Massive Sandstone Research Articles

Depositional setting and U-Pb detrital record of rift-related deposits in the Moeda Formation (Minas Supergroup) at the Gandarela and Ouro Fino synclines, Quadrilátero Ferrífero, Brazil

Abstract The Moeda Formation (Caraca Group, base of Minas Supergroup) registers the initial rift stages of the Minas Basin in the Quadrilatero Ferrifero, Southern Sao Francisco craton, SE-Brazil. We present stratigraphic and U-Pb detrital zircon dating analyses of the Moeda Formation that contribute to the comprehension of its sedimentary evolution in the southernmost Gandarela and Ouro Fino synclines (Central-Eastern Quadrilatero Ferrifero). The Moeda Formation sequence consists of a basal proximal alluvial fan with clast-supported conglomerates, grading upward into an alluvial floodplain with quartz arenites, and upper massive sandstones from distal fluvial fans. Because the Moeda Formation is normally limited by similar lithologies at both its base (Nova Lima Group, Rio das Velhas Supergroup) and top (Batatal Formation, uppermost Caraca Group) and stratigraphic inversion has occurred in the study area, U-Pb detrital zircon dating was also extended to these units to differentiate them stratigraphically. The youngest clusters of detrital zircon ages in the Nova Lima Group and Moeda and Batatal formations were 2716, 2777 and 2786 Ma, respectively. Based on our data and relevant literature, the depositional age of the Moeda Formation was interpreted as between 2716 and 2520 Ma with the Mesoarchean continental crust, the Rio das Velhas Supergroup and the Archean TTG complexes as its main source areas.

Geochemistry of Eocene Bawang Member turbidites of the Belaga Formation, Borneo: Implications for provenance, palaeoweathering, and tectonic setting

The Belaga Formation of the Rajang Group or Rajang Fold and Thrust Belt (Late Cretaceous to Late Eocene) is mostly exposed in Sibu Zone along with some exposures in the Miri Zone of Central Sarawak. This entire turbiditic sequence was believed to have been deposited in a deep marine environment in a basin having an overall passive margin setting, that is, the Rajang Sea. However, the Eocene age‐related stratigraphic record of this group (including Bawang Member) is much more complex, due to the complicated geological and tectonic settings which prevailed during their deposition. Here, we present field observations along with the application of various geochemical proxies and their constraints for the understanding of provenance, palaeo‐weathering, and tectonic evolution of the area during the deposition of Bawang turbidites. Based on field observation, it has been found that this member consists of four main lithofacies, including massive sandstone facies (MSF), thick‐bedded facies (TBF), heterolithic facies (HF), and mud facies (MF). Using geochemical data, chemical weathering indices (CIA and CIW) values and A‐CN‐K plot show that the source area for Bawang turbidites has undergone a moderate to an intense degree of chemical weathering and was influenced by the recycling effect. The slight depletion in sandstones and shales for Cr, Ni, and V values is consistent with the felsic dominated source region; however, La/Sc versus Co/Th and La/Th versus Hf plots show a mixed source (felsic and intermediate volcanic source) with some input of recycled sediments from the older sedimentary to metasedimentary rocks. Various geochemical ratios and discriminant diagrams verify that the Schwaner Mountains and its metamorphic group of rocks were the principal provenances for these sediments, along with some input from West Borneo. The results of the geochemical analysis also show that Bawang turbidite sediments were deposited in a basin associated with an initial active continental margin setting and the basin was shifting towards a passive setting (Late Eocene–Oligocene). The volcanic input in Bawang Member during the Late Eocene also suggests the involvement of some subsequent possible arc setting around the “Bawang subbasin”.

Paleocene storm-related event beds in the Gaoyou Sag of the Subei Basin, eastern China: A new interpretation for these deep lacustrine sandstones

