Sandstone Outcrops Research Articles

Provenance of the He 8 Member of the Upper Paleozoic Shihezi Formation, Ordos Basin, China: Insights from Heavy Minerals, Paleocurrents, Detrital Zircon Chronology, and Hf Isotopes

The Ordos Basin is located in the western part of the North China Craton. The Upper Paleozoic Shihezi Formation, particularly the He 8 Member, is one of the main gas-bearing strata. However, the source areas for the north and south sections have not been clearly distinguished, which has constrained oil and gas exploration to some extent. Therefore, understanding the source rock evolution of He 8 Member in both the south and north basins will provide a favorable theoretical basis for oil and gas exploration. The provenance of the He 8 Member of the Shihezi Formation in the Ordos Basin has not been well defined until now. Seven wellbore sandstone samples and three field outcrop sandstone samples from the He 8 Member in the Ordos Basin were analyzed. Based on zircon U–Pb dating and Lu–Hf isotope analyses, zircon assemblages of 520–386 Ma and 350–268 Ma in the southern Ordos Basin might have originated from the North Qinling Orogenic Belt (NQinOB) and the North Qilian Orogenic Belt (NQiOB); the 350–268 Ma age group of zircons from the NQinOB, and a large number of ~320–260 Ma detrital zircons supplied to the southern Ordos Basin by the NQinOB suggest that NQinOB magmatic and/or metamorphic events may have occurred in the NQinOB during the ~320–260 Ma period. From ~320–260 Ma, the NQinOB might have experienced significant tectonic activity that has not been fully revealed thus far. The zircons from 2600–2300 Ma, 2000–1600 Ma, and 450–300 Ma in the northern Ordos Basin might have been derived from the Trans-North China Orogenic Belt (TNCO), the Khondalite Belt, the Yinshan Belt, and the Alxa Belt. The paleocurrent and heavy mineral analyses determined that there are certain differences between the northern Ordos Basin and southern Ordos Basin, with unstable minerals such as barite and pyrite, as well as moderately stable minerals such as garnet, showing an increasing trend from south to north. There are also differences in the dominant paleocurrent directions between the south and north parts of the basin, and the Hf isotope data in the Ordos Basin show two-stage Hf model ages (TDM2) ranging from 918 Ma to 3574 Ma. As a result, the He 8 Member deposits in the southern Ordos Basin and northern Ordos Basin had different sources. The southern Ordos Basin might have derived from the NQinOB, the NQiOB, and the TNCO, and the northern Ordos Basin might have derived from the TNCO, the Khondalite Belt, the Yinshan Belt, and the Alxa Belt.

The primary porosity heterogeneity characteristics of braided river sandbody and implications for predicting the current physical properties heterogeneities

Understanding the heterogeneity of reservoirs is crucial for enhancing the efficiency of hydrocarbon exploration and development. The primary porosity of samples from modern braided river sands and outcrops of braided river sandstone was calculated using a model previously proposed by the authors. The characteristic parameters (Vx) for calculating primary porosity are closely related to the architectural–elemental configurations (AEC), and the AEC of braided river sand bodies (BRSD) has apparent effects on the distribution of the primary porosity heterogeneities. Analysis of our results has established a simple primary porosity heterogeneity model of BRSD. The center of braided river channel and mid-channel bars have excellent strong primary petrophysical properties with high primary porosity exceeding 38%. The contact areas between the braided river channel and channel bars exhibit relatively low primary porosities of less than 33%. The area between the center and edge of the braided bars and channels displays medium primary porosities. The nonlinear correlation in the Q–Q plot of the primary porosity and present porosity of samples from BRSD in the Ahe Formation is mainly caused by chemical diagenesis. The present porosity heterogeneity of BRSD in the Ahe Formation is less influenced by compaction and cementation, it predominantly arises from the differential of dissolution. Q–Q plots attempt to correlate the geological information from an individual sample with the heterogeneity of present porosity in BRSD. In addition, by utilizing Q–Q plots of the primary and current petrophysical properties of the sand body, the relative extent of heterogeneity modification caused by different diagenetic processes can be assessed. This assessment is crucial for modeling macroscopic models of physical properties during geological history periods.

