Characteristics Of Assemblages Research Articles

Modern pollen assemblages of agricultural land, wasteland, and natural vegetation in China and their significance for reconstructing the intensity of agricultural activity

Knowledge of the modern pollen assemblage characteristics of artificial and disturbed vegetation can help reconstruct changes in the intensity of human activity and land use/land cover (LULC) based on Holocene stratigraphic pollen records. We obtained pollen assemblage data from 217 agricultural land (cultivated cereals) sites, 79 wasteland sites, and 389 natural vegetation sites in different regions in China. The results show that the pollen of cereals Poaceae and the associated agricultural weeds in agricultural land and wasteland vegetation contexts are effective indicators of the intensity of agricultural activity, and that the pollen assemblages of natural vegetation accurately reflect the regional zonal vegetation composition. Although the cereals Poaceae proportion varied greatly among the agricultural sites in different regions, due to factors like cultivation practices, crop types, and terrain, all of them were significant indicators of agricultural activity. The pollen assemblages of wasteland and natural vegetation in different regions were also different, and the indicator taxa exhibit distinct zonal characteristics. There was no consistent linear relationship between cereals Poaceae proportion and the area of agricultural land. The cereals Poaceae proportion did not vary with increasing agricultural area in regions with higher or lower levels of agricultural production; only in Northeast and North China, when the agricultural area was below 60%, did the cereals Poaceae proportion increase with increasing agricultural area. These results provide a modern process basis for the use of stratigraphic pollen data to reconstruct past changes in agricultural activity and LULC.

Organic petrography and palynofacies of the Upper Cretaceous (Campanian-Maastrichtian) organic rich strata of the Quseir-Safaga Region, Eastern Egypt

The Campanian-Maastrichtian organic-rich rocks in the Quseir – Safaga Region in the Eastern Desert of Egypt have growing economic importance. This economic importance is discussed in many of previous studies by many of different geological tools that lacked the petrographic examination of organic matter occurrence modes. The organic petrography provides the essential tools for microscopic analysis to study the organic matter that are applied for the first time in the present study. The palynofacies and organic petrography are used in the present study to investigate the nature of the organic matter and the paleoenvironmental settings that controlled their distribution in the Duwi and Dakhla formations in the Younis and Mohamed Rabah areas (Egypt). The study of dinoflagellate cysts allowed the identification of the biostratigraphically characteristic assemblages of the Campanian – Maastrichtian in the Eastern Desert including Assemblage II/I (in Duwi Formation) and Assemblage III (in Dakhla Formation) that were identified in Egyptian oil shales of this time range. The identified assemblages are correlated with local and regional studies to delineating the formal biozonation. The organic matter in the Duwi Formation comprises rich fluorescent amorphous organic matter, prasinophytes, sporomorphs, dinocysts as well as a minor terrigenous component of phytoclasts. In the Dakhla Formation, the fluorescent AOM is found to be highly mixed with Botryococcus in addition to prasinophytes and marine palynomorphs. The paleoenvironmental analysis indicates deposition in distal anoxic to proximal suboxic marine conditions with high paleoproductivity. The results are confirmed with the inorganic geochemical composition of redox sensitive elements. The analysis reveals that the Younis section is differentiated into two palynofacies types (proximal, suboxic high productivity in the Duwi Formation and distal anoxic in the Dakhla Formation). The Mohamed Rabah section, one palynofacies type is recognized that is proximal, suboxic high productivity. The principal component analysis is used to interpret the distribution of organic matter abundances. The kerogen types are distinguished based on the area percentages of the fluorescent organic matter and application of kerogen plots. The samples of both formations fall within oil prone kerogen type II. The spore coloration and measured vitrinite reflectance indicate immature kerogen in the studied sections. The organic matter in the studied rocks comprises hydrogen rich compounds that can be treated for direct composition or retorted to extract shale oil. The heavy metals concentrations are significant and present technology will increase its economic value.