Lacustrine storm deposits in hydrocarbon-rich lake basins can be excellent reservoirs; therefore, the identification and interpretation of storm deposits have great significance for future petroleum exploration. Recent progress in facies analysis helps to discriminate the sedimentary effects of combined flow and oscillatory flow in the depositional processes. Through core and well log data and thin-section analysis, the sandy deposits of Paleocene E1F3 member in the middle part of the Gaoyou Sag, Subei Basin, are interpreted as storm-induced deposits. Petrologic analysis shows that the coarser sediments are mostly fine-grained to silt-sized feldspathic litharenite. Five lithofacies were identified based on core observation, including massive sandstone, cross-bedded sandstone, hummocky cross-stratification (HCS) sandstone, wave rippled sandstone and siltstone, and massive mudstone. Lithofacies associations revealed a storm “sequence” beginning with an erosional surface and then fining upward, indicating hydrodynamic conditions that ranged from gravity flow, unidirectional flow, combined flow to oscillatory flow, which are attributed to storm-related processes. According to the different lithofacies associations and depositional processes, a depositional model including four facies tracts of storm-related deposits are recognized in plane view: (1) storm-induced turbidity channel facies characterized by coarser particles and formed by storm-triggered turbidity current, (2) proximal facies dominated by gravity, unidirectional, and combined flows, (3) transitional facies influenced by all the flow regimes and exhibiting a relatively complete storm “sequence”, (4) distal facies formed by low-energy deep-lake turbidity flow. Because storm deposits have petroleum significance in an oil-bearing basin such as Subei Basin, this study provides practical examples and guidance for future hydrocarbon exploration in other ancient lacustrine basins.

Bed type and flow mechanism of deep water sub-lacustrine fan fringe facies: an example from the Middle Permian Lucaogou Formation in Southern Junggar Basin of NW China

Submarine or sub-lacustrine lobe deposits are important reservoirs, but the fan fringe deposits form heterogeneities within deep water fan deposits. Fan fringe facies records the complex sediment gravity flow types. By understanding of the bed types and flow mechanisms, we can identify the fan fringe deposit, which aids in the reconstruction of deep water fan and reservoir evaluations. The Jiucaiyuanzi and Dalongkou sections in the West Bogda Mountains preserve well-exposed 536-m and 171-m thick successions, respectively, of a deep water lacustrine depositional system from the Middle Permian Lucaogou Formation. Bed types of the Lucaogou Formation include high-density turbidite, low-density turbidite, incomplete Bouma-type turbidite, hybrid event beds, and slump deposits. The Lucaogou Formation is interpreted here as a fan fringe facies due to the thin bed thickness that characterize turbidites and hybrid event beds, as well as the predominance of the isolated sheet architecture. Previous studies suggest that these deposits were considered as deposited in a deep water setting due to the absence of wave-related structures. The presence of abundant mud clasts in massive medium-coarse grained sandstone beds reflects the significant erosional capability and interactions between high-density turbidity currents and lake floor. The fan fringe facies here contains amalgamated and thick-bedded homolithic facies (~ 30%) and thin-bedded heterolithic facies (~ 70%). The examination of the bed type is of wider significance for facies prediction and reservoir heterogeneity in the sub-lacustrine fan fringe facies.

Environment Of Deposition Of The Jurassic-Cretaceous Continental Deposit In Central Pahang (Peninsular Malaysia) By Sedimentary Facies Analysis

Spatial lithofacies and lithofacies association serves as one of the reliable methods in assessing the depositional process of sediments and interpreting its depositional environment. The method of facies analysis is adapted in this study where four newly exposed stratigraphic sections along the Jerantut-Maran road in Jerantut, Central Pahang of Peninsular Malaysia were studied. Previous studies showed that the environment of deposition of these continental deposits is broadly of braided-meandering river. Sedimentological data from the newly exposed stratigraphic sections had given a better understanding on the sedimentation processes involved in these deposits where interpretation on the environment of deposition is construed up to its sub-environment. The main lithofacies recognized include conglomerate, sandstone, and fine-grained facies. The facies associations identified include (i) massive to laminated silt/mudstone, (ii) massive sandstone, (iii) thin to thick ripple to parallel laminated sandstone, (iv) conglomeratic sandstone, (v) graded channelized sandstone, (vi) coarsening upwards medium bedded sandstone and (vii) heterolithic sandstone. The different facies associations are grouped to four (4) facies assemblages showing characteristics of certain environment: (1) floodplain, (2) channel bar complex, (3) point bar and (4) crevasse splay. Floodplain facies assemblage is marked by fine-grained facies, mainly siltstone/mudstone and fine-grained sands with lower flow regime structures. Channel bar complex is identified by high energy deposits of coarse-to-medium grained sandstones often with scoured bottom and lenticular geometry. Point bar is recognized by the lateral accretion surfaces often consisting of normal graded sandstone with sharp top and bottom contact, sometimes capped with thin mudstones. Crevasse splay facies assemblage is characterized by heterolithic sandstone, dominated by flaser-wavy bedding and coarsening upwards medium bedded sandstone that is overlain by fine-grained facies of the floodplain assemblage. The overall facies based on an outcrop scale suggests general features of fluvial facies with fluctuations in flow energy. The environment of deposition is thus interpreted to be of braided river with floodplains and isolated point bar.

