Lithological mapping using remote sensing techniques: A case study of Alagbayan area, Dornogobi province, Mongolia

This study investigated the multispectral remote sensing techniques including ASTER, Landsat 8 OLI, and Sentinel 2A data in order to distinguish different lithological units in the Alagbayan area of Dornogobi province, Mongolia. Therefore, Principal component analysis (PCA), Band ratio (BR), and Support Vector Machine (SVM), which are widely used image enhancement methods, have been applied to the satellite images for lithological mapping. The result of supervised classification shows that Landsat data gives a better classification with an overall accuracy of 93.43% and a kappa coefficient of 0.92 when the former geologic map and thin section analysis were chosen as a reference for training samples. Moreover, band ratios of ((band 7 + band 9)/band 8) obtained from ASTER corresponds well with carbonate rocks. According to PCs, PC4, PC3 and PC2 in the RGB of Landsat, PC3, PC2, PC6 for ASTER data are chosen as a good indicator for different lithological units where Silurian, Carboniferous, Jurassic, and Cretaceous formations are easily distinguished. In terms of Landsat images, the most efficient BR was a ratio where BRs of 5/4 for alluvium, 4/7 for schist and 7/6 to discriminate granite. In addition, as a result of BR as well as PCA, Precambrian Khutag-Uul metamorphic complex and Norovzeeg formation can be identified but granite-gneiss and schist have not given satisfactory results.

Main features of modeling terrigenous deposits in East-Siberia using the example of the Hamakinsky horizon

Background. The article considers the results of updating the geological model of the khamakinskii horizon reservoirs of the Chayandinskoe oid and gas field. The main aim is project the production of the oil rims and form a positive business case of the project. Materials and methods. Conceptual sedimentary model bases on the core of the 14 wells. Updating of the petrophysical model is the key to identify post-sedimentary transformations (like anhydritization and halitization) and the opportunity to correct the permeability trend. The tectonic pattern of the horizon based on the interpretation of 3D seismic data. There are two groups of faults were identified: certain and possible. Neural networks algorithm uses for a creating the predictive maps of anhydritization, which are used in the geological model. Results. Estuary sands influenced by fluvial and tidal processes dominate the khamakinskii horizon. The reservoir is irregular vertically: at the base of the horizon, there are sandstones of the delta front and there are alluvial valley with fluvial channels in the middle and upper parts. Eustary sands eroded by incised valleys (alluvial channels). According to the core and thin section analysis, the main uncertainty is sedimentary transformations of reservoir. It affects the net thickness and then the volume of oil in productive wells. 3D geological model includes the trends of anhydritization and halitization over the area, which makes it possible to obtain a more accurate production forecast. Conclusion. As part of the probability estimate of oil reserves, the main geological parameters that affect the volume of reserves were identified. Pilot project is planning to remove geological and technical uncertainties.

Morphometric Analysis through 3D Modelling of Bronze Age Stone Moulds from Central Sardinia

Stone moulds were basic elements of metallurgy during the Bronze Age, and their analysis and characterization are very important to improve the knowledge on these artefacts useful for typological characterization. The stone moulds investigated in this study were found during an archaeological field survey in several Nuragic (Bronze Age) settlements in Central Sardinia. Recent studies have shown that photogrammetry can be effectively used for the 3D reconstruction of small and medium-sized archaeological finds, although there are still many challenges in producing high-quality digital replicas of ancient artefacts due to their surface complexity and consistency. In this paper, we propose a multidisciplinary approach using mineralogical (X-ray powder diffraction) and petrographic (thin section) analysis of stone materials, as well as an experimental photogrammetric method for 3D reconstruction from multi-view images performed with recent software based on the CMPMVS algorithm. The photogrammetric image dataset was carried out using an experimental rig equipped with a 26.2 Mpix full frame digital camera. We also assessed the accuracy of the reconstruction models in order to verify their precision and readability according to archaeological goals. This allowed us to provide an effective tool for more detailed study of the geometric-dimensional aspects of the moulds. Furthermore, this paper demonstrates the potentialities of an integrated minero-petrographic and photogrammetric approach for the characterization of small artefacts, providing an effective tool for more in-depth investigation of future typological comparisons and provenance studies.