Joint Biodiversity Management Committees: A Mechanism to Manage and Conserve Eco-Regions

Sasthamkotta Lake eco-region is a freshwater Ramsar site in Kerala, India. Eco-regions are ecologically and geographically defined larger land or water mass areas with a characteristic assemblage of the ecosystem and significant biodiversity. A decentralized and locally self-sustaining mechanism has been achieved in managing this eco-region by a participatory model through a joint Biodiversity Management Committee (jBMC) constitution. BMCs are custodians of the environment, and biodiversity, confined to a village/Panchayat, as per Convention on Biological Diversity (CBD) guidelines and the Indian Biodiversity Act. This jBMC constitutes a network of statutory biodiversity experts from the BMCs of three Local Self Governments (LSGs) or Panchayath administrations, where the Sasthamkotta Lake is located. It has been formed to develop strategies to manage and conserve the freshwater lake and its biodiversity. The management action plan proposed by the jBMC for the Sasthamkotta Ramsar site includes systematic and continuous assessment of the current biodiversity status, identifying and mitigating threats, appropriate use of its resources for eco-restoration and better administrative programs for biodiversity enhancement. Our case study shows that the conservation model of a Ramsar site Eco-region is successful and could be replicated in other damaged natural ecosystems which need attention, for a sustainable future.

Petrological Characteristics and Rock Nomenclature of Sedimentary Bauxite Gas Reservoir: A Case Study of Bauxite in Taiyuan Formation of Ordos Basin

With the great breakthrough in natural gas exploration of Paleozoic Taiyuan formation in Longdong exploratory area in the southwestern part of Ordos Basin, it is urgent to solve the petrological nomenclature of sedimentary bauxite, so as to further study the pore formation mechanism, distribution law, and controlling factors of bauxite reservoirs. In this paper, X-ray diffraction, polarizing microscope, scanning electron microscope, and other methods are used to analyze the mineral composition and structure of bauxite rocks in the study area and give appropriate names. The results show that the sedimentary sequence of bauxite in the study area can be divided into five sections: A, B, C, D, and E. The main mineral components are diaspore (C section content can be more than 90%), illite, kaolinite, and chlorite; accessory mineral include anatase and pyrite; trace components include quartz, feldspar, rutile, hematite, and rock salt; and some of the pores are filled with calcite, siderite, and (iron) dolomite. The rock structure is mainly bedding and massive structure, and some of them have geopetal structure. The texture mainly consists of granular texture, grain (powder crystal) texture, gel texture, and algal bonding texture. Considering the special lithology of section A~C and the lack of existing nomenclature method, based on mineral composition and sedimentary fabric, a triangulation classification nomenclature method is established, which adopts structure+texture as secondary name and the main mineral components diaspore-mud-pyrite of the three end-member mineral components as primary name. It can not only highlight the mineral assemblage characteristics of sedimentary sequence of bauxite but also reflect the lithologic characteristics of reservoir development section and the influencing factors of reservoir formation, effectively reflecting the petrological characteristics of bauxite reservoir. Among them, the diaspore rocks with granular, bean-oolitic, and grain texture are the main lithologies forming the natural gas reservoir space of Taiyuan formation in Longdong area. The naming method is feasible and reliable for sedimentary bauxite rocks, which lays a good foundation for the study of natural gas reservoir, pore formation mechanism, and distribution law in Longdong area, southwest of the basin.

South Anze Structure and Its Control on Coalbed Methane Aggregation in the Qinshui Basin and the Mechanism of Syncline Gas Enrichment in the Qinshui Basin

The phenomenon of coalbed-methane synclinal accumulation in the Qinshui Basin has been widely reported, but it has mainly been observed in the core block of the Qinshui Syncline. The questions arise: does this phenomenon exist in the wing of the Qinshui Syncline and, if so, what is the mechanism behind it? Further study is required to answer these questions. This paper focuses on the South Anze No. 3 coal seam in the Qinshui Basin as an example. It conducts a systematic sorting of coalbed-methane geological characteristics and an analysis of the effects of structural assemblage characteristics, genetic mechanisms, and structural control on coalbed-methane accumulation. Additionally, it examines the basin structure and evolution during the critical period of the Qinshui Basin, as well as the gas geological characteristics of adjacent areas, in order to discuss the gas-rich mechanism of the syncline in the Qinshui Basin. Key insights obtained from the study include the following: (i) The whole South Anze is a nosing structure that plunges from west to east and superposes secondary folds and faults in different directions. Four deformation zones can be identified based on the characteristics of structural assemblage, including NEN-oriented compressive structures, ENE-trend shear fractures, EW-trend compressive fractures, and EW-trend compressive folds. The formation of structural assemblage in the study area is attributed to the compression in the Indosinian and Yanshanian, and the fault inversion in the Himalayan period. (ii) The ENE-trend shear fracture deformation area located in the nosing uplift is a low CBM (coalbed methane) content area due to gas diffusion during the Himalayan extension. The syncline in the combination of NEN-trend and EW-trend “ejective folds” in the west and south of the study area is a high-value area of coalbed-methane content. It is further verified that the law of syncline gas accumulation in the Qinshui Basin is also applicable to the wing of the Qinshui Syncline. (iii) Since the formation of the Qinshui Syncline, the main coal seam has been in an extensional environment below the neutral plane, resulting in the main dissipation of coalbed methane. During its geological history, surface water penetrated the aquifer above the main coal seam through two channels: the extensional area above the neutral plane of the adjacent anticline and the shear fracture. A hydrostatic pressure seal is formed in the Qinshui Syncline and the secondary syncline is superimposed upon it, which is the cause of gas enrichment in the syncline of the Qinshui Basin. (iv) Weak deformation in the syncline basin is the focus of global coalbed-methane exploration and development. The mechanism proposed in this paper can provide ideas and references for further understanding of coalbed-methane enrichment in this type of basin.

