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Facies analysis in outcrops on land is strongly dependent on the lateral variability of lithofacies. Interpretation of conventional core in wells relies principally on the vertical succession of lithofacies. To better understand depositional environments and reservoir sandstone connectivity, the lithofacies of reservoir sandstones sampled in conventional core were correlated laterally through two sets of closely spaced wells in the Scotian Basin: in the Barremian-Albian succession around the Panuke-Cohasset field and in the Late Jurassic succession west of the Venture field. Regional correlation by gamma logs is confirmed by lithologically similar transgressive units including shelly mudstones or coals. A standard scheme of lithofacies and recognition of three types of parasequences were used for comparisons between wells. Some transgressive surfaces are of limited extent and may represent delta distributary switching and subsidence rather than regional changes in sea level. Major sandstone packets extend at least 10-30 km laterally, but commonly show lateral changes in lithofacies, and some are bounded by the margins of incised valleys. Such packages show poor correlation of lithofacies with porosity and permeability, probably because of the variable effects of diagenesis. Lateral transitions from tidal estuary sandstones in Panuke B-90 to thick-bedded river-mouth turbidites in Lawrence D-14, over a distance of 15 km, demonstrates the scale of delta lobes and confirms that sharp-based sandstone beds are turbidites related to river floods, not storm deposits. Similar lateral transitions in the Venture field are on a similar scale and pass distally into prodeltaic muddy landslide deposits. [ABSTRACT FROM AUTHOR]

Abstract: This investigation presents and interprets fluid inclusion data from different lithological units of the Cu skarn deposits at Mazraeh, north of Ahar, Azarbaijan, NW Iran. The results provide an assessment of the P–T conditions and mineral–fluid evolution and suggest new exploration parameters. Five types of inclusions are recognized from quartz and garnet. The temperature of homogenization of Type I inclusions with daughter minerals halite and sylvite ranges from 312° to 470 °C with total salinity of 52 to 63 wt.% NaCl equiv.; Type II and III inclusions with halite have homogenization temperatures of 230° to 520 °C and salinity of 31 to 50 wt.% NaCl equiv. The salinity of Types IV and V biphase (liquid+vapor) inclusions, based on their final ice melting temperature, varies between 10.2 to 20.8 wt.% NaCl equiv. T h vs. salinity plots of inclusions show that the salinity of the fluids correlates positively with temperature. The inclusions formed at low pressure. Changes in the temperature and salinity of the fluids can be reconstructed from the inclusions. Highly saline, high-temperature fluids were most abundant during the main chalcopyrite ore-forming phase in the skarn and mineralized quartz veins. Low-salinity aqueous fluids were abundant in barren veins, in which there is no evidence for early hot high-salinity brine, and might have resulted from late-stage dilution and mixing of hydrothermal fluids with meteoric water. Based on petrographic features and fluid-inclusion data, early-stage magnetite deposition is related to boiling of fluid at temperatures of about 500 °C. At a later stage, boiling at temperatures of around 320° to 400 °C favored the deposition of sulfides and Fe mobility was decreased at these lower temperatures. The following inclusion characteristics may be used as exploration parameters in the Mazraeh area. (i) Presence of high-temperature, salt-bearing inclusions, with T h between 300 and 500 °C; (ii) High-salinity fluid inclusions; and (iii) Inclusions showing evidence of boiling of the fluid. In addition, the presence of magnetite is an important exploration parameter. [Copyright &y& Elsevier]

