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Integration of the geological context, core analysis, and petrographic investigation, together with data from wireline logs, resulted in the recognition of petrofacies types and the representation of facies models characterizing the X-XII sand groups of the K2qn3 Formation in the Daqingzijing area of the Songliao Basin, China. The results show that the lithology of the reservoir’s X-XII sand groups includes shale calcium-bearing siltstone and sandstone, calcareous siltstone and silty sandstone. The petrofacies consist mainly of quartz, feldspar and rock fragments cemented by clay, and some samples include calcite. The studied interval was deposited onto a delta front. Four types of petrofacies were recognized: subaqueous distributary channel, mouth bar, distal bar and subaqueous interdistributary bay. According to background investigation, the study area’s X-XII sand groups have experienced a large-scale decline in lake level. There are many subaqueous distributary channels in layers 36-40, while other layers were mainly deposited in a subaqueous interdistributary bay. [ABSTRACT FROM AUTHOR]

The image logs played a key role in interpreting the lithology and sedimentary structures of uncored units. An integrated analysis of the borehole images and open-hole logs, which are calibrated with core observations, is conducted to reveal the detailed sedimentary characteristics of the Upper Triassic Xujiahe Formation in the Central Sichuan Basin. To establish borehole image interpretation guidelines, the interpretations of sedimentary textures and lithology from cores and outcrops are calibrated with borehole images and conventional logs. Lithologies in the Xujiahe Formation include conglomerates, fine to medium-grained sandstones, siltstones, mudstones and coals. Sedimentary structures in terms of bedding, scour surface and stacking style of beds are interpreted from the image and open-hole logs. Depositional microfacies are defined on the basis of grain size and sediment texture, sedimentary structures, thickness, basal and upper contacts derived from core observations, openhole logs and image logs. The Xujiahe Formation sandstones in Central Sichuan Basin are deposited in a braided delta front, of which the depositional microfacies consist of underwater distributary channel, river mouth bar, distal bar or sand sheet and underwater interdistributary bay. The depositional microfacies is predicted in a single well using a combination of openhole conventional logs, borehole images, and cores. The distributary channels, which show box-shaped or bell-shaped GR log character, are generally infilled with fine to medium-grained sandstone with massive, tabular, wedge-shaped or trough-cross-laminated bedding. Repeated fining-upwards cycles, as well as the stacked nature of individual bedsets and the presence of scour surfaces represent multistory, amalgamated, channel-fill deposits. The underwater distributary channel deposits can also be overlain by interdistributary bay mudstones, known as channel abandonment. Mouth-bar deposits, which are characterized by coarsening- up successions, infill the channels as they migrate laterally, and sometimes could be overlain by a channel deposit. The methodology has potential application to other braided delta front reservoirs with appropriate calibration and scaling. [ABSTRACT FROM AUTHOR]

The Yanchang gas field is located in the Ordos Basin of central China to the southeast of the Yishan Slope, covers an exploration area of 2.6×10 km and has approximately 3.5×10 m of gas reserves. The gas field is dominated by lithologic gas reservoirs but also has a few structural gas reservoirs. Sand bodies were deposited in the Carboniferous Benxi Formation around offshore barrier islands and in distributary channel fillings in the delta front of the P s and P s divisions of the Permian Shanxi Formation. The P h division of the Shihezi Formation contains the main reservoirs. The depths of the reservoirs are between 1 970 and 3 500 m. The Yanchang gas field can be classified as a typical tight sandstone gas reservoir filed because its porosity is lower than 10% and permeability lower than 1 mD. The discovery and development of the Yanchang gas field has led to a great increase in total natural gas reserves in the Ordos Basin. Its exploration has improved methods of locating large gas fields in deep-water depositional environments in the south part of the basin. [ABSTRACT FROM AUTHOR]

