East-central Iran Research Articles

New insights into the conodont biostratigraphy and paleobiogeography of the Katkoyeh Formation (Lower–Upper Ordovician) at the Katkoyeh Section, East-Central Iran

The Katkoyeh Formation comprises most of the Ordovician strata in the Kerman Province of East-Central Iran. However, determining its depositional timing remains challenging due to conflicting biostratigraphic ages, regional stratigraphic gaps, and tectonic complexities in the area. To enhance the understanding of the Katkoyeh Formation, a new conodont sampling was conducted at the Katkoyeh type section, which revealed 1,937 conodont elements belonging to 31 species of 26 genera. They allow the recognition of the Juanognathus variabilis Range Zone (middle–upper Floian) and the Icriodella superba Range Zone (Katian–?Hirnantian) in the Katkoyeh Formation, leading to better biostratigraphic and intercontinental correlations of the Ordovician strata in East-Central Iran with the Precordillera, the Famatina System, and the Central Andean Basin of northwestern Argentina, as well as with North American Midcontinent and North Atlantic basins, and South China. Moreover, the oral structure of Juanognathus variabilis Serpagli is reassessed based on the new Iranian records, recognizing 7 morphotypes in its apparatus structure, referred to the M, Pa, Pb, Sa, Sba, Sbb and Sc positions.

Coal petrology, sedimentology and depositional environment of the Parvadeh coals in the Upper Triassic, Tabas Block of Central-East Iran

Peat forming environment strongly influences the economic value of any coal seam and coal-bearing strata. Hence, palaeoenvironmental studies provide important information for coal resource exploration. In this context, detailed studies on selected coals from the Parvadeh Area, Iran, were conducted using sedimentology, coal petrology, X-ray diffraction (XRD), scanning electron microscopy- energy dispersive X-ray analyzer (SEM-EDX), and proximate analysis. The sedimentary facies above and below the coal seams are mainly marine or marine-influenced facies, supporting that the coal-forming mires in the Parvadeh Area developed in a paralic environment, where the base level must be closely related to sea level. Sulfur contents are moderate to high and mark the influence of brackish/marine water, especially during transgression after peat growth in a lower delta plain environment. The peat-forming mires extended on coastal/delta plain lobes. The lower delta plain/coastal plain coals are characterized by lateral continuity and substantial thickness, whereas few coals possibly representing the upper delta plain are thin and more discontinuous. The detrital nature and composition of the numerous partings and the overall high ash yield in the coal seams indicate an active tectonic area with high rates of creation of accommodation space over peat growth. Coal petrology and coal facies analysis exhibits a permanently high water table within a forest swamp and mostly rheotrophic conditions, sometimes with connection to the seawater. According to paleoenvironmental reconstructions, it seems that coal layers may be thicker, with less sulfur (pyrite), but more clastic minerals and partings toward the western part of the area. Although these coal seams presently have low economic potential for the mining operation, partly due to great depth, this humic, high-volatile to medium-volatile bituminous coal may be suitable for exploration of coal bed methane resources.

Palaeoenvironmental reconstruction of a coal bearing unit: the Upper Triassic Nayband Formation, Tabas Block, East-Central Iran

Palaeoenvironmental reconstruction of a coal bearing unit: the Upper Triassic Nayband Formation, Tabas Block, East-Central Iran

Quaternary deformation patterns in East–Central Iran, constrained by coseismic–postseismic displacements of the 2017 Hojedk triplet earthquake in the Kerman Province

The Central Iranian Microcontinent (CIM) in east-central Iran is located north of the active Arabia–Eurasia collision zone. Here, we report on the structure, deformation patterns, and earthquake occurrences along the dextral Lakar–Kuh and Godar fault systems in the CIM. The geometry of these fault systems marks a major restraining bend responsible for surface and rock uplift in the Plio–Pleistocene that produced the Mian Kuh mountain range. The 2017 Hojedk triplet earthquake (Mw = 5.8–6.0) occurred in the Mian Kuh Range. Sentinel–1 A Interferometer Synthetic Aperture Radar (InSAR) images (descending and ascending) were used to extract the coseismic displacements associated with the earthquake and its aftershocks. The results indicate a maximum displacement of ∼20 cm, corresponding to hanging wall uplift along the radar Line-of-Sight (LOS) direction. The Geodetic Bayesian Inversion (GBIS) of the coseismic deformation indicates that the causative faults of the Hojedk earthquakes were two reverse faults with NW–SE–strikes and SW–dips, with minor dextral slip components. Given the focal mechanism solutions and the epicenter locations of the triple earthquake sequence, we infer that these faults at the southern termination of the Lakar–Kuh Fault represent two segments (with different dip angles) of a previously unrecognized, blind reverse fault (a splay of the Godar Fault at depth). The Hojedk Earthquake and the geometry and kinematics of its causative faults highlight the strong potential of seismic hazard zones along the strike-slip fault systems in the CIM.

