Foreland Basin Development Research Articles

Tectonostratigraphy and depositional history of the Neoproterozoic volcano-sedimentary sequences in Kid area, southeastern Sinai, Egypt: Implications for intra-arc to foreland basin in the northern Arabian–Nubian Shield

This paper presents a stratigraphic and sedimentary study of Neoproterozoic successions of the South Sinai, at the northernmost segment of the Arabian–Nubian Shield (ANS), including the Kid complex. This complex is composed predominantly of thick volcano-sedimentary successions representing different depositional and tectonic environments, followed by four deformational phases including folding and brittle faults (D1–D4). The whole Kid area is divisible from north to south into the lower, middle, and upper rock sequences. The higher metamorphic grade and extensive deformational styles of the lower sequence distinguishes them from the middle and upper sequences. Principal lithofacies in the lower sequence include thrust-imbricated tectonic slice of metasediments and metavolcanics, whereas the middle and upper sequences are made up of clastic sediments, intermediate-felsic lavas, volcaniclastics, and dike swarms. Two distinct Paleo- depositional environments are observed: deep-marine and alluvial fan regime. The former occurred mainly during the lower sequence, whereas the latter developed during the other two sequences. These alternations of depositional conditions in the volcano-sedimentary deposits suggest that the Kid area may have formed under a transitional climate regime fluctuating gradually from warm and dry to warm and humid conditions.Geochemical and petrographical data, in conjunction with field relationships, suggest that the investigated volcano-sedimentary rocks were built from detritus derived from a wide range of sources, ranging from Paleoproterozoic to Neoproterozoic continental crust. Deposition within the ancient Kid basin reflects a complete basin cycle from rifting and passive margin development, to intra-arc and foreland basin development and, finally, basin closure. The early phase of basin evolution is similar to various basins in the Taupo volcanics, whereas the later phases are similar to the Cordilleran-type foreland basin. The progressive change in lithofacies from marine intra-arc basin to continental molasses foreland basin and from compression to extension setting respectively, imply that the source area became peneplained, where the Kid basin became stabilized as sedimentation progressed following uplift. The scenario proposed of the study area supports the role of volcanic and tectonic events in architecting the facies and stratigraphic development.

Distinguishing Similar Volcanic Source Areas From An Integrated Provenance Analysis: Implications for Foreland Andean Basins

Abstract The Mata Amarilla Formation marks the onset of the foreland stage of the Austral basin, which is composed of mostly nonmarine and littoral siliciclastic sediments, thus providing an opportunity to study the detrital record of the Late Cretaceous southern foreland Andes. Our dataset provides, for the first time, a comprehensive picture of the Late Cretaceous evolution of the Austral foreland basin, constituting a possible analogue to other foreland basins at the foot of the Andes. Sandstones from the Mata Amarilla Formation testify to variable contributions from Jurassic bimodal volcanic rocks of the Deseado Massif and the Patagonian fold-and-thrust belt, in the context of an eastward-advancing orogen. Sandstone petrography shows an overall feldspathic litharenite composition, whereas sandstones coming from the northeast (Deseado Massif) have higher Lv and lower Qp proportions than samples coming from the west (Patagonian fold-and-thrust belt). In the central part of the study area, sandstones are characterized by higher proportions of Qt associated with a greater distance and time of transport relating to its position in the Austral foreland basin. In spite of the increased maturity of sandstone in the central area, X-ray analyses permit recognition of the compositional signature of Mata Amarilla Formation, in which four clay-mineral assemblages were identified: S (rich in smectite), S-K (rich in smectite and kaolinite), Pg (rich in palygorskite), and I/S (rich in illite–smectite mixed layers). S-assemblage evidences well-crystallized smectite, characteristic of volcaniclastic origin. Most smectite was formed during early diagenesis through alteration of labile tuffaceous material derived from the Southern Andes. The stratigraphic variations in clay-mineral assemblages reveal a strong environmental control on their distribution. The transformation of smectite into illite and kaolinite is considered as product of pedogenesis, whereas the presence of palygorskite indicates a coastal environment with paleosol development under poorly drained conditions.

