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Density instabilities in the lithosphere can founder gravitationally via viscous dripping and decoupling from overlying crust. The lithospheric dripping concept has been invoked across the globe, but the diversity of crustal effects, observable evidence, and tectonic settings involved in dripping remain underexplored. Here, we synthesize numerical and analogue modeling studies and geologic data from the literature, including all proposed lithospheric dripping events to‐date. We argue that two distinct styles of dripping can occur depending on crustal strength (relative to that of the mantle lithosphere). Near‐surface contraction and subsidence of strong crusts contrasts with near‐surface extension and uplift of weak crusts. We discuss these events in terms of tectonic setting, timing, size, and the main types of data associated with each event. We also find that lithospheric dripping is associated with a distinct suite of geological observations including sedimentological, structural, volcanic, and geophysical data, which can be used to distinguish strong crusts from weak crusts. We find 27 events for which lithospheric dripping is a key hypothesis, including 9 with clear evidence for strong‐crust dripping and 3 with clear evidence of weak‐crust dripping. We review emerging research methods have the potential to detect the signals of dripping in the geologic and geophysical record, and we suggest additional techniques in light of our strong‐crust versus weak‐crust framework. The diverse tectonic settings and inferred consequences of these lithospheric drips, if confirmed, would demand a shift in our understanding of continental geology to emphasize the role of vertical removal of continental lithosphere. Plain Language Summary: If part of the lithosphere (Earth's crust and the rigid upper part of the mantle) increases in density, it may become heavier than the underlying mantle and sink, or founder. Foundering results in the removal of blobs of lithosphere from overlying crust, a process called dripping. Dripping may have occurred in several locations across the globe, but the effects it is capable of producing are not well understood. We synthesize numerical models of dripping with studies of real‐world locations and compile available evidence to better understand the dripping process. We suggest that key observable effects are driven by the strength of the crust relative to the foundering lithosphere. In particular, when the crust is weak and able to flow in response to a lithospheric drip, complex patterns of deformation and sedimentation can result. For the 27 events that have been discussed to date, 9 have clear evidence for strong‐crust behavior, and 3 for a weak‐crust behavior. This framework will help researchers understand what lithospheric dripping looks like in geological and geophysical data, and we discuss avenues for further research on this topic. Key Points: Lithospheric dripping has been proposed for 27 locations throughout the globe and may be responsible for a wide range of observable effectsA synthesis of modeling studies suggests two distinct types of dripping depending on crustal strength relative to mantle lithosphereExisting data support the strong‐crust versus weak‐crust drip framework and suggest future research opportunities [ABSTRACT FROM AUTHOR]

Abstract Density instabilities in the lithosphere can founder gravitationally via viscous dripping and decoupling from overlying crust. The lithospheric dripping concept has been invoked across the globe, but the diversity of crustal effects, observable evidence, and tectonic settings involved in dripping remain underexplored. Here, we synthesize numerical and analogue modeling studies and geologic data from the literature, including all proposed lithospheric dripping events to‐date. We argue that two distinct styles of dripping can occur depending on crustal strength (relative to that of the mantle lithosphere). Near‐surface contraction and subsidence of strong crusts contrasts with near‐surface extension and uplift of weak crusts. We discuss these events in terms of tectonic setting, timing, size, and the main types of data associated with each event. We also find that lithospheric dripping is associated with a distinct suite of geological observations including sedimentological, structural, volcanic, and geophysical data, which can be used to distinguish strong crusts from weak crusts. We find 27 events for which lithospheric dripping is a key hypothesis, including 9 with clear evidence for strong‐crust dripping and 3 with clear evidence of weak‐crust dripping. We review emerging research methods have the potential to detect the signals of dripping in the geologic and geophysical record, and we suggest additional techniques in light of our strong‐crust versus weak‐crust framework. The diverse tectonic settings and inferred consequences of these lithospheric drips, if confirmed, would demand a shift in our understanding of continental geology to emphasize the role of vertical removal of continental lithosphere.

The study area is situated in the northern part of the Arabian Plate. The evolution of the Zagros Foreland basin is related to the compressional tectonic system at the beginning of the Tertiary Period. This study gives an adequate nomenclature for the Oligocene – Early Miocene Sequence is Missan Group. The Buzurgan Oilfield was chosen to represent the stratigraphic column corresponding to that period. These sediments were subdivided into two cycles, where each one ends by a sequence boundary, equivalent to the lowstand siliciclastic residues in the basin center. The first cycle, PaleoceneOligocene Epoch, was deposited marly limestone with planktonic foraminifera in the basin center during the transgressive and highstand conditions. The Lower Missan Group was deposited during the latest Oligocene lowstand conditions and overlaid the deep marine Oligocene sediments. The second cycle represented the Early Miocene Epoch (Aquitanian), by which the Euphrates Formation was deposited during the transgressive and high stand conditions and ended by the lowstand conditions sediments in the basin center as an Upper Missan Sandstone Member. These two cycles are conformably bounded by Lower Miocene (Jeribe Formation) and Oligocene (Tarjil Formation). [ABSTRACT FROM AUTHOR]

[Display omitted] • Understand the role of crustal blocks in the final configuration of the Central African Fold Belt. • Clarify some of the elements of correlation between Central Africa and NE Brazil. • Present a model of two subductions for the Central African Fold Belt north of the Congo craton. The Central African Fold Belt (CAFB) is the least well-known of all major Pan African belts. Here, we present new geochronologic work carried out in several critical areas of western Central African Republic, the region standing between northern Cameroon and southwestern Chad, and southern Cameroon. Our results allow us to: (1) clarify the regional extension of the Congo Craton in SE Cameroon and in the SW Central African Republic; (2) demonstrate that the units thrust along the northern edge of the Congo Craton from Cameroon to the Central African Republic are comparable in nature and in age; (3) better constrain the limits and described better the role of the Adamawa-Yadé crustal block during the Pan-African pre-collisional and collisional events in relation to the Congo Craton and the Yaoundé-Yangana nappe units to the South, and to the Poli-Leré magmatic arc to the North and; (4) clarify some of the elements of correlation with NE Brazil. Overall, a model involving two subduction zones is proposed to explain the evolution of the Pan-African belt north of the Congo Craton. The main steps include; (1) break-up and basin development from the early Tonian to at least 620 Ma on the northern edge of the Congo Craton, and on both the southern and the northern edges of the Adamawa-Yadé Block, concomitantly with the development of the Poli-Leré arc in northern Cameroon and Chad; (2) pre-tectonic plutonism in all domains since c. 800 Ma with culmination between 650 and 620 Ma; (3) collisional events starting around 620 Ma with metamorphism reaching the granulite facies at c. 600 Ma in all the domains; (4) nappe tectonics with thrusting of the Yaoundé-Yangana units onto the Congo Craton, accretion of the Poli-Leré arc to Adamawa-Yadé Block, and widespread syntectonic magmatism (600–580 Ma) with emplacement partly controlled by transcurrent regional shear zones, and emplacement of post-tectonic granitoids (c. 550 Ma) in both Adamawa-Yadé block and Poli-Leré magmatic arc. Collisional and post-collisional (620–550 Ma) events were synchronous along the entire belt from Central Africa to Brazil. [ABSTRACT FROM AUTHOR]

