The offshore Bengal Basin experienced sedimentation due to the interaction between the Indo-Asian collision and the amalgamation of Indo-Burma. To infer the provenance, paleoweathering and tectonic evolution of the Neogene sedimentary rocks from the Sangu Gas Field in the Bay of Bengal, Bangladesh, this study presents a new set of whole-rock geochemical and detrital zircon U-Pb data. Major and trace element geochemistry indicates that these Neogene sediments originated from an active continental margin (ACM) tectonic environment associated with the recycled orogen, aligning well with the sandstones' quartz-feldspar-lithic composition. The geochemical characteristics and elemental ratios of the Neogene sedimentary rocks [e.g., Eu/Eu* (0.55-0.58), (La/Lu)(N) (9.2-10.0), La/Sc (2.30-3.98) and (La/Yb)(N) (8.46-10.03)], indicate a primary origin from felsic source rocks. The source rocks are dominantly granites that had undergone mild to moderate chemical weathering. The U-Pb ages of the Pliocene Tipam Group and the Miocene Surma Group range from 22.49 to 2794.45 and 28.04 to 3168.21 Ma, respectively. The sandstones of the Tipam and Surma groups exhibit a notable zircon age peak at around 440-620 Ma, which bears similarities to the Tethyan Himalaya (TH), Upper Lesser Himalaya (ULH) and Indo-Burman Ranges (IBR). The secondary peaks at similar to 1500-2000 Ma correspond to the Lesser Himalaya (LH) ages. The additional subordinate peaks at similar to 700-1200 Ma reflect the age of the Higher Himalaya (HH). The notable increase in the younger detrital zircon (< 200 Ma) populations was observed in the Tipam Group samples (similar to 22%). These additional young zircons were possibly derived from the recycled Paleogene arc of the Indo-Burma Ranges that might have originated from the Burma magmatic arc.

The origin of Oligocene sediments in the Bengal Basin and associated tectonic setting remain poorly understood. This study investigates the framework mineralogy and major element geochemistry of the Barail Group sandstones from the Sylhet Trough within the Bengal Basin to clarify the provenance and tectonic history of the Oligocene. Modal analysis (Q83F7L10) and geochemical data support a classification of sublitharenite to subarkose, some with Fe enrichment. The heavy mineral assemblage is dominated by opaque minerals, followed by ultrastable minerals with zircon > tourmaline > rutile. The sub-angular to sub-rounded sand grains with a compositionally moderate mature nature suggest that the sediments were deposited close to the source area. The mineralogical and geochemical provenance discrimination diagram suggests contributions from felsic igneous, sedimentary/metasedimentary, and low-grade metamorphic sources, with detritus derived from the Indian craton and proto-Himalaya region. Data suggest moderate to intense chemical weathering, indicative of low relief and a sub-humid to humid climate in the source area. The tectonic analyses indicate that the Bengal Basin transitioned from a predominantly passive margin to an active tectonic margin setting during the Oligocene.

The Rashidpur anticline, trending N-S, is a surface anticline with reverse faulting located in an area characterised by low hillocks. It is part of the youngest structural province along the western flank of the Indo-Burman Ranges, formed by the oblique subduction of the Indian plate beneath the Burmese plate. Many folds in the area are influenced by faults along their axes. Seismic transect analysis and wireline log data reveal four main reflecting horizons: Lower Gas Sand, Top Bhuban, and Upper Marine Shale. Time contour maps for these horizons show that the Rashidpur structure is an N-S trending asymmetrical anticline with a steep eastern flank. The eastern flank is thrusted and associated with west-dipping faults, though some structures exhibit pop-up features. Well log interpretation identifies gasbearing sands within the Dupitila to Bhuban Formations. The onlapping geometry and thinning of reflectors toward the anticline crest correspond to the Pliocene Tipam and Pleistocene Dupitila Groups, while the base corresponds to the Surma Groups. This structure is interpreted as a syn-kinematic package, indicating that the structural development began in the Miocene. Seismic data interpretation and well information suggest that Rashidpur is a fault propagation fold. Both 2D seismic sections and time contour maps indicate fault-bounded closures to the east, previously unreported. These prospects should be further investigated using 3D data and fault seal analysis to assess the sealing ability of the fault and the potential of fault-bounded trapping mechanisms in the Rashidpur anticline.

