Kachchh Mainland Research Articles

Holocene surface-rupturing paleo-earthquakes along the Kachchh Mainland Fault: shaping the seismic landscape of Kachchh, Western India

This study explores the seismotectonics of Kachchh in western India, a region with a low-to-moderate strain rate and a history of significant earthquakes, notably the 1819, Mw 7.8 Allah Bund, and the 2001, Mw 7.6 Bhuj. Despite its substantial seismic risk, comprehensive studies on Kachchh’s seismogenic sources are scarce. This is attributed to the concealed nature of active structures, hindering definitive age constraints in paleoseismological research. Our research comprises a detailed paleoseismic analysis of the north-verging, reverse Jhura Fault underlying the Jhura anticline, a segment of the Kachchh Mainland Fault. This fault segment shows evidence of surface-rupturing earthquakes in the area south of the Great Rann of Kachchh. The investigation reveals three paleoseismic events: Event I before 9.72 ka B.P., Event II between 8.63–8.20 ka B.P., and Event III between 6.20–6.09 ka B.P. The elapsed time since the last event on this fault is > 8000 years, suggesting that the area is exposed to a significant earthquake hazard. This highlights the need for more precise characterization of individual seismogenic sources for future earthquake preparedness.

Structural analysis and neotectonic evidences of the dip-slip transverse fault system in the central Mainland Kachchh region, Western India

The spatio-temporal changes in the fluvial system and landform of the central Kachchh Mainland region are caused by distinctive ongoing tectonic deformations. The present study aims to decipher ongoing tectonic processes resulting modification of landscape in the Central Mainland Kachchh region during the Late Quaternary period. The region marks the presence of several neotectonic features along the faults indicating rejuvenation of the landform due to tectonic activity. The paleostress analysis of the faults indicates normal faulting due to WNW-ESE, E-W to WSW-ENE directed radial to pure extension. The OSL dates from the strath terrace section confirm accommodation of Quaternary sediments from ∼42ka till ∼32ka. The presence of abandoned channels and obstructed tributary channels across the fault plane deciphers reactivation of extensional fault planes at ∼42ka, constituting accommodation space for sedimentation on the downthrown block forming several sag-fill deposits. The sedimentation ceased after ∼32ka due to regional Kachchh Mainland Uplift (KMU) upliftment triggering vertical incision of channels forming several strath and fluvial terraces. The paleostress analysis and dynamic modification of landform depict reactivation of the hinge faults on the structural Mesozoic bend of the basement high known as the ‘Median High’.

Deep Seismic Reflection Imaging of Mesozoic Kachchh Rift, NW India: Implications for Evolution

AbstractDeep crustal seismic reflection profiling is carried out for first time across various tectonic domains of seismically active Mesozoic Kachchh rift basin, formed during the breakup of Gondwanaland. The seismic data, processed using the common reflection surface stack approach, provided maiden images of the shallow and deep sub‐surface structures in the region. These images reveal a 15 km thick subhorizontal lower crustal reflection fabric and crustal‐scale domal‐type structure extending from the surface to the Moho. We interpret the earlier structure represent magmatic underplating and the latter as the Kachchh Mainland uplift. We find large variations in the thickness of sediments from 150 m to 6.5 km and crustal thickness from 45 to 35 km from north to south, with a Moho up warp of 4 km beneath the Kachchh Mainland fault. The Kachchh rift basin exhibits an unusually thick crust of 45 km, contrary to many rift basins. We interpret the syn‐rifting and the Reunion mantle plume activity, manifested as Deccan volcanics, are responsible for magmatic underplating and crustal thickening. Uplift in the region is multi‐genetic in origin. Present study illuminated new faults and nature of various other faults. Moderate to large earthquakes in the region are attributed to the regional and local stresses resulting from the plate boundary and heterogeneous crustal structure. Based on the mafic lower crust and distribution of aftershocks through the entire crust, we interpret the lower crust is brittle, contrary to most models of continental rheology.