Understanding active tectonics and seismicity in extensional settings requires the analysis of high‐angle normal faults (HANFs) and the transfer of deformation at depth. The debate surrounds the role of low‐angle normal faults (LANFs) in triggering high magnitude earthquakes. The central Betic Cordillera is an active seismic zone affected by the NNW‐SSE Eurasia‐Nubia convergence and orthogonal extension. The seismicity and present‐day stress determined by earthquake focal mechanisms reveals the activity of a NE‐SW extensional system in the shallowest 12 km of the Granada Basin. The structure of the sedimentary infill, as derived by geological field and gravimetric techniques, suggests the formation of a half‐graben tilted to the N‐NE. Seismologic data suggest the activity of HANFs above 6–7 km depth and a LANF zone around 6–12 km depth, with related earthquakes of up to Mw 4.0 and 20° to 30° fault dips. High‐precision leveling lines highlight the importance of the Granada Fault in the system, with average vertical displacement rates of 0.35–1.1 mm/yr. These data suggest creep fault behavior at the surface and increased seismicity at depth. The upper crustal extension in the collisional Betic Cordillera is accommodated by a top‐to‐the‐WSW extensional detachment related to westward motion and rollback in the Gibraltar Arc and the gravitational collapse of the cordillera, in a framework of NNW‐SSE shortening. This comprehensive study draws a new scenario that advances understanding of relationships between HANFs and LANFs. Key Points: Gravimetric data highlight the geometry of the sedimentary infill of the Granada Basin, which constitutes a half‐graben tilted to the N‐NEGranada Basin's high‐angle normal faults might be linked at depth to an active low‐angle extensional deformation zoneThe active Granada Fault zone shows low‐magnitude seismicity and a current average vertical rate that varies from 0.4 to 1.1 mm/yr [ABSTRACT FROM AUTHOR]

The Hartha Formation is one of the important formations deposited during Late Campanian age. The present study deals with four boreholes (EB-53, 54, 55 and 56) within the East Baghdad oil field to diagnoses the microfacies and interpret the depositional environments. Six major microfacies were recognized in the succession of the Hartha Formation. Their characteristic grain types and depositional texture enabled the recognition of paleoenvironment. There are Orbitoides wackestone-packstone, Orbitoides - miliolid wackestone, Peloidal and Pellets - echinoderm wackestone to packstone, Peloidal wackestone to packstone, Pelletal wackestone to packstone, and Planktonic foraminifera wackestone-packstone. Four associations’ facies were recognized in this succession, which are shallow open marine, deep open marine, semi-resricted, and restricted. The distribution of these associations led to the recognition of three major depositional stages in the studied succession. The first stage is represented by the semi-restricted facies within the lower part of the Hartha Formation, which is characterized by Orbitoides - miliolid wackestone to the northwest direction and developed to shallow open marine and deep marine to the southeast direction. In the second stage, the sea level was rising to deposit the deep open marine facies represented by planktonic foraminifera wackestonepackstone microfacies above the semi-restricted facies,where the succession became characterized by Peloidal and Pellets - echinoderm wackestone to packstone microfacies of restricted association. The third stage is represented by the continuation of sea level rise. This caused the building of carbonate ramp of Shiranish Formation above the shallow open marine of Hartha Formation with conformable surface. [ABSTRACT FROM AUTHOR]

The opening and evolution of the Western Carpathians Miocene basins was closely related to the north-eastward tectonic extrusion of the ALCAPA Mega-Unit lithosphere caused by the final stage of collision of the Eastern Alpine–Western Carpathian orogenic system with the European Platform and Alpine convergence with the Adria plate. The roll back effect of the oceanic or thinned continental crust of the Magura–Krosno realms, subduction below the front of the Carpathians in the north-east, east and relative plate velocities led to gradual stretching of the overriding micro-plates (defined as the ALCAPA and Tisza Dacia Mega-Unit). Diverse movement trajectories of the ALCAPA crustal wedge individual segments (Eastern Alps, Western Carpathians, and Northern Pannonian domain) were accompanied by several counter-clockwise rotational phases. Beside the interpreted Early Miocene “en-block” counter-clockwise rotation, most of the rotations in the Central Western Carpathians were caused by “domino-effect tectonics” inside strike-slip zones and took part in the basin opening, which was in most cases followed by rapid subsidence.

North China Craton experienced significant lithospheric destruction or delamination during the Late Mesozoic, accompanied with the emergence of numerous basins and intensive volcanism. Extensional basins also formed in East Shandong Province. Even though they have been studied for decades, the relationship between basin development and tectonic processes still remains obscure. Recently, a set of Early Cretaceous strata has been found in Lingshan Island. It is characterized by translating from turbidite deposits to terrestrial strata units and ending up with a unique volcaniclastic layer within a relatively short time span. Previous studies have reached an agreement that Lingshan Island strata are formed in a distinct sedimentary background compared with the coeval sedimentary units in Jiaolai Basin. Essential information about basin development and its tectonic setting in this region during Early Cretaceous are preserved in Lingshan Island strata. In this study, it shows the characteristics of heavy mineral assemblage and the characteristics of detrital minerals' chemical component in the two representative samples. Based on these studies, it indicates that Lingshan Island Basin was developed in a transpressional tectonic setting with complex source materials, mainly from Qianliyan Uplift during the period ca. 123–120 Ma. Then, the basin evolved within an extensional setting and was filled with locally derived clastics during 120 to 105 Ma. In addition, the basin evolved during the process of progressive lithospheric thinning and asthenosphere upwelling. [ABSTRACT FROM AUTHOR]

Abstract The Wuhai Basin is located in the northwestern corner of the Ordos Block. Analyzing the geometry, along with the kinematic and dynamic characteristics of the boundary fault, the Zhuozishan West Piedmont Fault (ZWPF), will elucidate the regional tectonic environment and guide earthquake prevention and disaster reduction projects. Six representative sites were selected for topographic measurements, from the northern, middle and southern parts. Displacements of the ZWPF were calculated by measuring the top surface elevation of a widely distributed lacustrine layer in the footwall from outcrops at each site, and from boreholes in the hanging wall. The vertical slip rate of the ZWPF was then calculated based on the displacement and age of the lacustrine layer. Three to four normal fault-controlled terraces have developed on the footwall of the ZWPF, and the top surface of the lacustrine layer is at 1092–1132 m elevation. Data from boreholes showed that the top surface of the lacustrine layer is at an elevation of 1042–1063 m in the hanging wall. Vertical slip rates since 70 ka were estimated as 0.5 ± 0.2 to 1.0 ± 0.2 mm/a. The highest rate of vertical slip was observed at Fenghuang Ridge, in the central part of the fault system, and decreased to the south. In the northern Wuhai Basin, normal faulting still controls the piedmont landscape. However, NW-SE trending reverse faults and secondary folding have resulted from dextral strike-slip movement of the fault. The Wuhai Basin developed as a dextral-tensional negative flower structure. This study indicates that stress conditions of the northwestern margin of the Ordos Block include NE–SW compression and NW–SE extension, and an S-shaped rift zone has dominated the scale, structure, and evolution of the Yinchuan, Wuhai, and Hetao Basins, along with the active mode of faulting in these basins. Highlights • Vertical slip rates between 0.5 ± 0.2 and 1.0 ± 0.2 mm/a were calculated for the ZWPF. • The ZWPF has a larger strike-slip rate, resulting in development of reverse faults. • The Wuhai Basin has developed a dextral- tensional negative flower structure. • Stress conditions and S-shaped distribution dominate the development of basins. [ABSTRACT FROM AUTHOR]