Sedimentary Structures and Petrography of Rocks within Akpoha Area of the Afikpo Basin Southeastern Nigeria; Constraints on Provenance

Sedimentary structures and petrographic studies of Akpoha area in Afikpo/Abakiliki basin was undertaken in an attempt to understudy and determining constraints in depositional processes in the area . The major outcrops in the area are alternating succession of sandstones and shales striking in a NE-SW direction primarily as a result of folding due to past orogeny in the area. The sandstone outcrops at Akpoha are highly indurated due to age, compaction and tectonism and occur in ridges within the shale unit. The studied shale outcrops were poorly laminated and low in fossil content.Sedimentary structures identified include;Wavy/ripple lamination, Mud cracks, Parallel lamination and Fissility.The results of the petrographic modal analysis from thin section studies show that the sandstone consists predominantly of quartz (55 - 64%); feldspar (22 - 30%) and rock fragment (1 – 9%). The sandstones were immature, poorly to moderately sorted with angular to sub-angular grain shapes which gives clear indication of high energy of sediment deposition and short transport history from provenance.The abundance of well preserved sedimentary structures is an indication of prolong calmness of tectonic/orogenic activities in the area. The fissility observed in shale outcrops and the high induration of the Akpoha sandstones was as a result of compaction from overburden pressure before uplift and exposure.

Surfactant-Enhanced Assisted Spontaneous Imbibition for Enhancing Oil Recovery in Tight Oil Reservoirs: Experimental Investigation of Surfactant Types, Concentrations, and Temperature Impact

Surfactant-assisted spontaneous imbibition is an important mechanism in enhanced oil recovery by capillary pressure in low permeability and tight oil reservoirs. Though many experiments have been conducted to study the mechanism of enhanced oil recovery by surfactant-assisted spontaneous imbibition, the effects of surfactant type, concentration, and temperature have not been well studied. Using tight sandstone outcrop core samples with similar permeability and porosity, this paper experimentally studies surfactant-assisted spontaneous imbibition using three different surfactant types, i.e., sodium dodecylbenzene sulfonate (SDBS), cocamidopropyl betaine (CAB), and C12–14 fatty alcohol glycoside (APG). In addition to the type of surfactant, the effect of the surfactant concentration and the temperature is also investigated. The study results show that the ultimate oil recovery of spontaneous imbibition with formation water and denoised water is about 10%. Surfactant can significantly improve the oil recovery of spontaneous imbibition by reducing the interfacial tension between oil and water, emulsifying crude oil and improving oil mobility. APG showed better performance compared to SDBS and CAB, with a maximum oil recovery factor of 36.19% achieved with formation water containing 0.05% APG surfactant. Lower concentrations (0.05% APG) in the formation water resulted in a higher oil recovery factor compared to 0.1% APG. Increasing temperature also improves oil recovery by reducing oil viscosity. This empirical study contributes to a better understanding of the mechanism of surfactant-assisted spontaneous imbibition and enhanced oil recovery in tight oil reservoirs.

Diagenesis, Provenance, Tectonic Setting and Palaeoclimate of the Eocene Kopili Sandstone, Assam, India: A Petrographic Study

Abstract The Eocene Kopili Sandstone outcropping in the North Cachar Hills (NCHs) of Assam, India, was petrographically studied to unravel its diagenetic features, provenance, tectonic setting and palaeoclimate conditions. The modal analysis of the Kopili Sandstone reveals that the detrital mineralogy is dominated by quartz (48.78 to 83.70 %), with variable amounts of rock fragments (0.37 to 7.35 %), feldspar (0.37 to 8.33 %), micas (0.36 to 7.84 %) and subordinate amount of heavy minerals. The matrix and cement content varies from 9.88 to 21.50 % and 1.12 to 19.41 % respectively. The Kopili Sandstone is classified as quartz arenite to sub lithic arenite. Compaction, cementation, dissolution and replacement are the observed diagenetic processes in the studied sandstones. Diagenetic transformations are manifested in the fractured detrital grains, overgrowth of quartz, corrosion of grain boundaries of quartz, modification of grain boundaries, and silica and iron oxide cement precipitation in the interstices of the framework grains. The provenance is of granite-gneissic rock terrain. The detritus in the depositional basin is derived predominantly from craton interior with minor input from recycled orogen. The study discerns humid palaeoclimate conditions for the Kopili Sandstone.