The implication of transfer faults in foreland basin evolution: application on Pindos foreland basin, West Peloponnesus, Greece

AbstractPindos foreland basin in west Peloponnesus (Tritea, Hrisovitsi and Finikounda sub‐basins) during Late Eocene to Early Oligocene was an underfilled foreland basin. The basin's geometry was affected by the presence of internal thrusting and transfer faults, causing changes in depth and width. Due to internal thrusting, the foreland basin changed through time from a uniform to non‐uniform configuration, whereas transfer faults have an intensive impact on depositional environments within the basin. Internal thrusting (Gavrovo, internal and middle Ionian thrusts) activated synchronously with the major Pindos Thrust, creating intrabasinal highs that influenced palaeocurrent directions. The transfer faults cross‐cut the intrabasinal highs and produced low relief areas that act as pathways for sediment distribution. The sediments are thicker and sandstone‐rich on the downthrown sides of the transfer faults. In these areas, sandstone reservoirs could be produced. Such tectonically active areas constitute promise for oil and gas reservoirs and traps.

Responses of two lithosomes of Lower Cretaceous coarse clastic rocks to tectonism in Kuqa foreland sub-basin, Northern Tarim Basin, Northwest China

Coarse clastic rocks, developed widely at foredeep adjacent to orogene, were usually regarded as the mark of renewed thrusting action. However a good example from the Lower Cretaceous in Kuqa foreland sub-basin illustrated that the coarse clastic rocks developed not only in initial thrusting stage but in early quiescence stage. The Kuqa foreland sub-basin, adjacent to the south Tianshan Orogene, lies to the north of Tarim Basin, northwest China. The Lower Cretaceous outcrop in the front of south Tianshan Orogene was identified as a filling sequence of foredeep which includes two depositional cycles of Kapushaliang Group and Bashijiqike Formation. Each of them presents fining-upwards and then coarsening-upwards sequences. Two lithosomes of coarse clastic rocks developed in the lower of Yageliemu Formation of Kapushaliang Group and Bashijiqike Formation, respectively. Both of them are mainly composed of thick-bedded, massive and chaotic conglomerate with debris flow microfacies of fan delta plain. The analyses on stratigraphic and depositional records for tectonism revealed abrupt sedimentary change from delta facies to fan delta facies, stratal geometry transformation, and reflection termination migration of truncation and top-lap between the Kapushaliang Group and the Bashijiqike Formation. These records indicated that: foredeep subsided rapidly while forebulge uplifted in the development of Kapushaliang Group, which coincided perfectly with lithosphere deformation during thrusting stage; foredeep uplifted rapidly while forebulge subsided in the later development of Bashijiqike Formation, which coincided with lithosphere deformation during quiescence stage of foreland basin development. Therefore, the Lower Cretaceous recorded a whole episode of foreland basin evolution from earlier thrusting to later quiescence. The underfilled cycle of Kapushaliang Group, corresponding to the thrusting stage, is much thick with mainly muddy and silty sediments. The overfilled cycle of Bashijiqike Formation, corresponding to the quiescence stage, is thin with mainly sandy sediments. The two lithosomes of coarse clastic rocks were very similar with each other in the lithology and sedimentology. However, the one from lower Yageliemu Formation is responded to the renewed thrusting, but the other from the lower Bashijiqike Formation is responded to the lithosphere rebounding during primary quiescence stage. Therefore, cannot only coarse clastic rocks indicated a renewed thrusting.

Palaeontological age and correlations of the Tertiary deposits of the NW Iberian Peninsula: the tectonic evolution of a broken foreland basin

Ages of Cenozoic sedimentary basins yield information that can be used to infer detailed spatial and temporal evolution in the Alpine foreland. The Tertiary deposits of the NW Iberian Peninsula comprise the remains of a broken foreland basin (the West Duero Basin). This work constrains the timing of tectonic fragmentation and the evolution of the western termination of the Alpine Pyrenean–Cantabrian Orogen (NW Iberian Peninsula). The discovery of Issiodoromys cf. minor 1 and Pseudocricetodon in the lower formation of the Tertiary depression of Sarria (the Toral Formation) constrains its age to the late Early Oligocene (MP23–MP25), similar to its age in the El Bierzo depression (MP24–MP25). Sedimentation initiated in the NE of the study area at Oviedo during the Middle Eocene (Bartonian–Early Priabonian MP16–MP17) and migrated towards the west and south during the Early Oligocene. The Toral Formation was deposited in a foreland basin that connected the present day outcrops of the El Bierzo, Sarria and As Pontes Tertiary depressions. The basin was segmented during the westward migration of structural deformation associated with the Orogen, and the subsequent uplift of the Galaico–Leoneses Mountains. The present-day height above reference level of the base of the Toral Formation has been used to quantify Alpine segmentation that took place after Early Oligocene times. Minimum tectonic uplift assessed is 960 m in the Cantabrian Mountains and 1050 m in the Galaico–Leoneses Mountains. Copyright © 2013 John Wiley & Sons, Ltd.