Bed parallel slip and paleostress analysis of the Kodki fault zone, Kachchh, Western India

The Kodki fault zone comprises a unique fault system along the Median High (MH) zone in the Kachchh Mainland Uplift (KMU) region of the Kachchh Rift Basin (KRB). The structural and paleostress investigation of the Kodki fault zone shows a typical style of bed-parallel slip (BPS) due to repeated reactivation of the normal faults. The fault growth is accompanied by the reactivation of one or both of the fault segments followed by offset due to BSP. In sections where both fault planes reactivate, and propagate past one other forms a bulk between coinciding fault segments that display typical characterization of relay zones. These structures in the Kodki fault section differ from the conventional relay zone in the strata. The thickness of BPS surfaces along the strata equals the fault's throw at the time of the BPS event. Geometrical restoration of the Mesozoic cross-sections exposed across the selected fault displays repeated BPS forming a complex intersecting structure along the Kodki fault zone. Further, the paleostress analysis determines E-W to WNW-ESE maximum extensional stress inhibits recurrences from the reactivation of faults with the MH zone.

Investigation of hydrological characteristics of the Kachchh Mainland Fault (KMF) Zone, Gujarat, Western India using time domain electromagnetic study

Investigation of hydrological characteristics of the Kachchh Mainland Fault (KMF) Zone, Gujarat, Western India using time domain electromagnetic study

Volcanic craters and cones in central Kachchh mainland, western India: Potential analogue for the Martian studies?

Volcanic craters and cones in central Kachchh mainland, western India: Potential analogue for the Martian studies?

The sensitivity of the intraplate Kachchh Rift Basin, NW India to the direction of incoming seismic waves of teleseismic earthquakes

SUMMARY The dynamic stresses generated during the passage of surface waves perturb most major plate boundaries and active volcanic/geothermal regions. The present investigation aims to understand and find evidence for dynamic triggering in the intraplate Kachchh Rift Basin, northwestern India. We analysed the local earthquake catalogues and waveforms of 36 teleseismic earthquakes with Mw ≥ 7.5, which occurred between 2007 and 2017 and generated peak dynamic stresses of at least 1 kPa. The study manually examines the waveforms 24 hr before and after the teleseismic P wave and detects missing earthquakes by applying the matched filter technique. Notably, the analysis reveals that 6 out of 36 earthquakes (17 per cent of the analysed earthquakes) are responsible for triggering non-volcanic tremors or microearthquakes during the passage of surface waves and later. Although the triggering potential in the region seems insensitive to the amplitude of dynamic stresses imparted by the teleseismic surface waves, the direction of the incoming waves appears critical. The surface waves of events whose backazimuths are parallel to the strike of the active faults are capable of triggering. The triggered earthquakes lie along the Kachchh Mainland Fault, North Wagad Fault and South Wagad Fault, in the vicinity of the epicentre of the 2001 January 26, Mw 7.7 Bhuj earthquake. The largest triggered event of magnitude 3.2 occurred ∼7 hr after the 2009 October 7, Mw 7.7 Vanuatu event.

Lower crustal intraplate seismicity in Kachchh region (Gujarat, India) triggered by crustal magmatic infusion: Evidence from shear wave velocity contrast across the Moho

The genesis of intraplate seismicity remains a topic of debate among seismologists. Here, we address this issue by investigating shear wave velocity contrast across the Moho (δβM) in the Deccan volcanic-covered Kachchh seismogenic region, located in the Gujarat state of western India. This region, having complex geology, has witnessed several large damaging intraplate earthquakes since historical times. Most of the shallow focused earthquakes clustered in the eastern part of Kachchh often occurred due to the fluid pressure in the fractured rock matrix at the intersection of a fault network consisting of mainly three prominent faults, viz. Gedi, Kachchh Mainland, and North Wagad. However, the causes of lower crustal earthquakes are not well understood – whether it is due to the reactivation of faults or processes related to the fluid-filled fracked rock matrix of mafic/ultramafic material or magmatic infusion from the underlying mantle. Our results show that the δβM in the study area varies widely from ∼0.15 to 0.86 km/s. The lowest value of δβM (∼0.15 km/s) coincide with lower crustal seismicity. Further, the scaling relation between δβM and crustal thickness is negative, i.e., the thick crust has a low δβM, implying that the magmatic material has enveloped the lower crust, which ascended through the deep rifts during Deccan volcanism at ∼66 Ma. Higher values of δβM below a few stations have been ascribed to the pockets of trapped magmatic material or fluid below the lower crust. We suggest that the presence of mafic/ultramafic material in the crust-mantle transition zone, together with the fluid-filled fractured rock matrix in the intersecting fault geometry might accumulate enough strain to generate seismic activity in the lower crust. The presence of volatile influx or fluid pressure facilitates the triggering of deep-seated faults, and CO2-rich carbonatite-type magma percolated from the shallow asthenosphere.