Rare faction of flora of the designed landscape reserve “Balka Shchurovka”

The article is devoted to the study of the modern distribution of certain rare plant species within the "Balka Shchurovka" beam system (near the settlements of Dniprovske, Novomykolaivka of the Verkhnyodniprovska OTG of the Dnipropetrovsk region) and substantiation of the prospects for granting the object the status of a nature conservation area. The natural diversity of the vegetation cover of the designed reserve consists of zonal steppe vegetation, bairach forests, psamophilic and petrophilic communities, and meadow vegetation. According to indicators of biodiversity, the territory b. Shchurovka is one of the most valuable within the borders of Verkhnyodniprovska OTG of Dnipropetrovsk region. In the process of researching the flora of the planned reserve, a number of new locations of species rare for the region and the region were discovered. 26 regionally rare plant species grow here, 13 species listed in the Red Book of Ukraine, 3 species from Resolution 6 of the Berne Convention and Annexes of the Habitats Directive, presented in the flora of Ukraine, 1 species from the World Red List. The list of plants of the Dnipropetrovsk region included in the Red Book of Ukraine includes 56 species of vascular plants, of which 13 species grow within the b. Rat, which is 23% of the total number of red book species of Dnipropetrovsk region. An important and interesting feature of the layer of sand exposed on the right slope of the gully is the presence of blocks of red sandstone enriched with iron oxides. Near the sandstone outcrops, a characteristic complex of flora has formed on sandy soil with the participation of Sempervivum ruthenicum Schnittsp. & C.B. Lehm, Pulsatilla pratensis (L.) Mill. s.l., Thymus pallasianus Heinr.Braun, Peucedanum arenarium Waldst. & Kit. (Taeniopetalum arenarium (Waldst. & Kit.) V. N. Tichomirov), Achillea leptophylla M. Bieb. Jurinea cyanoides (L.) Rchb and Pulsatilla patens (L.) Mill grow here. s.l. - rare species from the Annexes of the Habitats Directive, Annex I of the Berne Convention, which prefer biotopes with an intact structure as part of rare coenoses. The study of the rare fraction of the flora of the beam system in the context of the conservation of biodiversity of the Right Bank Steppe of the Dnieper region can become the basis of the nature conservation concept of sustainable development of the region.

Rare faction of flora of the designed landscape reserve “Balka Shchurovka”

The article is devoted to the study of the modern distribution of certain rare plant species within the "Balka Shchurovka" beam system (near the settlements of Dniprovske, Novomykolaivka of the Verkhnyodniprovska OTG of the Dnipropetrovsk region) and substantiation of the prospects for granting the object the status of a nature conservation area. The natural diversity of the vegetation cover of the designed reserve consists of zonal steppe vegetation, bairach forests, psamophilic and petrophilic communities, and meadow vegetation. According to indicators of biodiversity, the territory b. Shchurovka is one of the most valuable within the borders of Verkhnyodniprovska OTG of Dnipropetrovsk region. In the process of researching the flora of the planned reserve, a number of new locations of species rare for the region and the region were discovered. 26 regionally rare plant species grow here, 13 species listed in the Red Book of Ukraine, 3 species from Resolution 6 of the Berne Convention and Annexes of the Habitats Directive, presented in the flora of Ukraine, 1 species from the World Red List. The list of plants of the Dnipropetrovsk region included in the Red Book of Ukraine includes 56 species of vascular plants, of which 13 species grow within the b. Rat, which is 23% of the total number of red book species of Dnipropetrovsk region. An important and interesting feature of the layer of sand exposed on the right slope of the gully is the presence of blocks of red sandstone enriched with iron oxides. Near the sandstone outcrops, a characteristic complex of flora has formed on sandy soil with the participation of Sempervivum ruthenicum Schnittsp. & C.B. Lehm, Pulsatilla pratensis (L.) Mill. s.l., Thymus pallasianus Heinr.Braun, Peucedanum arenarium Waldst. & Kit. (Taeniopetalum arenarium (Waldst. & Kit.) V. N. Tichomirov), Achillea leptophylla M. Bieb. Jurinea cyanoides (L.) Rchb and Pulsatilla patens (L.) Mill grow here. s.l. - rare species from the Annexes of the Habitats Directive, Annex I of the Berne Convention, which prefer biotopes with an intact structure as part of rare coenoses. The study of the rare fraction of the flora of the beam system in the context of the conservation of biodiversity of the Right Bank Steppe of the Dnieper region can become the basis of the nature conservation concept of sustainable development of the region.