In the context of the harmonisation of the Swiss lithostratigraphic scheme, the Late Ladinian to Early Norian Bänkerjoch Formation and the Norian to Rhaetian Klettgau Formation of northern Switzerland are formally defined. The Bänkerjoch Formation replaces the «Gipskeuper». Delimitation generally follows the traditional Swiss scheme with the onset and offset of sulphate facies as basal and upper boundary. The Klettgau Formation includes six members (from base to top): The Ergolz Member (formerly «Schilfsandstein» and «Untere Bunte Mergel») consists of variegated silty dolomitic marl with dolocretes and channels filled by fine-grained sand of Scandinavian origin. The Gansingen Member (formerly «Gansinger Dolomit s.l.») starts with partly porous dolomite with Carnian bivalves and continues with an alternation of dolomite beds with thin dolomitic marl interlayers. At several places, the member has been eroded to great parts during the Late Triassic. Towards east and southeast, dolomitic sulphates, locally altered to dolomite or limestone, replace the marine carbonates. The Berlingen Member includes coarse alluvial and fluvial sandstones of Vindelician origin. It is restricted to the Lake Constance area. For practical reasons, the Gruhalde Member (formerly «Obere Bunte Mergel» and «Knollenmergel») encompasses all playa sediments above the Gansingen Member and Berlingen Member. Evidence in good outcrops suggests that it consists of several sedimentary cycles separated by long time spans of omission and erosion. The Seebi Member (formerly «Stubensandstein») includes layers of coarse-grained sandstones of Vindelician origin with calcitic, siliceous or clayey matrix. Locally, matrix fraction increases and becomes mostly dolomitic in the upper part. The Belchen Member (formerly «Rhät») consists of partly fossiliferous sandstone and greenish dark marl of estuarine to marine origin. Due to late Triassic and early Jurassic erosion, the Belchen Member is restricted to northwestern Switzerland and the Lake Constance area. [ABSTRACT FROM AUTHOR]

Evidences of CO 2 induced diagenesis in the Quantou Formation, Southern Songliao Basin, have been investigated using petrographic analyses, X-ray diffraction, stable isotopes, fluid inclusions and kinetic-thermodynamic modeling. The studied sandstones have two distinct zones based on their mineralogy, one “pristine” being composed of quartz, plagioclase, chlorite, calcite and dolomite, and one “altered” mainly consisting of quartz, illite and illite/smectite, ankerite, and dawsonite. The ankerite/dawsonite and secondary clay-bearing zones are related to the major deep rooted faults in this area. The δ 13 C value of carbonate cements in the altered zone (mainly centered on −0.9‰ to −8.0‰) is higher than that in the “pristine” sediments. We therefore proposed that these zones have experienced CO 2 charged hydrothermal (∼120–140 °C) alteration and with a similar precursor mineral assemblage as in the plagioclase/chlorite rich zones. Kinetic modeling furthermore suggests that the observed alteration must have been under high CO 2 partial pressures, with the closest match between simulations and XRD data found at the highest attempted pressure of 100 bar. The modeling furthermore suggests that using kinetic data from the literature together with reactive surface areas normalized to the surface area of the pores provides good estimates for the alteration of tight sandstones such as the Quantou Fm (∼8% porosity). [ABSTRACT FROM AUTHOR]

The common presence of oil seepages in dolostones is widespread in Cretaceous carbonate successions of the Kurdistan Region of Iraq. This integrated field, petrographic, chemical, stable C, O and Sr isotopes, and fluid inclusion study aims to link dolomitization to the origin and geochemical evolution of fluids and oil migration in the Upper Cretaceous Bekhme carbonates. Flux of hot basinal (hydrothermal) brines, which is suggested to have occurred during the Zagros Orogeny, resulted in dolomitization and cementation of vugs and fractures by coarse-crystalline saddle dolomite, equant calcite and anhydrite. The saddle dolomite and host dolostones have similar stable isotopic composition and formed prior to oil migration from hot (81–115 °C) basinal NaCl–MgCl 2 –H 2 O brines with salinities of 18–22 wt.% NaCl eq. The equant calcite cement, which surrounds and hence postdates saddle dolomite, has precipitated during oil migration from cooler (60–110 °C) NaCl–CaCl 2 –H 2 O brines (14–18 wt.% NaCl eq). The yellowish fluorescence color of oil inclusions in the equant calcite indicates that the oil had API gravity of 15–25° composition, which is lighter than present-day oil in the reservoirs (API of 10–17°). This difference in oil composition is attributed to oil degradation by the flux of meteoric water, which is evidenced by the low δ 13 C values (− 8.5‰ to − 3.9‰ VPDB) as well as by nil salinity and low temperature in fluid inclusions of late columnar calcite cement. This study demonstrates that linking fluid flux history and related diagenesis to the tectonic evolution of the basin provides important clues to the timing of oil migration, degradation and reservoir evolution. [ABSTRACT FROM AUTHOR]