Petrography and geochemistry of late Devonian sandstones (Shishtu Formation): Middle East central Iran

The petrography of sandstones integrated with geochemistry is important to infer the provenance, paleoclimate, and tectonic setting. An integrated petrographic and geochemical study of the late Devonian sandstones, Shishtu Formation in central Iran was performed to determine the provenance, tectonic setting, and weathering history. These sandstones are classified into quartz arenite, subarkose, and litharenite types. Sandstones consist of quartz, feldspars, and sedimentary rock fragments, and also provenance shows a recycled orogen and craton interior. Moreover, petrographic data indicate quartz-rich sedimentary (recycled), metamorphic, and plutonic parent rocks. Major and trace elements suggest a quartzose sedimentary provenance in a passive continental margin. As indicated by the chemical index of weathering (CIA), the sandstones underwent a moderate degree of chemical weathering. Diagenetic processes consist of cementation, compaction, and dolomitization. Dolomitization in the carbonate particles of sandstones in the upper part of organic Frasnian-Famennian shale indicates the potential for producing Mg fluid and shows that this unit differs from other shales in these strata.

New data on conodonts and ostracods of the Katkoyeh Formation (Lower-Upper Ordovician) at the Banestan Section of East-Central Iran: biostratigraphical and palaeobiogeographical significance

New data on conodonts and ostracods of the Katkoyeh Formation (Lower-Upper Ordovician) at the Banestan Section of East-Central Iran: biostratigraphical and palaeobiogeographical significance

Development of probabilistic seismic hazard microzonation maps at the surface level for central-east Iran (Kerman region), using a hybrid site condition model

This study presents the spatial distribution of a grid-based probabilistic seismic hazard model at the surface level for the Kerman region in central-east Iran, using a hybrid site condition model. The hazard model has provided the variation of the peak ground acceleration (PGA), and 5% damped spectral accelerations (SA) at the fundamental periods of 0.2 and 1.0 seconds (s) on 0.05° grids. The study has used a seismotectonic dataset including ∼400 linear seismic sources to characterize the seismic source models. In order to capture the uncertainties of the seismic hazard sources, the model used a logic tree approach, including eight ground motion prediction equations (GMPEs), three characteristic source models, two different declustering methods, three choices for earthquake recurrence parameters, and three alternatives for the maximum credible earthquake. Besides, various GMPEs have been evaluated against local datasets. For this, a series of GMPEs developed based on local, regional, and global data have been selected to find their compatibility with the studied area through statistical analyses, so-called likelihood (LH), and log-likelihood (LLH) tests. Generally, the results display that a wide range of seismic hazards can be expected in the region. For instance, the horizontal PGA with a 10% probability of exceedance in 50 years, ranges between ∼(0.1–0.5)g in the north-eastern and south-western parts of the region, respectively. Moreover, the results indicate that the ad-hoc 1.5 factor to scale a 475-year return period (RP) spectrum for making the ground shaking similar to a 2475-year RP not only is unrealistic, but also creates substantially an underestimated ground shaking; thus, it seems too crude for the seismic design purposes. We have also developed some relationships, dependent on site conditions, for describing general relations between the obtained results in the return periods of 475- and 2475-years for PGA, SA (0.2s), and SA (1.0s). The computed hazard spectra have also been compared to the minimum acceptable level of seismic hazard in the region, according to the latest version of the Iranian national seismic hazard map. In addition, in order to make the results more transparent to the scientific and engineering community, the range of uncertainty contributed to the hazard modeling has also been explored in terms of a relative uncertainty metric. In total, the outcome of this study can make transparency into the picture of the seismic hazard level in central-east Iran and shed insight into possible developing plans.