Mapping the near‐surface trace of the seismically active Kachchh Mainland Fault and its lateral extension in the blind zone, Western India

ABSTRACTThe W–WNW‐striking Kachchh Mainland Fault (KMF) is the largest intra‐basinal fault in the Kachchh Rift Basin (KRB) located at the western continental margin of the Indian plate, and is responsible for several historic earthquakes, including the 2001 Bhuj earthquake and the 1956 Anjar earthquake. The objective of the study is to constrain the precise location and near‐surface characteristics of the KMF using field and ground penetrating radar (GPR) studies. Efforts were also made to ascertain and map the eastward continuity of the KMF. The fault has a prominent geomorphic expression up to the east of Devisar, where the KMF scarp finally dies out. The KMF marks the lithotectonic contact between Mesozoic rocks in the south and Tertiary rocks in the north. The segmented nature of the KMF has been previously attributed to transverse faults, complex deformation zones and heterogeneous assemblages of unconformable Quaternary deposits. Eight survey sites between Nirona and Sikra were chosen for near‐surface investigation of KMF using GPR. Comparatively, high‐amplitude radar reflections were received from well‐compacted sand‐ and shale‐rich Mesozoic rocks, whereas low‐amplitude weak reflections were observed from softer and clay‐rich Tertiary rocks. In the upper section of the GPR profiles, Quaternary deposits display low‐ to moderate‐amplitude semi‐continuous to wavy reflections. The traceable length of the KMF has been extended eastward by ∼20 km through the current study, which is considered a blind zone as feeble surficial evidence is present, but the fault trace is confirmed near the surface using GPR. The eastern part of the KMF is inferred to be a near‐vertical north‐dipping normal fault based on GPR data analysis. The tendency of the KMF to transform into a reverse fault in the vicinity of the intersection with transverse faults implies zones of relatively higher stress accumulation that might activate and trigger devastating earthquakes in the future.

Occurrence of small to moderate magnitude earthquakes in Kachchh intraplate zone: A special emphasis to the 2020 Bhachau earthquake

Since the 2001 Mw 7.7 Bhuj earthquake in Gujarat, western India, a number of small-to-moderate earthquakes have occurred to the east of the Bhuj rupture, near the town of Bhachau. In this paper, we present an overview of seismic monitoring in the region, and analysis of a Mw 5.3 earthquake that occurred near Bhachau on 14 June 2020. Moment tensor analysis of regional broadband data reveals a reverse mechanism with a small strike-slip component, generally similar to that of the 2001 Bhuj earthquake. A total of 20 aftershocks with magnitudes ranging from 2.0 to 4.6 were recorded within the first 10 days of the sequence. After that, this region recorded 129 tremors of magnitude 2.0–4.2 until June 2021. We conclude that this sequence occurred on the South Wagad fault (SWF)-Kachchh Mainland fault (KMF) system, a complex zone comprising many separate mapped faults. A recent analysis of Global Positioning System (GPS) data reveals that the area is under broad compressive stress, with a maximum strain of 5 nano-strain/year. The occurrence of the 2020 Bhachau earthquake underscores concerns for continuing seismic hazard in the region.

First population-level study of the ammonite genus Hildoglochiceras Spath, and the Lower Tithonian record of the Hildoglochiceras Horizon in the Kachchh Basin, India

A Hildoglochiceras-rich horizon is reported from a thin carbonate intercalation within the siliciclastic Upper Jurassic Jhuran Formation of the Jara Dome, western Kachchh Mainland. The Hildoglochiceras specimens have been used for the first population-level study of the genus based on a multivariate analysis. High phenotype instability in the large sample confirms the occurrence of transient forms between morphospecies. Key morphological traits for interpreting Hildoglochiceras are stated, and the morphospecies Hildoglochiceras kobelli (Oppel) and H. kobelliforme (Bonarelli) are interpreted as a dimorphic pair. The ammonite-rich level is interpreted as a Hildoglochiceras Horizon, which is related to a transgressive pulse and maximum flooding zone interrupting largely restrictive conditions for ammonites. The endemic character of Hildoglochiceras is confirmed and related to its environmental restriction to shelf areas on the palaeomargins of the Trans-Erythraean Trough. A comprehensive review of biostratigraphic interpretations of Hildoglochiceras shows the influence of natural and experimental forcing factors. The uppermost Kimmeridgian to lowermost Upper Tithonian interval is the widest biostratigraphic range assumable for Hildoglochiceras based on existing reports, but most probably it was restricted to, or at least better represented in, Lower Tithonian horizons. The Hildoglochiceras Horizon described here is correlated with a lower part of the Albertinum/Darwini Zone in the Secondary Standard Scale for ammonite-based bio-chronostratigraphy in European and West-Tethyan areas. According to the current state of knowledge, a local rather than wide regional significance is favoured for Hildoglochiceras records before its significance for precise correlation across the Trans-Erythraean Trough.