Subsidence controls on foreland basin development of northwestern offshore Cuba, southeastern Gulf of Mexico

We reviewed the tectonostratigraphic evolution of the Jurassic–Cenozoic collision between the North American and the Caribbean plate using more than 30,000 km (18,641 mi) of regional two-dimensional (2-D) academic seismic lines and Deep Sea Drilling Project wells of Leg 77. The main objective is to perform one-dimensional subsidence analysis and 2-D flexural modeling to better understand how the Caribbean collision may have controlled the stratigraphic evolution of the offshore Cuba region. Five main tectonic phases previously proposed were recognized: (1) Late Triassic–Jurassic rifting between South and North America that led to the formation of the proto-Caribbean plate; this event is interpreted as half grabens controlled by fault family 1 as the east-northeast–south-southwest–striking faults; (2) Middle–Late Jurassic anticlockwise rotation of the Yucatan block and formation of the Gulf of Mexico; this event resulted in north-northwest–south-southeast–striking faults of fault family 2 controlling half-graben structures; (3) Early Cretaceous passive margin development characterized by carbonate sedimentation; sedimentation was controlled by normal subsidence and eustatic changes, and because of high eustatic seas during the Late Cretaceous, the carbonate platform drowned; (4) Late Cretaceous–Paleogene collision between the Caribbean plate, resulting in the Cuban fold and thrust belt province, the foreland basin province, and the platform margin province; the platform margin province represents the submerged paleoforebulge, which was formed as a flexural response to the tectonic load of the Great Arc of the Caribbean during initial Late Cretaceous–Paleocene collision and foreland basin development that was subsequently submerged during the Eocene to the present water depths as the arc tectonic load reached the maximum collision; and (5) Late Cenozoic large deep-sea erosional features and constructional sediment drifts related to the formation of the Oligocene–Holocene Loop Current–Gulf Stream that flows from the northern Caribbean into the Straits of Florida and to the north Atlantic.

Sedimentary record of the Dukla Basin (Outer Carpathians) and its implications for basin evolution

The Late Cretaceous to Oligocene strata of the Dukla Nappe, which is a part of the accretionary wedge formed in front of the Carpathian orogen, record a history of the basin development from remnant to foreland basin stages. The lower part of the succession indicates the first stage of basin evolution characterized by turbidite systems fed from the E (NE) to W (SW). The system encompasses deposits of the Łupkow and Cisna formations deposited in a channel-lobe transition (Łupkow Fm.) and in sandstone-rich channelized lobes (Cisna Fm.) The transitional phase is represented by deposits of the Submenilite Formation derived from two different sources (SE and N) and deposited in a submarine slope/ramp environment. The third stage of basin evolution is marked by the advancing front of the Carpathian orogen resulting in peripheral foreland basin development. Increased tectonic activity led to a switch in sediment source from the SE to the NW, more complex topography of the basin and a change in sediment distribution. The initial phase of this stage is characterized by low-density turbidites and suspension fall-out sediments of the Menilite Fm. Discrete tectonic pulses are recorded by the thick Cergowa sandstones, mostly deposited by hybrid flows and high-density turbidity currents. A decrease in tectonic activity is suggested by heterolithic deposits of the Krosno Fm. capping the sedimentary succession.

A revised stratigraphy and depositional history for the Horseshoe Canyon Formation (Upper Cretaceous), southern Alberta plains

The Upper Cretaceous paralic to nonmarine Horseshoe Canyon Formation (HCFm) of southern Alberta is divided into seven mappable members: Strathmore, Drumheller, Horsethief, Morrin, Tolman, Carbon, and Whitemud (bottom to top). This subdivision, based on combined outcrop and subsurface analyses, reflects lithostratigraphic variations related to changes in sea level (previously recognized) and newly documented changes in climate, volcanism, and orogenesis in an evolving foreland basin. Million-year-scale cycles of orogenesis resulted in changes in sediment supply and rates of subsidence in the basin and are interpreted in the context of a simple, two-phase foreland-basin sequence stratigraphic model: (i) overthrust loading resulting in reduced rates of sediment supply and subsidence in the most distal portions of the Alberta foredeep (our field area); (ii) tectonic quiescence leading to increased rates of sediment supply and subsidence during proximal-foredeep rebound. During the first ∼2.5 Ma of its history (Strathmore and Drumheller members), the HCFm was tectonically and climatically “stable”, and depositional style and stratigraphic architecture were influenced by vertical aggradation and modest progradation of shorelines. During the remaining ∼4.5 Ma (Horsethief, Morrin, Tolman, Carbon, and Whitemud members), there were more complex and frequent changes in climate, volcanism, orogenesis, landscape weathering, and soil formation. Understanding this previously unrecognized complexity is critical for correctly assessing hydrocarbon resource distributions and biostratigraphic and taphonomic patterns.