Communal aggregation of Brown Tree Snakes Boiga irregularis at the southern limit of their distribution

ABSTRACT On a remote sandstone outcrop within the Royal National Park, New South Wales, numerous instances were documented involving the aggregation of Brown Tree Snakes Boiga irregularis. Over the period from 2018 to 2023, a total of 8 visits to the site were logged, revealing 3 observed aggregations. Notably, the occurrences of these aggregations appeared to be influenced by seasonality, with each observation being made during late autumn or winter. The peak aggregation count documented involved six adult snakes.

Investigating the enigma of an irregular groundwater age pattern in a confined, presumed “fossil” complex aquifer through mixing cell flow modeling

Significant fluctuations in the groundwater (GW) age along the eastern flow path of the Nubian Sandstone Aquifer's (NSA), as derived from Krypton-81 groundwater dating, have suggested that this aquifer, located in Israel's Negev Desert and previously presumed to be a fossil, is not entirely isolated but mixes with younger and even recent water. The intermittent rejuvenation and drastic increases in the GW age across short distances most likely imply hydraulic connectivity with the surrounding aquifers, which contribute both younger and more ancient water to the NSA. The current study aims at modeling the GW flow system to locate and quantify its water sources despite the aquifer's hydrogeological complexity and the scarcity of hydrological data. We implemented the Mixing Cell Modeling (MCM) approach, understanding that the alternating rejuvenations and increases in the GW age downstream of the NSA's eastern flow trajectory reflect the mixing of the NSA's groundwater with young and old GW bodies, respectively. Thus, prompted by the 81Kr water age distribution, yet independent of the Kr radioisotope data, a multi-tracer mixing cell flow model was adopted based on a set of balance equations of water, dissolved minerals, and stable environmental isotopes. The findings indicate that (1) there is a small, yet substantial, intrusion of old brackish GW from a deep-seated, highly pressurized aquifer into the NSA in the northeastern Negev; (2) the rejuvenation of GW in the NSA is due to significant mixing with water from nearby overlying carbonate and chert aquifers, and (3) the NSA is substantially replenished through the Nubian Sandstone (NS) outcrops along the Negev Desert anticlines. Most GW intrusions into the NSA occur near the intersections of the eastern flow path with some of the Negev's major faults and synclines, such as the Paran and Ramon Fault zones and the Zin Syncline. In light of the relatively young GW age at the end of the NSA's western flow path in the northern Negev, and based on the similarities in the hydrogeological structures in the Negev and northern Sinai Deserts, we propose that similar mixing processes with GW from the overlying carbonate aquifers and direct GW recharge through the NS outcrops also occur in the northern Sinai Peninsula. The approach presented in this study might apply to examining recharge processes and hydraulic connectivity in other aquifers that were formerly classified as “fossil,” such as the immense NSA found in the Arabian (Jordan & Saudi Arabia) and the Western (Egypt) Deserts.