Building tectonic framework of a blind active fault zone using field and ground-penetrating radar data

Blind active faults may lead to earthquake, therefore their identification and characterization constitute an important structural exercise. Such faults can be mapped by high-resolution shallow subsurface geophysical techniques, which offer meter-scale sub-seismic images. The Kachchh Rift Basin (KRB), situated on the western continental edge of the Indian plate, is tectonically active. The KRB is affected by the reactivation of ∼W-striking dip-slip/strike-slip faults. The Kachchh Mainland Fault (KMF) is the largest intra-basinal fault in KRB. The long-term terrain rejuvenation presumably masks the surface expression of the KMF. Shallow subsurface geophysical investigations, assisted by mesoscale structural observations were performed along the western part of the KMF.A ground-penetrating radar (GPR) was used to decipher the sub-seismic position and geometry of KMF. The KMF is inferred to be a near-vertical north-dipping normal fault. GPR data reveal potential colluvial wedges, faulted alluvial and colluvial Quaternary deposits, small-scale horst-graben and off-fault folding, which are not at all apparent in surficial observations and satellite imageries. A sequential evolution of colluvial wedges is explained attributed to KMF reactivation during Cenozoic. The results suggest that the western part of the KMF is tectonically active, and it should not be overlooked despite low seismicity.

Distribution of neotectonic variability between the Kachchh Mainland Fault and Vigodi Fault, Northwestern Mainland Kachchh, Western India

As per the Bureau of Indian Standards (BIS), the Kachchh region of the western peninsular India falls under seismically active region, where the faults experienced existence of several moderate to high magnitude earthquakes in the historic past. The present-day seismicity is mainly concentrated toward the eastern part of Kachchh Mainland Fault (KMF). Even though, the western segment of the KMF does not exhibit seismicity at present, but the tectono-geomorphology of this segment reveals various active geomorphic features which indicates its active nature. In this study, we are focusing on the distribution of neotectonic variability between the western segment of the KMF and the Vigodi Fault (VF), as the detailed geomorphometric studies is lacking in this region, believing that the area is not promising for such studies because the lack of seismicity. Therefore, we applied the conventional morphometric parameters to assess the neotectonic behaviour of the study area. The computed morphometric parameters had been grouped and mixed to create the Relative Index of Active Tectonics (RIAT), Furthermore, we used DInSAR results to estimate the active vertical displacement in between the fault zones which ranges from 0.15 to 0.28 cm. The results of each geomorphic indices indicates active deformation within the central portion of the western KMF and VF zone. This study would be certainly beneficial for seismic hazard assessment and future infrastructure planning of the region.

Geodetic characterization of active Katrol Hill Fault (KHF) of Central Mainland Kachchh, western India

After the M7.7 earthquake in 2001, the Kachchh rift basin became the focus of various geological and geophysical researches on the western Indian plate. As an essential technology, the Global Navigation Satellite System (GNSS) has been utilized to study the deformation pattern in the central mainland Kachchh. We select the east-west striking Katrol Hill Fault (KHF) as the study area and analyze the crustal deformation pattern using the datasets from 2014 to 2019. The geodetic results along the KHF reveal a mean deformation of about 2.1 mm per year, which is higher in the eastern part and lower in the central and western parts. The investigation of deformation and derived strain reveals the segmented behavior of KHF, while the dominance of compressive strain (maximum 22 nanostrain/yr) in the eastern segment makes it the most active segment of the KHF. A higher deformation rate along the eastern KHF can be considered significant in terms of seismic hazard for this part of the Indian plate.