Kong Karls Land, easternmost in the Svalbard archipelago, displays a 300 m-thick Upper Triassic (Norian) to Lower Cretaceous (Aptian) succession. The islands are situated within a set of large-scale, NE-SW-trending folds. The sediments are poorly consolidated as a result of relatively shallow burial. Lower Cretaceous plateau lavas and sills cap the islands and have protected older strata from extensive Pliocene and Pleistocene erosion. Correlation between onland exposures and subsea seismic units shows that Kong Karls Land is a key reference area for the Late Triassic to Early Cretaceous development of the northern Barents Sea shelf, but also to the southwestern Barents Sea. The unique exposed succession can be correlated with nearby offshore data, enabling the recognition of key sequence stratigraphic surfaces which define major tectonic events. These enable subdivision of the succession into six tectonic megasequences (TMS 1 to TMS 6) of latest Permian to Early Cretaceous age. The TMS 1 is linked to denudation of the Uralian orogen and includes most of the northwestward prograding Triassic coastline in the northwestern Barents Sea and eastern part of Svalbard. The 200 m-thick estuarine to shoreface deposits of the Rhaetian to Pliensbachian TMS 2 in Kong Karls Land stands in contrast to the 5 to 20 m-thick condensed succession with numerous hiatuses in western Spitsbergen. This significant difference is suggested to be a response to an evolving foreland basin linked to the northern Barents Sea Basin and Novaya Zemlya Fold and Thrust Belt. The four youngest tectonic megasequences are represented by only thin remnants onshore and on the adjacent platform. Outcrop mapping and seismic profiles show high-amplitude weak folding in the Late Jurassic followed by Early Cretaceous reactivation, prior to deposition of the Helvetiafjellet Formation. The volcanism in Kong Karls Land is related to the High Arctic Large Igneous Province and opening of the Amerasian Basin, which resulted in uplift of the northern Barents Shelf and southwards tilting of the Svalbard Platform. [ABSTRACT FROM AUTHOR]

The present study is focused upon the sedimentology and basin development of the Jeribe and Fatha Formations by using the field observations and microfacies analysis. The area of study situated in the Zurbatiyah area to the south of the Shur sharin valley about 21 km northeast of Badrah city to the southeast of Baghdad. This area lies within the Zagros foreland basin, and located between the Zagros mountains at the northeastern and the Arabian shield at the southeastern. The studied succession which including the Jeribe and Fatha Formations were deposited within four associated facies for the Jeribe Formation and three for the Fatha Formation, as shown below: - Jeribe Formation includes dolomitized mudstone-wackstone (semi restricted); Milliolid wackestone-packstone (shallow open marine), Dolomitic packstone (lagoon). Fatha Formation includes pelecypods bioclastic wackestone-packestone (lagoon); peloidal bioclastic packstone (lagoon); massive gypsum (evaporitic lagoon); laminated gypsum (supratidal and evaporitic lagoon) The facies analysis for the studied succession showing two stages of deposition:- The first stage is represented the final transgression stage in the studied area. The fall sea level gradationally appeared by shallowing up-ward and more dolomitized upward from the middle part of the Jeribe Formation. The second stage the deposition was started when the first beds gypsum and anhydrite is appeared for the Fatha Formation refer to the restricted and supratidal environment. The uplifted of the eastern and northeastern parts of Iraq generate a tectonic depositional ridge to the west and northwestern resulted in the formation of restricted basins and regional regression in the Arabian plate. [ABSTRACT FROM AUTHOR]

Abstract: The complete natural drainage in 2008, 2011, and 2012 of Mountain Lake in Giles County, Virginia, allowed detailed observations of the only natural lake basin in the southern Appalachian Mountains. Here we use these observations to support geomorphic analysis and develop a model of basin evolution, which may advance the understanding of rare flow‐through lakes with subsurface drainage elsewhere. Key features included (a) an angle‐of‐repose slope with a smoothly concave planform across the entire 260 m width of the north end of the basin, (b) an arc of steep‐sided depressions along the deep northern margin of the basin floor, and (c) an abrupt transition between colluvial and finer‐grained sedimentary deposits on the floor. Our geomorphic analysis suggests that subsurface erosion has enabled long‐term northward scarp retreat in the basin by removing water and sediment. Mountain Lake formed on the northern limb of a breached anticline along the Eastern Continental Divide, where strong‐over‐weak stratigraphy and a small watershed have enabled the basin to evolve generally as follows. (1) Pond Drain, a first‐order tributary of the New River, incised north‐dipping sandstones and underlying shales on the northern limb of the anticline. The valley floor subsequently accumulated meters to tens of meters of mostly late Pleistocene colluvial fill. (2) Subsurface drainage developed likely along the contact between the sandstones and shales, facilitated by pre‐existing fractures. (3) Ongoing subsurface erosion has progressively undermined the sandstone, causing scarp retreat along the northern margin of the basin while a surface stream intermittently incised the shallow southern end. Sedimentary deposits indicate that only the deeper northern portion of the basin is usually flooded under Holocene conditions. Our basin evolution model suggests slow development of the basin over hundreds of thousands of years rather than sudden damming by a catastrophic landslide. Copyright © 2018 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The South China Sea (SCS) is one of the classical example of a non-volcanic passive margin situated within three tectonic plates of the Eurasian, Indo-Australian and Philippine Sea plate. The development of SCS resulted from interaction of various types of plate boundaries, and complex tectonic assemblage of micro blocks and accretionary prisms. Numerous models were proposed for the formation of SCS, yet none can fully satisfy different aspects of tectonic forces. Temporal and geographical reconstruction of Cretaceous and Cenozoic magmatism with the isochrones of major basins was conducted. Our reconstruction indicated the SE margin of Asia had gone through two crustal thinning events. The sites for rifting development are controlled by localized thermal weakening of magmatism. NW-SE extension setting during Late Cretaceous revealed by magmatism distribution and sedimentary basins allow us to allocate the retreated subduction of Pacific plate to the cause of first crustal thinning event. A magmatic gap between 75 and 65 Ma prior to the initiation of first basin rifting suggested a significant modification of geodynamic setting occurred. The Tainan basin, Pearl River Mouth basin, and Liyue basins started to develop since 65 Ma where the youngest Late Cretaceous magmatism concentrated. Sporadic bimodal volcanism between 65 and 40 Ma indicates further continental extension prior to the opening of SCS. The E-W extension of Malay basin and West Natuna began since late Eocene followed by N-S rifting of SCS as Neotethys subducted. The SCS ridge developed between Pearl River Mouth basin and Liyue basin where 40 Ma volcanic activities concentrated. The interaction of two continental stretching events by Pacific followed by Neotethys subduction with localized magmatic thermal weakening is the cause for the non-volcanic nature of SCS. [ABSTRACT FROM AUTHOR]