Major unconformities, tectonostratigraphic frameword, and evolution of the superimposed Tarim basin, Northwest China

The Tarim basin experienced a complex tectonic evolutionary history from Sinian to Cenozoic. Eight large-scale and more than 20 subordinate unconformities defining tectonosequences of different protobasins formed in various tectonic settings have been identified within the Phanerozoic in the Tarim basin, their distribution determining the general characteristics of sequence stratigraphic framework of the basin. Tectonostratigraphic unit I (magasequence) consists mainly of the Sinian System, which formed in a rift or aulacogen setting and can been subdivided into two subordinate stratigraphic units (supersequences). Unconformity (Tg9) between Sinian and Cambrian with surface karstification is regarded as a post-rift unconformity. Tectonostratigraphic unit II comprises the Cambrian and the Ordovician and can be divided into six subordinate tectonostratigraphic units, recording the tectonogeographic evolution of the prototype basins from Cambrian to Early Ordovician passive carbonate continental margin or cratonic depression and the Late Ordovician submarine to neritic retroarc foreland and cratonic depressions. The tectonic uplift related to the formation of the unconformity Tg5-2 resulted in the remarkable change in basin tectonic setting from a passive divergent to an active convergent, with the development of the Tazhong (塔中) uplift, the Tangguzibasi (塘古孜巴斯), and the northern depression at the end of the Middle to the early Late Ordovician. The widespread angular unconformity Tg5 formed by a relatively strong compressive deformation, which caused an abrupt tectonogeographic change of the basin from abyssal to a neritic setting in response to the collision and associated tectonic deformation of the North Kunlun (昆仑) orogenesis during the Late Ordovician to the Early Silurian. Tectonostratigraphic unit III is composed of the Silurian and the Lower to Middle Devonian and characterized by the development of fluvial or deltaic and clastic littoral and neritic deposits. Large-scale terrigenous clastic depositional wedges progradated from the north to south in the southeastern slope of the basin indicate the continuously shallowing and uplifting along the northern basin margin. Tectonostratigraphic unit IV includes the Upper Devonian, Carboniferous, and Permian and can be classified into two subordinate tectonostratigraphic sequences. The angular unconformity (Tg3) at the base of the unit is the most widespread unconformity and the strong compression and uplift of the basin during this period has been suggested to be related to the collision of the Tianshan (天山) orogenesis and resulted in fundamental change in tectonic geomorphology with higher to the northeast and lower to the southwest. Tectonostratigraphic unit IV records another tectonic cycle from weak extension to compression in basin setting and is composed mainly of nearshore clastic deposits of embayment basin fills. From the Triassic, the Tarim basin evolved into a period characteristic of development of intracontinental depressions and marginal foreland basins and experienced several cycles from rapid subsidence to strong uplift and deformation, resulting in superimposition and reformation of differently orientated protobasins filled with a series of regional depositional cycles bounded by major unconformities and consisting of extremely thick alluvial and lacustrine deposits. The Kuqa foreland depression in the northwestern basin margin developed since the Triassic and deposited a clastic wedge of the Mesozoic to Cenozoic more than 100 000 m in thickness, which progradated and thin towards the southern Tabei (塔北) forebulge. The large-scale sedimentary cycles from alluvial, fluvial to lacustrine, and finally fluvial deposits are attributed to the results of foreland tectonisim from active to relatively quiet stages. The foreland tectonisim was active during the Triassic, relatively quiet during the Jurassic, and active again from the Late Jurassic to the Cretaceous. To the Eogene, the depression subsided again and the compression intermittently increased, resulting in a series of faulted and folded structural belts.

Deformation partitioning in the Llanos foreland basin during the Cenozoic and its correlation with mountain building in the hinterland

Abstract Previous studies have argued that deformation in foreland basins is either controlled by inherited structures, is a direct response to the advancing orogenic load or is a combination of these two factors. To provide insights into the relative importance of these processes in foreland basin development, we generated an inventory of syn-kinematic relationships for the Llanos foreland of Colombia using an extensive (∼5000 km) network of 2D seismic lines. The results of this work indicate that most of the Miocene extensional deformation in the central Llanos trends parallel to the orogen and follows the propagation of orogenesis to the east. Thus, the dominant control on deformation of the Llanos foreland basin is related to flexure during episodes of enhanced orogenic load. This observation is fundamental to understand the nature of deformation in continental interiors and cratonic areas in front of active orogens.