A reappraisal of active faults in central-east Iran (Kerman province)

Fault lineaments are the main input data in earthquake engineering and seismology studies. This study presents a digitally-based active fault map of the Kerman region in central-east Iran which experienced several devastating earthquakes on poorly exposed and/or not identified active faults. Using Landsat 8 data, we have carried out the image-based procedures of fault mapping, which include applying the contrast stretching technique, the principal component analysis, the color composite technique, the spectral rationing, and creating the false-color composite images. Besides, we have cross-checked the resulting map with the geological maps provided by the Geological Survey of Iran to decrease the associated uncertainties. The resulting map includes 123 fault segments, still, a part of which has been expressed in the previously compiled active-fault maps of Iran. Indeed, the new one is mapping the poorly exposed active faults, so-called secondary faults, which are able to produce strong events. These faults are primarily associated with poorly defined areas that accommodate low levels of seismicity; however, sporadic strong events are likely to occur. It has also been investigated that these kinds of faults are seismogenic and are able to produce destructive events. In total, the outcome of this study can also be jointed with seismic studies for investigating parts of the earthquake activity in central-east Iran, in particular for the fault-based approaches in impending earthquake-resistant buildings.

Upper Neoproterozoic garnet-bearing granites in the Zeber-Kuh region from east central Iran micro plate: Implications for the magmatic evolution in the northern margin of Gondwanaland

Upper Neoproterozoic garnet-bearing granites in the Zeber-Kuh region from east central Iran micro plate: Implications for the magmatic evolution in the northern margin of Gondwanaland

Ammonoids from the Carboniferous-Permian boundary of east-central Iran

Ammonoids from the Carboniferous-Permian boundary of east-central Iran

Depositional environment of the Bagh-e-Vang Formation – the only occurrence of upper Lower Permian in Iran

AbstractA transgression of the Tethys Ocean occurred in east central Iran, like in other areas of the Tethys Ocean, around the Yakhtashian/Bolorian (regional chronostratigraphical units corresponding with the Artinskian/Kungurian of the Early Permian) transition. This led to the development of a carbonate platform that is represented in the Shirgesht area on the northern part of the Tabas Block by the Bagh-e-Vang Formation, which constitutes the only known sedimentary unit from the late Early Permian in Iran. Field data and thin-section analysis indicate deposition on a carbonate ramp with barriers separating a lagoonal area with intertidal mud flats from the open-marine environment. The overall transgressive development is indicated by the presence of open-marine sediments on top of the barrier and lagoonal sediments.

New data on the Rectogordius (foraminifera) abundance zone (Latest Carboniferous: Gzhelian) of the Zaladou Formation (east-central Iran, Tabas block, Shishtu section)

The Rectogordius (Foraminifera) abundance zone is described in the east of the Shishtu village in the Ozbak Kuh Mountain. The samples were collected in the Zaladou Formation., which is 60m thick and composed of shales, sandstones, sandy limestones, microconglomerate, bioclastic limestones, coral limestone and fusulinid limestones. The Rectogordius abundance zone was found in sandy bioclastic limestone. It displays two species and three subspecies of this foraminifer, including Rectogordius iranicus, R. iranicus gadukensis, R. minimus and R. minimus shishtuensis n. subsp., R. iranicus ozbakensis n. subsp. The age of this abundance zone is considered to be Gzhelian, due to the distribution of Rectogordius in Central Iran (Ozbak Kuh; Zaladou Formation), central and eastern Alborz (Emarat Fm.), Sanandaj-Sirjan zone (Vazhnan Formation), as well as in the Donets, Arctic Canada, Afghanistan, and the Carnic Alps. The genus Rectogordius is possibly restricted to the northern Paleotethys margin, northern Cimmerian margin, shelf of the Uralian Ocean as far as the northernmost part of North America. Two new subspecies Rectogordius minimus shishtuensis n. subsp. and Rectogordius iranicus ozbakensis n. subsp. are described.

Sedimentary environment and provenance of sandstones from the Qadir member in the Nayband Formation, Tabas block, east-central Iran

Qadir Member of Nayband Formation, located in East of Central Iran, has developed to a great extent. Investigation of the lithofacies and sedimentary environment, resulted in identification of the deltaic and marine deposits. Based on field evidence and facies features, Qadir Member consists of two lithofacies, including carbonate and siliciclastic facies. The siliciclastic facies were identified as having four sandstone facies including Sr, Sh, Sp, St, three fine-grained lithofacies, including FI, Fm, Fl (Sr) / Sr (FI) and one coal facies. Also, regarding the field, laboratory studies, and identification of lithofacies, the coastal plain, deltaic (including deltaic plain, proximal delta front, distal delta front, and prodelta) and open marine environments were identified for Qadir Member which is is under the impact of tidal currents. The chemical weathering index (71%) indicated semi-arid to semi-humid conditions and plotting the geochemical data showed the provenance of re-cycling and active continental margin and because of Chemical Index of Alteration, the weathering rate was found to be rather medium to high. The geochemical diagrams also showed a probable source of the intermediate igneous and sedimentary rocks. The active continental margin conditions for this deposit could suggest the Neotethys subduction under Iran’s plate and volcanic activity at the end of Triassic, which coincided with the early Cimmerian orogeny in Alborz and Central East Iranian Microcontinent.