[Display omitted] • Genesis of breccias in the Central Africa Copperbelt is complex and often results of multiple superimposed tectonic processes during the fold-and-thrust Lufilian orogeny. • Lufilian orogeny caused the fracturation and brecciation in the Katanga Supergroup. • Breccias play a major role in the syn -orogenic ore-forming process of the world-class sediment-hosted Cu-Co. • Sedimentary breccia formed during the rifting stage of the Neoproterozoic Katanga basin. • Breccias related to glacio-volcanic, hydrofracturing, dissolution and collapse processes also occur. The Katanga Supergroup, host of several world class Neoproterozoic sediment-hosted stratiform copper and cobalt deposits, is part of the Central Africa Copperbelt (CACB). The origin and classification of the breccia, which is one of the most characteristic features of the Katanga Supergroup, has been a matter of discussion since the 19th century. Different nomenclatures and various classifications have been used in the mining operations across the CACB. The difficulty to identify genetically related types of breccia creates some problems in regional correlations and comparisons. In addition, their origin is most relevant for the metallogenesis of the world-class copper and cobalt sediment-hosted deposits. This paper classifies the breccia according to their characteristics, reviews the mechanisms of brecciation, and thus addresses their origin, and highlights their potential in metal resources. The different types of breccias found in CACB include sedimentary breccia (gravity flow, sedimentary breccia stricto sensu), dissolution and collapse breccia, hyaloclastite breccia, hydraulic breccia and tectonic breccia (thrust-breccia and fault breccia). The spatial and chronological distribution of these breccias in the CACB follows the geodynamic history of the area starting from early Neoproterozoic rifting up to the Lufilian orogeny and post-Lufilian tectonism. [ABSTRACT FROM AUTHOR]

The architecture of Middle to early Late Triassic carbonate platforms in the eastern Lombardian Alps is analysed following the accommodation and supply concept. This allows proposing a new sequence stratigraphic scheme. The selected study area can be seen as an earth sciences lab where in a relatively small area distinct synsedimentary tectonics in combination with global sea-level fluctuations caused pronounced differences in basin evolution, leading to repercussions in the carbonate platform development from the Anisian to the Carnian. A base-level fall in the Pelsonian favoured in the area of a long-lasting topographic high and shortly after the Permian- Triassic crisis of carbonate platforms the growth of the first in a cycle of carbonate build-ups, the Camorelli Bank. Slow subsidence combined with high carbonate production caused strong progradation of this carbonate bank. The Calcare di Camorelli is followed later but in the same area by the Pora Platform succession. This underlines that palaeotopography and related subsidence was an important mechanism for platform growth in the area. The well-dated base-level rise at the Pelsonian/ Illyrian boundary caused platform flooding and the change to the marly Prezzo Fm (shallow basinal facies) and nodular- cherty Buchenstein Fm (deep basinal facies). In the early Longobardian, base-level fell gradually and the slow subsequent base-level rise triggered the growth of four carbonate platforms in the study area attributed to the Esino Fm: the Pora, Concarena, Pizzo Camino and Presolana platforms. In this paper, the results from detailed sequence stratigraphic studies from the Pora and Concarena area are presented. The cycle of carbonate platforms attributed to the evolution of the Esino Fm led to formation of a much thicker platform and slope succession compared to the preceding Camorelli platform cycle. This development can be best studied at the Concarena area. Initially, an aggradational to weak progradational pattern can be observed, indicating strong subsidence combined with high carbonate production. The lagoonal upper part of the Concarena platform shows much reduced cyclethicknesses compared with the cycles of the preceding platform stage, combined with strong progradation of the platform slope. At its top, only the Pora Platform shows distinct emersion features, due to a base-level fall and underpinning the position on a local structural high, in contrast to the Concarena, which had somewhat higher subsidence rates and do not show signs of emersion. [ABSTRACT FROM AUTHOR]

We investigated a palynological section from middle Miocene sediments at Eskihisar (south-western Anatolia) to establish biogeographic links of the palynoflora and to infer the palaeoenvironment. Four algal palynomorphs, nine spore taxa, eight gymnosperms, three monocots and 67 dicot pollen types were encountered and investigated using the 'single grain method' that combines light microscopy and scanning electron microscopy. Two pollen zones reflect different phases of basin development. Zonal vegetation remained fairly stable across the section and reflects heterogeneous environments including broad-leaved deciduous forest, subtropical forest and sclerophyllous and semi-evergreen oak forest. Conifers were accessory elements in the broad-leaved deciduous forest communities and replaced these at higher elevations. Some herbaceous taxa (Plumbaginaceae) indicate scattered occurrences of sandy and/or rocky soils. Biogeographic affinities are general Northern Hemisphere, North American and East Asian, as also suggested by the macrofossil record. Only two taxa provide potential biogeographic links with the African flora. This suggests that biome shifts of plant taxa between African subtropical/tropical biomes and Anatolian (western Eurasian) temperate forests and shrublands may have been rare in the middle Miocene. [ABSTRACT FROM AUTHOR]

A complete updated and revised lithostratigraphic scheme for the Jurassic succession of the onshore and offshore Danish areas is presented together with an overview of the geological evolution. The lithostratigraphies of Bornholm, the Danish Basin and the Danish Central Graben are described in ascending order, and a number of new units are defined. On Bornholm, the Lower-Middle Jurassic coal-bearing clays and sands that overlie the Lower Pliensbachian Hasle Formation are referred to the new Sorthat Formation (Lower Jurassic) and the revised Bagå Formation (Middle Jurassic). In the southern Danish Central Graben, the Middle Jurassic succession formerly referred to the Lower Graben Sand Formation is now included in the revised Bryne Formation. The Lulu Formation is erected to include the uppermost part of the Middle Jurassic succession, previously referred to the Bryne Formation in the northern Danish Central Graben. The Upper Jurassic Heno Formation is subdivided into two new members, the Gert Member (lower) and the Ravn Member (upper). The organic-rich part of the upper Farsund Formation, the former informal `hot unit', is established formally as the Bo Member. Dominantly shallow marine and paralic deposition in the Late Triassic was succeeded by widespread deposition of offshore marine clays in the Early Jurassic. On Bornholm, coastal and paralic sedimentation prevailed. During maximum transgression in the Early Toarcian, sedimentation of organic-rich offshore clays took place in the Danish area. This depositional phase was terminated by a regional erosional event in early Middle Jurassic time, caused by uplift of the central North Sea area, including the Ringkøbing-Fyn High. In the Sorgenfrei-Tornquist Zone to the east, where slow subsidence continued, marine sandy sediments were deposited in response to the uplift. Uplift of the central North Sea area was followed by fault-controlled subsidence accompanied by fluvial and floodplain deposition during Middle Jurassic time. On Bornholm, deposition of lacustrine muds, fluvial sands and peats dominated. The late Middle Jurassic saw a gradual shift to shallow marine deposition in the Danish Central Graben, the Danish Basin and Skåne, southern Sweden. During the Late Jurassic, open marine shelf conditions prevailed with deposition of clay-dominated sediments while shallow marine sands were deposited on platform areas. The Central Graben received sand by means of sediment gravity flows. The clay sediments in the Central Graben became increasingly rich in organic matter at the Jurassic-Cretaceous transition, whilst shallow marine coarse-grained deposits prograded basinwards in the Sorgenfrei- Tornquist Zone.