Lithofacies Study of the Mesozoic Rocks of Wandhaya Area, Southwest of Bhuj, Kachchh Mainland, Gujarat

Abstract The stratigraphic sequence exposed in Wandhaya area comprises of marine clastic sediments of Mesozoic, which includes M-III and M-IV of Jumara Formation, Lower Member of Jhuran Formation and Upper Member of Bhuj Formation. Lithofacies erected from the study area are Shale Facies (SF), Oolitic Limestone Facies (OLF), Intercalated Shale Siltstone Facies (ISSF) and Massive Sandstone Facies (MSF). SF is developed in M-III and M-IV of Jumara Formation suggesting its deposition in transition zone. Oolitic Limestone Facies (OLF) occurs only in M-IV of Jumara Formation indicates its depositional environment as offshore region. Intercalated Shale Siltstone Facies (ISSF) is deposited in lower shoreface to transitional and Massive Sandstone Facies (MSF) in foreshore environment, are exposed in Lower Member of Jhuran Formation and also in Upper Member of Bhuj Formation. The sediment characteristics and association of trace fossils in the rocks indicate distinction in sedimentation from foreshore to offshore environments.

Architecture of deepwater turbidite lobes: A case study of Carboniferous turbidite outcrop in the Clare Basin, Ireland

Abstract Through lithofacies analysis and architecture anatomy of the Carboniferous Ross Sandstone turbidites outcropped at western Ireland, the depositional model of deepwater turbidite lobes is established. Seven types of lithofacies are recognized including goniatites-rich shale, laminated shale, laminated siltstone, massive sandstone, fine-medium sandstone with mud-clast, basal gravel, and chaotic mudstone, which can be subdivided into units of three origins, turbidite lobe, turbidite channel, and slide-slump; and four hierarchical levels, lobe complex, lobe, lobe element and single sandstone layer. The lobes show apparent compensational stacking pattern, lobe elements display typical thickening-upward cycles on vertical profile, and the higher the hierarchical level, the better the preservation of the hierarchical boundary is. In general, turbidite lobe deposits appear as tabular, parallel/sub-parallel sandstone and mudstone interbeds, and change from thick, massive sandstone in the proximal end to thinner sandstone and mudstone interbeds from axis to fringe, with the sand-shale ratio and degree of sandstone amalgamation decreasing.

A numerical modeling approach for evaluation of spalling associated face instability in longwall workings under massive sandstone roof

The majority of the longwall panels in India have been worked underneath massive sandstone main roof with soft coal/shale immediate roof. As the mining goes deeper, ensuring stability and consistent production from such workings is a great challenge for their safety and sustainable performance. In this scenario, understanding the face instability mechanism and its rock mechanics precursors have evolved as a significant design challenge for obtaining an optimal longwall geometry in complex geo-mining conditions. Research to date mostly focused on the failure mechanism and, in some part, displacement characteristics of the coal wall. In contrast, minimal work has been performed to address the critical research gap from the face failure to spalling with the associated rock mechanics parameters and its three-dimensional quantification. This paper considered the longwall panel of 250 m face length and 3.5 m working height in the Godavari Valley Coalfield, which was worked underneath 23.5 m massive sandstone roof at a cover depth of 323 m. The finite difference software FLAC3D was employed to investigate stress redistribution, failure characteristics, strain dynamics, and horizontal displacement of the coal wall until the occurrence of the main weighting. Accordingly, a set of criteria, namely, Percentage of Critically Strained Zone (PCSZ) and Percentage of Spalling Zones (PSZ), were proposed based on the critical limits of the lateral strain and the horizontal displacement of the face. The formation of these critical zones around the face was further correlated with the failure and caving characteristics of the massive sandstone roof.The study revealed that within 0–3 m distance ahead in the central region of the face, the extent of PCSZ in the Peak stress period was 46, which further enhanced and contributed in PSZ of 78 as noted during the weighting period. It is indicated that the impact of spalling dominated in the middle and the middle to the top portions of the face, covering 53% of total face length within 0–3 m regions ahead of the face. The relative influence of the failure and caving characteristics of the key roof positively correlated with the PCSZ and PSZ at the face. The critical limits of lateral strain (0.58%) and horizontal displacement (−15.40 mm), as projected in this study for evaluation of face instability, provided closer agreement with field observed extent of face spalling. The findings of the study supplements the existing knowledge about the mechanism of face spalling and its quantification in the Indian geo-mining conditions. The approach developed in this paper can be employed to analyze the extent of face instability during weighting periods.