A substantial eastern disjunction of Douglas’ Knotweed (<i>Polygonum douglasii</i> Greene, Polygonaceae) in New Brunswick, Canada

We report an isolated population of the native annual Douglas’ Knotweed (Polygonum douglasii Greene) from a dry, south-facing outcrop of conglomerate and sandstone at Big Bluff, near Sussex Corner, New Brunswick, Canada, consisting of about 2500 plants in 2018 and 2022. This occurrence is disjunct by ~450 km from the eastern limit of the known range of Douglas’ Knotweed in southwestern Maine, USA. The nearest known occurrence in Canada is in southern Quebec, ~660 km from Big Bluff. Several lines of evidence indicate that the population in New Brunswick is native. New state records for Wisconsin and Alaska found in online data sources are also verified.

Piper alwynii (Piperaceae), a New Species from the Cordillera del Cóndor at the Border of Peru and Ecuador

Piper alwynii M. A. Jaram. (Piperaceae), a new species occurring in sandstone outcrops of the Cordillera del Cóndor at the border of Ecuador and Peru, is here described and illustrated. Morphologically it shows similarities to species in the Radula clade. Piper alwynii is similar to P. purdiei C. DC. but differs in having leaves pinnately nerved within the lower two thirds of the midvein, nerves pubescent on the abaxial surface, villous peduncles, and spikes 2–2.7 cm long. An identification key for 32 northern South American Piper L. species with small (≤ 10 cm) leaves is presented.

Experimental study on equilibrium initiation and extension of multiple clusters of fractures based on true triaxial physical simulation

In the context of tight sandstone reservoirs in the Ordos Basin characterized by compact and heterogeneous rock formations, conventional fracturing techniques yield monolithic fracture shapes, rendering 3D reservoir reconstruction unattainable. This study investigates the principles governing balanced initiation and propagation of fractures in multi-cluster fracturing within unconventional fracturing technology. Employing a large-scale true triaxial simulation experiment system, we utilize the dimensional analysis method (π theorem) to design a physical simulation experiment similarity criterion. Through various experimental adjustments involving proportioning, curing, and mechanical testing, we generate an artificially cured rock mass with mechanical parameters akin to the target layer. The rock mass is maintained at a size of 30 cm × 30 cm × 30 cm. Systematic physical simulation experiments on unconventional volume fracturing are carried out using the 30 cm-sized dense sandstone outcrop rock mass. Taking the conventional fracturing technology as a reference and manipulating experimental conditions and design parameters, we simulate the non-equilibrium initiation and extension behaviors of fracturing fractures under five unconventional volume fracturing technologies, namely hydraulic pulse pretreatment, temporary plugging between clusters, flow-limiting method, cyclic loading and unloading, and pulse intermittent fracturing. Through this, we elucidate the non-equilibrium initiation and extension laws governing multi-cluster fractures. Comparative analysis with conventional fracturing, known for inducing stress interference on fractures and inhibiting their expansion, revels that the five unconventional volume fracturing techniques mitigate stress interference in multi-cluster fracturing. This promotes uniform fracture initiation and expansion, facilitating the creation of complex fractures and larger reconstructed volumes. Among these techniques, inter-cluster block fracturing stands out for its exceptional ability to generate complex fracture networks. The research culminates in the development and refinement of a balanced fracture and extension control technique tailored for multiple cluster fractures in bulk fracturing. This technique significantly contributes to enhancing the degree of 3D reconstruction achievable in unconventional tight oil and gas reservoirs.

Detrital zircon and apatite U-Pb provenance and drainage evolution of the Newark Basin during progressive rifting and continental breakup along the Eastern North American Margin, USA