Estimating the maximum earthquake magnitude in the Iranian Plateau

The Iranian Plateau has been subjected to destructive earthquakes throughout its history. Reliable assessment of the seismic hazard in this earthquake-prone region is therefore essential. Our study focuses on estimating the maximum earthquake magnitude as one of the main parameters of seismic hazard analysis. We implemented two quantitative approaches, namely, probabilistic and deterministic. The probabilistic method allows combining the historical (i.e. incomplete) and the instrumental parts of a catalogue with different levels of completeness and considers the uncertainties in earthquake magnitude determination. In this study, we used a unified, declustered, and complete catalogue of earthquakes in Iran, covering the period from the fourth century BC to 2019. We calculated the maximum possible magnitudes for hundreds of grid points by using the seismicity data in a 200-km radial region around each grid point. The maximum possible earthquake was observed to vary between 6.0 and 8.2, and the highest values were found in the Alborz-Azarbayejan seismotectonic province, Kopeh-Dagh, central east Iran, Makran, and the southeast Zagros. The lowest mmax values were found in the Persian Gulf, Arabian Platform, Esfahan-Sirjan region, and the Dasht-e-Kavir Desert in central Iran. As a second part to this study, we calculated the maximum credible earthquakes for 1103 identified major faults by using five empirical magnitude-scaling relationships. Our results were consistent with both the observed earthquakes and the seismic potential of the various seismogenic zones of Iran. The study results can be used in future seismic hazard analyses and have fundamental implications for mitigating seismic risk in Iran.

The Upper Jurassic Garedu Red Bed Formation of the northern Tabas Block: elucidating Late Cimmerian tectonics in east-Central Iran

The Garedu Red Bed Formation (GRBF) of the northern Tabas Block (Central-East Iranian Microcontinent, CEIM) is a lithologically variable, up to 500-m-thick, predominantly continental unit. It rests gradually or unconformably on marine limestones of the Esfandiar Subgroup (Callovian–Oxfordian) and is assigned to the Kimmeridgian–Tithonian. In the lower part, it consists of pebble- to boulder-sized conglomerates/breccias composed of limestone clasts intercalated with calcareous sandstones, litho-/bioclastic rudstones and lacustrine carbonates. Up-section, sharp-based pebbly sandstones and red silt-/fine-grained sandstones of braided river origin predominate. Palaeocurrent data suggest a principal sediment transport from west to east and a lateral interfingering of the GRBF with marine greenish marls of the Korond Formation at the eastern margin of the Tabas Block. Westwards, the GRBF grades into the playa deposits of the Magu Gypsum Formation. Red colours and common calcretes suggest arid to semi-arid climatic conditions. The onset of Garedu Red Bed deposition indicates a major geodynamic change with the onset of compressive tectonics of the Late Cimmerian Tectonic Event (LCTE), being strongest at the eastern margin of the northern Tabas Block. When traced southwards, the same tectonic event is expressed by extension, indicating a shift in tectonic style along the boundary fault between the Tabas and Lut blocks. The complex Upper Jurassic facies distribution as well as the spatio-temporal changes in tectonic regime along the block-bounding faults are explained by the onset of counterclockwise vertical-axis rotation of the CEIM in the Kimmeridgian. The block boundaries accommodated the rotation by right-lateral strike slip, transpressional in today’s northern and transtensional in today’s southern segments of the block-bounding faults. Rotation occurred within bracketing transcurrent faults and continued into the Early Cretaceous, finally resulting in the opening of narrow oceanic basins encircling the CEIM. Palaeogeographically, the GRBF is part of a suite of red bed formations not only present on the CEIM, but also along the Sanandaj-Sirjan Zone (NW Iran), in northeastern Iran and beyond, indicating inter-regional tectonic instability, uplift and erosion under (semi-)arid climatic conditions across the Jurassic–Cretaceous boundary. Thus, even if our geodynamic model successfully explains Late Jurassic tectonic rotations, fault motions and facies distribution for the CEIM, the basic cause of the LCTE still remains enigmatic.