The Oligocene and Early Miocene Khojak Formation represent a deltaic to sub-marine fan succession in the Khojak-Pishin flysch belt within the Katawaz basin of Pakistan. The sandstone within this succession is dominated by sedimentary and metamorphic clasts and has been derived from recycled orogeny. The higher SiO2/Al2O3 atios (4.0) show moderately mature nature of the sandstone. The weathering indices such as 2 2 3 Chemical Index of Alteration (CIA; 76.69), Chemical Index of Weathering (CIW; 86.79), Chemical Proxy of Alteration (CPA; 92.33) and Index of Chemical Variability (ICV; 16.83) suggest moderate to intense weathering at the source terrain. The high Th/U values (5.25) as compared to Upper Continental Crust (UCC; 3.82) also support the enhanced weathering of the source area. Trace elements such as Zr, Nb, Y, Th and U are slightly enriched compared to UCC suggest the dominantly felsic sources for the formation. High enrichment of Cr, Ni and V, and moderate ratios of Cr/Ni (1.72) and Cr/V (1.83) indicate substantial contributions from ultramafic sources while fairly high percentages of Fe2O3 (7.66) and MgO (3.90) as compared to UCC (5.03% 2 3 and 2.20%, respectively) hints toward mafic sources. The tectonic setting for the Khojak sandstone is considered as continental arc to active continental margin. This study supports the notion that the western Himalayan orogenic belt was shedding largely felsic detritus to Katawaz basin through proto-Indus River, while mafic and ultramafic detritus were being fed by distant Kohistan Island Arc and en-route Waziristan, Zhob and Muslim Bagh Ophiolite and associated mélanges. The sediment dispersal towards south-southwest was controlled by Chaman-Nushki transform fault system. [ABSTRACT FROM AUTHOR]

The Shulu Sag is a typical rift valley basin in Eastern China, where the formation mechanism of Cenozoic salt-bearing series has been poorly understood. In this paper, petrologic analysis, X-ray powder Diffraction (XRD) analysis and the analysis of halite ion concentrations of the first member of the Shahejie Formation from two drilling cores were conducted to interpret the formation mechanism of these salt-bearing series in Shulu Sag. The results indicated that the salt-bearing series is mainly composed of calcilutite or mudstone at top and bottom, and anhydrite-bearing halite and thin interbeds of salt-bearing calcilutite and dark grey shale in the middle part. These thin interbeds with porphyritic or petalshaped glauberite crystals or some thinner dark grey shale interbeds separated halites into several members with the average thickness of only 9~12 cm in the two drilling holes. This typical rhythmic pattern due to frequent alternation of concentration was evidenced by the variation of chemical composition and hydrogen isotopes of halite fluid inclusions. The presence of large number of primary fluid inclusions within chevron crystals and vertically oriented bottom-growth crystals showed that the halite were precipitated in shallow water (<60 cm). These features are direct evidence for this frequent alternation of dissolution and concentration of brines and terrigenous detrital-chemical shallow-water sedimentary model of these small rift-valley basins in Eastern China. [ABSTRACT FROM AUTHOR]