Abstract: Clay mineral assemblages in alluvial mudrocks are important for paleoclimatic interpretation and for understanding burial diagenetic cementation in sandstones, but it is commonly difficult to unravel the relative importance of source weathering, pedogenesis and diagenesis in their origin. The clay mineral assemblages in fluvial overbank mudrocks from the Lower Cretaceous Chaswood Formation in central Nova Scotia, investigated by X-ray diffraction analysis of the <2 µm fraction of 45 samples, include kaolinite, illite, vermiculite, and mixed layer kaolinite/expandable clay and mica/vermiculite. The assemblages vary with depositional facies. Wetland organic-rich mudrocks have large amounts of amorphous material and kaolinite is the dominant clay mineral. In the eastern part of the basin, where overbank mudrocks were episodically uplifted by syn-sedimentary strike-slip faulting, cumulate ultisol and alfisol paleosols are common. In the ultisols, hematite is enriched and kaolinite increases at the expense of illite in the B horizon. Alfisols contain more illite and vermiculite and the B horizon is enriched in goethite. In the western part of the basin, where thin sandstones with abundant diagenetic kaolinite cement are interbedded with the mudrocks, the distinctive clay mineral assemblage of mica/vermiculite mixed layer, vermiculite with 15.5 Å peak, and kaolinite/expandable mixed layer clay with a 17.7 Å peak is interpreted to result from bacterially-mediated oxidation of organic matter below the paleo-water table during early burial diagenesis. Deeper burial diagenesis may lead to slightly higher kaolinite crystallinity. Volcanic ash appears to alter to kaolinite/expandable mixed layer clay with a 7.9 Å peak. Comparison with the continuously subsiding and rapidly accumulated Wessex Formation of southern England, formed at a similar paleolatitude, shows the strong role of pedogenic processes and early diagenesis by meteoric water in development of clay mineral assemblages in the locally tectonically uplifted Chaswood Formation. [Copyright &y& Elsevier]

This paper reports, for the first time, on a garnet-bearing granite body at Zeber-Kuh and interprets its petrogenesis, age and tectonic setting within the context of the evolution of the Cadomian subduction system. The primary minerals imply an origin at pressures greater than 8-6 kbars (~ 25 km depth) and at temperatures above 700 °C with >10 % water. The Zeber-Kuh granite is in tectonic contact with neighboring rocks. This igneous body has average SiO2 of 71 wt. %, average Al2O3 of 14 wt. %, 3.1-3.6 wt. % Na2O, 3.0-6.2 wt. % K2O and 3.3-0.1 wt. % MgO. The granite is characterized by light rare earth element (LREE)-enrichment, relatively flat heavy rare earth element (HREE) patterns with a small negative Eu anomaly and moderately fractioned REE patterns [average (La/Yb)N = 11.32]. Decreasing Fe2O3T, MgO, CaO, TiO2, Ba, Eu and Sr with increasing SiO2 contents are consistent with fractional crystallization and can be related to fractionation of plagioclase, clinopyroxene, hornblende, and apatite. Two granite samples yielded U-Pb zircon ages of 533±3 and 534±6 Ma, which regionally correspond to the younger Cadomian magmatism. Cathodoluminescence images of zircon grains from the studied samples show well-developed oscillatory bands, typical of felsic magmas zircons, and Th/U ratios range from 0.79 to 0.45 with an average of 0.60. The REE patterns of the zircons show progressive enrichment from LREE to HREE with a positive Ce anomaly and a negative Eu anomaly.The garnet-bearing granite of Zeber-Kuh represents the final stage of Cadomian magmatism along an extensional continental arc adjacent to the northern active margin of Gondwanaland. [ABSTRACT FROM AUTHOR]

The Permian to early Triassic terrestrial successions in the Mahu sag constrain the tectonic evolution of northwestern edge of the Junggar basin. This study analyzes the sequence stratigraphy of the Mahu sag in order to understand the interplay between tectonic process and the sedimentary fill of the basin. It uses detailed analysis of drill cores, geophysical well logs, 2D seismic reflection profiles and isopach maps. Sixteen lithofacies are grouped into three facies associations: fan delta, fluvial delta and lacustrine. The Permian to Triassic strata are organized into two second-order transgressive-regressive (T-R) sequences, further separated into transgressive systems tracts (TST) and regressive system tracts (RST). Based on seismic profiles, paleogeographic facies distribution and isopach maps, two stages of tectonic evolution are recognized: 1) early Permian syn-rift to middle Permian post-rift; 2) late Permian to early Triassic tectonic inversion. During the early Permian, sediments of TST1 record two cycles of depositional system transition from fan delta to deep lacustrine setting within the half-graben structure shown by 2D seismic profiles. At this time, tectonic mechanical subsidence exceeded sediment supply. The middle Permian post-rift stage (RST2) is characterized by gradual and slow peneplanation, which is documented by sediment supply exceeding thermal subsidence, so that the location of depocenter shifted and the depositional system transitioned from lacustrine to fan delta setting. Late Permian-early Triassic tectonic inversion is demonstrated by a striking change of the sediment dispersal patterns along the Hong-Che, Ke-Bai and Wu-Xia fault zones and alluvial fan deposition at the base of TST2. Tectonism is the main factor controlling sediment dispersal, paleogeographic evolution and hence hydrocarbon accumulation, providing a new perspective to oil and gas exploration and development in the Mahu sag. • Mahu sag has two Permian-Triassic 2nd-order transgressive-regressive cycles. • Sediment dispersal and depocenter migration controlled by evolving rift tectonics. • Basin-margin inversion by end-Permian strike-slip on original normal rift faults. • Permian mechanical and thermal rift basin subsidence, not a foreland basin. • Tectonic evolution controlled the accumulation of oil and gas in the Mahu sag. [ABSTRACT FROM AUTHOR]