An expanded database of Southern Hemisphere surface sediment dinoflagellate cyst assemblages and their oceanographic affinities

Abstract. Dinoflagellate cyst assemblages present a valuable proxy to infer paleoceanographic conditions, yet factors influencing geographic distributions of species remain largely unknown, especially in the Southern Ocean. Strong lateral transport, sea-ice dynamics, and a sparse and uneven geographic distribution of surface sediment samples have limited the use of dinocyst assemblages as a quantitative proxy for paleo-environmental conditions such as sea surface temperature (SST), nutrient concentrations, salinity, and sea ice (presence). In this study we present a new set of surface sediment samples (n=66) from around Antarctica, doubling the number of Antarctic-proximal samples to 100 (dataset wsi_100) and increasing the total number of Southern Hemisphere samples to 655 (dataset sh_655). Additionally, we use modelled ocean conditions and apply Lagrangian techniques to all Southern Hemisphere sample stations to quantify and evaluate the influence of lateral transport on the sinking trajectory of microplankton and, with that, to the inferred ocean conditions. k-means cluster analysis on the wsi_100 dataset demonstrates the strong affinity of Selenopemphix antarctica with sea-ice presence and of Islandinium spp. with low-salinity conditions. For the entire Southern Hemisphere, the k-means cluster analysis identifies nine clusters with a characteristic assemblage. In most clusters a single dinocyst species dominates the assemblage. These clusters correspond to well-defined oceanic conditions in specific Southern Ocean zones or along the ocean fronts. We find that, when lateral transport is predominantly zonal, the environmental parameters inferred from the sea floor assemblages mostly correspond to those of the overlying ocean surface. In this case, the transport factor can thus be neglected and will not represent a bias in the reconstructions. Yet, for some individual sites, e.g. deep-water sites or sites under strong-current regimes, lateral transport can play a large role. The results of our study further constrain environmental conditions represented by dinocyst assemblages and the location of Southern Ocean frontal systems.

Distribution of recent Benthic foraminifera in Kongsfjorden and Krossfjorden; North-West Svalbard, High Arctic

Benthic foraminifera assemblages from two fjords of Svalbard—Kongsfjorden and Krossfjorden in the High Arctic—have been studied. The foraminifera assemblages show three characteristic assemblages from the two fjords’ glacial proximal, middle and distal parts. The Cassidulina reniforme– Elphidium clavatum, Textularia spp. assemblage dominates the foraminifera fauna near the glacier proximal that indicates increased sedimentation and meltwater runoff; a Nonionellina labradorica– Islandiella helenae– Lobatula lobatula assemblage relates to well-oxygenated and high energy conditions and mainly occupies the middle part; and the Nonionellina labradorica– Islandiella helenae assemblages dominate in the distal region that indicates high surface primary productivity. Krossfjorden contains an oxygen deficiency zone around the middle part characterised by Stainforthia loeblichi. The abundance of Islandiella helenae and Nonionellina labradorica indicates that the high surface primary productivity of Krossfjorden is more than that of Kongsfjorden.