Hierarchical scales of soft-sediment deformation in erg deposits, Lower Jurassic Navajo Sandstone, Moab area, Utah, U.S.A.

ABSTRACTExtensive soft-sediment deformation (SSD) of multiple expressions and scales record active and dynamic events and processes in erg deposits of the Lower Jurassic Navajo Sandstone near Moab, Utah. The erg deposits preserve depositional environments of eolian dune, interdune, fluvial, playa, lake, and spring. A large range of SSD features, from intact beds showing little deformation to pervasively disturbed beds, exist in many of these deposits. A simplified classification index captures the different scales of SSD in ascending order of deformation intensity: 1) mostly intact bedding with small-scale wavy or undulatory deformation structures within single beds; 2) dish and flame structures; 3) meter-scale, kinked, slumped, rolled, overturned, vertical, and detached contorted crossbedding, and associated centimeter- to meter-scale pipes; and 4) disruptive diapirs and laterally extensive massive sandstone. The SSD features of deformed crossbed sets, diapirs, and massive sandstone beds, are consistently juxtaposed, and are thus genetically linked.Although the Navajo Sandstone has been considered a classic example of an extensive dry eolian system, both individual and combinations of strata bounded SSD features exemplify dynamic deformation, liquefaction, and fluidization that took place at various times after deposition. The lowest degree of deformation, SSD 1, is largely attributed to autogenic––inherent to the eolian system––or local allogenic processes. Larger degrees of deformation, SSD 2–4, were more likely produced by allogenic, external-forcing processes from regional changes in climate and/or near-surface groundwater conditions originating from the Uncompahgre uplift, with the deformation triggered by some event(s). Possible significant ground motion could have led to large-scale disruption in the Navajo sand sea across kilometer-scale intervals. The Navajo example establishes valuable hierarchical relationships of processes and products for recognizing and interpreting SSD in other ancient and modern eolian systems. This has particular relevance to sedimentary discoveries on Mars, where SSD features are visible from remote sensing imagery and rover exploration.

Spatial and temporal variations in depositional systems in the Kazusa Group: insights into the origins of deep-water massive sandstones in a Pleistocene forearc basin on the Boso Peninsula, Japan

A detailed chronostratigraphic framework established by the mapping of tephra key beds and application of oxygen isotopic data allows assessment of the synchroneity and diachroneity of depositional systems formed in coastal and deep-water environments. This framework also allows estimation of the timing of active delivery of coarse-grained sediments beyond the shelf margin in relation to relative sea-level changes. The depositional processes of deep-water massive sandstones (DWMSs) are still enigmatic; their formation is a result of active delivery of sands in association with the supply of organic carbon into deep-water environments. DWMSs are also important as reservoirs for hydrocarbon explorations. This study investigated the origins of DWMSs in the upper Umegase, Kokumoto, and Chonan formations (in ascending order) of the Pleistocene Kazusa Group on the Boso Peninsula, central Japan. Each formation contains several packets of DWMSs that are interpreted to have formed in response to the progradation of gravelly shelf-margin deltas or fan deltas during the falling and lowstand stages of relative sea-level changes controlled primarily by glacioeustasy. The development of DWMSs and associated sandstone beds is interpreted to have been induced by hyperpycnal flows, in association with sediment gravity flows that were initiated by breaching and/or collapse of sandy substrates on the shelf-margin deltas or fan deltas. The timings of the initial and final deposition of the packets vary within and between the formations, and are considered to have been controlled by the interaction between allogenic and autogenic processes operating in the gravelly shelf-margin deltas or fan deltas. A muddy horizon that contains the Lower–Middle Pleistocene Subseries boundary (the base of the Chibanian Stage) in the Kokumoto Formation is also underlain and overlain by the packets and represents a deposit formed in a condensed section in an upper slope environment. This depositional setting may have favored the development of the Global Boundary Stratotype Section and Point (GSSP) for the Lower–Middle Pleistocene Subseries boundary in the formation.