The Anacleto Formation is the uppermost unit of the Neuquén Group, which makes up the foreland stage infill of the Neuquén Basin, during Late Cretaceous. The detailed sedimentological study performed in the excellent outcrops of this formation on the eastern border of the basin allowed the identification of eight fluvial lithofacies, grouped into six facies associations. A meandering fluvial system with palaeo flows from the SW can be interpreted from distribution of facies associations, architectural framework, channel/floodplain ratio, etc. The compositional analysis of the sandstones was performed by mean of petrographic characterization and modal analysis. Sandstones of the Anacleto Fm are mainly subarkosic, arkosic, lithic arenites and, to a lesser extent, sublitoarenites (Q54-F25-R21; Q52-F24-L25). The composition suggests underlying igneous, metamorphic and sedimentary rocks in the main source area. Sedimentological and petrographic analyses, jointly with palaeocurrents orientations suggest that high areas of the North Patagonian Massif were the main source of the fluvial system. The diagenetic stages interpreted from the petrographic characters, SEM observations and X-ray diffraction determine eodiagenesis and telodiagenesis, which are consistent with the burial history of the Neuquén Group. Furthermore, palaeoclimatic considerations based on compositional analysis suggest semiarid to semihumid conditions for the deposition of the Anacleto Fm. These conditions are also supported by clay mineralogy that confirmed smectite as dominant species. A strong climatic seasonality is also deduced by the presence of calcrete levels and frequent discharge channels. [ABSTRACT FROM AUTHOR]

The continental block of the Earth's crust was separated in the Paleozoic into two unequal parts: (i) huge supercontinent Gondwana located at high latitudes of the Southern Hemisphere and (ii) several small continents (Laurentia, Baltica, Siberia, Kazakhstan, South Chinese block, and North Chinese blocks) located at low latitudes south and north of the equator. Morphology of the Paleozoic seas between these blocks was subjected to changes (expansion and contraction) with time. Their closure was provoked by several orogenic (Taconian, Caledonian, Acadian, and Hercynian) phases. At present, relicts of these ancient orogenic structures extend as belts along the boundaries of many petroliferous basins and record the position of past seas. One of the oldest oil-and-gas deposition belts, which appeared in southern Iapetus in the Precambrian/Phanerozoic, was confined to a passive margin of Gondwana. In the Early Paleozoic, small blocks of the continental crust (Avalonia, Armorica, Perunica, Iberica, and others) were successively detached from the passive margin. This process was accompanied by the opening of a new deep basin (Rheic Sea or Paleotethys). The Uralian and Central Asian paleoseas were formed approximately at the same time. Many petroliferous basins existing now were located in the Paleozoic at the margins of these paleoseas. [ABSTRACT FROM AUTHOR]

Abstract: Ten samples of Carbondale Formation (late Middle Pennsylvanian, Westphalian D) roof shale strata from the Western Kentucky Coal Field (Eastern Interior Basin, USA) were analyzed petrographically to gain a better understanding of the organic composition of the shales. The samples were collected in conjunction with a coal bed methane exploration program, so a direct comparison of the organic composition of the shales, and the coal beds that directly underlie them, could be made. Petrographically, total vitrinite contents in the shales average 20.8% (mineral matter free basis, mmf), which is significantly lower than the average vitrinite content of Carbondale Formation coal beds (avg. 81.8%, mmf; n=32). In contrast, total liptinite contents average 49.7% (mmf) in the shales, which is significantly higher than the average liptinite content of Carbondale coals (avg. 7.0%, mmf). Amorphinite and bituminite were found to be the most abundant liptinite macerals in the shales, but were not recorded from the coal samples. Likewise, total inertinite contents were much higher in the shales (avg. 29.6%, mmf), than in the coals (avg. 11.0%, mmf). A type of macrinite identified as “granular macrinite” was the dominant inertinite maceral in the shales, but was absent in the coal samples. Although the average desorbed gas contents of Carbondale Formation coals and shales are low and currently uneconomical (avg. 0.9ml/g [28.8scf/ton] for the shales, 2.4ml/g [76.9scf/ton] for the coals, as received basis), they nonetheless represent a potential future gas resource. [Copyright &y& Elsevier]