In the Late Jurassic to Early Cretaceous palaeogeography of the Alpine Tethys the term Ocean is used for different parts of these sedimentary areas: eg. Ligurian - Piedmont and Penninic, Magura, Pieniny, Valais and Ceahlau-Severins oceans. The Magura Ocean occupied the more northern position in the Alpine-Carpathian arc. During the Late Cretaceous-Paleogene tectono-sedimentary evolution the Magura Ocean was transformed into several (Magura, Dukla, Silesian, sub-Silesian and Skole) basins and intrabasinal source area ridges now incorporated into the Outer Western Carpathians. [ABSTRACT FROM AUTHOR]

The validity of the history of basin development in the east of Greymouth Coalfield, as broadly accepted for the past 60 years, is examined through reinterpretation of the structure and stratigraphy. Rather than a Late Cretaceous–Paleocene fault-angle basin (extensional half-graben) west from the Mount Davy Fault Zone, a downwarping basin extended across the location of that future fault zone. This basin developed within regionally extensive deposition of Late Cretaceous sediments. Uplift and erosion in the east was followed by the development of an Eocene fault-angle basin extending from the Montgomerie Fault west across the developing Mount Davy Fault Zone. A thick Miocene sequence accumulated in the Grey Valley Trough to the east, and a thinner sequence is inferred to have covered the whole coalfield. Inversion in the coalfield, rather than being intermittent throughout the whole Palaeogene, began c. 4.5 Ma ago with development of the Brunner Anticline and reversal of movement on both the Mount Davy Fault Zone and the Montgomerie Fault. [ABSTRACT FROM PUBLISHER]

The Qamchuqa succession in this study is represented by the Upper Qamchuqa, Jawan, Upper Sarmord and Lower Qamchuqa formations which were deposited during the Early Aptian Late Albian within the Zagros foreland basin. Petrographic study and microfacies analysis enabled the recognition of six main paleoenvironments. These are the shallow restricted, shallow semi-restricted, shallow open marine, shoal, deep outer ramp and deep basinal environments. The study succession represents the deposition of four third-order cycles; these cycles were deposited during successive episodes of relative sea level rises and still stand. The Lower Qamchuqa basin in the study area stretched from the southwest to the northeast with its deepest parts with high rate of subsidence and accumulation located to the north near well Kirkuk-117 and in the center near Bi Hassan-13, Khabaz-5, Kirkuk-109, -130, -229, and −260; and to the Southeast in well Jambour-13 and −15. The Upper Sarmord depocenter was located in the northeast near well Taq taq-1, with the general direction of southwest-northeast. The rates of subsidence and accumulation were high, where accommodation rates matched accumulation rates. The Jawan basin is extended in the west of the studied area with two depocenters; the first is extended from Makhul oil fields to the Northern Bi Hassan oil fields and the second in the Northwestern part in well Najmah-29 and surrounding area. These areas were characterized by high rates of subsidence and accumulation. The Upper Qamchuqa basin stretched from Southwest to Northeast with its deepest parts located at wells Ajeel-8 and Jambour-13. The high thickness values in depocenters of the Upper Qamchuqa formation reflect the high rates of subsidence and accumulation. [ABSTRACT FROM AUTHOR]

• We provide geochronological constraints on the tectonothermal evolution of the Kiruna mining district in northern Sweden. • Basin development at 1887 ± 3 Ma. • Syn-volcanic faulting at 1889 ± 26 Ma coeval with iron ore emplacement and associated hydrothermal alteration. • Burial and upper greenschist facies conditions and subsequent cooling due to tectonic exhumation at 1805 ± 26 Ma. • Basin inversion at 1812 ± 3 Ma during a protracted tectonothermal event that may have lasted up to c. 20 m.y. The basin inversion coincides with the regional D2 event in northern Norrbotten. To constrain the tectonothermal evolution of the type locality for iron oxide-apatite deposits, we have obtained U-Pb zircon, titanite, and apatite age data for the Kiruna mining district in northernmost Sweden. The results indicate that the host basin initiated in an overall extensional regime as indicated by the deposition of alluvial conglomerates and greywackes. A volcanic intercalation in a conglomerate unit approximately 1 km northwest of the Luossavaara iron oxide-apatite deposit yields a U-Pb zircon concordia age of 1887 ± 3 Ma representing the timing of the earliest Orosirian volcanism in the central Kiruna mining district coinciding with the onset of basin development. In-situ analysis of titanite sitting on hydrothermally altered fracture planes within a cataclastic fault damage zone (c. 270 m from the fault core system associated with the Luossavaara iron oxide-apatite deposit) yields complex U-Pb data. Applying a strict discordance filter yields seven analyses (<1.5 % relative discordance which included six common Pb-corrected analyses and one analysis where no significant common Pb was detected) that yield a 207Pb/206Pb weighted average age of 1889 ± 26 Ma that we interpret as the most probable minimum age of fault initiation. The overlap in age of the host volcanic rock and the fault implies that during basin development, contemporaneous volcanism and syn -volcanic faults may have played an important role during iron ore emplacement. A U-Pb lower intercept age of apatite from the Nukutus iron oxide-apatite deposit provides a first indication that the area was subsequently buried and metamorphosed under upper greenschist-facies conditions and later tectonically exhumed and cooled below the apatite closure temperature at 1805 ± 26 Ma. Further temporal constraints on exhumation and basin inversion is given by syn -tectonic titanite along a brittle-ductile reverse shear zone to the east of the study area that shows limited presence of significant common Pb and is part of a sodic-calcic + Fe + Cl hydrothermal alteration assemblage. Titanite grains that show a well-developed zonation yield a U-Pb concordia age of 1812 ± 3 Ma, which we interpret as the onset of basin inversion. Titanite grains from the same sample that show less pronounced zonation yield a U-Pb concordia age of 1802 ± 8 Ma, tentatively indicating that the tectonothermal activity lasted up to c. 20 m.y. [ABSTRACT FROM AUTHOR]

The Leitha Mountains in Austria are a chain of hills separating the southern Vienna Basin and the Danube Basin. The Lower East Alpine basement of the Leitha Mts. is covered by Middle Miocene sediments of the Badenian and Sarmatian regional stages. Close to the northeastern margin of these hills, upper Badenian successions are exposed, which are part of a coralline algal-dominated carbonate platform with hydrodynamically influenced sediments. Six sections have been logged and subjected to detailed investigation and sampling. They are characterized by inclined beds (foresets), which have been formed by unidirectional transport of sediments. Large-scale asymmetrical ripples indicate strong currents affecting shallow topset deposits. Generally, this hydrodynamically controlled sedimentation, documented by seven facies types, is reflected in a strongly reduced diversity of facies and biota, contrary to the older facies-rich middle Badenian sediments. This change from biologically to hydrodynamically controlled sedimentation led to a reduction in diversity of facies and biota. Sediment transport, however, caused secondary mass occurrences of echinoids or foraminifers derived from seagrass meadows. This study unravels the distribution and differences of middle and upper Badenian deposits of the Leitha Mountains and the influence of tectonic activity. Changes in hydrodynamics on the Leitha Platform are linked to the formation of the Danube Basin starting in the middle Badenian when a new seaway to the southeast has started to form. [ABSTRACT FROM AUTHOR]

The Chaco--Paraná Basin was initiated during the late Oligocene as a result of shortening in response to Nazca--South America plate convergence, which produced a fold and thrust belt in the backarc region of the Central Andes. Foreland basins are the result of the flexural isostatic response of an elastic plate to orogenic and/or thrust sheet loading. We carried out flexural modeling along a W--E profile (22.5°S) to determine flexural, crustal, and Chaco--Paraná foreland basin development using available information on ages, elastic and sedimentary thicknesses, topographic and structural histories. We also developed a 3D flexural model, considering present day topography and elastic thickness values, in order to assess the possible existence of major differences with 2D models. It is possible to reproduce present day elevation, gravity anomaly, Moho depth, elastic thicknesses, foreland sedimentary thicknesses and the basin geometry. The 2D modeling also permits to reproduce foreland sedimentary thicknesses documented at 10Ma and 12Ma. The new results indicate that any decrease of the elastic thickness beneath the Eastern Puna--Eastern Cordillera would have occurred during the 14--12/10Ma interval, suggesting a major change in the thermal state of the lithosphere during such time span. Coincidently, other authors determined the occurrence of a rapid elevation increase of the Southern Altiplano/Eastern Cordillera at 13--9Ma, possibly related to piecemeal removal of lower lithosphere. In spite of the numerous limitations and simplifications mentioned above, our flexural model has shown to be a useful tool for the better understanding of the relationships between the development of the Chaco--Paraná foreland basin and the spatiotemporal evolution of the Andean orogen. [ABSTRACT FROM AUTHOR]

