Search Results (62)

A multidisciplinary study was conducted to reconstruct the paleoenvironmental evolution of Maladroxia Bay, one of the principal bays of the islet of Sant’Antioco in southwestern Sardinia, over the past eight millennia. As part of an archaeological landscape project, this study explores the paleogeography and environment of the bay from a diachronic perspective to gain insights into the Holocene relative sea level history, shoreline displacements, and the environmental conditions during different phases. This study is based on an analysis of four sediment cores in conjunction with a chronological model that is based on radiocarbon dates. Four relative sea level indicators were produced. These are the first such indicators from the early and middle Holocene for the island of Sant’Antioco. The results indicate that in the early Holocene, the area was a terrestrial, fluvial environment without marine influence. In the 6th millennium BCE, the rising sea level and marine transgression resulted in the formation of a shallow inner lagoon. It reached its maximum extent in the middle of the 5th millennium BCE. Afterwards, a gradual transition from lagoon to floodplain, and a seaward shift of the shoreline occurred. The lagoon potentially served as a valuable source of food and resources during the middle Holocene. During the Nuragic period (2nd to 1st millennium BCE), the Bay of Maladroxia was very similar to how it is today. Its location was ideal for use as an anchorage, due to the calm and sheltered conditions that prevailed. Full article

The Caucasian Sea was among the vast tropical water masses that existed on Earth in the Mesozoic. The knowledge of Kimmeridgian–Hauterivian deposits from the central Western Caucasus can facilitate the understanding of the Caucasian paleogeography at the Jurassic–Cretaceous transition. Taking into account the scale of the study area and its geological complexity, a generalized synthesis of the published information seems to be an appropriate option to propose a tentative paleogeographical model. Some original field and laboratory studies, including the examination of the composition of Hauterivian alluvial sandstones, contribute to this model. Kimmeridgian–Hauterivian deposits crop out in the northern, western, and southern domains of the study area, but older rocks are exposed in its central and eastern parts. The Caucasian Sea covered the study area in the early Kimmeridgian, but a large land appeared in the late Kimmeridgian and existed until the end of the Hauterivian despite certain shoreline shifts. The land was eroded deeply, with exposure of pre-Upper Jurassic rocks, including Precambrian–Paleozoic crystalline complexes, and the sedimentary material was delivered to an alluvial plain on its periphery. The registered sea–land interplay was controlled tectonically. Full article

Samotherium boissieri is a giraffid typical of the Pikermian biome, well documented at Samos and occurring in the late Miocene of the Greco-Iranian paleobioprovince. The species has been also recorded at Cessaniti in Calabria (Southern Italy), in a faunal association including other Pikermian species as well as species of Eurasian and African affinity. In this paper, Calabrian specimens are studied and compared to Samos ones. Morphological and biometrical data fall within the variability of Samotherium boissieri and clearly differ from the co-occurring giraffid, Bohlinia attica. Two partially complete forelimbs, probably referring to the same individual, permit the first full description of the manus bones for the species, carpals in particular. The occurrence of Samotherium boissieri in Calabria contributes to the wide discussion on paleobiogeographical assessments of the central Mediterranean in the late Miocene, still not well-understood. Full article

The Lower Congo Basin (LCB) is a rift-type basin with petroleum systems that developed at the western African margin in association with the opening of the South Atlantic. Two pre-salt siliciclastic units of the LCB, Lucula (uppermost Jurassic to Lower Cretaceous) and Chela (Aptian) formations, were sampled in deep wells and outcrops. Heavy mineral assemblages, XRD mineralogy and geochemistry indicate prevailing source in high rank metamorphic rocks from western regions of the Lower Congo Belt. However, sediment composition reveals some provenance heterogeneity. For the Chela Formation, occasionally abundant amphibole in the heavy mineral fraction, coupled with relatively high Fe and Ti proportions, suggest that it formed when deeper crustal units were exhumed. The Lucula Formation collected in outcrops have composition substantially different from Lucula and Chela samples collected in deep wells, indicating distinct provenance and the incorporation of recycled material. A significant diagenetic overprint compromises the interpretation of compositional features in terms of paleoclimate. The presence of a chemical component with dolomite, halite and diverse sulphates and the stratigraphic position of the Chela Formation at the transition to a thick evaporitic succession are compelling evidence of deposition under warm and dry conditions, which are probably more extreme than those associated with the original stages of rifting recorded by the Lucula Formation. Full article