Soft-sediment deformation structures (SSDS) are an important tool for interpreting paleoseismicity and depositional environments in ancient basin successions. The northwestern margin of Junggar Basin is a key region for understanding the paleogeography and basin attribute of the Junggar Basin during the early Permian. In the Lower Permian (Kungurian) Fengcheng Formation, nine lithofacies are grouped into fan delta, fluvial delta, and shallow, deep and alkaline lacustrine facies associations. Vertical transitions of the sedimentary environments show that the lake basin experienced expansion during deposition of the Lower (P 1 f 1) and Middle (P 1 f 2) members and the shrinkage during the Upper Member (P 1 f 3), which is consistent with the paleogeographic distribution of lithofacies in different members. Conventional cores show a wide variety of SSDS, including ductile (folds, convolute lamination, and load structures), hybrid ductile-brittle, and brittle deformation structures (microfaults, breccias, boudinage and sedimentary dikes). SSDS mainly occurred in a still and deep lacustrine environment. These deformation structures were not formed in any specific lacustrine environment, as there is no difference with the undeformed sedimentary units of the same sedimentary facies. Thus, the triggering mechanism is interpreted as intermittent earthquakes. Lake expansion under arid condition and SSDS intervals with vertical repetition and possible lateral continuity indicate that most seismicity was during the Middle Member (P 1 f 2), corresponding with the main activity on basin-bounding normal faults. The enhanced faulting at this time generated accommodation, creating lacustrine conditions in the basin depocenter. It is thus clear that the early Permian Mahu sag represents an active rift basin with bounding faults, and is not a foreland basin. • Lacustrine Fengcheng Fm of Junggar Basin has abundant soft-sediment deformation. • Deformation structures were triggered by earthquakes on bounding normal fault. • 11 deformation horizons show the fault was most active in middle member. • Early Permian Junggar Basin was a rift basin rather than a foreland basin. [ABSTRACT FROM AUTHOR]

Siliceous (chert) concretions are a prominent component of Cretaceous limestones in the Ionian zone of western Greece. This study investigates the diagenetic evolution of such cherts from two localities: largely undeformed strata on Kastos Island and highly faulted strata at Araxos. In both areas, lower Cretaceous limestones contain abundant small chert nodules, whereas in the upper Cretaceous nodules are larger but less abundant. Seventy seven powdered samples, from 67 representative field samples, were analyzed by X-ray Powder diffraction (XRPD). The analyzed samples came from both nodular and siliceous beds and showed that quartz is the dominant mineral, with rare to common residual calcite. The presence of moganite and opal-A minerals suggests that quartz recrystallized from original amorphous silica. A few samples from Araxos contain traces of halite and anhydrite. The variability in the calcite content and the presence/absence of halite and anhydrite in the different studied areas are related with the different tectonic activity in these areas, with more intense tectonic activity in NW Peloponnesus than in Kastos Island. Size of nodules is related to variation in primary porosity of the host rocks. Finally, the presence of dolomite was related with the pre-existing underlying dolomites of Early Cretaceous age in Ionian basin, whereas the presence of maghemite is due to the presence of iron minerals in water solutions. • Zoned chert nodules and beds in Cretaceous calcturbidites and landslide deposits. • Moganite and opal-A minerals recrystallized from original amorphous silica. • Size of chert concretions related to porosity of host limestones. • Dolomite in cherts only where underlying dolostone. • Halite and anhydrite in cherts due to Paleogene deformation of Triassic evaporites. [ABSTRACT FROM AUTHOR]