Initial India-Asia Continental Collision and Foreland Basin Evolution in the Tethyan Himalaya of Tibet: Evidence from Stratigraphy and Paleontology

AbstractThe onset of the India-Asia continent-continent collision in Tibet was accompanied by the elimination of oceanic crust and the development of a peripheral foreland basin on the subducting continental crust. However, owing to the progressively southward migration of this foreland basin, the appearance of flexural uplift (forebulge) predated flexural subsidence (foredeep) at the distal location, such as at Gamba and Tingri in the southern Tethyan Himalaya. Consequently, to trace and date this forebulge may provide a better constraint on the India-Asia collision. At Gamba and Tingri, our studies on the stratigraphy, paleontology, and paleoenvironment show that depositional cessation of the limestones occurred at Shallow Benthic Zone 7 (SBZ 7, ∼54–55 Ma) in the Gamba area and at the base of SBZ 10 (∼52.8 Ma) in the Tingri area. At Gamba, a conglomerate layer within the upper Zongpu Formation is suggested to represent the formation of the forebulge at the onset of the foreland basin, and the coincidenc...

The role of inherited structures in a foreland basin evolution. The Metán Basin in NW Argentina

The foreland basin of the Central Andes in NW Argentina is formed by partially unconnected basins limited by uneven high ranges. The Metán Basin is located in the foothills of the Central Andes in NW Argentina between the Eastern Cordillera, the Sierras Pampeanas and the Santa Bárbara System. This basin resulted from a Cretaceous to Paleogene rifting event and from two Neogene to Quaternary foreland basin stages. For this study field data, log well, seismic reflection and satellite images have been interpreted. The propagation of deformation in this sector of the Andes is influenced by inherited structures (e.g. Cretaceous extensional faults), which have been reactivated during Andean compression as high angle and oblique reverse faults. Deformation does not advance regularly throughout the foreland in a normal forward sequence but jumps across inherited faults. Fault reactivation has resulted in uplift of basement cored ranges and hanging wall anticlines that divided the foreland into small basins (e.g. the Metán Basin).

Late Eocene–Pliocene basin evolution in the Eastern Cordillera of northwestern Argentina (25°–26°S): regional implications for Andean orogenic wedge development

AbstractImportant aspects of the Andean foreland basin in Argentina remain poorly constrained, such as the effect of deformation on deposition, in which foreland basin depozones Cenozoic sedimentary units were deposited, how sediment sources and drainages evolved in response to tectonics, and the thickness of sediment accumulation. Zircon U‐Pb geochronological data from Eocene–Pliocene sedimentary strata in the Eastern Cordillera of northwestern Argentina (Pucará–Angastaco and La Viña areas) provide an Eocene (ca. 38 Ma) maximum depositional age for the Quebrada de los Colorados Formation. Sedimentological and provenance data reveal a basin history that is best explained within the context of an evolving foreland basin system affected by inherited palaeotopography. The Quebrada de los Colorados Formation represents deposition in the distal to proximal foredeep depozone. Development of an angular unconformity at ca. 14 Ma and the coarse‐grained, proximal character of the overlying Angastaco Formation (lower to upper Miocene) suggest deposition in a wedge‐top depozone. Axial drainage during deposition of the Palo Pintado Formation (upper Miocene) suggests a fluvial‐lacustrine intramontane setting. By ca. 4 Ma, during deposition of the San Felipe Formation, the Angastaco area had become structurally isolated by the uplift of the Sierra de los Colorados Range to the east. Overall, the Eastern Cordillera sedimentary record is consistent with a continuous foreland basin system that migrated through the region from late Eocene through middle Miocene time. By middle Miocene time, the region lay within the topographically complex wedge‐top depozone, influenced by thick‐skinned deformation and re‐activation of Cretaceous rift structures. The association of the Eocene Quebrada del los Colorados Formation with a foredeep depozone implies that more distal foreland deposits should be represented by pre‐Eocene strata (Santa Barbara Subgroup) within the region.