Samara fossils of Acer were unearthed from the Early Miocene Hannuoba Formation in central Inner Mongolia, China. Based on macro- and micro-characteristics, they were identified as Acer pretataricum sp. nov. of section Ginnala, and cf. Acer mono of section Platanoidea. We reconstructed the dispersal routes of these two sections according to their fossil records. During the Early Eocene, section Ginnala was confined to North America. In the Late Eocene, this section expanded westward to East Asia. It was distributed widely in East Asia. In the Late Tertiary, it potentially recolonized the European and American continents. Meanwhile, section Platanoidea was distributed disjunctively in East Asia and North America during the Eocene. Members of this section likely expanded westward from East Asia into Europe in the Oligocene. By the Miocene, it had achieved extensive distribution in the Northern Hemisphere. However, by the Pliocene, it was confined to East Asia and Western Europe. It may have spread eastward from East Asia to North America during the Holocene, finally forming its current existence in North America and the Eurasian continent. This investigation reveals distinct differences in the dispersal pathways of two sections, suggesting that the reconstruction of dispersal routes for Acer taxa should be conducted separately at the section level. Full article

During the Late Miocene, Giraffidae of the genus Bohlinia were widespread in the Greco-Iranian bioprovince (Pikermian biome), while the occurrence in Africa (Chad) was disproven. The fossils of Bohlinia cf. attica described and compared here come from the Late Miocene of Cessaniti (southern Italy), associated with another giraffid, Samotherium cf. boissieri, and the large mammals Stegotetrabelodon syrticus, Tragoportax cf. rugosifrons, cf. Ceratotherium advenientis, and an undetermined Anthracotherid. In terms of paleogeography, the association should be related to the expansion of Pikermian species out of the Greco-Iranian bioprovince and calls for more in-depth considerations. Pikermian giraffids, and Bohlinia in particular, play an important role in understanding the paleoenvironmental and paleogeographical contexts in the Central Mediterranean, an area undergoing major geological changes. Full article

Beachrock is a sedimentary rock that forms rapidly through the cementation of beach-associated clasts by calcium carbonate within the intertidal zone. On the southern coast of Israel, Holocene beachrock exposures typically appear as linear, shore-parallel platforms that dip seawards. In the archeological record, beachrock was exploited as a natural resource for various purposes, including the production of querns, millstones, basins, building stones, and other architectural elements. At Tel Yavne, a site continuously settled from the Chalcolithic period to the present day, excavations in the eastern and southern fringes revealed an extensive industrial compound dating to the Byzantine and early Islamic periods. This compound underscores the settlement’s economic and industrial prominence during those eras. Numerous beachrock artifacts were uncovered, and this study examines their practical applications while characterizing their composition and microstructure. This research highlights the role of beachrock as a key resource, providing insights into inland–coastal economic interactions in antiquity and broadening our understanding of its use within the socio-economic landscape of the region. Full article