Micropore structure and water driving characteristics of tight sandstone reservoirs in Ordos Basin

In order to explore the influence of the micropore structure of the tight sandstone reservoir in the water driving characteristics, the studies on the Chang 6 tight sandstone reservoir of the middle-western part of Ordos Basin are carried out by various experiments such as cast-thin section analysis, scanning electron microscopy, high-pressure mercury injection and micro-water driving. The result shows that the permeability contribution curves of samples shift to the left as the sample permeability decreases, indicating that the greater the permeability, the greater the proportion of large pores. The permeability is mostly dominated by pores with the radius larger than R50–R60. There are big differences in the water driving type, oil-driven efficiency and residual oil distribution characteristics between reservoirs of different types. The type II reservoir is the major target of subsequent exploration and development, where water driving types consist of mesh and finger, leaving the residual oil mainly locked by water or isolated as oil drops. The size and distribution feature of pores are the key factors dominating the oil-driven efficiency.

Pottery of Early Iron Age from the Glinjeni II-La Șanț (North-Western Pontic Sea Region): Composition, Technology and Raw Material Sources

Transition to the Early Iron Age was marked by the appearance of innovations such as iron technology and changes in the lifestyle of local societies on the territory of the North-Western Pontic Sea region. One of the most interesting sites of this period is the Glinjeni II-La Șanț fortified settlement, located in the Middle Dniester basin (Republic of Moldova). Materials of different cultural traditions belonged to the Cozia-Saharna culture (10th–9th cc. BC) and the Basarabi-Șoldănești culture (8th–beginning of 7th cc. BC) were found on this site. The article presents the results of a multidisciplinary approach to the study of ceramic sherds from these archaeological complexes and cultural layers as well as raw clay sources from this area. The archaeometry analysis, such as the XRF-WD, the thin section analysis, SEM-EDX of ceramics, m-CT of pottery were carried out. The study of ancient pottery through a set of mineralogical and geochemical analytic methods allowed us to obtain new results about ceramic technology in different chronological periods, ceramic paste recipes and firing conditions. Correlation of archaeological and archaeometry data of ceramics from the Glinjeni II-La Șanț site gives us the possibility to differ earlier and later chronological markers in the paste recipes of pottery of 10th–beginning of 7th cc. BC in the region of the Middle Dniester basin.

The Xlendi Bay shipwreck (Gozo, Malta): a petrographic and typological study of an archaic ceramic cargo

An underwater survey off the southwest coast of the island of Gozo revealed a well-preserved shipwreck 110 m below the surface. The site belonged to a previously unknown wreck with a cargo of volcanic millstones and ceramic amphorae dating to the 7th century BC. This article presents the first results of thin-section analysis taken from the pottery objects, and concludes that the ship was carrying a heterogeneous cargo of amphora-borne goods from the Maltese islands, North Tunisia, and possibly Sicily, making it the earliest, known shipwreck in the central Mediterranean; and provides the earliest evidence for Maltese external trade in the central Mediterranean.

Geomorphology of the Mirador-Calakmul Karst Basin: A GIS-based approach to hydrogeologic mapping

This paper classifies the karst landscapes of the Petén Plateau and defines the Mirador-Calakmul Karst Basin by illustrating the distribution of its karst hydrologic features. Archaeological and spatial research of the Mirador-Calakmul area of Guatemala and Mexico has shown it to be a karst basin with geopolitical implications. Current research characterizes the karst landscapes of the Petén Plateau, maps the distribution of karst hydrologic features, and delineates the basin in geomorphological terms. To further this aim, multiple forms of remote sensing data including orthophotographs, a satellite Digital Elevation Model, satellite multispectral images, and Light Detection and Ranging (LiDAR) data have been integrated to interpret the karst features in the study area. Outcrop study and thin section analysis of the upper Buena Vista Formation document that the dominant lithologies are a shallow water algal boundstone interbedded with terrestrial caliche. Karst landforms have been mapped over the Petén Plateau and we identify five karst landscapes, the largest of which is a fluviokarst landscape dominated by karst valleys. We further map karst hydrologic features including seasonal swamps, dolines, intermittent lakes, intermittent streams, solution-enhanced fractures, and springs all of which are characteristic of drainage basins. Boundaries of the karst basin are mapped from multiple lines of evidence including distribution of the karst valleys, a line of springs along the western boundary of the fluviokarst landscape, and a surface drainage analysis. We capture and classify hydrologic data points and develop a regional groundwater map that indicates subsurface flow from east to west within the basin. A drainage map illustrates the extensive system of karst valleys, boundaries, and inferred groundwater flow paths of the Mirador-Calakmul Karst Basin. It was within this geomorphological setting that the ancient Maya developed an extensive civilization during the Middle and Late Preclassic periods (1000 BCE-150 CE).