Abstract Mesozoic rift basins of the Eastern North American Margin (ENAM) span from Florida in the United States to the Grand Banks of Canada and formed during progressive extension prior to continental breakup and the opening of the north-central Atlantic. The syn-rift strata from all the individual basins, lumped along the entire margin into the Newark Supergroup, are dominated by fluvial conglomerate and sandstone, lacustrine siltstone, mudstone, and abundant alluvial conglomerate and sandstone lithofacies. Deposition of these syn-rift sedimentary rocks was accommodated in a series of half grabens and subsidiary full grabens situated within the Permo-Carboniferous Appalachian orogen. The Mesozoic ENAM is commonly depicted as a magma-rich continental rift margin, with magmatism (Central Atlantic magmatic province [CAMP]) driving continental breakup. However, the southern portion of the ENAM shows evidence of magmatic breakup (e.g., seaward-dipping reflectors), and rifting and crustal thinning appeared to start ~30 m.y. prior to CAMP emplacement in the Jurassic. This study provides extensive new detrital zircon and apatite U-Pb provenance data to determine the provenance and reconstruct the paleodrainages of the Newark Basin during progressive rifting and magmatic breakup and the implications for the overall rift configuration and asymmetry during progressive rifting along the ENAM rift margin. Detailed new detrital zircon (N = 21; n = 3093) and apatite (N = 4; n = 559) U-Pb results from sandstone outcrop and core samples from the Newark Basin indicate a distinct provenance shift, with relatively older Carnian syn-rift strata predominately sourced from the hanging wall of the basin bounding fault in the east while relatively younger Norian strata were regionally sourced from both the hanging wall and footwall. The syn-rift strata at the Triassic-Jurassic boundary were sourced from the hanging wall before a transition to local footwall terranes. These results suggest two major provenance changes during progressive rifting—the first occurring during Carnian crustal necking and rift flank uplift as predicted by recent numerical models and the second occurring at the onset of the Jurassic due to regional and local thermal uplift during CAMP magmatism as seen along other magma-rich margins, such as the North Atlantic and the southern portion of the South Atlantic margin.

Tight Sandstone Reservoir Characteristics and Controlling Factors: Outcrops of the Shanxi Formation, Liujiang River Basin, North China

Tight sandstone reservoirs are of interest due to their potentially favorable prospects for hydrocarbon exploration. A better understanding of tight sandstone outcrop reservoir characteristics and their influencing factors is thus needed. By laboratory observation, thin section analysis, and experimental analysis, the current work carried out a detailed investigation of densely sampled tight sandstone outcrops of the Shanxi Formation in the Liujiang River Basin, paving the way for further research on rock types, reservoir spatial distribution, physical properties, and their key controlling factors. The application of the Pressure Pulse Attenuation Method made it possible to determine the porosity and permeability, as well as the analysis of debris composition and filling content. The findings indicate that the main rock type of the tight sandstone outcrop reservoirs in the Shanxi Formation in the Liujiang River Basin is lithic quartz sandstone, some of which contains fine sand-bearing argillaceous siltstone, giving them very low porosity (average porosity of 4.34%) and low permeability (average permeability of 0.023 mD) reservoirs. Secondary pores—mostly dissolved pores among and in grains—are widely developed in the target region. In addition, diagenesis primarily includes mechanical compaction, cementation, and dissolution. The main controlling factors of tight sandstone reservoirs in the target region are sedimentation, diagenesis, and tectonics, whereby sedimentation affects reservoir physical properties that become better as the clast size increases, reservoir properties are negatively impacted by compaction and cementation, and reservoir properties are somewhat improved due to dissolution and the impact of tectonism. In addition, the tilt of the crust will produce faults during the tectonic action, generating reservoir cracks that improve the reservoir’s physical properties. This study tends to be helpful in the prediction of high-quality reservoirs in the Permian Shanxi Formation in North China and can also be used for analogy of high-quality reservoirs in similar areas with complete outcrops.

Identification of the Potential Quartz Sandstone in the Sambong Area By the Dipole-Dipole Configuration of Resistivity Method

The presence of quartz sandstone outcrops in the southeast of the study site suggests the presence of quartz sandstones in the northwest, according to the strike direction. This geoelectrical measurement aims to determine the distribution of these sandstones below the surface. The method used is geoelectric with a dipole dipole configuration.
 Measurements were made on four track lines. Tracks A and B indicate the existence of a layer of sandstone below the surface. Tracks C and D do not show any layers of quartz sandstone. This is caused by the presence of faults or folds that cause the layer to shift from the previously predicted path.