Mineralization of groundwater for drinking purposes is a complex parameter of groundwater chemical composition. In the Shaim oil- and gas-bearing area, as in the whole West Siberian megabasin, the main target horizon for solving the issues of domestic and technical water supply is the Oligocene aquifer. It has significant groundwater reserves to cover the needs of the population and production requirements. However, it also faces a huge anthropogenic load in the form of water withdrawal and possible contamination from the surface with oil products. In Western Siberia, various deviations in the chemical composition of groundwater of the Oligocene horizon are recorded in connection with significant water withdrawal; for example, a sharp increase in chromaticity or total iron concentration, with changes in mineralization acting as a factor necessarily accompanying these deviations. Based on the data obtained in the course of monitoring for the period from 2013 to 2023, the main factors and trends of changes in the components of mineralization of the Oligocene horizon were determined. The lithological and mineralogical peculiarities of the water-bearing rocks of the horizon, the paleogeographic conditions of its formation and their relation to trends in mineralization change were studied. Water withdrawal data were processed for two cluster water withdrawal sites (50 and 5 wells, respectively). Analysis of the results showed that the increase in water withdrawal leads to an increase in infiltration from the overlying Neogene-Quaternary aquifer, which leads to the dilution of groundwater of the Oligocene horizon and a decrease in its mineralization. Here, we show that, during further monitoring, it is necessary to pay attention to the appearance of sites where significant amounts of chloride ions are fixed in the anion composition, which can potentially lead to a sharp deterioration in the quality of drinking groundwater. Full article

Precambrian tropical glaciation is an enigma of Earth’s climate. Overlooking fundamental difference of land/sea icelines, it was equated with a global frozen ocean, which is at odds with the sedimentary evidence of an active hydrological cycle, and its genesis via the runaway ice–albedo feedback conflicts with the mostly ice-free Proterozoic when its trigger threshold was well exceeded by the dimmer sun. In view of these shortfalls, I put forth two key hypotheses of the tropical glaciation: first, if seeded by mountain glaciers, the land ice would advance on sea level to be halted by above-freezing summer temperature, which thus abuts an open cozonal ocean; second, a tropical supercontinent would block the brighter tropical sun to cause the required cooling. To test these hypotheses, I formulate a minimal tropical/polar box model to examine the temperature response to a varying tropical land area and show that tropical glaciation is indeed plausible when the landmass is concentrated in the tropics despite uncertain model parameters. In addition, given the chronology of paleogeography, the model may explain the observed deep time climate to provide a unified account of the faint young Sun paradox, Precambrian tropical glaciations, and Phanerozoic glacio-epochs, reinforcing, therefore, the uniformitarian principle. Full article

Shandong Province in China is rich in paleontological fossils and has a long history of fossil research. However, research on the distribution characteristics and potential factors of discovered fossil sites in Shandong Province is limited and insufficient, making it difficult to comprehensively plan for the protection and utilization of fossil sites in Shandong Province. The study constructs a basic geographical information system (GIS) database with 133 discovered fossil sites and geological and socio-economic data of Shandong Province and studies fossil sites’ spatial distribution characteristics and the spatial relationship with potential factors at a regional scale. The results are as follows: (1) The fossil sites in Shandong Province are concentrated in the mountainous area of central Shandong and the hilly area of the Shandong Peninsula, with significant uneven distribution characteristics, including two agglomeration areas and seven sub-agglomeration areas. (2) Natural geographical conditions, such as topography, paleogeography, and stratigraphy, play a positive role in the distribution of fossil sites, and there are apparent concentrations in the following areas: at an altitude greater than 100 m; the Lower Paleozoic and Cretaceous sedimentary rocks; and the active areas of paleo-tectonics. (3) A certain degree of negative correlation exists between socio-economic conditions, such as roads and population density, and the number of fossil sites, and a positive correlation exists between disposable personal income and those fossil sites. The operational procedure presented here is a simple, objective, applicable method that can enhance our understanding of the spatial distribution patterns and influencing factors of the discovered fossil sites of Shandong Province and support more effective and appropriate planning for paleontological heritage conservation. Full article