GEOTECHNICAL CHARACTERISTICS AND FOUNDATION CONDITION OF PEGU GROUP IN YANGON AREA

Yangon is highly dense populated city in Myanmar. Today Yangon area has undergone very rapid development and expansion because of its socio-economic cum political significance. Therefore it is required to expand the new satellite town. Therefore, geotechnical site characteristics and zonation of Yangon area is carry out. In Yangon, three geological rock units such as alluvial deposits, Irrawaddy Formation and Pegu Group can be found. For this research, geotechnical characteristics and foundation condition of Pegu Group is investigated. Based on the sample collected and the laboratory results, foundation condition of Pegu Group are studied. The purpose of the research is to point out the engineering characteristics and foundation properties of Pegu Group in the Yangon Area. The Pegu Group consists of three lithostratigraphic units recognizable from surface geologic characters and subsurface data. They are Besapet Alternation, Thardugan Sandstone and Hlawga Shale from youngest to old. Besapet Alternation consists of shales and thinly laminated sandstone which are exposed in the vicinity of Besapet Lake and also exposed behind the police training school. Besapet Alternation is characterized by blunish grey to greenish grey, bedded to nonbedded, silty shale with very thin parting of micaceous sandstones. Thardugan Sandstone consists of blunish grey to brownish grey, fine to medium grained micaceous and argillaceous sandstone with ferruginous bands. They are exposed around the Thardukan Pagoda, southwestern and south of Hlawga Lake.It exposes as massive body sandstone around Thadukan Pagoda and thin bedded sandstone at police training school. Hlawga Shale consists of shale and laminated clay. They occur at the low land area at the west of Hlawga Lake beside the Thardugan Sandstone. According USCS classification, CL, ML, MH, SC, SM and SW soil types are found as residual soil in Pegu Group. The ultimate bearing capacity of residual soil of Pegu Group is 15 kPa to 600 kPa. The unconfined compressive strength of Thardugan Sandstone varies from 8 MPa to 61 MPa.

Gravity-flow deposits caused by different initiation processes in a deep-lake system

Gravity flows may be triggered by different initiation processes in both marine and lacustrine basins. Recognizing the different initiation processes of gravity flow based on their deposits is vital to accurately establish gravity-flow sandstone distribution, which is important for defining paleogeography and for efficient oil and gas exploration. Gravity-flow deposits in the Dongying sag were analyzed using three-dimensional seismic, well-log, grain size, and porosity and permeability data, along with core descriptions. Eleven lithofacies, nine bed types, and six bed-type associations were recognized in the gravity-flow deposits in the Dongying sag. Gravity-flow deposits around well Niu-110 were caused by delta-fed sediment failure. These deposits are characterized by medium to very fine-grained sandstone, abundant liquefaction and soft-sediment deformation structures, and thick laminae rich in plant debris. They formed massive sandstones accompanied by normally graded sandstone and lenticular-shaped sandbodies and are composed of chaotic deposits and tongue lobes. The above features collectively are indicative of typical collapsed-sediment transport to deep water by slumping and poorly cohesive debris flow to low-density turbidity current. Gravity-flow deposits around well Shi-100 are interpreted to have been caused by flooding river-fed hyperpycnal flows. These deposits are characterized by gravel to very fine-grained sand, abundant erosional structures and climbing ripples, and thin laminae rich in plant debris. They formed massive sandstone with some space stratification accompanied by inverse-then-normal grading sandstone and elongate or fan-shaped sandbodies and are composed of channel-levee systems and lobes. Stratified hyperpycnal flow is prone to form a hydraulic jump at the slope break. After the hydraulic jump, coarse-grained sediments were transported to the basin under the drag and shear of the upper part of the suspension flow. Gravity-flow deposits caused by flooding river-fed hyperpycnal flow are better reservoirs than those caused by delta-fed sediment failure under the same conditions. This study offers insight into the recognition criteria and flow processes of gravity flows caused by the different initiation processes in a lacustrine basin.