The Fenghuoshan Group marks the initiation of terrestrial deposition in the Hoh Xil Basin and preserves the first evidence of uplift above sea level of northern Tibet. The depositional age of the Fenghuoshan Group is debated as are the stratigraphic relationships between the Fenghuoshan Group and other terrestrial sedimentary units in the Hoh Xil Basin. We present new radiometric dates and a compilation of published biostratigraphic data which are used to reinterpret existing magnetostratigraphic data from the Fenghuoshan Group. From these data, we infer an 85-51 Ma depositional age range for the Fenghuoshan Group. U-Pb detrital zircon age spectra from this unit are compared to age spectra from Tibetan terranes and Mesozoic sedimentary sequences to determine a possible source terrane for Fenghuoshan Group strata. We propose that these strata were sourced from the Qiangtang Terrane and may share a common sediment source with Cretaceous sedimentary rocks in Nima Basin. Field relationships and compiled biostratigraphic data indicate that the Fenghuoshan and Tuotuohe Groups are temporally distinct units. We report late Oligocene ages for undeformed basalt flows that cap tilted Fenghuoshan Group strata. Together, our age constraints and field relationships imply exhumation of the central Qiangtang Terrane from the Late Cretaceous to earliest Eocene, followed by Eocene-Oligocene deformation, and shortening of the northern Qiangtang and southern Songpan-Ganzi terranes. Crustal shortening within the Hoh Xil Basin ceased by late Oligocene time as is evident from flat-lying basaltic rocks, which cap older, deformed strata. [ABSTRACT FROM AUTHOR]

The Neogene succession in the studied area is represented by seven formations (Serikagni, Euphrates, Dhiban, Jeribe, Fatha, Injana, and Muqdadiya formations). The area of study is located in the Unstable Shelf within the Low Folded Zone and the north part of the Stable Shelf (Mesopotamian Zone). This study included the geohistory analysis of the Neogene succession and interpretation the changes of the accumulation and subsidence rates and compared them with the space available to explanation the basin development. At The Early Miocene (Aquitanian age), the Sirekagni and Euphrates formations was deposited during a major transgression with high rates of subsidence and accumulation in the Himreen, Makhul, and north of Tigris subzones, while the Chemchemal-Arbil and Butmah-Mosul subzones were positive areas. This period ended with a sea withdrawal to the southeast to generate the Dhiban lagoonal basin which was characterized by low accumulation and subsidence rates. During the Early Burdigalian, the Jeribe Formation was deposited during another sea level rise that covered the area except the Chemchemal-Arbil and Butmah-Mosul subzones representing the uplifted positive area. The sea level rise continued to the early Langhian age where the transition beds for the Fatha Formation was deposited to mark the maximum flooding surface covering all the study area. The Fatha Formation was deposited at the Late Langhian to the Early Serravallian during sea level stillstand with high accumulation and subsidence rates in the Himreen subzone and the Chemchemal-Arbil subzone. This period ended without a clear tectonic activity. The period from Late Miocene to Pliocene was characterized by high tectonic activity and sea level fall where fluvial-lacustrine environment prevailed to deposit the Injana and Muqdadiya formations. The Injana Formation was deposited during the Late Serravallian-Tortonian in the Himreen and Chemchemal-Butmah subzones; in addition to the northern part of Tigris subzone. The areas of high rates of accumulation and subsidence were located near Jambour while the southwestern part was affected by an uplift generating the Himreen structure. The Chemchemal-Butmah subzones was characterized by a high uplift in the southeast part where Kirkuk and Chemchemal structures were forming, while The northeastern part (from Bi Hassan to the borehole Kirkuk-117) was with low accumulation and subsidence rates. The linear region between these parts (Khabaz oil field) showed an abnormal values for accumulation and subsidence rates (very high); this region corresponds to the location and direction of Anah-Fatha-Qalat Dizah Fault which suggest that the fault was active during that time. The tectonic activity continued to uplift all the north of the study area as well as the West and the East during the Late Tortonian to the Piacenzian where the Muqdadiya Formation was deposited in the area between Jambour to Khabaz oilfields. Then the succession was deformed and uplifted to approximately 800 m above the sea level as in the present day. [ABSTRACT FROM AUTHOR]

Abstract: We integrated a systematic sedimentary data into a regional Early Mesozoic stratigraphic framework which demonstrated a detailed picture of spatiotemporal variations in basin deposition and formation in the North China Craton. The Early Mesozoic basin sedimentary evolution is utilized to interpret polyphase tectonism and to unravel the craton deformation. The Late Triassic, nearly WNW-trending, giant intracratonic Ordos basin was widely distributed across most of North China Craton, with a southern wedge-top depozone along the northern East Qilian–Qinling orogenic belt and a northwestern rift depozone along the Helanshan. The continuous subsidence and deposition within the basin were dominantly related to the thrust load of the East Qilian–Qinling belt and inferred mantle flow effects associated with paleotethys plate subduction, and the rift in the northwestern Ordos was driven by nearly north-vergent compression of the eastern North Qilian–North Qinling active margins with the stable North China Craton. This intracratonic Ordos basin formation initiated the deformation of the North China Craton. Formation of the Jurassic NNE-trending walled intracratonic Ordos basin and the broken flexural basins indicates the North China Craton underwent the second, even more abroad nearly NNE trending crustal deformation, with lithosphere thickening in the eastern part of the North China Craton, and dynamic subsidence in the west, which may have been driven by nearly northwestward subduction of the Izanagi plate and the eastward extrusion and underthrusting of the western North China Craton crustal basement. [Copyright &y& Elsevier]

Abstract: The Campos, Santos and Pelotas basins have been investigated in terms of 2D seismo-stratigraphy and subsidence. The processes controlling accommodation space (e.g. eustacy, subsidence, sediment input) and the evolution of the three basins are discussed. Depositional seismic sequences in the syn-rift Barremian to the drift Holocene basin fill have been identified. In addition, the subsidence/uplift history has been numerically modeled including (i) sediment flux, (ii) sedimentary basin framework, (iii) relation to plate-tectonic reconfigurations, and (iv) mechanism of crustal extension. Although the initial rift development of the three basins is very similar, basin architecture, sedimentary infill and distribution differ considerably during the syn-rift sag to the drift basin stages. After widespread late Aptian–early Albian salt and carbonate deposition, shelf retrogradation dominated in the Campos Basin, whereas shelf progradation occurred in the Santos Basin. In the Tertiary, these basin fill styles were reversed: since the Paleogene, shelf progradation in the Campos Basin contrasts with overall retrogradation in the Santos Basin. In contrast, long-term Cretaceous–Paleogene shelf retrogradation and intense Neogene progradation characterize the Pelotas Basin. Its specific basin fill and architecture mainly resulted from the absence of salt deposition and deformation. These temporally and spatially varying successions were controlled by specific long-term subsidence/uplift trends. Onshore and offshore tectonism in the Campos and Santos basins affected the sediment flux history, distribution of the main depocenters and occurrence of hydrocarbon stratigraphic–structural traps. This is highlighted by the exhumation and erosion of the Serra do Mar, Serra da Mantiqueira and Ponta Grossa Arch in the hinterland, as well as salt tectonics in the offshore domain. The Pelotas Basin was less affected by changes in structural regimes until the Eocene, when the Andean orogeny caused uplift of the source areas. Flexural loading largely controlled its development and potential hydrocarbon traps are mainly stratigraphic. [Copyright &y& Elsevier]