The Pleistocene tectono‐‐sedimentary evolution of the Apenninic foreland basin between Trigno and Fortore rivers (Southern Italy) through a sequence‐stratigraphic perspective

AbstractA basin‐scale, integrated approach, including sedimentological, geomorphological and soil data, enables the reliable reconstruction of the infilling history of the southern Apenninic foredeep, with its subsequent inclusion in the wedge‐top of the foreland basin system. An example is shown from the Molise‐Apulian Apennines (Southern Italy), between Trigno and Fortore rivers, where the Pleistocene tectono‐sedimentary evolution of the basin is framed into a sequence‐stratigraphic scheme. Specifically, within the traditional subdivision into Quaternary marine (Qm) and Quaternary continental (Qc) depositional cycles, five third‐order depositional sequences (Qm1, Qm2, Qc1, Qc2 and Qc3) are identified based on recognition of four major stratigraphic discontinuities. The lower sequence boundaries are represented by angular unconformities or abrupt facies shifts and are generally associated with distinctive pedological and geomorphological features. Three paleosols, observed at top of depositional sequences Qm2, Qc1 and Qc2, represent pedostratigraphic markers that can be tracked basinwide. The geomorphological response to major tectono‐sedimentary events is marked by a series of paleosurfaces with erosional, depositional and complex characteristics. Detailed investigation of the relationships between stratigraphic architecture and development of unconformities, paleosols and paleosurfaces suggests that the four sequence boundaries were formed in response to four geomorphological phases/tectonic events which affected the basin during the Quaternary. The first three tectonic events (Lower‐Middle Pleistocene), marking the lower boundaries of sequences Qm2, Qc1 and Qc2, respectively, are interpreted to be related to the tectonic regime that characterized the last phase of thrusting recorded in the Southern Apennines. In contrast, sequence Qc3 does not display evidence of thrust tectonics and accumulated as a result of a phase of regional uplift starting with the Middle Pleistocene.

LATE CRETACEOUS TECTONIC AND SEDIMENTARY EVOLUTION OF THE BANDAR ABBAS AREA, FARS REGION, SOUTHERN IRAN

The Upper Cretaceous succession in the SE Zagros (Bandar Abbas area) is characterized by marked changes in fades and thickness. These changes relate to sediment deposition in a foreland basin along the NE margin of the Arabian plate. The succession was measured at eight outcrop sections in the Khush, Faraghun, Gahkum, Genow and Khamir anticlines. The measured sections illustrate a transition from shallow‐water carbonate platform deposits (Cenomanian to Coniacian) to deep‐water fades (Santonian to Maastrichtian). Outcrop observations were compared to data from ten off‐ and onshore wells and to a series of seismic profiles.Four cross‐sections were constructed using well and outcrop data and illustrate fades and thickness variations within the Upper Cretaceous. Based on these regional profiles, the Late Cretaceous depositional history of the Bandar Abbas area was reconstructed and can be divided into two tectono‐sedimentary phases suggesting a transition from a passive to an active margin. Sedimentation during Phase I (late Albion to Coniacian) took place in shallow‐water carbonate platform and intrashelf basin settings (Sarvak Formation), and four third‐order sequences can be recognised. The uppermost sequence is locally capped by fresh‐water, pisolith‐bearing carbonate sand and conglomerates with local laterite and palaeosols of the Coniacian Laffan Formation. Shallow‐water facies consist mainly of wackestone to packstones with abundant benthic foraminifera. Sediments deposited in intrashelf basins are dominated by oligosteginid‐bearing fades. Eustatic variations in sea level, the creation of a foreland basin and salt tectonics most probably controlled patterns of sedimentation during this phase.During the second tectono‐sedimentary phase (Phase II: Santonian to Late Maastrichtian), sediments were dominated by pelagic marls and gravity flow deposits. Lateral thickness variations become more marked to the NE as a result of obduction processes and the creation of the foreland basin.Allochthonous ophiolitic and radiolarite‐bearing units are common in the northern part of the Fars region but are restricted to a few localities in the Bandar Abbas area. Traces of allochthonous materials occur in the SE‐most part of the Khush anticline; thrust slices in offshore seismic profiles may link to the Hawasina nappes of Oman. At the top of the Phase II succession, pelagic facies locally interfinger with Omphalocyclus and Loftusia‐bearing fades (Tarbur Formation) and evaporites (Sachun Formation). These deposits are overlain by slumped and dolomitized shallow‐water carbonates of the Paleocene – Eocene Jahrum Formation.The sedimentary sequence in the Bandar Abbas area illustrates a far‐field response to Late Cretaceous obduction processes and foreland basin development, as well as to halokinetic activity. Rapid variations in thickness and fades document the evolution of depositional processes in the foreland basin.