Origin and composition of three heterolithic boulder- and cobble-bearing deposits overlying the Murray and Stimson formations, Gale Crater, Mars

Heterolithic, boulder-containing, pebble-strewn surfaces occur along the lower slopes of Aeolis Mons (“Mt. Sharp”) in Gale crater, Mars. They were observed in HiRISE images acquired from orbit prior to the landing of the Curiosity rover. The rover was used to investigate three of these units named Blackfoot, Brandberg, and Bimbe between sols 1099 and 1410. These unconsolidated units overlie the lower Murray formation that forms the base of Mt. Sharp, and consist of pebbles, cobbles and boulders. Blackfoot also overlies portions of the Stimson formation, which consists of eolian sandstone that is understood to significantly postdate the dominantly lacustrine deposition of the Murray formation. Blackfoot is elliptical in shape (62 × 26 m), while Brandberg is nearly circular (50 × 55 m), and Bimbe is irregular in shape, covering about ten times the area of the other two. The largest boulders are 1.5–2.5 m in size and are interpreted to be sandstones. As seen from orbit, some boulders are light-toned and others are dark-toned. Rover-based observations show that both have the same gray appearance from the ground and their apparently different albedos in orbital observations result from relatively flat sky-facing surfaces.Chemical observations show that two clasts of fine sandstone at Bimbe have similar compositions and morphologies to nine ChemCam targets observed early in the mission, near Yellowknife Bay, including the Bathurst Inlet outcrop, and to at least one target (Pyramid Hills, Sol 692) and possibly a cap rock unit just north of Hidden Valley, locations that are several kilometers apart in distance and tens of meters in elevation. These findings may suggest the earlier existence of draping strata, like the Stimson formation, that would have overlain the current surface from Bimbe to Yellowknife Bay. Compositionally these extinct strata could be related to the Siccar Point group to which the Stimson formation belongs.Dark, massive sandstone blocks at Bimbe are chemically distinct from blocks of similar morphology at Bradbury Rise, except for a single float block, Oscar (Sol 516). Conglomerates observed along a low, sinuous ridge at Bimbe consist of matrix and clasts with compositions similar to the Stimson formation, suggesting that stream beds likely existed nearly contemporaneously with the dunes that eventually formed the Stimson formation, or that they had the same source material. In either case, they represent a later pulse of fluvial activity relative to the lakes associated with the Murray formation.These three units may be local remnants of infilled impact craters (especially circular-shaped Brandberg), decayed buttes, patches of unconsolidated fluvial deposits, or residual mass-movement debris. Their incorporation of Stimson and Murray rocks, the lack of lithification, and appearance of being erosional remnants suggest that they record erosion and deposition events that post-date the exposure of the Stimson formation.

Sandy Debris Flow Sedimentary Characteristics and Patterns in the Meishan Formation of Northern Lingshui Sag, Qiongdongnan Basin

Based on drilling core descriptions and micro sedimentary features, combined with regional paleogeographic features, imaging logging and 3D seismic attribute analysis, the sedimentary characteristics and representative identification mark of sand debris flow sandstone in Meishan formation of northern Lingshui Sag, Qiongdongnan basin are discussed in detail, and the sand debris flow sedimentary pattern in the study area is established. Meishan formation sandy debris flow sandstone in the study area is mainly consist of 2 lithological associations, thick massive siltstone to very fine sandstone without sedimentary structure on the upper part and silty mudstone, mudstone and siltstone interbeds with abundant contemporaneous deformation structure on the lower part, and the “mud-encased sand” structure in massive sandstone can be used as an important symbolic evidence to identify the sand debris flow deposits. The distribution of sandy debris flow sandstone is controlled by shelf slope break, and the area with relatively gentle, constructive slope, where the slope break line is characterized by “bulge” form to the sea, is the most favorable area for the development of sandy debris flow sandstone reservoirs.