Abstract: The dynamics of depositional environments and the spatial deformation of drainage networks in foreland basins reflect the tectonic and erosional dynamics associated with the development of mountain belts. The spatial and temporal organization of the Eocene–Oligocene (40–25Ma) sedimentation in the external part of the South Alpine Foreland Basin of France was reconstructed using an integrated cartographic, sedimentological and petrographic analysis of the Tertiary sedimentary successions. The depositional geometries and variations in facies and thickness of the Palaeogene Nummulitic succession, as well as the observed flow directions in various continental and marine sediments, suggest that the Barrême, Blieux and Taulanne synclines were present as palaeovalleys since the Eocene. The sedimentological analysis of the Nummulitic succession allows the identification of three depositional sequences separated by transgressive surfaces that are recognized in the Barrême, Blieux and Taulanne synclines. Correlation of these sequences between the three synclines suggests that these palaeovalleys were connected by a local valley network that recorded the same sea-level fluctuations during the marine Nummulitic sedimentation. The palaeovalley network was structurally controlled by the east–west axes of the Blieux and Taulanne synclines and the north–south axis of the Barrême syncline formed during the “Pyrenean–Provençal” (Late Cretaceous–Middle Eocene) shortening and the first stage of the Alpine history (Middle Eocene) respectively. Later on, the westward “Alpine” compression (since the Early Oligocene) induced local depocenter migration and reversal in flow direction. However, compared to the modern river pattern, the palaeovalley orientation highlights a geometrical stability since their formation (about 40Ma), suggesting a long-term stability of the early structures in the foreland basin. This constancy can be explained by the location of the study area in a piggy-back basin transported at the top of the Provençal thrust sheet that facilitated the preservation of the overall axis orientation of the palaeovalleys. [Copyright &y& Elsevier]

Abstract: There are several source rock units in the Zagros Basin, but the Cretaceous Kazhdumi and Paleogene Pabdeh formations probably have produced the majority of the commercial hydrocarbons in this area. Among the hydrocarbon provinces of Iran, the Dezful Embayment, which is located southwest of Zagros Mountains, is one of the most prolific regions in the Middle East. Numerous studies have been made in the northern part of the Dezful Embayment, but relatively few have been done in its southern part. The present study focuses on organic matter characterization of two potential source rocks (Kazhdumi and Pabdeh formations) in southern part of the Dezful Embayment. Cuttings samples (114) were collected from 10 wells and evaluated using Rock–Eval pyrolysis and organic petrography in order to characterize the content and type of organic matter and thermal maturity. The results showed that the average total organic carbon (TOC) content of Kazhdumi and Pabdeh formations are 2.48 and 1.62wt%, respectively. The highest TOC contents for both formations are found in the northern compartment and decreased gradually toward the south. Pyrolysis data reveal that organic matter has a fair to very good hydrocarbon generation potential and are classified as Type II–III and Type III. Rock–Eval T max and vitrinite reflectance show that the majority of samples are in the early mature to mature stage of the oil generation window. [Copyright &y& Elsevier]

Abstract: The Upper Jurassic Madbi Formation, located in the Masila Basin, eastern Yemen, represents the major source rock in this basin. Organic rich shales from two oilfields (Kharir and Wadi Taribah) were analysed to evaluate the type and origin of the organic matter and to determine the factors controlling its deposition. This study is based on geochemical analyses of whole rock (total organic carbon content, Rock-Eval pyrolysis and carbon isotope data) and petrographic analyses on organic matter (kerogen maceral composition and palynofacies) by optical and scanning electron microscopy. Organic petrographic composition of kerogen shows that the Madbi shale is characterized by high amounts of organic matter, consisting predominantly of yellow fluorescing amorphous organic matter and alginite of marine origin. Terrigenous organic materials such as vitrinite, spores and pollen are present in low quantities. The predominance of marine plankton, as indicated by visual kerogen analysis, is consistent with reported carbon isotopic values. It appears that the high amounts of organic matter in the Madbi shale succession might be mainly due to good preservation under suboxic–anoxic conditions. Consequently the Madbi shales possess very good petroleum generative potential, owing to high content of hydrogen rich Type II and I oil prone kerogen. [Copyright &y& Elsevier]