The Pliocene Tipam Sandstone Formation is widely exposed in various structures of the Chittagong Tripura Fold Belt in the Bengal Basin. Petrography and major element geochemistry of sandstones from this formation have been examined to infer their provenance signature and tectonic setting. The average modal (Q77F11L12) composition and geochemical results reveal that the Tipam sandstones are classified as litharenite to sublitharenite and lithic subarkose. The higher ICV (> 1) values and the negative correlation between SiO2/Al2O3 and total quartz (Qt) indicate that the investigated sandstones are compositionally immature. The petrographic and geochemical provenance discriminant diagrams suggest a recycled sedimentary provenance, with sediments derived predominantly from felsic igneous sources. The weathering indices, including the CIA (Chemical Index of Alteration), PIA (Plagioclase Index of Alteration), CIW (Chemical Index of Weathering), and A–CN–K [Al2O3 − (CaO* + Na2O) − K2O], (A–K)–C–N [(Al2O3–K2O) − CaO* − Na2O)], A–CNK–FM [Al2O3–(CaO* + Na2O + K2O) − (Fe2O3 + MnO)], and MFW [Mafic–Felsic–Weathering] models, indicate a weak to moderate degree of chemical weathering. The paleoclimate model reflects a sub-humid climate condition in the source area. The results imply that the Tipam Sandstone Formation accumulated in an active continental margin context, with the majority of sediments sourced from the Lesser Himalayan Sequence and a smaller portion from the Higher Himalayan Crystalline Sequence, Sub-Himalaya, and Indo-Burma Ranges during the Pliocene.

The Bengal Basin is a well‐known foreland basin that archives the tectonic evolution of the Himalayan and Indo‐Burman Ranges (IBR). The Dupi Tila Formation is the youngest among the stratigraphic successions of the Bengal Basin, which witnessed the last phase of the Himalayan uplift. However, there is still controversy regarding sediment provenances since the Himalayan and IBR are in the late Neogene exhumation stage. In this study, the petrographical and geochemical compositions of the Dupi Tila sandstones from the Lalmai Anticline of the Bengal Basin are examined to infer the source rocks, tectonic settings, palaeoclimate and weathering intensity in provenance areas. The detrital modes and geochemical discriminations, as well as Chondrite‐normalized rare earth elements patterns with enrichment in light rare earth elements and nearly flat heavy rare earth elements and negative Eu anomalies (average Eu/Eu* = 0.77) indicate dominantly felsic source rocks. The geochemical data also suggest that these source rocks in provenance areas were influenced by weak to moderate chemical weathering (chemical index of alteration: 65.64–75.62) and multiple recycling under warm and humid to semi‐humid climatic conditions. The detrital zircon ages show three dominant peaks at ca. 100, 500 and 1000 Ma with minor 1700 Ma. The amount of young zircon grains (<120 Ma) is noticeably higher (~18%) in this Lalmai outcrop compared to the Dupi Tila samples from the Sylhet Trough and Chittagong‐Tripura Fold Belt. Results from integrated zircon geochronology and geochemistry indicate that the detritus are likely derived from a recycled orogen provenance related mainly to active continental margin setting with subordinate influence from passive setting. Therefore, the regionally extensive Himalayan Orogen appears to be the primary sediment source, with additional mixing from the IBR and recycled sediments originating from the Gangdese batholith of the Trans‐Himalaya.

The Atrai River rises in the southeast Himalaya and empties into the Bengal Basin in the northwest. In this study, major and trace element geochemistry of the Atrai River sediments is carried out in addition to petrography to determine the compositional maturity, provenance, chemical weathering, and tectonic setting. X-ray fluorescence (XRF) spectrometry was employed for geochemical studies. Results reveal that, in comparison to the Upper Continental Crust (UCC), the sediments are significantly enriched in SiO2, Fe2O3, Cr, and Ni and markedly depleted in Na2O, MgO, CaO, MnO, and TiO2. This is likely because feldspars were lost during chemical weathering. The sediments of the Atrai River are sub-arkosic in composition. The index of compositional variability (ICV) (0.95 to 1.35), and SiO2/Al2O3 ratio (6.15 to 6.81) in the Atrai River sediments suggest poorly sorted grains, and low compositional and mineralogical maturity. The geochemical and petrographic discriminate diagrams and high Al2O3/TiO2 values (20.57 to 32.55) indicate a felsic igneous provenance for the Atrai River sediments. They are mainly derived from granitic sources, with subordinate metamorphic and pre-existing sedimentary sources. The Higher Himalayas and the Lesser Himalayas are considered the possible source areas of the Atrai River sediments. Weathering indices (CIA, CIW, and PIA), as well as major and trace element discriminating diagrams, point to a weak-to-moderate degree of chemical weathering that may be prevalent in the source area under semi-arid climatic conditions. Petrographic and geochemical discriminating diagrams reveal an active margin tectonic setting for the Atrai River sediments.