Climatic history from early Weichselian (MIS 5D-C) valley-fill deposits and associated factors for basin sedimentation, mainland Kachchh, western India

Ephemeral fluvial systems in the dryland region of Kachchh are susceptible to climatic fluctuations. An increase in Indian Summer Monsoon Intensity (ISM) is responsible for the aggradation of sediments as valley-fill deposits in the river basins. In the present study sedimentological, chronometric, and geochemical analysis on the fluvial terrace sequences of Nirona and Bhukhi river basins are being used to interpret southwest summer monsoon variability from MIS 5D-5C along with the fluvial response to local tectonics. The sediment record indicates increased ISM precipitation from ∼110ka to ∼90ka, which corresponds to the MIS 5D to MIS 5C (Interstadial stage). The ISM became progressively weaker during the MIS-5B (stadial stage), leading to present-day arid conditions. The climatic factors weakened along with an interplay of local tectonics, leading to present-day conditions of bedrock incision.

Magnetotelluric evidence for trapped fluids beneath the seismogenic zone of the Mw6.0 Anjar earthquake, Kachchh intraplate region, Northwest India

Lithospheric rheological heterogeneities across a rift play a significant role in intraplate deformation and seismic activity. The Kachchh rift in the northwestern part of the India has not only experienced lithospheric stretching but also witnessed large magnitude devastating earthquakes. Here, we present the results of a magnetotelluric (MT) investigation carried out in the southeastern part of the Kachchh intraplate region illuminating the seismogenic zone of the 1956 Anjar earthquake (Mw 6.0). The two-dimensional geoelectrical model derived from the MT data acquired at 21 sites along a NE-SW profile reveals assemblage of conductive and resistive zones in the upper and the mid crustal depths in the close vicinity of the major fault zones and the hypocentral depths. The results reveal a very high conductive zone near the Moho, affirming the presence of an upper mantle fluidized zone. Unlike the South Wagad Fault, the Kachchh Mainland Fault and the Katrol Hill Fault do not have a downward lower crustal extension, and terminate at the mid crustal depths. We suggest that the presence of trapped fluids in the brittle-ductile transition zone (12–15 km) and their seepage to the resistive plutons might be a possible mechanism for triggering the 1956 event as well as the current seismic activity in the region.

Evidence for reactivation of new faults and seismicity migration away from the causative fault of the 2001 MW 7.7 Bhuj earthquake, western India

SUMMARY The Kachchh Rift Basin of western India that hosted the devastating 2001 MW 7.7 Bhuj earthquake has been witnessing minor to moderate seismicity since then. The genesis of these intraplate earthquakes and geometry of the causative faults is still elusive. In this study, we relocated all the earthquakes recorded between 2006 and 2018 and utilized a set of 4285 best located earthquakes to provide rare insights into the orientation and depth distribution of the currently active faults. We also analysed previously computed source mechanisms, in perspective of our location results. It is revealed that the present seismic activity is primarily aligned along two planes—one steeply dipping (∼60°) to the northeast with a NW–SE strike and the other gently (∼34°) dipping to the SSW, striking WNW–ESE. The traces of these fault surfaces coincide with the Kachchh Mainland fault (KMF) and the North Wagad Fault (NWF) when extrapolated to the surface, respectively. Activity along the NWF has been shown in earlier studies, however, clear evidence of activity along the steep north-dipping KMF is presented for the very first time. Thrust earthquakes dominate the NWF while strike-slip earthquakes are seen across the KMF. Our results show that the two fault surfaces converge between 70.30°E and 70.43°E longitudes in the depth range 22–32 km, however, there is large E–W offset between the northern and southern extremities of the fault-system. This convergence zone hosted the largest earthquakes (ML 4.7–5.1) between 2006 and 2018 and the hypocentre of 2001 main shock also coincide with it. The earthquakes occurring in the interfault region show major strike-slip motion and are probably influenced by the relative motion between the NWF and KMF. Consistent seismicity, assisted probably by high conducting material, is seen across the NWF while intermittent seismicity is revealed along the KMF. Scrutiny of earlier studies revealed that the 2001 main shock and first few weeks of aftershocks were hosted on another south-dipping fault, the South Wagad Fault (SWF), however, activity along the SWF is found to be meagre during 2006–2018. Instead, seismicity has currently migrated to faults north and south of the SWF. These currently active faults most likely were reactivated during/after the 2001 main shock.