Longitudinal patterns of abundance, diversity and functional feeding guilds of benthic communities in East African tropical high‐altitude streams

AbstractIn temperate and tropical rivers, macroinvertebrates are commonly utilised for biological monitoring. Therefore, it is important to understand their functional feeding guilds and assemblage structure. However, there have been few studies in high‐altitude rivers in East Africa aimed at assessing macroinvertebrate functional guilds. In this study, we examined the macroinvertebrate assemblage characteristics using abundance/diversity metrics and the functional feeding groups (FFGs). We collected physicochemical data and macroinvertebrate samples at seven sites along the Gura River and three sites on the Sagana River. Dissolved oxygen concentration, water temperature, electrical conductivity, pH, turbidity, ammonia, and soluble reactive phosphorus showed significant differences among the sites (p < 0.05). A total of 32 families belonging to 11 orders of macroinvertebrates were collected during the study period. Overall, scrapers were the most abundant FFG, dominated by Heptageniidae (Afronurus). Collector filters and collector gatherers were the second most abundant, while shredders and predators exhibited the least relative abundance. Across all the dominant orders, macroinvertebrate abundance decreased from upstream to downstream sites, with upstream sites exhibiting high diversity and abundance of Ephemeroptera, Diptera, Coleoptera, and Trichoptera taxa. Furthermore, the FFGs in this study differed widely from the River Continuum Concept predictions. Our findings provide crucial understanding of macroinvertebrate assemblage characteristics in high‐altitude rivers. Thus, this study provides additional evidence on the high abundance and diversity of Ephemeroptera and Trichoptera taxa in tropical rivers.

Paleo-vegetation and paleo-climate characteristics of Cretaceous and Paleogene strata in several typical basins in China: palynological evidence

ABSTRACT The paleovegetation and paleoclimate characteristics are studied in the Palaeogene strata of Hetao Basin, Subei Basin and Qaidam Basin in China, and the Cretaceous Guyang Formation (K1 g) in the Hetao Basin. These three basins receive high attention, different distribution areas, representative. Pollen evidence shows that: (1) The sporopollen assemblage of Palaeogene Linhe Formation (E3 l) in Hetao Basin is characterised by Pinaceae-Ephedripites-Ulmipollenites-Chenopodipollis. It reflects that the ancient vegetation types were mainly coniferous and evergreen woody plants, and the climate was cold temperature. The sporopollen assemblage characteristics of the upper member of the Palaeogene Xiaganchaigou Formation (E3 2) in the Qaidam Basin are similar to it. (2) The sporopollen characteristics of the K1 g in the Hetao Basin reflect that its ancient vegetation was dominated by evergreen woody plants and belongs to a warm and humid subtropical climate. (3) The assemblage of Palaeocene Funing Formation (E1 f) in Subei Basin was Pterisisporites undulatus-Ulmipollenites minor-Taxodiaceaepollenites hiatus. The climate type was humid north temperate climate, vegetation was mainly deciduous trees and evergreen woody plants. (4) Leiosphaeridia/Granodiscus, Pediastrum and Botryococcus were also detected in the E1 f of Subei Basin. The appearance of these algae indicates the special saline water environment and good hydrocarbon potential.

Carbonatization of Serpentinites of the Mid-Atlantic Ridge: 1. Geochemical Trends and Mineral Assemblages

Abyssal peridotite outcrops compose vast areas of the ocean floor in the Abyssal peridotite outcrops compose vast areas of the ocean floor in the Atlantic, Indian, and Arctic Oceans, where they are an indispensable part of the structure of the oceanic crust section formed in low-velocity oceanic spreading centers. The final stage in the evolution of abyssal peridotites in the oceanic crust is their carbonatization, which they undergo on the surface of the ocean floor or near it. The main goal of this study was reconstruction of the geochemical trends accompanying the carbonatization of abyssal peridotites using the example of MAR ultramafic rocks and to identify the main factors that determine their geochemical and mineralogical differences. It is shown that variations in the composition of rock-forming minerals and their characteristic assemblages indicate that the initial stages of carbonatization of abyssal peridotites occur in intra-crustal conditions simultaneously with the serpentinization of these rocks. The final stage in the crustal evolution of abyssal peridotites is their exposure to the surface of the ocean floor, to which they are transported along the detachment faults. Here, abyssal peridotites in close association with gabbro form oceanic core complexes, and the degree of their carbonatization sharply increases with the duration of their exposure on the surface of the ocean floor. The presented data made it possible to qualitatively reconstruct the sequence of events that determined the mineralogical and geochemical features of carbonatized abyssal peridotites of the MAR.