The Eastern Fold Belt (EFB) of the Bengal Basin remains an under-explored petroleum province in Bangladesh. Interbedded sandstones and shales of the Miocene Surma Group are thought to host hydrocarbon accumulations in EFB. The diagenetic history and their controls on sandstone reservoir quality and distribution are largely unknown in this region. Therefore, this paper aims to improve the understanding of diagenetic processes and their impacts on reservoir quality in the Surma Group sandstones. Thin section petrography, Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analysis have all been used to this end. The results of this study show that the sandstones are very fine- to medium- grained, moderately to moderately well-sorted, matrix- rich and dominantly sublitharenites. The principle diagenetic minerals/cements are calcite, authigenic chlorite, illite/illite–smectite, minor quartz cement, and minor kaolinite. Poikilotopic calcite cement drastically reduces the porosity and permeability down to 0%. Authigenic chlorite rims along quartz grain prevent quartz overgrowth, which acts to preserve porosity. The primary porosity (0–22%, average 9%) is by far the most dominant porosity in the Miocene Surma Group reservoirs, with burial enhanced secondary porosity caused by dissolution. Reservoir quality is mainly controlled by mechanical and ductile grain compaction and calcite cement.

Clay minerals are common constituents of the Miocene Surma Group reservoir rocks in the Sylhet Trough, Bengal Basin, and may exert significant controls on reservoir quality. The relationship between diagenetic clay minerals and reservoir quality in the petroliferous Sylhet Trough is poorly understood, however. The current study was aimed at the origin and diagenetic pattern of clay minerals in interbedded sandstones and shales using thin-section petrography, scanning electron microscopy (SEM), and X-ray diffraction (XRD), and understanding their diagenetic effects on reservoir quality. The results showed that the clay mineral cements in sandstones comprise mainly chlorite, illite/illite-smectite, and minor smectite and kaolinite. In the early diagenetic stage, clay rims and growth of vermiform kaolinite occur and partly occlude the pore throats. Deep burial effects include pore-filling, pore-lining, and grain-coating authigenic clays (mainly chlorite and illite). Diagenetic clay minerals and mechanical clay infiltration showed a systematic distribution in sandstones lying in the vicinity of sequence and parasequence boundaries. In a lowstand systems tract (LST), clay minerals within the sandstones commonly include mechanically infiltrated smectitic clays that eventually evolved to grain-coating chlorite and/or illite during the meso-diagenesis stage. The presence of clays/clay minerals has no significant impact upon reservoir quality of sandstones. The Surma Group shales are enriched in illite with significant proportions of chlorite and kaolinite and are likely to be mainly detrital, with diagenetic changes of smectite to illite.

The Sylhet Trough of the Bengal Basin in the northeastern Indian Plate had started to develop since the Late Mesozoic Gondwana break-up and subsequent onset of the Cenozoic Himalayan Orogeny. However, very little is known about evolution of the Cenozoic Sylhet Trough in response to the latter tectonic event. Therefore, we aim at providing insights into the nature of basement, variations in structural style, kinematics and possible timing of structural activation(s) and tectonostratigraphic evolution of the Sylhet Trough based on geophysical data interpretation. Results show that the Sylhet Trough is mostly underlain by an attenuated continental or oceanic crust, bounded by a NE-SW-trending geophysical feature in the northwest that corresponds to the boundary with the Precambrian continental crust. The overlying Cenozoic sediments show variations in style of deformations and can be divided into three structural domains. Domains 1 and 2 in the southeastern and northeastern parts of the Sylhet Trough, respectively, are characterized by anticlines that are highly deformed to the east and are mostly associated with west- or northwest-dipping reverse faults. However, the anticlinal trends are deviated from a generalized NS-orientation in the Domain 1 to a dominant NE-SW-orientation in the Domain 2. Many of these anticlines resemble positive flower structures, indicating possible impacts of regional transpression associated with the Dauki and Kaladan faults to the north and east; respectively. In contrast, the Domain 3 to the west shows NE-SW-trending extensional structures. A southward thickening of the Oligocene to Miocene pre-kinematic packages indicates an early episode of foreland basin subsidence, although there is no evidence of a major structural activation. Rather, the presence of the Pliocene syn-kinematic packages indicates a major structural reactivation in response to the E-W and N-S crustal shortening since the Pliocene. This younger episode of structural activation can be directly linked with the late Cenozoic subduction related processes of the Indian Plate to the north and to the east, which is also responsible for the transformation of the Sylhet Trough into a remnant ocean basin. This latter (i.e., Pliocene and onward) episode of crustal shortening played a significant role in structural trap formation and preservation of hydrocarbons in the Sylhet Trough.