The Permian clastic sediments in the Mahu sag offer outstanding conditions to test the control of tectonism and paleoclimate on sedimentation in a rift basin. A synthesis of petrological and geochemical analyses of sandstones, zircon U–Pb geochronology of granitic conglomerates, and principal component analysis have been used to investigate the source composition and chemical weathering indices. The rare earth and trace element compositions of 16 sandstone samples are consistent with first cycle sources from the Carboniferous–Lower Permian mafic and felsic igneous rocks in West Junggar. Lower Permian sandstones contain abundant volcanic lithic clasts and plagioclase grains, and have high Na 2 O, CaO, Sr and V, suggesting a coeval proximal volcanic source in Central West Junggar during the syn-rift stage. Middle Permian sandstones consist of trachyte and rhyolite clasts, and quartz and albite grains, and show a gradual increase of Th, U and SiO 2 , indicating an expansion of source areas to more distant Southern and Northern West Junggar during the post-rift stage. In the Lower Triassic, an abrupt increase in the percentages of quartz and K-feldspar, as well as the zircon U–Pb geochronology of granite-clast conglomerates (290–330 Ma), all indicate regional uplift and unroofing of Carboniferous–Permian granitic plutons in West Junggar during the tectonic inversion stage at the Permian-Triassic boundary. Various chemical weathering indices indicate cold and arid climate conditions during the early Permian, followed by a transition to warm and humid climatic conditions. Comprehensive analysis of petrography and geochemistry sheds a new light for studying the source-to-sink evolution of a rift basin, and has further implication for paleoclimate fluctuation and change. • ●Chemical weathering intensity increased upwards in the Permian. • ●Permian detrital material was supplied by the igneous rocks in West Junggar. • ●Early – middle Permian rift basin was ended by late Permian – late Triassic tectonic inversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chemical weathering intensity increased upwards in the ∼ 280 Ma Fengcheng Formation. • Detrital material of the FC Formation was supplied by the West Junggar, due to active normal faults. • Syn-rift sediments were deposited in an alkaline lake under arid climatic conditions. Source-to-sink evolution of intracontinental rift basins is an effective tool to evaluate syn -rifting tectonic processes and sediment dispersal. Provenance analysis, using petrological and geochemical analysis and detrital zircons U-Pb dating of the Lower Permian Fengcheng Formation, provides new insights into the provenance of alkaline lake deposits in the Mahu sag, Junggar Basin. Volcanic detritus and detrital feldspar grains are abundant, indicative of proximal sources. The rare earth and trace element characteristics of three sandstone samples are consistent with a dominant source from the Carboniferous – early Permian mafic and felsic rocks in West Junggar. Sandstone geochemistry suggests that chemical weathering intensity increased upwards, probably in response to reduced aridity. The detrital zircon U-Pb age patterns show a prominent Carboniferous peak (340–300 Ma), minor early Permian (∼280 Ma) and Silurian peaks (440–420 Ma). Quantitative unmixing modelling suggests that most detrital zircons were derived laterally from the Central West Junggar (CWJ), and a few zircons were derived axially from the Zharma-Saur and Boshchekul-Chingiz arcs in Northern and Southern West Junggar. The lateral source was more important in the Middle Member than in the Lower Member of the Fengcheng Formation. The average age of the youngest five detrital zircons and the low weathering indices indicate that the maximum slip of the bounding normal fault occurred at 284–?279 Ma. Seismic and hydrothermal activity caused by the normal fault displacement, as well as the increase in the supply of volcanic composition from the lateral CWJ, played an important role in the alkaline lake deposition. [ABSTRACT FROM AUTHOR]