Estimation of regional surface deformation post the 2001 Bhuj earthquake in the Kachchh region, Western India using RADAR interferometry

The key objective of the present study is to estimate the surface displacement and to understand/monitor the active deformation pattern in the Kachchh region post the 2001 Bhuj Earthquake by implementing the Persistent Scatterer Interferometric Synthetic Aperture Radar (PSI) and Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques. We employed the ENVISAT ASAR (15 images), ALOS PALSAR (6 pairs) and SENTINEL-1A (117 images) data sets acquired during the periods 2003–2005, 2007–2009, and 2016–2020 respectively. The PSI results of the Envisat dataset reveals that the Kachchh mainland region has undergone an average surface deformation of ± 22 mm/yr during 2003–2005. The maximum displacement observed from the ALOS PALSAR data sets (Window-1 to 6) during the period 2007–2009 is ∼ ± 1.2 cm. Further, the ground displacement observed from the Sentinel-1A dataset during the period 2016–2020 is ±16 mm/yr for the west-central region and 6 mm/yr uplift and 8 mm/yr subsidence in the eastern Kachchh mainland region. Surprisingly, high rate of deformation is detected towards the Pachham Island, Banni, Rann and the eastern region of the Kachchh after the 2001 Bhuj event. Correlating the results of different data sets, it is concluded that the deformation is high near the vicinity of the fault zones indicating the tectonically active nature of the faults. From the obtained results, we infer that, post the 2001 Bhuj earthquake, the surface displacement in the Kachchh mainland region is escalated till 2009 which is due to continuous aftershock activity and then started declining because of the ongoing seismic settlement. The acquired deformation rates are correlating well with the GPS derived displacement rates. Further, our results will assist in accurately demarcating the extent of the fault zones and also helps in precisely marking the areas undergoing active deformation, which will aid in micro zonation studies, mitigation planning and also for the preparation of an active tectonic map for the region.

Quaternary Landform Development in the Central segment of tectonically active Kachchh Mainland Fault zone, Western India

The landform aggradation in an arid climatic region is often regulated by external forces, that provide signatures of climate and tectonic perturbations. The landforms in the central segment of Northern Hill Range (NHR), which marks the surface expression of Kachchh Mainland Fault (KMF), are investigated in this study to understand the role of climatic changes and tectonic activity during the time of aggradation and incision. Geomorphologically, the KMF is expressed by the presence of ∼80–150 m high E-W trending escarpment. The central segment of KMF preserves the alluvial fan surfaces which have been truncated at several places with anomalous incision. Conventional morphometric analyses indicate that the KMF is affected by tectonic activity in recent times. The optical chronology of oldest alluvial fan dated from back limb and forelimb of an anticline was around 28 ka (with gradual onset of aridity) and 25 ka (with peak aridity). This arid phase is correlated with enhanced tectonic uplift along the KMF, which is manifested in the form of strath terraces and incision of river valleys. The oldest activity pre-dated to 25 ka and continued till 14 ka and there was a tectonic stability between 14 and 8 ka. The younger activity began soon after 8 ka and continuous till today, which is most likely caused by the manifestation of the Early Holocene climatic optima that lead to severe erosional processes. The younger Middle Holocene (4.3 ka) event is correlated with enhanced uplift and was accountable for the down cutting of the fill sediments and the Mesozoic bedrock. The study suggests that the deformation pattern close to KMF is the result of localized compressive stress generated between two fault segments.

Lithofacies Study of the Mesozoic Rocks of Wandhaya Area, Southwest of Bhuj, Kachchh Mainland, Gujarat

Abstract The stratigraphic sequence exposed in Wandhaya area comprises of marine clastic sediments of Mesozoic, which includes M-III and M-IV of Jumara Formation, Lower Member of Jhuran Formation and Upper Member of Bhuj Formation. Lithofacies erected from the study area are Shale Facies (SF), Oolitic Limestone Facies (OLF), Intercalated Shale Siltstone Facies (ISSF) and Massive Sandstone Facies (MSF). SF is developed in M-III and M-IV of Jumara Formation suggesting its deposition in transition zone. Oolitic Limestone Facies (OLF) occurs only in M-IV of Jumara Formation indicates its depositional environment as offshore region. Intercalated Shale Siltstone Facies (ISSF) is deposited in lower shoreface to transitional and Massive Sandstone Facies (MSF) in foreshore environment, are exposed in Lower Member of Jhuran Formation and also in Upper Member of Bhuj Formation. The sediment characteristics and association of trace fossils in the rocks indicate distinction in sedimentation from foreshore to offshore environments.