The Lalmai anticline is one of the westernmost structures within the Eastern Fold Belt of the Bengal Basin that has surficial expression. The tectonic evolution of the Eastern Fold Belt is directly linked with the development of the Indo-Burman Range in response to the late Cenozoic convergence between the Indian and Burmese plates. However, very little is known about the Plio-Pleistocene to Recent tectonic evolution of the Lalmai anticline in the context of regional tectonics. Therefore, this research is aimed at lucid understand the Plio-Pleistocene to Recent tectonostratigraphic evolution of the Lalmai anticline based on detailed lithofacies and structural observations. Results show that Plio-Pleistocene Dupitila and Pleistocene Madhupur Clay formations are exposed in the Lalmai area. Based on sedimentary texture and structures, a total of six prominent lithofacies types have been identified. These are trough cross-stratified sandstone (St), planar cross-stratified sandstone (Sp), parallel laminated sandstone (Sl), massive sandstone (Sm), laminated shale (Fl), and mudstone (Fm) facies. The facies characteristics indicate a possible fluvial depositional environment for both the formations. Structural mapping shows that the bedding surfaces are nearly horizontal. Based on the missing of strata (both the Dupitila and Madhupur Clay formations) and presence of a fault escarpment, a N-S trending east-dipping reverse fault (namely, the Mainamati Fault) has been identified on the western margin of the Lalmai anticline. The tectonostratigraphic evolutionary models show that the last major structural activation along this Mainamati Fault can be linked to late Pleistocene to Recent time. This structural activation was possibly controlled by the latest ongoing E-W crustal shortening in response to the Indo-Burman subduction processes to the far east.

The Sylhet Trough in the Bengal Basin (Bangladesh) hosts a number of gas fields. The evolution of the trough is closely associated presumably with the growth and the tectonics of the Dauki Fault Zone (DFZ). Hence understanding the transpression tectonics of the NE Bengal Basin is crucial in petroleum geoscience. The eastern segment of the DFZ in the NE Bengal Basin transpressed dextrally and activated since the latest Miocene up to the earliest Pliocene due to compression along the north, east and southeast. The structural and the tectonic elements of the area are assessed from geomorphic features and deformation structures. Nature of faults and comparison of fault-slip stress field with modern geodetic measurement allow establishing geometric and kinematic relationship between different tectonic elements with the DFZ. Bedding attitude measurements from the study area indicate sub-horizontal east-west-trending antiform fold axis gently plunging towards west confirming the existence of a large-scale monocline. Out of the two interpreted compression directions N-S and E-W, the former explains the orientation of the monocline while the later may cause the dextral transpression in combination with the former compression direction. Fault kinematics and incremental strain axes indicate a bulk north-trending subhorizontal shortening and vertical thickening of the fold and faults approximately perpendicular to the east-west oriented DFZ. The timing of the compressional deformation and fault activation in the study area is inconclusive. Paleostress analyses results match with the present day stress regime and this implies that all the deformations are genetically linked with the DFZ.

The Bengal Basin accommodates an extremely thick Cenozoic sedimentary succession that derived from the uplifted Himalayan and Indo-Burman Orogenic Belts in response to the subduction of the Indian Plate beneath the Eurasian and Burmese Plates. The Hatia Trough is a proven petroleum province that occupies much of the southern Bengal Basin. However, the style of deformation, kinematics, and possible timing of structural initiation in the Hatia Trough and the relationship of this deformation to the frontal fold-thrust system in the outer wedge (namely, the Chittagong Tripura Fold Belt) of the Indo-Burman subduction system to the east are largely unknown. Therefore, we have carried out a structural interpretation across the eastern Hatia Trough and the western Chittagong Tripura Fold Belt based on 2D seismic reflection data. Our result suggests that the synkinematic packages correspond to the Pliocene Tipam Group and the Pleistocene Dupitila Formation. This implies that the structural development in the western Chittagong Tripura Fold Belt took place from the Pliocene. In the Hatia Trough, the timing of structural activation is slightly later (since the Plio-Pleistocene). In general, fold intensity and structural complexity gradually increase toward the east. The presence of reverse faults with minor strike-slip motion along the frontal thrust system in the outer wedge is also consistent with the regional transpressional structures of the Indo-Burman subduction system. However, to the west, there is no evidence for strike-slip deformation in the Hatia Trough. The restored sections indicate that the amount of east–west shortening in the Hatia Trough is very low (maximum 1.2%). In contrast, to the east, the amount of shortening is high (maximum 13.5%) in the western margin of the Chittagong Tripura Fold Belt. In both areas, the key trapping mechanism includes anticlinal traps, although stratigraphic and combinational traps are possible, but this requires further evaluation.