Cambrian subsalt dolomite is an important strategic area for natural gas exploration in the Tarim Basin. The gypsum-salt rocks, argillaceous mudstone and argillaceous dolomite strata developed in large areas of the Middle Cambrian can be used as good caprocks. The sealing ability and favorable area distribution of the Middle Cambrian caprock in the Tarim Basin are studied through the lithofacies paleogeography and microscopic evaluation of the Middle Cambrian strata in this paper. Based on the 2D seismic interpretation covering the entire basin, combined with data from drilling, outcrops, well logging, core samples and thin sections, the sedimentary characteristics and lithofacies paleogeography of the Middle Cambrian were studied and then the thickness of the Middle Cambrian gypsum-salt rocks, gypsiferous mudstone and gypsiferous dolomite was analyzed in the Tarim Basin. Studies suggest that the Middle Cambrian is primarily characterized by the development of restricted-platform facies. In the Awati Depression, the northern part of the Tazhong Uplift, the southern part of the Manxi Low Uplift, and the central and northern parts of the Bachu Uplift, the thickness of the gypsum-salt rock strata is relatively large. Moreover, centered on the northern part of the Bachu Uplift, the thickness of the gypsum-salt rocks decreases irregularly towards the periphery, forming a circumferential distribution. To investigate the sealing ability of caprocks, 64 core samples from four wells were examined under a microscope, and physical parameters as well as breakthrough-pressure tests were conducted. By establishing correlations between various parameters, the sealing ability of different rock types in the Cambrian formation within the study area was quantitatively assessed. The research suggests that gypsum-salt rocks exhibit superior sealing ability compared to gypsiferous mudstone and gypsiferous dolomite, but factors such as faults and geological conditions of gypsum can influence the sealing performance of caprocks. According to both micro- and macro-scale evaluations of the Cambrian strata in the study area, along with constraints imposed by actual drilling exploration results, a comprehensive evaluation method for assessing caprock sealing ability has been established. The results suggest that the Awat Depression, the western and southern parts of the Manxi Low Uplift, the northern and western parts of the Tazhong Uplift, and the central part of the Tabei Uplift are favorable areas for the development of caprocks. Full article

A phylogeographic study on the chloroplast DNA of natural white oak forests (Quercus subgen. Quercus, sect. Quercus) was carried out to identify possible haplotype-structured distribution within the Italian Peninsula, Sicily, and Sardinia. Sixty white oak populations belonging to Q. frainetto, Q. robur and the collective groups Q. petraea and Q. pubescens were considered and analyzed by combining five Chloroplast Simple Sequence Repeat (cpSSR) markers. A total of 28 haplotypes were detected. Central and southern Italy displayed the highest variability (14 and 10 haplotypes, respectively), followed by northern Italy (7), Sardinia (7), and Sicily (5). A complex geographical structure of the haplotype distribution emerged, highlighting (i) a high number of low-frequency haplotypes; (ii) the marked isolation of Sardinia; (iii) the occurrence of haplotypes widely distributed throughout the Italian Peninsula; (iv) the idiosyncrasy of Sicily, which exhibits exclusive haplotypes, and haplotypes shared with Sardinia and the rest of the Italian Peninsula. The haplotype distribution was also found to be partially related to the taxonomic identity of the specimens, with the following features emerging: a geographic separation between the central Italy and southern Italy Q. frainetto populations, an unexpected discontinuity between the Calabrian and Sicilian Q. petraea subsp. austrotyrrhenica populations, and the absence of the most common haplotype among the Q. pubescens populations of central and southern Italy. Full article

The objective of our work was to reconstruct transgressive-regressive events in the Northern Caspian Sea during the Khazarian epoch of its Pleistocene history to determine the natural conditions of the development of the basins and to assess their response to climate change. This work is based onstudies of the sedimentary formations of the upper part of the Quaternary sequence in the Northern Caspian Sea. The borehole was drilled in the eastern part of the depression Shirotnaya, the sea depth was 11.9 m, and the depth of drilling was 56.4 m. The core was subjected to lithological, malacological, and palynological analysis. This paper discusses the results related to the interval 56.0–26.6 m. The structure, facies-lithological, and malacological composition of the core capture three transgressive stages of the Caspian, namely the Early Khazarian, Late Khazarian, and Hyrcanian stages, separated by regressive phases. The representative spore-pollen assemblages made it possible to carry out the climatic and stratigraphic subdivision of the studied Khazarian deposits and to suggest a provisional version of the history of climatic and phytocenotic events during the sedimentation period. The results of our studies have introduced new discussion points into the paleogeography of the Northern Caspian Sea. Full article