Abstract: The Chaco foreland basin was initiated during the late Oligocene as a result of thrusting in the Eastern Cordillera in response to Nazca–South America plate convergence. Foreland basins are the result of the flexural isostatic response of an elastic plate to orogenic and/or thrust sheet loading. We carried out flexural modelling along a W–E profile (21.4°S) to investigate Chaco foreland basin development using new information on ages of foreland basin strata, elastic and sedimentary thicknesses and structural histories. It was possible to reproduce present-day elevation, gravity anomaly, Moho depth, elastic thicknesses, foreland sedimentary thicknesses and the basin geometry. Our model predicted the basin geometry and sedimentary thicknesses for different evolutionary stages. Measured thicknesses and previously proposed depozones were compared with our predictions. Our results shed more light on the Chaco foreland basin evolution and suggest that an apparent decrease in elastic thickness beneath the Eastern Cordillera and the Interandean Zone could have occurred between 14 and 6 Ma. [Copyright &y& Elsevier]

Changes in plate movements cause intraplate deformation and lead to basin development, fluid flow and mineralisation phases. Movement changes are detailed by seafloor-spreading data, back to the Oxfordian, and by paleomagnetic data before that time. Paleomagnetism records and interprets plate movement changes as pole path features—loops, bends, overprints—and these are applicable as tectonic and stratigraphic baselines at continental and global scales. Australian pole path features, from Late Paleozoic to Holocene, are interpreted in terms of regional evolution of eastern Australian basins and in relation to global plate movements. Emphasis is on the Late Paleozoic pole path of Australia. Two opposing views, the SLP path and the KG path, are discussed. Discussed also is an emerging pole path for the New England Orogen (NEO path), representing a potentially more detailed version of the KG path. The Mesozoic pole path of Australia is understudied and poorly defined. The Cenozoic path is better defined, but disputed in detail. The Late Paleozoic to Holocene pole path shows four major loops, L2 to L5, and several bends and lesser features. The L2 loop (mid-Carboniferous apex) relates to formation of the Westralian Superbasin; the L3 loop (Late Carboniferous-Early Permian) relates to formation of the Bowen-Gunnedah-Sydney basin system and oroclinal deformation of the Southern New England Orogen; the poorly defined L4 loop (Late Triassic-Early Jurassic) relates to formation of basins in eastern Queensland and rifting along the New Guinean margin of the Australian Plate; the poorly defined L5 loop (Late Jurassic-Early Cretaceous) relates to rifting along the western, northeastern and southern margins of the Australian Plate. Other features—minor Early Permian and Late Permian loops, bends of mid-Late Triassic, Early-Late Cretaceous and latest Cretaceous-earliest Tertiary age, and a Mio-Pliocene excursion—likewise are interpreted in terms of tectonostratigraphic and basin-forming phases. The L2 and L3 loops in particular are interpreted also within a global context. The L2 loop indicates a Late Devonian to mid-Carboniferous northward excursion of northeastern Gondwanaland, interpreted as leading to contact with the central Asian Altaids. This identifies the Central Asian Orogenic Belt and the Kanimblan and Alice Springs Orogenies as Pangea-forming, Variscan orogens on conjugate, northeastern Gondwanaland and southeastern Laurasian, margins of the Paleoasian Ocean. Alice Springs Orogeny-related deformation may have led to eastward extrusion of the Thomson Orogen, a Variscan equivalent to Cenozoic India-Asia deformation. The succeeding early-Late Carboniferous southward movement of northeastern Gondwanaland was extremely fast and created an extensional environment, initiating the Westralian Superbasin. The L3 loop reflects a fundamental change in rotation of Gondwanaland from counterclockwise (Late Carboniferous) to clockwise (Early Permian), leading to Stephanian initiation of the Bowen-Gunnedah-Sydney basin system and Early Permian oroclinal deformation of the Southern New England Orogen. The Texas, Coffs Harbour and Manning Oroclines are interpreted as telescoped mega dragfolds related to a major dextral shear system along the Protopacific margin of Gondwanaland and Alice Springs Orogeny-related dextral shear along the Darling River and Cobar-Inglewood Lineaments. A relationship between magnetic overprint phases and the younger limb and/or apex of pole path loops is emerging. Practical application in identifying and dating fluid flow and mineralisation phases has been demonstrated for the Paleoproterozoic-Mesoproterozoic pole path of Australia, but not yet so for the Phanerozoic pole path. [ABSTRACT FROM AUTHOR]

This paper deals with the evolution of sedimentary basins not delimited by normal faults, with a substratum characterized by an upward concave shape and with infilling sediments synclinally deformed. We describe the middle-late Miocene Radicondoli Basin, representing an example of such bowl-shaped basins. Its tectonic origin is controversial, being related both to compression and extension; these opposite interpretations bear significant consequences on the geodynamic context in which the inner northern Apennines developed during the middle-late Miocene. The results of our structural studies, carried out in the substratum and infilling sediments, indicate that the Radicondoli Basin is an example of a hanging wall basin developed in an extensional setting. Extensional tectonics determined the lateral segmentation of the substratum competent levels (i.e., Tuscan Nappe and Verrucano Group) and the consequent collapse of overlying less competent levels (i.e., the Ligurian units) with the formation of a bowl-shaped tectonic depression. Here, the syntectonic sediments (Serravallian-late Messinian) are deformed in a large syncline, characterized by minor gravity-driven folds, with vergences toward the depocenter and traces of their axial planes parallel to the basin margins. This paper highlights the role of the competence contrast during the postcollisional tectonic evolution and the influence of substratum lateral segmentation for the accommodation of syntectonic sediments. [ABSTRACT FROM AUTHOR]

The Oligocene to Lower Miocene of Site 1148, Ocean Drilling Program (ODP) Leg 184 was investigated palynologically to explore environmental change within the newly formed rifted South China Sea. The basin first developed 32.8 Ma ago during an initial rifting phase, and before sea floor spreading. Palynomorph Assemblage A contains abundant coastal and neritic dinoflagellate cysts (for example, Lingulodinium and Spiniferites) and a small number of oceanic Impagidinium species, together with abundant pollen, spores, and terrigenous phytoplankton. Offshore transportation induced by basement subsidence played an important role in the makeup of this assemblage. Paleoenvironments during the earliest Oligocene include shallow shelf, shelf/slope boundary, and mid slope regimes. The latter is indicated by the intermittent and rare occurrences of Impagidinium. Later, in the Early Oligocene to earliest Late Oligocene, there was a deepening of the basin with increasing influence of lower slope environments, indicated by increasing abundances of Impagidinium. A barren zone corresponding to a period of sea floor spreading during the latest Oligocene to the earliest Miocene effectively separates assemblages A and B. The Early Miocene environment deepened to a lower slope (>1500 m) regime, indicated by Assemblage B with consistent Impagidinium. This regime was relatively stable with much less terrigenous input, indicated by the rare occurrence of pollen and spores, and the absence of terrigenous phytoplankton. [ABSTRACT FROM AUTHOR]