Tectonic development of the Bengal Basin is related to the complex interplay among the Himalaya orogen to the north, the Indo-Burma orogen to the east, and Stable Indian Craton to the west. To the north, convergence tectonic loading presumed to transfer from the deformation front, along the Oldham and Dauki faults to the south and shaped not only the Shillong Plateau and Assam Basin, but also the northern part of the Bengal Basin. To the east, oblique subduction related transpressional tectonics splits along different morphotectonic units separated by large-scale transpressive dextral strike-slip faults and produces fold thrust belt, thrust front, and emerging fold belt, whose western limit is marked by the deformation front to the east. The Stable Shelf part of the basin to the west is characterized by the presence of passive margin rift faults with numerous graben and half-graben structures, which show sign of tectonic reactivation in response to the ongoing N-S collision and E-W subduction of the Indian Plate.

The Sylhet Trough, a petroleum province of the Bengal Basin, accommodates a huge thickness of Eocene to Recent sedimentary successions. However, the basin-fill history of the trough is poorly understood; specifically, constrains on timing of deposition of the individual units are yet to be established. Therefore, we aimed at establishing sedimentation and basin-fill history of the Sylhet Trough based on detailed lithofacies analysis of the outcropping Cenozoic succession. We have divided the entire Cenozoic succession into three megasequences which can be further sub-divided into nine lithostratigraphic units based on bounding discontinuities, such as transgressive erosion surface, regressive erosion surface, transgressive surface, marine flooding surface, and incised valley floor. The oldest is the Megasequence 1, comprised of shallow marine shelfal deposits overlain by shallow marine to nearshore deposits. In the middle, the Megasequence 2 is representing tide-dominated marine to coastal (deltaic) depositional systems with evidence of cyclic marine regression and transgression. Repetitive occurrence of incised channel, tidal inlet, tidal ridge/shoal, tidal flat and other tidal deposits are separated by shelfal deposits. The top of the Megasequence 2 is marked by a pronounced erosion surface interpreted as an incised valley floor indicating the final phase of marine regression followed by the gradual establishment of the overlying continental-fluvial depositional systems (i.e., the Megasequence 3). This youngest megasequence is characterized by stacked braided river sand bars that pass up-sequence into meandering river deposits. Based on the Cenozoic eustatic sea level curve, we suggest that the upper boundaries of the Megasequence 1 and Megasequence 2 are approximately at 39.5 Ma and 5.0 Ma, respectively.

The Sylhet Trough is located in the northeastern part of the Indian plate, was developed as a part of a foreland basin (i.e., the Bengal Basin) in response to the uplift of the mountain belts of Himalaya and Indo-Burman Ranges and accommodated one of the thickest sedimentary piles. The present study aims to understand the possible provenance of the Neogene sediments in the trough based on results from detrital zircon U-Pb dating and detrital mode of sandstone petrography. Provenance analysis based on the modal composition of these Neogene sediments indicates a 'recycled orogen', suggesting significant reworking and recycling of the detrital sediments during the mountain building process. The detrital zircon age spectra of the Miocene Surma Group and Plio-Pleistone Dupitila sediments from the Sylhet Trough suggest that the sediments were mostly derived from three Himalayan litho-tectonic units; the Tethyan Himalaya, the Higher Himalaya and the Lesser Himalaya. However, younger detrital zircons (<200 Ma) from the Sylhet Trough are aged similar to 143-32 Ma, are identical to similar to 85-50 Ma Gangdese batholith, located north of the Himalayan belt. Such observation suggests that the sediments of the Sylhet Trough are sourced from the Late Cretaceous-Eocene Gangdese Trans Himalayan Batholith that includes the Bomi-Chayu, the Dianxi-Burma and the Northern Magmatic Belt (i.e., the Northern Lhasa block).