Genetic mechanisms of deep-water massive sandstones in continental lake basins and their significance in micro–nano reservoir storage systems: A case study of the Yanchang formation in the Ordos Basin

Abstract Based on field geological surveys of two deep-water sedimentary outcrops in the Yanchang formation of the Ordos Basin, X-ray diffraction analysis, elemental geochemical analysis, and polarizing microscope observations were conducted to investigate the causes of various sedimentary structures inside the massive sand bodies from deep-water debris flow. A genesis model of deep-water debris-flow sandstone is established: during the handling of the mass transport complexes in the basin slope, the soft sandy sedimentary layer with relatively strong shear resistance tears the soft muddy sedimentary layer with weak shear resistance and pulls various clumps inside the muddy layer. Finally, debris-flow massive sandstones with rich sedimentary structures are formed. Through argon ion polishing and field emission scanning electron microscopy, the debris-flow sandstones mainly develop micron-scale pores, and the pore radius is mainly distributed in the range of 1–8 µm. The sedimentary rocks from the semi-deep lake to deep lake facies only have a small number of nano-scale pores, and the pore radius is distributed between 20 and 120 nm.

Analysis of the state of recreational and tourist activity in Yavoriv National Nature Park

The article analyzes the sites of Yavoriv National Nature Park, which are of great recreational and tourist importance. The features of the development of ecological tourism in Yavoriv National Nature Park are highlighted, the tourism and resource potential of the park is estimated. The problems and prospects of using the region's recreational and tourism resources were noted. The reasons for hindering the further development of the tourist and recreational industry in the park are indicated. National nature parks create a unique opportunity to coordinate the tasks of nature conservation with the needs of balanced use of natural resources and rest of the population. Yavoriv National Nature Park is a catalyst for the sustainable development of the region and a base for the development of recreational, tourist, environmental, environmental, scientific, as well as an incentive for the development of related types of entrepreneurial activity in the area. Information on the species diversity of the park makes it possible to develop and implement measures aimed at preserving biotic, ecosystem, landscape diversity, sustainable nature and improving the socio-economic standard of living of the local population. Yavoriv National Nature Park has significant natural, historical and cultural resources. There are many attractive places for the development of cognitive tourism: numerous picturesque hills-remains with rocky outcrops of massive limestones and calcareous sandstones, caves, boulders of Scandinavian origin; favorable conditions have also arisen for the development of various types of tourism: local cognitive, sacral, sports (hiking, horseback, cycling), skilled tourism (fishing). Recreational activities on the territory of the park are a direct investment in the economic development of the region, it is carried out by creating favorable conditions for visitors' recreation and covers: arrangement of ecological and tourist routes and recreation areas; organization of ecological camps for schoolchildren and youth; involvement of the local population in recreational activities (provision of paid services for visitors in accommodation, meals and support); providing information services through print, photo and video production, production of information stands; Attraction and cooperation with the recreational institutions of the region to visit the park territory.

The facies analysis of a fan delta by integrating multiple discipline data — A case study of the KL-A oilfield, Bohai Bay Basin, China

The third member of the Shahejie Formation (Es3) is the main hydrocarbon exploration target in the KL-A oilfield, Bohai Bay Basin, East China. The facies classification is an essential step in mapping the depositional system of Es3 within the Bohai Bay Basin. The facies model is important for identifying the “sweet” lithology within the reservoirs. We characterize the facies of Es3 by integrating cores, well logs, and seismic data. The analysis indicates that the Es3 consists of fan delta deposits. The analysis using well logs and cores indicates that there are five different lithofacies for the Es3 Formation: massive sandstone, horizontally bedded sandstone, trough cross-bedded sandstone, ripple cross-laminated sandstone, and massive mud. The microfacies of Es3 include distributary channel, distributary mouth bar, interdistributary bay, and lacustrine mudstone deposits. The sweet lithologies for hydrocarbon accumulation within the KL-A oilfield include the coarse- and fine-grained sand developed within the channels and distributary mouth bar. We use seismic rms amplitude strata slices to determine the horizontal distribution of facies of the fan delta. The correlation between rms amplitude and well logs indicates that relatively low rms amplitude anomalies on the strata slices can be used as an indicator for sandstone within the KL-A oilfield.