Silurian (Aeronian) rhynchonelliform brachiopods of Shabdjereh, south-west Central Iran and their significance for early spiriferide evolution

The Silurian (Aeronian) post-extinction recovery brachiopod fauna of Iran and Afghanistan is characterized by a proliferation of the Stegocornu Brachiopod Association, which includes prominent endemic rhynchonellide and spiriferide components. A local variety of that association, recently recovered from the Shabdjereh Formation of Kerman Province, East-Central Iran, contains eight brachiopod species, including the rhynchonellide Kermanirhyncha granulata gen. et sp. nov., and the spiriferides Levanispirifer alatus gen. et sp. nov. and Mictospirifer obtusus sp. nov. A new phylogenetic analysis of the earliest Late Ordovician to Aeronian spiriferides, within the general context of the Ordovician radiation of rhynchonelliform brachiopods with calcified brachial supports, reveals the following two major centres of biodiversification and dispersal: (1) the Laurentian palaeocontinent, which is the likely place of origin and initial diversification of the atrypide suborders Lissatrypidina and Anazygidina; and (2) the assemblage of Kazakh island arcs and microplates (known also as Kazakh Archipelago), which was the centre of origin and initial dispersal of the atrypid suborder Atrypidina and the order Spiriferida. South China represents a major refuge, where spiriferides survived the terminal Ordovician extinction and from where they dispersed towards adjacent parts of Gondwana including the Iranian terranes. The latter areas were an important secondary centre of spiriferide biodiversification during the Aeronian Age. http://zoobank.org/urn:lsid:zoobank.org.pub:B8726A08-7D90-4AAF-8ECF-B81E78119712

A summary of the Jurassic System in North and East-Central Iran

The rocks of the Jurassic System in North and Central Iran are represented by very thick sedimentary successions reflecting the deposition during two tectono-stratigraphic megacycles, bounded by three important unconformities. The older (Early to early Middle Jurassic) cycle starts, after the Late Triassic closure of the Palaeotethys and the collision of the Iran Plate with the southern margin of Eurasia (Turan Plate), with an abrupt uplift of the Cimmerian Mountains around the Triassic–Jurassic boundary (Main-Cimmerian Event) and is terminated by the Mid-Cimmerian Tectonic Event in the mid-Bajocian. The predominantly siliciclastic sediments of this tectono-stratigraphic cycle are accommodated in the Ab-e-Haji Subgroup of the (upper) Shemshak Group. The Ab-e-Haji Subgroup consists of thick and widespread, partly coal-bearing siliciclastic strata and also records some important marine ingressions, especially in the Toarcian and Aalenian. The younger tectono-stratigraphic cycle starts with an extensive marine transgression in the Late Bajocian and ends around the Jurassic-Cretaceous boundary with the Late Cimmerian Tectonic Event. In the aftermath of the Mid-Cimmerian Tectonic Event, the Iran Plate was dissected into several structural units, the geological histories of which differed and so did their facies patterns. Thus, in North Iran two main sedimentary areas developed, namely the Alborz and Koppeh Dagh basins, which show moderate diffe-rences in lithology and thicknesses. However, the differentiation is much more pronounced on the Central-East Iranian Microcontinent, which comprises three N–S-oriented and independent structural units, i.e., from east to west the Lut, Tabas and Yazd blocks. During the Jurassic Period, the sea mostly covered the Tabas and Lut blocks, whereas the Yazd Block remained largely emergent. The lithologically diverse and numerous formations of the area are combined in the Magu and Bidou groups. Early to Early Middle Jurassic ammonite fau-nas of North and Central Iran are palaeobiogeographically closely related to Northwest European (Subboreal) ammonite faunas, allowing a similar biozonation. Concurrent with the Late Bajocian transgression, there is an abrupt change in faunal composition and the Middle and Late Jurassic ammonite faunas of North and Central Iran are much more similar to those of epicontinental seas bordering the nort-hern margin of the western Tethys and occupy an intermediate position between the Mediterranean and the Submediterranean Province. The results of the studies on ammonoid palaeobiogeography are in line with Early Jurassic palaeogeographic reconstructions that place the Iran Plate at fairly high palaeo-latitudes of about 45°N, followed by a rapid southward shift throughout the Middle and Late Jurassic to a position of about 30°N.

