LREE enrichment, light rare earth elements (LREE)/heavy rare earth elements (HREE) = 9.93–11.97, (La/Yb)N = 11.08–15.16, and δEu = 0.69–0.95. On the trace element spider diagram, large ion lithophile elements such as Rb, Ba, K, Th, and U are enriched, whereas the high field strength elements Ti and P are depleted. The eHf(t) values of zircon from the granite porphyry vary between − 17.1 and − 13.2, and their Hf two-stage model ages vary from 2.01 to 2.26 Ga, implying that the magma was derived from partial melting of old lower crust. The granite porphyry dykes and many A-type granites in the region formed at the same time, suggesting an extensional environment. The combination of the occurrence of strong magmatism, large-scale mineralization, and extensional tectonics throughout much of Eastern China indicate that the Early Cretaceous was a period of significant lithospheric thinning. The southern Jilin Province, therefore, experienced lithospheric thinning during the Early Cretaceous.

Significant post-orogenic extension of the renowned Semail Ophiolite and substrata in Oman resulted in the formation of metamorphic core complexes juxtaposed with an array of Maastrichtian-Paleogene extensional basins. During this evolution, basins became progressively localized. The geometry of the large-scale and long-lived extensional system changes laterally across the core complexes and reveals several generations of domes and detachments, some of which were progressively exhumed. Progressive excision and dismemberment of the ophiolite link to major fabrics in the core complexes and gradual focusing of extensional basins.

The 1500-km-long Jiangnan tectonic belt in China is well known for large outcrops of Proterozoic basement rocks, although the exhumation history of the exposed basement is poorly constrained. The thermochronology of the Sanfang batholith in the southernmost section of this belt was used to constrain the timing and mechanism of exhumation using apatite fission track analysis of granite samples collected along three transects. The results show that the ages of single apatite grains are much younger than the Neoproterozoic crystallization age of the Sanfang batholith. The apparent age v. elevation diagram shows two-stage cooling during the Paleogene and Miocene. The cooling stages are coincident with unconformities between the Paleogene and underlying strata, and between the Neogene and the Paleogene, with movement on high-angle normal faults. A compilation of apatite fission track data from this and previous studies suggests that the batholith was exhumed in the Cenozoic and the timing of rapid cooling is progressively younger to the east as a result of slab rollback leading to Cenozoic back-arc extension. The exhumation of the Sanfang batholith therefore indicates that Cenozoic erosion and extensional tectonics played a key part in exhuming the basement rocks and forming the present architecture of the Jiangnan tectonic belt.

Continental margins are often characterised by wide slope sectors with complex topography due to seafloor deformation linked with mobile shale or salt, or local tectonics. Within the resulting slope environments, sedimentary systems can be complex and often structured in variously connected, separate intraslope basins. In this paper, we investigate how the diverse arrangement of sedimentary systems on topographically complex slopes relate to regional differences in extensional tectonic setting. Our study is carried out through the analysis of bathymetric data in the central and southeastern portion of the Tyrrhenian Sea, a back-arc basin that displays wide slope sectors, surrounding the deep Marsili and Vavilov basin plains. A "connected tortuous corridor" forms in the Latium-Campanian slope, where extensional faults are parallel to the margin. Here, tectonic structures are important in controlling the relative extent of dip and strike sectors as well as depositional and erosional segments of submarine drainage networks. Confined, margin-parallel troughs, such as the Capo d'Orlando and the Paola Basins, form respectively landward from volcanic edifices and mud remobilisation ridges. Their depositional setting is mainly the result of the relationships between the basin dip and the site of major sediment input. An unconfined trough parallel to the margin forms when its edge coincides with down-to the basin extensional faults, such as in the case of the Gioia Basin. Its axis is the site of a longitudinal slope valley that shows morphologic variations controlled by tectonic structures. Transverse troughs cutting the entire slope form when tectonic structures are perpendicular to the margin, such as in the Cilento slope. Here, the pattern of extensional faulting is the major control on the degree of connection of successive basins and the eventual development of a drainage system. Throughgoing slope valleys form in graded slope, where sedimentary packages are thick enough to heal the relief associated with tectonic structures. They have planforms, relief and erosional or depositional attitude that is controlled by slope steps connected with faults. As a general outcome, our research provide a valid framework that illustrates the range of possible architectures of sedimentary systems and of their constituents in extensional continental margins.