Thickening-upward cycles in deep-marine and deep-lacustrine turbidite lobes: examples from the Clare Basin and the Ordos Basin

Deep-marine and deep-lacustrine reservoirs have been targets for conventional and unconventional oil and gas exploration and development for decades. Thickening-upward cycles in the deep-marine Carboniferous Ross Sandstone Formation outcrops in western Ireland and the deep-lacustrine Triassic Yanchang Formation outcrops in southeast Ordos Basin have been investigated and correlated in this study. Typical thickening-upward cycles consisting of, from bottom to top: (1) laminated shales/shales with interbedded siltstone beds; (2) interbedded sandstones/siltstones and mudstones; (3) structureless massive sandstones, are well recognized in these outcrops and are interpreted as turbidite lobes. A continuously prograding lobe-element model is proposed to explain the repeated stacking of thickening-upward cycles. Thickening-upward cycles developed within deep-marine and deep-lacustrine environments are highly comparable in many aspects, such as sedimentary structures, sheet-like geometries and amalgamation features. A frequent and strong degree of amalgamation is developed within the massive sandstone at the top of each thickening-upward cycle, suggesting a layer-by-layer depositional manner. Field observations and comparison with deep-marine counterparts support the occurrence of turbidity flows in the Yanchang Formation, Ordos Basin.

GEOMORPHOLOGICAL LANDFORM ANALYSIS OF THE AREAS IN THE UKRAINIAN CARPATHIANS ATTRACTIVE FOR RECREATION (THE CASE OF THE CHORNA TYSA BASIN)

The promising area – attractive for recreation – is located within two large geomorphological regions, the Polonynsko-Chornohorsky Carpathians (Svydivets Massif) and the Vododilno-Verhovynsky Carpathians (Bratkivsky Ridge of the Pryvododilny Gorgany). The area includes the highest part of the Svydivets Massif, i.e., Urdu-Flavantuch Ridge (Mt Blyznytsia, 1881 m), Apshynets and Svydivets Ridge (Mt Kotel, 1770.8 m; Mt Dogiaska, 1761.7 m; Mt Troyaska, 1762.6 m), whose structure contains sediments of fine rhythmic flysch and coarse sandstones of chalk and Paleogene. The morphostructure of the Bratkivsky Ridge (Mt Velyka Bratkivska, 1788 m) was formed on the Paleocene and Eocene sediments dominated by massive sandstones, whose outcropping created large masses of rock fields. The typical morpho-sculptural elements are relict landform tiers, as well as forms of Pleistocene icing and extraglacial forms. The dominating forms of Pleistocene ice accumulation are cirques with steep rocky lateral and back walls, troughs (ice plains), rocky cirque ridges (karlіngs), rock bars (transverse rocky cliffs at the bottom of ice plains), glacier deposits (moraines), and lakes in cirque bottoms. Within the area between the spurs of the Turbatska valley in the west and the Menchul valley in the east, there is a large group of Apshynets and Vorozhesky cirques. Most researchers note that the system of these cirques is the most striking area of the relict alpine relief of the Svydivets Mountain Group – with steep rocky walls, cirque lakes (tarns), numerous exarative & accumulative forms, snowfields, and nival niches. The area shows a full spectrum of modern morphodynamic processes: sheet erosion (deluvial erosion), linear erosion, defluxion, slow solifluction, nival processes, mudflows, windthrows & wind falls, as well as gravitational processes, that is, rock slides, talus deposits, avalanches, and landslides. When any slope process starts, it is always connected with geological, geomorphological and climatic factors, as well as economic activity. In fact, exogenous morphological processes are mutually conditioned ("chain reaction"). When designing recreational complexes, the geo-ecological approach is most often used. This approach ensures the most rational and secure use of natural resources, as well as preservation, enhancement and improvement of the environment. Key words: landform, morphostructure, morphosculpture, morphodynamic processes, Ukrainian Carpathians, Chorna Tysa, recreation, geographical forecasting.

Granulometry analysis of Ngrayong sandstone, Tempuran Area, Rembang Zone, North East Java Basin

The study area is located near Tempuran Village, Rembang Zone, North-East Java. Ngrayong sandstone is a famous reservoir in north-east Java, mainly composed of sandstones which are exposed along east-west trending along the southern flank of Pakel Anticline. Eighteen samples from four different facies from eight outcrops conducted for granulometry analysis. The objective of this paper is to predict the reservoir potential base on granulometry analysis especially grain size and sorting. The study area is still needs to confirm about reservoir quality. Ngrayong Formation consists of laminated to thin bedded sandstone facies, thick bedded to massive sandstone facies, calcareous sandstone facies and cross-bedded sandstone facies. According to the analytical results, sandstone facies are composed of very fine to fine, poorly sorted to very well sorted sandstones. Base on the results of analyzed samples, Ngrayong sandstone have good porosity and permeability, thus Tempuran area can be considered as a prospective reservoir.