Labyrinth patterns in Magadi (Kenya) cherts: Evidence for early formation from siliceous gels

Sedimentary cherts, with well-preserved microfossils, are known from the Archean to the present, yet their origins remain poorly understood. Lake Magadi, Kenya, has been used as a modern analog system for understanding the origins of nonbiogenic chert. We present evidence for synsedimentary formation of Magadi cherts directly from siliceous gels. Petrographic thin-section analysis and field-emission scanning electron microscopy of cherts from cores drilled in Lake Magadi during the Hominin Sites and Paleolakes Drilling Project in 2014 led to the discovery of two-dimensional branching "labyrinth patterns" in chert, which are a type of fractal "squeeze" pattern formed at air-liquid interfaces. Labyrinth patterns preserved in chert from Lake Magadi cores indicate invasion of air along planes in dewatering gels. These patterns support the precipitation of silica gels in the saline-alkaline Lake Magadi system and syndepositional drying of gels in contact with air as part of chert formation. Recognizing cherts as syndepositional has been critical for our use of them for U-Th dating. Identification of labyrinth patterns in ancient cherts can provide a better understanding of paleoenvironmental and geochemical conditions in the past.

Depositional environment of the Bagh-e-Vang Formation – the only occurrence of upper Lower Permian in Iran

A transgression of the Tethys Ocean occurred in east central Iran, like in other areas of the Tethys Ocean, around the Yakhtashian/Bolorian (regional chronostratigraphical units corresponding with the Artinskian/Kungurian of the Early Permian) transition. This led to the development of a carbonate platform that is represented in the Shirgesht area on the northern part of the Tabas Block by the Bagh-e-Vang Formation, which constitutes the only known sedimentary unit from the late Early Permian in Iran. Field data and thin-section analysis indicate deposition on a carbonate ramp with barriers separating a lagoonal area with intertidal mud flats from the open-marine environment. The overall transgressive development is indicated by the presence of open-marine sediments on top of the barrier and lagoonal sediments.

Distribution of Volcanic Rocks Porosity of Dissected Kromong Paleovolcano: Analogue of Volcanic Reservoir

The potentiality of unconventional play on the volcanic reservoir was evaluated for the purpose to deliver an integrated evaluation of shallow reservoir target associated with the Northwest Java Basin (NWJB). This study provides basis discovery for further exploration and dissemination of volcanic reservoir by presenting an overview of geometric and porosity type analysis of Kromong paleo-volcano complex deposits associated with the NWJB comprehensively. Furthermore, reservoir lithofacies and pore space deployment of Kromong volcanic deposits were studied. The detailed lithofacies analysis was carried out based on field observations from several dissected- and obscure dipping-outcrops in Kromong area associated with NWJB. Following this, a set of outcrop samples were processed for megascopic description integrated with thin-section analysis by using the polarized light microscope and XRF, respectively to assess different types of reservoir pore spaces and structure. Subsequently, the physical properties-porosity measurement was conducted using ImageJ software tools to understand the potentiality of high-quality reservoir formation. The results of this study show that rocks in Kromong area associated with NWJB can be comprehensively classified into reefal limestone for carbonate deposit and into 4 categories, including volcaniclastic lava, sheeting joint lava, pyroclastic breccia, volcanic intrusion, for volcanic deposits. The proposed volcanic reservoirs of volcanic play in this study are lithologically composed of autobreccia lava, sheeting joint lava, pyroclastic breccia to andesitic- and andescitic-dikes, which comprises explosive facies and intrusive facies. Pyroclastic breccia reservoirs are primary pore-type reservoirs with devitrified micropores as main reservoir space. Whilst volcanic dikes reservoirs are mainly porous-fractured-type reservoirs with cooling fracture porosity. In conclusion, following factors that control the presence of a volcanic reservoir are lithology, lithofacies, tectonism and vulcanism. Despite worldwide discoveries of volcanic reservoirs, neither the detailed potentiality evaluation nor the postulated assumption of volcanic reservoir development in NWJB field has been examined sufficiently. This contribution offers knowledge benefits by discussing the potentiality of the Cenozoic-Quarternary volcanic reservoir of the NWJB field and providing a reference for future exploration in the petroleum industry.