Biostratigraphy, taxonomy and paleobiogeography of the upper Cisuralian (upper Yakhtashian–Bolorian) foraminifers from east-central Iran, with clarification of the taxonomy of the fusulinid generaCuniculinellaandCuniculinapre-occupied

AbstractDetailed studies of upper Cisuralian (i.e., upper lower Permian) fusulinids make it possible to decipher the paleobiogeographic relations of central Iran, as part of the Cimmerian terranes, with other Paleotethyan regions. Two sections, Bagh-e Vang and Shesh Angosht, located in east-central Iran, are revised. Four local fusulinid biozones are distinguished: upper YakhtashianPamirina darvasicaandSakmarellaspp. Zone, lower BolorianMisellina(Brevaxina)dyrhenfurthiZone, mid-BolorianCuniculinellaZone, and upper BolorianMisellina(Misellina) cf.M. (M.)termieriZone (probably equivalent to the traditionalMisellina(Brevaxina)parvicostataZone). Taxonomically, the main results are as follows: (1) a clarification is provided of the fusulinid genus or subgenus “Cuniculina,” the name of which is pre-occupied, and its synonymy withCuniculinella; and (2) a lectotype is designated forDarvasites(Alpites)sinensis(Chen, 1934). The mid-BolorianCuniculinellaZone is recognized for the first time in Iran. Among the Bolorian fusulinids,Cuniculinellais reported in SE Pamir, Karakoram, central Afghanistan, SW Japan, central Japan, and California, confirming the faunal affinity of the study area in east-central Iran with both Paleotethyan and Panthalassan bioprovinces. Such a distribution is considered to have resulted from combined effects of global warming during the upper Cisuralian, warm oceanic currents along the Paleotethys Ocean, and the northward drift of the Iran block toward lower paleolatitudes.

Short-term seismicity patterns along the most active faults in Iran

In this study, six seismically active fault systems located in different tectonic regimes have been surveyed. The data were from three Persian seismotectonic provinces (Alborz-Azarbaijan, Zagros and East-Central Iran) with different seismic properties, covering a time span of 8 years. The earthquake (Eq.) data have been recorded by the seismological network of the Institute of Geophysics of the University of Tehran, Iran (IGUT), the International Institute of Earthquake Engineering and Seismology of Iran (IIEES), and also include the early large instrumental earthquakes in the Engdahl catalog. During this period, few months of seismic quiescence occurred on the entire length of both Dasht-e Bayaz (DB) and Abiz faults, while most of the moderate and large earthquakes occurred after few months of lack of seismicity on the Main Recent fault, DB, Golbaf and Kazeroun faults. Moreover, single and triple migration patterns of seismicity were regularly seen along Golbaf fault and North Tabriz fault (NTF), respectively. Some large earthquakes (the 2011, MN 5.2 Eq. of Golbaf F. and the 2008, MN 5.2 Eq. of NTF) occurred at the end of these seismicity migration patterns. Along NTF, a diffuse seismicity with no specific seismic pattern has been distinguished. In all the case studies and during the investigated time period the entire lengths of the fault systems were not active at the same time. Finally, there is not a clear relationship between the duration of the seismic gaps and the magnitude of large earthquakes with different co-seismic rupture lengths in depth.

Time-dependent probabilistic seismic hazard assessment in Kerman and adjacent areas in the west of Lut block, Central-East Iran

This study is the first attempt to apply fault-based and time-dependent seismicity models cooperatively for probabilistic seismic hazard assessment (PSHA) of the Kerman and adjacent areas (54–59° E, 28.5–34° N). For this study, almost all available literature and databases have been investigated to compile reliable information reported as instrumental, historical, and paleoseismological events, together with the geometry and kinematics information for active faults. This information systematically is integrated and contributed to PSHA. Conditional probabilities of occurrence for earthquakes greater than the maximum earthquake from which its standard deviation is deducted (M > Mmax − σMmax) are computed based on a Brownian passage time (BPT) model. The spatial distribution of the time-dependent peak ground acceleration (PGA) has been calculated, and spectral accelerations have been computed for three selected cities (Kerman, Rafsanjan, Ravar), with 10% probability of exceedance in 50 years. The time-dependent PSHA map for PGA shows variations from − 21 along the Gowk fault to + 32% near the Sabzevaran fault segments in comparison with the corresponding time-independent PGAs. The difference between the time-dependent and time-independent PGAs at most parts of the study area is negligible, especially at sites farther away from the faults, where the differences vary from − 7 to + 7%. Moreover, the difference between the time-dependent and time-independent spectral accelerations for Ravar and Rafsanjan cities is insignificant. However, this difference at periods of 0.1–0.3 s is significant in Kerman city. The results of this study provide a stimulus for considering time-dependency assumption and fault-based approach in future earthquake-resistant constructions required in Kerman and adjacent areas.