Abstract: A geophysical survey (side-scan sonar and high-resolution sub-bottom profiling) combined with established chrono- and bio-stratigraphic markers are used to reconstruct the evolutionary history of Lower Lough Erne, northwestern Ireland since the end of the last glacial. Discrete acoustic units define four prominent sedimentation cycles, one Late-glacial and three Holocene, within the seismic stratigraphy. Basin development is predominantly controlled by climate until the Mid Holocene when the effects of cultural activity are related to pronounced signatures in the seismic record. An enhanced reflector marking the termination of the Early Holocene sedimentation cycle is associated with the elm decline and forest clearance during the Neolithic (between approximately 5800 cal. BP and 5300 cal. BP). The associated increase in sediment input, by infilling minor topographic lows and basins, has a smoothing effect on the morphologic expression of the original basin. Onlapping and truncated reflectors in the penultimate acoustic unit define further modification of lake bed relief by removal of sediment from the system during engineered lowering of the lake levels that began in the 1880s. Acoustic anomalies identified on the side-scan sonar data are linked with cultural activity and are identified as having the potential to facilitate the recent establishment and migration of invasive zebra mussels through the Erne system. [Copyright &y& Elsevier]

The Cappadocian Volcanic Province (CVP) comprises predominantly of a thick succession of volcanogenic rocks and interbedded siliciclastic sediments of Middle Miocene to Recent age in Central Anatolia, Turkey. The conditions of basin development in the eastern part of the CVP have been elucidated by using sedimentological and geomorphological approaches. The prevailing tectonic regime, its extent and causes are also discussed. Sedimentological analysis supported by geomorphological observations revealed a major NE-trending probably normal, border fault and its several synthetics. This tectonic element constitutes the SE margin of the basin and divided the CVP from the Tauride range during Middle Miocene to Pliocene. The basin fill in the study area comprises gravelly alluvial fans near the border fault, while fluvial clastics and lacustrine carbonates dominate towards the centre. Some pyroclastic rocks and lava flows are also made part of the fill. The southeastern basin margin is characterized morphologically by a number of uplifted basement blocks, probably associated with synthetic faults, and some deeply incised canyons in the footwall. These canyons were subsequently filled with a Mid-Pliocene ignimbrite sheet, and represent the sediment supply conduits to the basin. The cessation of filling in the basin was determined by strike-slip faults that uplifted and detached the basin about 2.6 Ma. This date also marks the onset of the neotectonic period in the region. The overall extensional tectonic regime inferred for the eastern CVP appears coeval with events recognised in the southern basins, i.e. Adana and Mut Basins and the eastern Mediterranean. Some physical connections between these basins also have been demonstrated. It is suggested that the CVP and the southern basins were all created during a phase of extension resulting from continued northward subduction of the African plate beneath the Eurasia during the Late Cenozoic. [ABSTRACT FROM AUTHOR]

The article examines the Jurassic sedimentary successions of Denmark and East Greenland. In comparing the Jurassic succession of both regions, Denmark is limited to the subsurface with exposures on the island of Bornholm in the Baltic Sea while East Greenland is exposed extensively. In subdividing both regions into tectonostratigraphic packages, it reveals that the tectonic evolution and stratigraphic signals are similar but the timing of rift and lift transition is delayed in East Greenland.

The northern Qilian Shan, located along the northeastern margin of the Tibetan Plateau, experienced multiple phases of orogeny throughout the Phanerozoic, culminating in fold-thrust and strike-slip deformation associated with the Cenozoic India-Asia collision. Earlier phases of deformation in the Qilian Shan have been severely reactivated or transformed by the most recent Cenozoic strain. To better understand the tectonic evolution of this complex region, we conducted an integrated investigation of field observations, U–Pb dating of igneous and detrital zircons, and a synthesis of previously published data to constrain and reconstruct the pre-Cenozoic history of the northern Qilian Shan. This effort reveals five major age populations important to the history of this region: 2550–2350, 1850–1750, 1050–950, 500–435, and 320–240 Ma. Using this dataset, we identified three major depositional shifts and/or variations in drainage patterns that affected sediment provenance of the northern Qilian Orogen. Observed regional geologic constraints, the magmatic history, and new geophysical observations of the deep structure allow us to propose a coherent tectonic model for the pre-Cenozoic evolution of the northeastern margin of the Tibetan Plateau. (1) Late Neoproterozoic to Cambrian rifting opened the Qilian Ocean. (2) Early Cambrian subduction initiation along the margins of Qaidam and North China–Tarim continents resulted in Cambrian-Ordovician bivergent subduction, arc magmatism within these two continents, and consumption of the Qilian Ocean. (3) Final ocean closure and continental collision occurred at ca. 440 Ma and was associated with syn- and post-orogenic magmatism. (4) Collisional orogeny variably eroded the basement rocks, reorganized drainage networks, and altered sedimentary provenance for the lower Paleozoic to upper Paleozoic deposits. (5) Mesozoic extension led to the development of thick Jurassic–Cretaceous terrestrial basins. This pre-Cenozoic history resulted in preexisting weaknesses and/or low-friction detachment horizons that played a decisive role in controlling the pattern, distribution, and timing of Cenozoic deformation across the northern Tibetan Plateau. • The northern Qilian Shan experienced multiple phases of pre-Cenozoic orogeny. • Five age populations and three depositional shifts/variations have been identified. • Preexisting weak zones controlled early growth of the northern Tibetan Plateau. [ABSTRACT FROM AUTHOR]

• U–Pb and fission-track ages from two stratigraphic horizons in the Tanakura Basin. • We present a detailed chronostratigraphy of the basin development. • The basin experienced rapid subsidence, uplift, and short-term dacite volcanism. • The basin was rapidly filled by sediments that are >2000 m thick during 17.5–15.3 Ma. • Tectonics was likely related to Tanakura Fault activity caused by the opening of the Sea of Japan. The Tanakura Basin was formed by strike-slip movement of the Tanakura Fault during the opening of the Sea of Japan in the early to middle Miocene. In this study, we conducted U–Pb and fission-track (FT) double-dating of pyroclastic rocks from two stratigraphic units in the Tanakura Basin. Using these ages, we constructed a detailed chronostratigraphy and discuss the evolution of the Tanakura Basin with respect to regional tectonics and the opening of the Sea of Japan. We obtained new ages of 17.1 ± 0.6 Ma for the middle part of the Asakawa Formation and 17.4 ± 0.9 Ma for the lower part of the Nawashiroda Formation. Based on a comparison of the ages from this study and previously published data, we clarify the ages of each formation of the Miocene basin fill. We suggest that the Tanakura Basin was formed by sinistral movement on the Tanakura Fault between 17.2 and 16.7 Ma, followed by the development of lakes and the deposition of alluvial fans within the basin. Rapid tectonic subsidence and submarine dacite volcanism occurred just prior to 16.7 Ma. The basin then began to uplift due to dextral strike-slip movement on the Tanakura Fault at ca. 15.7–15.3 Ma. [ABSTRACT FROM AUTHOR]