Sacred objects from the sites of the Sargatka Culture in the context of interaction of the forest-steppe population with the nomads of the Ural-Kazakh steppes

The paper concerns the stone altars, clay dishes, and censers from the sites of the Sargatka Culture of the Early Iron Age. Analysis of their morphological features is carried out, as well as of the dynamics of changes in the forms, the context of their deposition in burials, and specifics of their use. As the result, the reasons for the appearance of these products in the forest-steppe zone of the Tobol-Irtysh and Baraba areas (Western Siberia) are clarified and their subsequent distribution in the given region is traced. Stone altars of types I, II, and IV started appearing in the 5th–4th cc. BC in the Irtysh Basin and Baraba regions as a consequence of the Saka mi-gration. Transformation of the religious and mythological views of the Sargatka population, as a result of the inter-actions of the Tobol-Irtysh communities with the nomads of the Ural-Kazakhstan steppes, led to the appearance of new rituals requiring small stone altars for their performance, due to which there was a growing demand for these products among local communities. However, by the 4th c. BC the production of altars in the Kazakhstan center ceased due to the decline of the Early Saka Culture. From this time, the population of the Sargatka Culture began making local copies of small type I altars from stone, although their production in the Sargatka area was difficult due to the lack of sandstone outcrops, which facilitated the use of more accessible material — clay, as reflected in the appearance of clay dishes of types III–V in the territory of the Baraba and Irtysh Basin. Connection between the local and imported products is indicated by the traces of their similar use. From the 3rd c. BC, scarce altars of type I could make their way into the Sargatka context as a result of close contacts with the population of the Upper Ob Basin, among whom these objects were widespread up until the 3rd–2nd cc. BC. The appearance of type III stone altars and type VI clay dishes in the complexes of the Sargatka Culture of the Tobol and Irtysh Ba-sins in the 5th–4th and 4th–3rd cc. BC might have been caused by the migration of a small group of nomads of the Southern Urals, or by close contacts with the population of the Gorokhovo Culture. Type V altars also were bor-rowed from the bearers of the Gorokhovo Culture. Their appearance may indicate the process of assimilation of the newly arrived Sargatka population in the Tobol Basin. In the 4th c. BC, clay dishes of type I appeared in the Irtysh Basin. From the 3rd c. BC, as a result of the intensification of contacts between the local population and nomads of the Sarmatian origin, these products became more widespread, while ceramic censers and clay dishes of type II also appeared.

Are metapopulation species drivers of metacommunity structure in sandstone outcrop communities?

AbstractQuestionsThe extent to which metacommunities contain species exhibiting metapopulation dynamics is poorly understood. We investigate this issue within sandstone outcrop plant communities scattered across an upland hardwood forest. We investigate the life forms of metapopulation species and relationships between taxonomic, phylogenetic, and functional diversity, composition, and environmental factors.LocationTwenty‐three sandstone outcrop communities in southern Illinois, USA.MethodsFollowing vegetation surveys, species exhibiting metapopulation dynamics were identified and compared to all species based on origin, growth form, and lifecycle. Cohesion, turnover, and boundary clumping were utilized to determine metacommunity structure. Correlations evaluated associations between site‐based variables, and regressions evaluated associations between diversity indices. Multivariate analyses compared sites to determine which variables contributed to compositional differences.ResultsTwenty of 130 species exhibited metapopulation dynamics and were usually annual or biennial exotics. Metacommunity elements indicated a metacommunity structure where groups of species tended to replace one another across sites, in which species exhibiting metapopulation dynamics were subordinate as opposed to dominant or transient. The largest sites were the most regularly shaped, but not the most diverse. Species richness and species exhibiting metapopulation dynamics determined phylogenetic and functional diversity, but largely non‐standardized measures of diversity, indicating independence between types of diversity. Multivariate analyses showed that diversity metrics explained community composition differences, where more species‐rich sites with more metapopulation species were also more phylogenetically and functionally diverse.ConclusionsSandstone outcrop communities exhibited diverse plant communities, where phylogenetic and functional diversity were driven by both the number of all species and the subset of metapopulation species independently. SM dynamics were usually short‐lived and exotic species with their low number likely constrained via dispersal limitations. The communities exhibited a metacommunity structure indicating predictable community assemblages which tend to be replaced with others as opposed to just individual species being replaced individually, consistent with the concept of an integrated community. Functional traits indicated that these communities include species adapted to xeric, substrate‐poor conditions.