Abstract: The Minas Fault Zone (MFZ) defines the boundary between the Avalon and Meguma terranes in the Canadian Appalachians and is exposed in mainland Nova Scotia and southern New Brunswick. These terranes originated along the Gondwanan margin, but had accreted to Laurentia by the middle Devonian. The surface trace of the MFZ is adjacent to the southern margin of the LateDevonian–Permian Maritimes Basin. The Late Devonian–Late Carboniferous evolution of the MFZ involves several episodes of oblique dextral shear that resulted in basin formation and inversion and at various times the zone was the focus of magmatism, regional fluid flow and mineralization. In the Late Devonian–Early Carboniferous, asymmetric rifting accompanied by dextral shear produced two coeval sequences: the Horton Group, which is dominated by continental clastic strata, and the Fountain Lake Group, which consists predominantly of bimodal volcanic rocks that overlie high-level plutons emplaced along active shear zones. The overall tectonic environment may have been dominated by dextral transtension along the southern margin of Laurentia, which corresponded with the northern flank of the Rheic Ocean. A major change in the evolution of the Minas Fault Zone occurred in the Late Mississippian–Early Pennsylvanian and produced the E-W Chedabucto Fault, clockwise rotation of pre-existing structures, local zones of transtension and transpression, as well as regional fluid flow and extensive mineralization. This major change may reflect the onset of Laurentia–Gondwana oblique collision, the effects of which continued into the latest Carboniferous with coeval development of flower structures and pull-apart basins in zones of local transpression and transtension. [Copyright &y& Elsevier]

In early Cretaceous time, high-energy braided rivers deposited complex deltas on the Scotian shelf. The manner in which sand was transferred from these deltaic systems to deep water is important for identifying exploration targets on the deepwater continental margin. We have logged conventional core from the Tantallon M-41, Thebaud I-93, Thebaud 3, Thebaud 5, and North Triumph G-43 wells, emphasizing sedimentological features that indicate either hyperpycnal river-mouth flow or prodeltaic slumping of sandy facies. The relative importance of slump-derived and hyperpycnal turbidity currents is critical for predicting sand distribution in deep water. Slump-derived turbidity currents generally evolve into highly turbulent flows that deposit only on low gradients of <0.2° on the basin floor. More concentrated hyperpycnal flows may deposit on higher gradients of 0.4°, and will thus give thick sand deposits more proximally. In the wells studied, hyperpycnal flow facies in conventional cores with deltaic and shelf facies are found stratigraphically below major channel sandstones. They show abrupt alternations of granule conglomerate, fine sandstone, and mudstone. In prodeltaic (shoreface) environments, sharp-based laminated to cross-laminated fine sandstone beds with abundant wood fragments or mudstone chips are also interpreted as the products of hyperpycnal flows. They can be distinguished from stormresuspended sandstone beds by their better sorting and lack of reworked shelly fossils. In conventional cores from prodeltaic settings, large slide blocks, tens of metres thick involve a wide range of primary sedimentological facies. These facies are recognized as allochthonous by the presence of a basal foliated mudstone and variably deformed contacts between sediment blocks, some of which include spaced shear zones. Preserved facies are predominantly shale-prone: we speculate that failure of sand-prone successions could have generated sandy turbidity currents. Prodeltaic slopes in many cases developed at growth faults on the shelf, so that failure would not have transferred sediment to the continental slope. In the Tantallon M-41 well on the present continental slope, conventional core from the Middle Missisauga Formation shows overbank turbidites with characteristic sparse bioturbation, Bouma Tb-c sequences, and fading ripples. In some sandstones, abundant woody fragments, sorted mudstone chips, and transported siderite nodules suggest a source from river discharge. Reverse grading at the base of some sandstone beds suggests hyperpycnal flow. Present data is insufficient to fully evaluate the relative importance of slump-derived turbidity currents and hyperpycnal turbidity currents in sand transport to deep water in the early Cretaceous. There is evidence that both types of current were present. The widespread evidence of hyperpycnal flow deposits interbedded with shelf sediments strongly suggests that some hyperpycnal flows reached deep water and like modern hyperpycnal flows could have deposited sand in relatively proximal settings. [ABSTRACT FROM AUTHOR]