Abstract: New research on basic geology has been done for Upper Carboniferous carbonate lithologic gas pools in the Huanglong Formation in the eastern Sichuan Basin. Based on the development characteristics of terrigenous clastic deposit and the development location of suspending gravels with some psephicity, the transgression direction and tidal depositional system distribution are deduced. It is believed that, two transgression channels were developed in southeast of Yunyang and northwest of Dazhou in the area, two tidal-flat depositional systems in Chongqing-Wanzhou and southeast of Dazhou respectively were formed, and a suit of complete type-I sequence composed of lowstand systems tract (C2h1), transgressive systems tract (C2h2) and early highstand systems tract (C2h3) was developed. Sedimentary microfacies features of each member of the Huanglong Formation were delineated finely. In the middle stage of late Carboniferous, transgressive systems tract was developed in eastern Sichuan, where shallow shoal and algal dolomite-flat microfacies were developed, which are favorable for the development of carbonate lithologic traps. In contrast, in the early and late stages of late Carboniferous, lowstand systems tract and highstand systems tract were developed, respectively, where shallow shoal microfacies were poorly developed, which limited the large scale development of carbonate lithologic traps. [Copyright &y& Elsevier]

Abstract: Natural gas exploration and discovery of hydrocarbons in the Xujiahe Formation in the Sichuan Basin are mainly concentrated in the Xu-2, 4 and 6 Members. The discovered gas reservoirs are characterized by a low filling degree, high water saturation in lower intervals, low levels of produced reserves and a limited number of gas-bearing reservoirs. The Xu-1, 3 and 5 Members are identified as source rocks. Based on the study of natural gas accumulations and several gas production wells in the Xu-1, 3 and 5 Members, this paper proposes that large scale sand bodies are developed in the Xu-1, 3 and 5 Members in the northwest, southwest and central parts of the Sichuan Basin. In each member, the favorable gas bearing area is about 5 000-11 000 km2, the reservoir rocks have good continuity with single layer extensions of up to 15-20 km. It is believed that these sand bodies have favorable conditions for gas accumulation within source kitchens to form lithologic or structural-lithologic gas reservoirs and have better accumulation potential and higher gas-bearing abundance than that of the Xu-2, 4 and 6 Members. Exploration practices have revealed that economic gas reserves may be generated. It is suggested that more efforts be made to study the gas accumulation conditions in the Xu-1, 3 and 5 Members (especially the Xu-3 and Xu-5 Members) and more exploration work be conducted in these strata. [Copyright &y& Elsevier]

In this study, new paleontology and lithology foundations on the Bakhtiari Formation were obtained from Shalamzar area in Zagros basin. A depositional mollasic cycle was divided into Bk1, Bk2 and Bk3 units from the base to the top of the Formation. Bk2, with limestone- and mudstone-dominated deposits, was found to alternate with conglomerates and form a marine succession between the two limestone clast-supported conglomeratic continental units. A diverse fossil association has been described for the first time and consists of foraminifera (Oolina spp., Oolina hexagona, Textularia spp., Spiroloculina spp., Peneroplis spp., Elphidium spp., Planulina sp., Amphistegina spp., Lagena spp. Globigerina spp., Globigerinoides spp., Uvigerina spp., Triloculina spp., Quinqueloculina spp., Spiroloculina spp. Nodosariid., Orbitina spp., Borelis melo, Bolivina spp. and Miogypsina spp.), a gastropod community of Strombus spp., Potamides spp., Turitella spp., Cyprea cf. persica and Pleurotomaria sp. and a higher energy colony of scleractinian corals comprising Porites branching, Porites-encrusting massive Favites spp., Favia spp., Tarbellastrea spp. and Acropora spp. The early-middle Miocene marine level of the Bakhtiari Formation, confirms a nearshore accommodation through a middle shelf and an open coastal lagoon (inner shelf) within a fluvial-dominated delta or open estuary during the last presence of a marine trough in the Zagros basin. This saline to hypersaline shallow marine regime was probably dominated in tropical to subtropical conditions. Palaeobiogeography analysis reflects a last seaway faunal exchange between the area and early-middle Miocene basins of Pakistan, India, Australia, Turkey, Greece, Romania Algeria, Egypt, Italy, France, Portugal and Austrian/Hungarian border, which reconstructs a shallow junction between Zagros basin and Mediterranean Tethys and Indo-pacific Ocean during Burdigalian-Langhian (Badenian) before the terminal Tethyan event in late middle Miocene and Tortonian. [ABSTRACT FROM AUTHOR]