Early Cretaceous Gangdese retroarc foreland basin evolution in the Selin Co basin, central Tibet: evidence from sedimentology and detrital zircon geochronology

Abstract The Selin Co basin in the northern Lhasa terrane includes more than 3000 m of upward coarsening Lower Cretaceous strata, and the sedimentary sequence from the flysch to the molasse indicates the evolution of a foreland basin. Petrographic analysis shows that sandstones are rich in volcanic and sedimentary lithics and most of them fall into recycled orogen and magmatic arc. Uranium–lead (U–Pb) ages were determined for 435 detrital zircons from the Lower Cretaceous strata in the Selin Co basin. Relative probability of detrital zircon ages shows the Eshaerbu Formation was rich in zircon grains with the age of 125–140 and 160–180 Ma, and the Duoni Formation was dominated by one main age cluster of 125–150 Ma. Analysis of the potential provenances suggests the Early Cretaceous zircon grains were primarily derived from the Gangdese magmatic arc to the south. The youngest zircon ages in the lowermost exposure of the Eshaerbru Formation are c . 130 Ma, providing a maximum depositional age of sediments in the Selin Co basin. Collectively, our studies, together with previously documented Cretaceous thrusting in the Lhasa terrane, suggest the Lower Cretaceous Selin Co basin was deposited in a retroarc foreland basin. From 145–90 Ma, a retroarc foreland basin was presumed to develop in the Lhasa terrane, migrating from the south to the north. Crustal thickening, likely associated with the evolution of the retroarc foreland basin, was speculated to start in the Early Cretaceous in the Lhasa terrane.

Thickness trends and sequence stratigraphy of the Middle Devonian Marcellus Formation, Appalachian Basin: Implications for Acadian foreland basin evolution

Analysis of more than 900 wireline logs indicates that the Middle Devonian Marcellus Formation encompasses two third-order transgressive-regressive (T-R) sequences, MSS1 and MSS2, in ascending order. Compositional elements of the Marcellus Formation crucial to the successful development of this emerging shale gas play, including quartz, clay, carbonate, pyrite, and organic carbon, vary predictably within the proposed sequence-stratigraphic framework. Thickness trends of Marcellus T-R sequences and lithostratigraphic units reflect the interplay of Acadian thrust-load-induced subsidence, short-term base-level fluctuations, and recurrent basement structures. Rapid thickening of both T-R sequences, especially MSS2, toward the northeastern region of the basin preserves a record of greater accommodation space and proximity to clastic sources early in the Acadian orogeny. However, local variations in T-R sequence thickness in the western, more distal, area of the basin may reflect the reactivation of inherited Eocambrian basement structures, including the Rome trough and northwest-striking cross-structural discontinuities, induced by Acadian plate convergence. Episodes of block displacement locally warped the basin into northeast-southwest–trending regions of starved sedimentation and/or erosion adjacent to depocenters in which regressive systems tract deposits were ponded. Block movement appears to have initiated in late Early Devonian time, resulting first in thinning and local erosion of the Oriskany sandstone in northwest Pennsylvania. This study, in addition to providing the basis for a predictive sequence-stratigraphic model that can be used to further Marcellus exploration, tells of a foreland basin more tectonically complex than accounted for by simple flexural models.

Arabia-Eurasia continental collision: Insights from late Tertiary foreland-basin evolution in the Alborz Mountains, northern Iran

A poorly understood lag time of 15–20 m.y. exists between the initial Arabia-Eurasia continental collision in late Eocene to early Oligocene time and the acceleration of tectonic and sedimentary processes across the collision zone in the early to late Miocene. The late Eocene to Miocene-Pliocene clastic and shallow-marine sedimentary rocks of the Kond, Eyvanekey, and Semnan Basins in the Alborz Mountains (northern Iran) offer the possibility to track the evolution of this orogen in the framework of collision processes. A transition from volcaniclastic submarine deposits to shallow-marine evaporites and terrestrial sediments occurred shortly after 36 Ma in association with reversals in sediment provenance, strata tilting, and erosional unroofing. These events followed the termination of subduction arc magmatism and marked a changeover from an extensional to a contractional regime in response to initiation of continental collision with the subduction of stretched Arabian lithosphere. This early stage of collision produced topographic relief associated with shallow foreland basins, suggesting that shortening and tectonic loading occurred at low rates. Starting from the early Miocene (17.5 Ma), flexural subsidence in response to foreland basin initiation occurred. Fast sediment accumulation rates and erosional unroofing trends point to acceleration of shortening by the early Miocene. We suggest that the lag time between the initiation of continental collision (36 Ma) and the acceleration of regional deformation (20–17.5 Ma) reflects a two-stage collision process, involving the soft collision of stretched lithosphere at first and hard collision following the arrival of unstretched Arabian continental lithosphere in the subduction zone.