The North-South Gravity Lineament (NSGL) is an important geophysical boundary within NE China. Gravity anomaly, heat flow, crustal and lithospheric thickness, terrain and altitude all change dramatically across the NSGL. However, the timing of onset of the NSGL remains enigmatic, and the Mesozoic lithospheric thinning mechanism to the east of the NSGL is still unclear in NE China. Here we study a Late Jurassic bimodal volcanic suite located on the NSGL including N-MORB-like basalts, which constrains the initial formation of the NSGL. The bimodal volcanic rocks consist mainly of basalts and basaltic andesites with subordinate rhyolites. Our results show that the bimodal volcanic rocks are products of crust-asthenosphere interaction. Calculations indicate that lithospheric thicknesses in NE China have significantly changed from ~90–100 km in the west to 49–62 km in the east since the Late Mesozoic. The variation of lithospheric thicknesses on both sides of the NSGL could be ascribed to lithospheric delamination. Zircons from the bimodal volcanic rocks yield Late Jurassic ages of 147 Ma, nearly synchronous with the onset of the Songliao Basin and marking the start of extensional tectonics in NE China. Combined with previous studies, we confirm that the delamination induced by Paleo-Pacific subduction gave rise to the formation of the NSGL, which initiated at the Late Jurassic in NE China.

Well-preserved SSE-dipping low-angle normal faults (LANF) active during the Early Permian (Cisuralian) were recognized along the northern margin of the Orobic Basin (central Southern Alps, N Italy). These faults, which escaped most of the Alpine deformations, exhumed the Variscan basement during the deposition of the upper part of the Lower Permian succession (Pizzo del Diavolo Formation). Fault planes show evidence of frictional processes typical of the upper crust associated with hydrothermal circulation, responsible for the deposition of cm to m thick tourmalinite and Uranium mineralization. The recognized LANFs interacted with high-angle normal faults producing half grabens that stored the Lower Permian deposits, where synsedimentary fault activity in their hangingwall is testified by abrupt vertical and lateral facies changes, thickness variations and by soft-sediment deformations. Mesoscopic structures, exposed in the hangingwall of a major LANF (the Aga-Vedello Fault system) along a synthetic high-angle normal fault, include conjugate normal faults, horst-and-graben, domino-style planar and listric faults, which clearly record synsedimentary deformations testified by liquefaction and dewatering structures, typical of pre-consolidation hydroplastic conditions. This xceptional record indicates deformations at shallow crustal level which occurred during the Early Permian along highangle normal faults soling into the LANFs, forming the northern boundary of the Orobic Basin. The outcrop continuity, the perfectly preserved relationships among high- and low-angle normal faults together with the synsedimentary record of fault activity and the occurrence of mesoscopic faults developed during the deposition of the sediments, make this case-study an excellent reference for the analysis of extensional tectonics in synsedimentary conditions. In addition, the occurrence of large LANF systems, typical of a stress regime characterized by a vertical σ1, suggests that the Lower Permian Orobic Basin was dominated by pure extension at least in the study area, alternatively to existing interpretations, which favor a transtensional origin of the basin. Strike-slip tectonics can be responsible for a later partial tectonic inversion of the basin, as testified by the angular unconformity with the overlying Upper Permian succession (Verrucano Lombardo), marking a Middle Permian stratigraphic gap.

Located in northern Niger, the NW–SE Tefidet trough is the western branch of the Tenere rift megasystem. Here we present a tectono-sedimentary analysis of the Tefidet trough, based on the combined use of satellite imagery, field observations and measures, and available literature. We use these data to analyse the sedimentary facies and the tectonic deformations (faults, folds, basins) in the Tefidet trough, and derive their relative chronology. Doing so, we characterize synrift and postrift deformations and their interactions with sedimentation. Altogether our analyses suggest that the Tefidet trough was affected from the Cretaceous to the Paleogene by three major tectonic periods. • The first period was a rifting stage with extension and transtension during the Albian–Aptian times. The mean extension was ∼N60° and dominantly produced NW–SE-trending normal faults, a few strike-slip faults locally associated with small folds with sigmoidal axis and small reverse faults, and progressive unconformities. • the second period was also a rifting time, which prevailed during the Upper Cretaceous. The regime was marked by transtensional to extensional tectonics, under a ∼N130° shortening and a ∼N60° trending stretching. The end of this period saw the closure of the Tefidet trough. • the third period was a postrift stage. It was characterized by a ∼N70° extensional to transtensional regime during the Oligocene–Pliocene. It mainly produced post-sedimentary extensional faults and fractures and alkaline volcanism. We eventually discuss these deformation phases in relation with the Cretaceous Gondwana breakup and its related rifting events in West and North Africa, and with the subsequent Africa–Europe collision.