Cambrian deformation associated with the Delamerian Orogeny is most evident in the Delamerian Orogen (southwestern Tasmanides) but has also been documented in the Thomson Orogen (northern Tasmanides). The tectonic evolution of the Thomson Orogen in the context of the Delamerian Orogeny is poorly understood. In particular, tectonostratigraphic relationships between the different parts of the Thomson Orogen (Anakie Inlier, Nebine Ridge, and southern Thomson Orogen) are still unclear. New detrital zircon data from the Nebine Ridge revealed an age spectrum that is consistent with published geochronological data from the Anakie Inlier. These results, in conjunction with petrographic observations and the interpretation of geophysical data, suggest that along the eastern part of the Thomson Orogen, the similar to NNE-trending Nebine Ridge represents the southward continuation of the similar to N-S-trending Anakie Inlier. New detrital zircon geochronological data are also presented for metasedimentary rocks from both sides of the Thomson-Lachlan boundary. The results constrain the maximum age of deposition (Ordovician-Devonian), and show that both sides of the Thomson-Lachlan boundary received detritus from a similar provenance. This might suggest that the Thomson-Lachlan boundary did not play a major role as a crustal-scale boundary prior to the Devonian. We speculate that transpressional deformation along this similar to E-W boundary, during the Early Devonian, was responsible for disrupting the original belt that connected the Delamerian Orogen (Koonenberry Belt) with the eastern Thomson Orogen (Nebine Ridge and Anakie Inlier).

The Bengal Basin originated during the collision of India with Eurasia and Burma. The provenance analysis of the Chittagong Tripura Fold Belt (CTFB), which is the folded eastern flank of the Bengal Basin as well as the Neogene belt of the Indo-Burman Ranges (IBR) is key to better understand the possible sources of sediment input from the complex interplay of the Indian, Eurasian and Burma plates. We report new whole rock geochemical and detrital zircon U-Pb data from the upper Neogene sandstones of Tipam-Dupi Tila formations (Pliocene to Plio-Plestocene succession) from the CTFB. Detrital zircon U-Pb age spectra show three predominant peaks at <200 Ma, 480-650, similar to 800-1000 Ma. The geochemical discriminations and elemental ratios of Eu/Eu* (similar to 0.70), La/Sc (similar to 16.13), La/Co (similar to 15.76), Th/Sc (similar to 2.95), La/Th (similar to 5.67), Th/Co (similar to 2.87), Cr/Th (similar to 4.63) as well as Chondrite-normalized REE patterns with flat HREE, LREE enrichment, and negative Eu anomalies for the Tipam and Dupi Tila formations are suggestive of a dominantly felsic source area experiencing moderate to intensive chemical weathering (Chemical index of alteration, CIA - 57 to 81) and have a recycled provenance orogen related to active continental or passive margin settings. Integrated geochemical and zircon UePb studies reveal that the main sediment input might have been from the Himalayan orogen with significant arc-derived detritus, possibly from the Gangdese arc as well as from the Burma magmatic arc. (c) 2019 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

The Paleozoic tectonic history of the Tasmanides in eastern Australia was dominated by subduction‐related processes along the margin of eastern Gondwana. The earliest deformation event, Delamerian Orogeny, took place in the middle‐late Cambrian and is recorded in rocks within the Delamerian and Thomson orogens. The Cambrian‐Ordovician Warburton Basin covers the boundary between the Delamerian and Thomson Orogens, but very little is known about its origin and deformation history. Here we interpret geophysical data, including 2‐D seismic reflection transects, Bouguer gravity, and aeromagnetic data that provide new insights into the deformation in the eastern Warburton Basin and the kinematics of major faults. Our results show that curvilinear NE‐trending faults in the eastern Warburton Basin are basement reverse faults that experienced multiple phases of contractional deformation. Evidence for a syn‐kinematic Cambrian package (Kalladeina Formation) suggests that faulting commenced in response to the Delamerian Orogeny. A subsequent Early Devonian deformation in the eastern Warburton Basin is evident from K‐Ar geochronology of low‐grade (subgreenschist) metasedimentary rocks. We suggest that the NE‐trending Cambrian fold‐thrust belt within the eastern Warburton Basin marks the continuation of the curved Delamerian Orogen into the Thomson Orogen. This oroclinal structure may have developed in the Early Devonian in response to dextral transpression along the northern boundary of the Delamerian Orogen. Our results provide a demonstration for the complex interactions that can take place during the evolution of convergent plate boundaries, involving deformation in the fold‐thrust belt, development of sedimentary basins, and oroclinal bending.