Composition of epilithic diatom and soft-algal assemblages in infralittoral zones of Tennessee reservoirs and correlations of composition to trophic state

Assemblages of infralittoral periphytic algae are understudied due partially to the historical emphasis on phytoplankton and other water-column characteristics to evaluate the integrity of lentic systems. We tested the null hypothesis that characteristics of epilithic algal assemblages at infralittoral sites in reservoirs of Middle and East Tennessee do not infer trophic state. One infralittoral site in five mesotrophic and five eutrophic reservoirs in Middle and East Tennessee was sampled to determine the relative abundance of the most common epilithic diatoms and soft algae, concentrations of epilithic chlorophyll (chl) a, and water concentrations of chl a, total phosphorus (TP), and total nitrogen (TN). The concentration of epilithic chl a correlates significantly to the concentration of TP but not to TN as determined by the probability values for Pearson’s correlation coefficients. The water concentration of chl a does not correlate significantly to concentrations of TP, TN, or epilithic chl a. Trophic-state indicator values for 162 epilithic diatom taxa and 102 epilithic soft-algal taxa are calculated as the abundance-weighted average of the concentration of epilithic chl a normalized between 0 and 100. The trophic-state indicator values indicate the relationship of the abundance of algal taxa to trophic state and contribute to our limited knowledge of the effects of eutrophication on infralittoral algal taxa. Trophic-state indices are calculated as the mean abundance-weighted average of trophic-state indicator values for algal taxa of an assemblage. The index values infer the trophic state of the sites and are the first to use epilithic concentrations of chl a as opposed to water-column characteristics to indicate trophic-state optima for periphytic algae of lentic systems. The indices are easy to calculate and provide novel tools to help evaluate and monitor the trophic state of infralittoral sites in reservoirs of Middle and East Tennessee.

Unravelling the influence of landscape alteration from flow alteration on benthic macroinvertebrate assemblage response in the Delaware River Basin

Quantifying the effects of streamflow alteration on assemblage response is central to understanding the role humans play in shaping aquatic environments. These changes represent a level of complexity that impedes developing quantitative links between flow and ecological response because stream hydrology is strongly intertwined with natural and anthropogenic factors. Better management outcomes require disentangling these linkages. Benthic macroinvertebrate data were combined with GIS-derived natural and anthropogenic basin characteristics to identify factors associated with changes in flow and assemblage characteristics. Models linking streamflow metrics and macroinvertebrate response at basin- and subregion-scales were developed using boosted regression tree (BRT) analysis. Basin-scale BRT analyses revealed that links between macroinvertebrate response and streamflow metrics were often obscured, whereas more homogeneous subregions were better able to discern relations with flow. Urban land cover was the primary factor accounting for changes in flow characteristics. Elevation, land cover and high flow frequency were the principal variables driving changes in assemblage structure within subregions. Assemblage metrics and traits were equally useful for building response models and were affected similarly by flow alteration. Our results indicate that response models based on upland and lowland subregions performed better than basin-scale models. However, when defining subregions, care should be taken to maintain data sufficiency. Developing practical flow-protection standards that support a balance between human water requirements and ecological integrity requires models that reduce uncertainty and identify management-relevant drivers. However, effective management often differs by location and models developed at the subregion level may be more applicable to management and stakeholder interests.

Meiofaunal Biodiversity in a Marine Protected Area: a Case Study in the Rocky and Sedimentary Shores of the Snake Island (North-Western Black Sea)

This study provided a preliminary comparative analysis of meiobenthic assemblages in different habitats of the Snake Island Marine Protected Area (MPA). Meiobenthos was studied in three habitats: Exposed Black Sea upper infralittoral rock with Corallinales turf (MB142), Mytilid dominated exposed Black Sea upper infralittoral rock with foliose algae (no Fucales) (MB143) and Black Sea infralittoral sand and muddy sand without macroalgae (MB542). A total of 10 higher meiobenthos taxa were recorded in the different habitats: 5 permanent groups (Platyhelminthes, Nematoda, Harpacticoida (Copepoda), Ostracoda, Halacaridae) and 5 temporary groups (Oligochaeta, Polychaeta, Bivalvia, Gastropoda, Cyrripedia). The preliminary study of meiobenthos in the habitats of the Snake Island MPA showed that habitat MB143 was more favourable for meiobenthos, with the highest mean density and biomass (190655 ± 23004 ind.-m-2 and 3170.90 ± 412.15 mg-m-2, respectively). The comparative nMDS and cluster analyses based on the density of meiobenthos taxa in the Snake Island MPA showed that the meiofauna of both MB142 and MB143 differed significantly from the MB542 habitat, with Bivalvia and Ostracoda making the largest percentage contribution to these differences. The meiobenthos assemblages in the different habitats of the Snake Island MPA were similar to the other regions of the Black Sea with some unique features (e.g. relatively lower total meiobenthos density, high percentage of ostracodes on the algal substrate, etc.). Further studies on the characteristics of meiobenthos taxa assemblages in other Black Sea MPAs could lead to the estimation of meiobenthos assemblage patterns and their possible use in biomonitoring.