- The 1.4-1.6 km thick Onaping Formation consists of a complex series of breccias and 'melt bodies' lying above the Sudbury Igneous Complex (SIC) at the Sudbury impact structure. Based on the presence of shocked lithic clasts and various 'glassy' phases, the Onaping has been described as a 'suevitic' breccia, with an origin, at least in part, as fallback material. Recent mapping and a redefined stratigraphy have emphasized similarities and differences in its various vitric phases, both as clast types and discrete intrusive bodies. The nature of the Onaping and that of other 'suevitic' breccias overlying impact melt sheets is reviewed. The relative thickness, internal stratigraphic and lithological character, and the relative chronology of depositional units indicate multiple processes were involved over some time in the formation of the Onaping. The Sudbury structure formed in a foreland basin and water played an essential role in the evolution of the Onaping, as indicated by a major hydrothermal system generated during its formation. Taken together, observations and interpretations of the Onaping suggest a working hypothesis for the origin of the Onaping that includes not only impact but also the interaction of sea water with the impact melt, resulting in repeated explosive interactions involving proto-SIC materials and mixing with pre-existing lithologies. This is complicated by additional brecciation events due to the intrusion of proto-SIC materials into the evolving and thickening Onaping. Fragmentation mechanisms changed as the system evolved and involved vesiculation in the formation of the upper two-thirds of the Onaping. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a stratigraphic, petrographic and sedimentologic analysis of felsic syn-eruptive deposits of the southernmost Permian basin in Europe (Viar Basin), an inner-orogenic, transtensional half-graben located between two major geotectonic zones of the Iberian Variscan Belt, SW Spain. The syn-eruptive deposits of the Viar Basin represent a mappable lithostratigraphic unit, that is herein named the Los Canchales Formation. This unit forms a wedge-shaped body bounded by alluvial–fluvial deposits (red layers) that are in gradational contact. The stratigraphic architecture of the Los Canchales Formation is complex with frequent facies changes and interfingering among pyroclastic rocks, resedimented–volcaniclastic rocks and sedimentary rocks. Abundant fossil flora is also recorded. A wax–wane cycle of volcanic activity is recognized during the syn-eruptive period. Two short-lived volcanic episodes were recorded including ignimbrites and a possible phreatomagmatic event. Explosive volcanism generated pyroclastic flow, surge and ash-fall deposits, in cases collapsing the drainage network. They also modified the vegetation and created a new depositional setting with four successive sedimentary environments: vegetated floodplain, ephemeral sandy braidplain, palustrine environment and again vegetated floodplain. Input of pyroclasts followed a NW to SE longitudinal–axial dispersal pattern. [Copyright &y& Elsevier]

Presents a lithologic summary of legs of measure section of Hanna Basin in Wyoming. Sequence of characterization based on standard geologic convention; Description of its ascending stratigraphic order; Information on the basin's coal beds.

Describes a study that re-evaluated the distribution, contact relationships, lithologies and basin evolution for part of the Swakop Terrane in Namibia. Description on the depositional environment; Evolution of the continental margin; Conclusions.