The Carboniferous Yanghugou Formation in the western margin of the Ordos Basin exhibits significant potential for oil and gas exploration. However, due to the influence of complex tectonic activities, there are substantial variations in stratigraphic thickness and depositional environments across the formation. The lack of a systematic source–sink comparative study has resulted in an unclear understanding of sediment sources and paleogeographic patterns, impacting the exploration for hydrocarbon accumulations. We conducted a comprehensive study of the source–sink system characteristics and paleogeography in the research area through field outcrop observations and drilling core sampling. By utilizing detrital zircon U–Pb geochronology and geochemistry, paleocurrent directions, lithofacies types, and sedimentary features, we delve into the understanding of the source–sink systems. Four major source–sink regions in the research area were identified: the Alxa, Yinshan, Alxa–Yinshan mixed and Qilian source–sink regions. The Alxa source–sink region formed a transitional delta-barrier-island sedimentary system. The northern part of the Yinshan source–sink region developed a transitional tidal-controlled delta-tidal-flat sedimentary system, while the southern deep-water area developed a shallow marine to semi-deep marine shelf sedimentary systems. The sediments of Alxa–Yinshan mixed source–sink region were deposited in a transitional tidal-controlled delta-tidal-flat barrier-island system. The Qilian source–sink region is characterized by small tidal-controlled delta-barrier-island system. From the analysis of the source–sink systems, it is inferred that the Alxa Block and the North China Craton had already merged before deposition of the late Carboniferous Yanghugou Formation. The delta sand bodies in the Alxa–Yinshan mixed source–sink region have the highest compositional and structural maturity, the best reservoir performance, and the great exploration potential. Full article

Forests of the Carpathians are of increasing research interest, as they cover a large area (>9 Mha) within European forests and are influenced by diverse environmental conditions and contrasting historical developments. We reviewed 251 papers dealing with Carpathian forests, their history, and future perspectives. Over 70% of articles and reviews appeared in the last ten years, and 80% refer to the Western and Eastern Carpathians, while the Serbian Carpathians remain a gap in this research field. Forest expansion and species changes have occurred since Holocene deglaciation, influenced by timber use, settlements, cropland development, and, since the Bronze Age, pasture activities. At higher elevations, early conifer successors have been increasingly replaced by Norway spruce (Picea abies), silver fir (Abies alba), European beech (Fagus sylvatica), and hornbeam (Carpinus betulus), while oaks have been present in the Carpathian foothills throughout the whole of history. In the 19th and 20th centuries, Norway spruce afforestation was favored, and timber use peaked. Recent transitions from agriculture to forest land use have led to a further increase in forest cover (+1 to +14% in different countries), though past forest management practices and recent environmental changes have impaired forest vitality in many regions; climate warming already causes shifts in treelines and species distributions, and it triggers pest outbreaks and diseases and affects tree–water relations. The risk of forest damage is the highest in monodominant Norway spruce forests, which often experience dieback after cascade disturbances. European beech forests are more resilient unless affected by summer droughts. In the future, increasing dominance of broadleaves within Carpathian forests and forest management based on a mix of intensive management and ecological silviculture are expected. Maintenance and promotion of silver fir and mixed European beech forests should be encouraged with respect to forest stability, biodiversity, and economic sustainability. As supported by the Carpathian Convention and related institutions and initiatives, connectivity, management, and stakeholder cooperation across administrative borders will be crucial for the future adaptive potential of Carpathian forests. Full article