Planktonic foraminiferal biostratigraphy and palaeobiogeography of the Albian–Turonian succession from the Sulaiman Range, Pakistan

Detailed taxonomy and biostratigraphy of the limestone, shale‐rich Cretaceous Goru Formation within the western Sulaiman Range refer to diverse and well‐preserved planktonic foraminifera. The age‐diagnostic planktonic foraminifera encountered are; Biticinella breggiensis (middle Albian), Rotalipora ticinensis (late Albian), Rotalipora appenninica (latest Albian), Rotalipora brotzeni (early Cenomanian), Rotalipora cushmani (late Cenomanian), Whiteinella archeocretacea (latest Cenomanian–Earliest Turonian), Helvetoglobotruncana helvetica (early to middle Turonian), and Marginotruncana sigali (late middle to late Turonian). Based on the recovered planktonic foraminifera a middle Albian–late Turonian age has been assigned to the studied formation. The Rotalipora reicheli (middle Cenomanian) Zone was not identified as the First Appearance Datum of the nominal taxa present within the Rotalipora cushmani Zone. The planktonic foraminiferal assemblage characteristics suggest that the bioprovince of the Cretaceous Goru Formation belongs to the subtropical, warm water environment belonging to the Cretaceous Tethyan Realm and the palaeobiogeographic reconstruction suggests that the Neotethys was well‐connected during the Albian–Turonian time interval.

The Technological Multiplicity of the Acheulean of the Southern Iberian Peninsula

The Acheulean of the southern Iberian Peninsula is markedly similar to the north African Acheulean. However, the characteristics of the stone tool assemblages are heterogeneous and represent complex cultural phenomena. From MIS 15, the lithic assemblages in fluvial (Guadiana, Guadalquivir and Guadalete rivers), fluvio-lacustrine (Solana del Zamborino) and karstic (Cueva del Ángel, Bolomor, Cueva Negra del río Quípar, Cueva Horá and Santa Ana) contexts exhibit analogies and technical differences representative of a phenomenon of multiplicity. Contributing to this phenomenon is the perception of technological stasis or conservatism of the Acheulean technocomplex and the different technical responses articulated by hominins to achieve equivalent results. These equivalences generate the uniformity that allows us to recognise typologies of large cutting tools (LCTs) regardless of the lithic materials used or the organisational structures of the operational sequences. These diversified typologies include handaxes, picks, and cleavers, which maintain a consistent presence despite innovations such as the Levallois flaking method. In some cases, the presence of cleavers and spheroids affects the range of represented typologies. Beneath the uniformity of the handaxes, lie organisational differences in the operational sequences. The changes and differences in the use of flakes to shape handaxes, the representation of cleavers and diversification of shaped-tool typologies all suggest differential cultural behaviours linked in part to divergent contexts. These aspects indicate that this multiplicity is related to diffusion, adaptation and cultural changes produced at the margins of the conservatism of this technocomplex. Observed changes could indicate inter-group cultural replacements, most of which retained a similar techno-typological diversity to that seen in the north African Acheulean until MIS 5. Cyclical climate change during the Middle Pleistocene affected the Strait of Gibraltar, regulating its function and conditioning the circulation of hominins and affecting cultural interactions between southern Iberian groups.