Induced seismicity in the Groningen gas field – arrest of ruptures by fault plane irregularities

AbstractFrom dynamic rupture simulations, we reveal under which conditions a rupture in the Groningen gas field stops along fault dip or along fault strike after it starts on a fault in the reservoir. The simulations focus on the capabilities of fault plane irregularities to arrest ruptures. Such irregularities can be recognised in sandstone outcrops. Fault planes in the Groningen field, extracted from the 3D seismic data by seismic attribute extraction methods, show similar irregularities. A detailed surface of a major fault plane in the field indicates that steps and jogs of tenths of metres are possible. Although these irregularities are close to seismic resolution and could be partially artificial, we investigated their effect on rupture arrest.For typical current stresses in the Groningen field, jogs and steps of this length scale are found to be remarkably effective to stop ruptures in the reservoir. Also, a significant increase in the fault dip along fault strike can stop these ruptures but a kink in the fault under a constant fault dip not.Including non-planar fault features and pressure diffusion in the Carboniferous, the simulations in this paper follow trends of previous simulations in the literature using 2D planar faults. In particular, the horizontal stress in this formation and the strength of the Carboniferous fault zone are important for rupture propagation. If the fault would have been reactivated in the Neogene or Quaternary and poorly healed in clay-rich parts, rupture propagation into the Carboniferous can only be prevented by jogs of sufficient size and lateral continuity under the present estimate of the horizontal field stress.

Textural and Depositional Environment Analyses of Maastrichtian Ajali Sandstone Outcrops at Igbere-Abiriba Area Afikpo Basin South Eastern Nigeria

The study presents the Textural characteristics of the Ajali sandstone at Igbere-Abiriba area in Afikpo basin, southeastern Nigeria. The intent is to highlight possible constraints of the environment of deposition of the source material on one hand and to infer the provenance on the other hand. The investigation approach includes field studies involving grain size analysis. Field studies shows that the Ajali Sandstone is friable at all location and range in colour from white in freshly cut stone, to reddish brown on weathering. In addition, the Ajali Sandstone units are cross-bedded and show graded bedding, exemplified by fining upward sequence. Textural examination indicates that the sandstone ranges from fine to medium grain and few coarse grain sizes constituting about 76-99% sand fraction, with graphic mean grain size of 0.93-2.60. Standard deviation (sorting) ranges from 0.71-1.48 and implies poor – moderately sorted sediments, also symmetrical, mesokurtic to leptokurtic were observed in skewness and kurtosis. Bivariate plot from the grain size parameter combination gives a more satisfactory approach toward predicting the sedimentary environment. General studies inferred from the Textural index, the depo-environmental description of the Ajali Sandstone revealed a Fluvial-river system-dominated sedimentary process.

Maastikule kleepuv tekst: põrgupärimus

On the landscape, there are natural caves known as hells or hell graves, formed, for example, as a result of the outflow of spring water and in some cases expanded and deepened by human hands over time, as well as sandstone outcrops, feather holes or sölls or valleys, where, according to folk tales, mythological creatures-giants have lived or live: old pagans or devils. In this article, the focus is on “hell” as a traditional landscape element and places named “hell” in place lore and place creation, in original fiction based on folk tales, in tourism economy, etc. I claim that hell-themed place stories written down by folk over the ages stick to the landscape in different ways, whether it is the reuse of stories based on standard motifs in place creation, the consolidation of the landscape image embedded in traditional texts in tourism, even when the landscape itself has long since changed, etc. Scenically interesting places need attractive stories; this is one of the key themes of placemaking. As a concept, I use local place lore as an umbrella term for oral tradition in the field that can be linked to certain places in the landscape. Local place lore includes both international motifs and local legends, which in some cases have also been told as true stories. Local lore, as a type of lore that shows the connection between a person and a place, has been valued mainly because of the aspect that creates and supports local identity. However, the landscape surrounding the community is not a static but a dynamic space, in which new meanings that reflect the life of the community arise or are created, and these are also reflected in the lore related to the landscape.