Magnetostratigraphy of the Ouarzazate Basin: Implications for the timing of deformation and mountain building in the High Atlas Mountains of Morocco.

Two magnetostratigraphic profiles (450 samples) have been carried out to constrain the age of synorogenic formations in the southern foreland of the High Atlas of Morocco. The Amekchoud profile covers the Aït Ouglif and Aït Kandoula alluvial formations that form the bulk of the Ouarzazate basin fill, indicating an age between the upper Langhian and the Messinian (Miocene). Data obtained in the previously unexplored Hadida formation profile covers the oldest terms of the foreland basin succession, but the low quality of the magnetic record only allows proposing a tentative age between the middle Lutetian and an undetermined middle to late Eocene. The correlation of the Amekchoud profile is based on the recognition of the long C5n chron (Tortonian) in the middle part of the section studied and a new vertebrate locality of upper Tortonian age found in the upper part. These results indicate a discontinuous record of foreland basin development in the southern Atlas domain from mid Eocene to late Miocene times, punctuated by an intermediate large hiatus of 20-25 ma (late Eocene to mid Miocene). Thrusting in the Sub-Atlas frontal thrust belt began before the Aït Ouglif and Kandoula formations, probably during the Oligocene, and extends up to recent times. The alternation of periods of deposition with others of no sedimentary record, which does not coincide with specific tectonic events, results probably from the interference of orogenic deformation and the mantle-related thermal uplift events that have been described for the Moroccan Atlas.

Linking sedimentation in the northern Andes to basement configuration, Mesozoic extension, and Cenozoic shortening: Evidence from detrital zircon U-Pb ages, Eastern Cordillera, Colombia

Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analyses of 29 samples from the Eastern Cordillera of Colombia reveal the origin of northern Andean basement and patterns of sedimentation during Paleozoic subsidence, Jurassic–Early Cretaceous extension, Late Cretaceous postrift subsidence, and Cenozoic shortening and foreland-basin evolution. U-Pb geochronological results indicate that presumed Precambrian basement is mainly a product of early Paleozoic magmatism (520–420 Ma) potentially linked to subduction and possible collision. Inherited zircons provide evidence for Mesoproterozoic tectonomagmatic events at 1200–1000 Ma during Grenville-age orogenesis. Detrital zircon U-Pb ages for Paleozoic strata show derivation from Andean basement, syn depositional magmatic sources (420–380 Ma), and distal sources of chiefl y Mesoproterozoic basement (1650–900 Ma) in the Amazonian craton (Guyana shield) to the east or in possible continental terranes along the western margin of South America. Sedimentation during Jurassic–Early Cretaceous rifting is expressed in detrital zircon age spectra as Andean basement sources, recycled Paleozoic contributions, and igneous sources of Carboniferous–Permian (310–250 Ma) and Late Triassic–Early Jurassic (220–180 Ma) origin. Detrital zircon provenance during continued Cretaceous extension and postrift thermal subsidence recorded the elimination of Andean basement sources and increased infl uence of craton-derived drainage systems providing mainly Paleoproterozoic and Mesoproterozoic (2050–950 Ma) grains. By Eocene time, zircons from the Guyana shield (1850–1350 Ma) dominated the detrital signal in the easternmost Eastern Cordillera. In contrast, coeval Eocene deposits in the axial Eastern Cordillera contain Late Cretaceous–Paleocene (90–55 Ma), Jurassic (190–150 Ma), and limited Permian–Triassic (280–220 Ma) zircons recording initial uplift and exhumation of principally Mesozoic magmatic-arc rocks to the west in the Central Cordillera. Oligocene–Miocene sandstones of the proximal Llanos foreland basin document uplift-induced exhumation of the Eastern Cordillera fold-thrust belt and recycling of the Paleogene cover succession rich in both arc-derived detritus (dominantly 180– 40 Ma) and shield-derived sediments (mostly 1850–950 Ma). Late Miocene–Pliocene erosion into the underlying Cretaceous section is evidenced by elimination of Mesozoic– Cenozoic zircons and increased proportions of 1650–900 Ma zircons emblematic of Cretaceous strata.