Prediction of multiscale laminae structure and reservoir quality in fine-grained sedimentary rocks: The Permian Lucaogou Formation in Jimusar Sag, Junggar Basin

Fine-grained sedimentary rocks have become a research focus as important reservoirs and source rocks for tight and shale oil and gas. Laminae development determines the accumulation and production of tight and shale oil and gas in fine-grained rocks. However, due to the resolution limit of conventional logs, it is challenging to recognize the features of centimeter-scale laminae. To close this gap, complementary studies, including core observation, thin section, X-ray diffraction (XRD), conventional log analysis, and slabs of image logs, were conducted to unravel the centimeter-scale laminae. The laminae recognition models were built using well logs. The fine-grained rocks can be divided into laminated rocks (lamina thickness of <0.01 m), layered rocks (0.01–0.1 m), and massive rocks (no layer or layer spacing of >0.1 m) according to the laminae scale from core observations. According to the mineral superposition assemblages from thin-section observations, the laminated rocks can be further divided into binary, ternary, and multiple structures. The typical mineral components, slabs, and T 2 spectrum distributions of various lamina types are unraveled. The core can identify the centimeter–millimeter-scale laminae, and the thin section can identify the millimeter–micrometer-scale laminae. Furthermore, they can detect mineral types and their superposition sequence. Conventional logs can identify the meter-scale layers, whereas image logs and related slabs can identify the laminae variations at millimeter–centimeter scales. Therefore, the slab of image logs combined with thin sections can identify laminae assemblage characteristics, including the thickness and vertical assemblage. The identification and classification of lamina structure of various scales on a single well can be predicted using conventional logs, image logs, and slabs combined with thin sections. The layered rocks have better reservoir quality and oil-bearing potential than the massive and laminated rocks. The laminated rocks’ binary lamina is better than the ternary and multiple layers due to the high content of felsic minerals. The abovementioned results build the prediction model for multiscale laminae structure using well logs, helping sweet spots prediction in the Permian Lucaogou Formation in the Jimusar Sag and fine-grained sedimentary rocks worldwide.

Composite GO/Ceramic Membranes Prepared via Chemical Attachment: Characterisation and Gas Permeance Properties.

Graphene oxide (GO) oligo-layered laminates were self-assembled on porous ceramic substrates via their simple dip-coating into aqueous GO dispersions. To augment the stability of the developed composite GO/ceramic membranes and control the morphology and stacking quality of the formed laminate, short-((3-glycidoxypropyl)trimethoxy silane-GLYMO, (3-aminopropyl)triethoxy silane-APTES), and long-chain (polydopamine-PDA) molecules were involved and examined as interfacial linkers. A comparative study was performed regarding the linker's capacity to enhance the interfacial adhesion between the ceramic surface and the GO deposit and affect the orientation and assemblage characteristics of the adjacent GO nanosheets that composed the formed oligo-layered laminates. Subsequently, by post-filtrating a GO/H2O suspension through the oligo-layered laminate membranes, the respective multi-layered ones have been developed, whereas ethylenediamine (EDA) was used in the suspension as an efficient molecular linker that strongly bonds and interlocks the GO nanosheets. The definition of the best linker and approach was conducted on macroporous α-alumina disks, due to the use of inexpensive raw materials and the ability to fabricate them in the lab with high reproducibility. To validate the concept at a larger scale, while investigating the effect of the porous substrate as regards its micrometer-scale roughness and surface chemistry, specific chemical modifications that yielded membranes with the best gas permeability/selectivity performance were replicated on a commercial single-channel monolith with a ZrO2 microfiltration layer. XRD, Raman, ATR, FESEM, and XPS analyses were conducted to study the structural, physicochemical, surface, and morphological properties of the GO/ceramic composite membranes, whereas permeance results of several gases at various temperatures and trans-membrane pressures were interpreted to shed light on the pore structural features. Concerning the short-chain linkers, the obtained results ascertain that GLYMO causes denser and more uniform assembly of GO nanosheets within the oligo-layered laminate. PDA had the same beneficial effect, as it is a macromolecule. Overall, this study shows that the development of gas-separating membranes, by just dipping the linker-modified substrate into the GO suspension, is not straightforward. The application of post-filtration contributed significantly to this target and the quality of the superficially deposited, thick GO laminate depended on this of the chemically attached oligo-layered one.

Evidence for the cooking of fish 780,000 years ago at Gesher Benot Ya'aqov, Israel.