Metamorphic core complexes (MCCs) are interpreted as domal structures exposing ductile deformed high-grade metamorphic rocks in the core underlying a ductile-to-brittle high-strain detachment that experienced tens of kilometres of normal sense displacement in response to lithospheric extension. Extension is supposedly the driving force that has governed exhumation. However, numerous core complexes, notably Himalayan, Karakoram and Pamir domes, occur in wholly compressional environments and are not related to lithospheric extension. We suggest that many MCCs previously thought to form during extension are instead related to compressional tectonics. Pressures of kyanite-and sillimanite-grade rocks in the cores of many of these domes are c. 10–14 kbar, approximating to exhumation from depths of c. 35–45 km, too great to be accounted for solely by isostatic uplift. The evolution of high-grade metamorphic rocks is driven by crustal thickening, shortening, regional Barrovian metamorphism, isoclinal folding and ductile shear in a compressional tectonic setting prior to regional extension. Extensional fabrics commonly associated with all these core complexes result from reverse flow along an orogenic channel (channel flow) following peak metamorphism beneath a passive roof stretching fault. In Naxos, low-angle normal faults associated with regional Aegean extension cut earlier formed compressional folds and metamorphic fabrics related to crustal shortening and thickening. The fact that low-angle normal faults exist in both extensional and compressional tectonic settings, and can actively slip at low angles (c. 60°) is needed.

In the southern part of the Khur area, there is faults system with predominantly North-West strike. This network of tectonic disturbances is one of the most important fault systems in Central Iran which crosses Paleozoic metamorphic rocks, Cretaceous limestones, and Eocene volcanic rocks. Interpretation of satellite imagery ETM+ (Enhanced Thematic Mapper plus, Landsat) and field observations showed the presence of left-lateral shifts along with fault system. This formed the structure of the branch faults at the northeast end of the main fault. Another feature associated with shear dislocations is the rotation of blocks in the northeastern and southwestern segments of the area under study. There are several basins and positive structures within the area such as a series of uplifts and thrusts, indicating the presence of compressional and extensional tectonics. Another part of the work is devoted to the study of the correlation between active faults and earthquakes. Processing of satellite images, field observations, records of micro-earthquakes within a radius of 17 km made it possible to analyze the earthquakes parameters and the position of tectonic disturbances, and, as a result, confirm the presence of active faults in the region. In addition, we have identified three successive stages of the Khur area tectonics: rifting, contraction, change of convergence and uplift direction.

The West Anatolia Extensional Zone, which has a width of about 300 km, is located within the Alpine-Himalayan belt and is one of the regions with intense seismic activity in the world. The most important geomorphological structures in this area are three main graben structures resulting from regional N-S extension since the Early Miocene. These structures are the E-W trending Büyük Menderes, Küçük Menderes, and Gediz grabens. Söke Basin is located at the SW end of the Büyük Menderes graben. The lineaments which control the NW of Söke Basin have a length of approximately 40 km and have been defined as the Priene-Sazli Fault (PSF). The PSF is seismically active, and the last large earthquake (the Söke-Balat earthquake; Ms: 6.8) was produced on July 16th of 1955. The ancient city of Priene, which was located in the study area, suffered from destructive earthquakes (in the 4th century and 2nd century BC, in the 2nd century AD, during the Byzantine period and after the 12th century BC). This study aims to reveal the effect of the PSF on the morphotectonic evolution of the region and the relative tectonic activity of the fault. To this end, it was the first time the stream length gradient index (SL: 130–1303), mountain-front sinuosity (Smf: 1.15–1.96), valley floor height and valley width ratio (Vf: 0.27–1.66), drainage basin asymmetry (AF: 0.15–0.76), hypsometric curve (HC) and hypsometric integral (HI: 0.22–0.86) and basin shape index (Bs: 1.04–5.75) along the mountain front that is formed by the PSF. Using a combination of the mountain-front sinuosity (Smf), valley floor height and valley width ratio (Vf), it is found that the uplift ratio in the region is not less than 0.05 mm/yr and the relative tectonic activity of PSF is high. According to the relative tectonic activity index (Iat) obtained from geomorphic indices, the southwest part of the PSF is relatively more active than the northeast part. As a result, I posit that the PSF has the potential to produce earthquakes in the future similarly to those that were produced in the past, and that the most destructive earthquakes will likely occur on the southwest segments of the fault according to geomorphic indices. © 2019, Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag GmbH Germany, part of Springer Nature.