Although cooking is regarded as a key element in the evolutionary success of the genus Homo, impacting various biological and social aspects, when intentional cooking first began remains unknown. The early Middle Pleistocene site of Gesher Benot Ya'aqov, Israel (marine isotope stages 18-20; ~0.78 million years ago), has preserved evidence of hearth-related hominin activities and large numbers of freshwater fish remains (>40,000). A taphonomic study and isotopic analyses revealed significant differences between the characteristics of the fish bone assemblages recovered in eight sequential archaeological horizons of Area B (Layer II-6 levels 1-7) and natural fish bone assemblages (identified in Area A). Gesher Benot Ya'aqov archaeological horizons II-6 L1-7 exhibited low fish species richness, with a clear preference for two species of large Cyprinidae (Luciobarbus longiceps and Carasobarbus canis) and the almost total absence of fish bones in contrast to the richness of pharyngeal teeth (>95%). Most of the pharyngeal teeth recovered in archaeological horizons II-6 L1-7 were spatially associated with 'phantom' hearths (clusters of burnt flint microartifacts). Size-strain analysis using X-ray powder diffraction provided evidence that these teeth had been exposed to low temperature (<500 °C), suggesting, together with the archaeological and taphonomic data, that the fish from the archaeological horizons of Area B had been cooked and consumed on site. This is the earliest evidence of cooking by hominins.

Effect of Structural Bonding Patterns on Mechanical Characteristics of Clay Brick Masonry under Different Loadings Using Digital Image Correlation Technique

This paper assesses the effect of two different structural bonding patterns on the mechanical characteristics of clay brick masonry assemblages under compression, flexure, and shear loading conditions. A 2D digital image correlation technique (DIC) was used to appraise the nonlinear compressive stress-strain characteristics, orthotropic properties, damage, and failure mechanisms of masonry prisms. The experimental investigation ascertained that full-brick thick masonry exhibited reasonably higher capacity and deformation characteristics than half-brick thick masonry under compression, flexure, and diagonal compression loadings, except in bed joint shear strength. The compressive strength and corresponding strain of full-brick thick Flemish bond prisms were higher and had more deformable (maximum strain recorded 2.4 times) behavior than half-brick thick masonry prisms. The failure mechanics of the masonry was quantitatively established by strain analysis obtained from DIC. The rupture modulus of Flemish bond masonry walls was four times higher, and its failure (a combination of tensile splitting of bricks and bed joint failure) was gradual compared to stack bond masonry. The diagonal compression strength of full-brick thick masonry wallettes was about 1.3 times as large as running bond wallettes, as the bond arrangement resisted diagonal cracks propagation. The applicability of the available idealized compressive stress-strain analytical models was evaluated, and a few improvements were recommended. The research study assessed that due attention needs to be given to structural bonding patterns in evaluating the mechanical characteristics of masonry required in the design and analytical modelling of masonry constructions. DIC technique can be conveniently used to capture the nonlinear strain characteristics and can be handy in detecting the damage early.

Holocene vegetation and climate reconstructions from pollen records in the Mu Us Sandy Land, China

Knowledge of changes in vegetation and climate during the Holocene is important for improved assessments of future climate change and for mitigating climate warming. Owing to the relative difficulty in obtaining high-resolution sedimentary records and identifying pollen, few paleovegetation reconstructions are available from the Mu Us Sandy Land, China. This study analyzes a naturally-exposed fluvio-lacustrine section in the hinterland of the Mu Us Sandy Land. Based on a chronological framework constructed by AMS 14C, a pollen-based random forest model was used to quantitatively reconstruct changes in Holocene climate and normalized difference vegetation index (NDVI) changes. The relationships between NDVI, pollen and precipitation, as well as pollen assemblage characteristics were combined to reconstruct the evolution of the Holocene vegetation in the Mu Us Sandy Land. Our results show that the climate was cold and humid, and the dominant vegetation type was Ephedra shrub-encroached steppe between 11.2 and 8.3 ka BP; the climate reached an optimum, and vegetation evolved into Artemisia–Taraxacum-type–Thalictrum steppe from 8.3 to 2.6 ka BP; and finally, the climate gradually deteriorated and vegetation became an Artemisia–Chenopodiaceae steppe after 2.6 ka BP. In comparisons with other climate records, we found that the Mu Us Sandy Land climate optimum occurred synchronously at 8.3–2.6 ka BP, and the pattern of climate change is closely consistent with the East Asian summer monsoon. We suggest that millennial-scale Holocene climatic change in this region was mainly driven by the influences of high-latitude ice volume and summer solar radiation on the East Asian summer monsoon.