Cretaceous Research Articles

Tempo-Spatial Tungsten Metallogeny in the Xing’an–Mongolia Orogenic Belt: Insights from the Early Cretaceous Shamai Tungsten Deposit Case Study in Northeastern China

The Xing’an–Mongolia Orogenic Belt (XMOB) is located in the eastern part of the Central Asian Orogenic Belt (CAOB). The region’s notable tectonic complexity and extensive tungsten mineralization offer a unique opportunity to explore metallogeny mechanisms in orogenic areas. This study focuses on the Shamai tungsten deposit as a case study, presenting results from LA–ICP–MS U–Pb dating of fine-grained, medium-grained, and porphyritic biotite monzogranite samples from the deposit, along with in situ zircon Hf isotopic and plagioclase Pb isotopic analyses. The fine-grained, medium-grained, and porphyritic biotite monzogranite were emplaced at 142.5, 141.9, and 140.2 Ma, respectively. These samples contain zircons with εHf(t) values ranging from 3.2 to 7.9 and 4.2 to 7.6, respectively, yielding TDM2 model ages from 996 to 692 Ma and 923 to 708 Ma. These findings suggest that the magmas in the Shamai deposit were produced by partial melting of juvenile crustal material mixed with mantle-derived components. The tungsten mineralization periods in the Eastern XMOB region can be divided into three stages: Early Paleozoic (ca. 520–475 Ma), Triassic (ca. 250–200 Ma), and Jurassic to Early Cretaceous (ca. 190–130 Ma). The highest concentration of tungsten mineralization in the XMOB occurs within the Xing’an Block during the Jurassic to Early Cretaceous period. Yanshanian magmatism and the most significant tungsten metallogenic events are likely influenced by an extensional setting and oceanic slab rollback, shaped by the tectonic evolution of the Mongol-Okhotsk Ocean and the Paleo-Pacific Ocean.

A new genus of metriorhynchid crocodylomorph from the Lower Cretaceous of Germany

Here we describe a new genus and species of metriorhynchid crocodylomorph, Enalioetes schroederi gen. et sp. nov., from the lower Valanginian Stadthagen Formation (Lower Cretaceous) of north-western Germany. Enalioetes schroederi is the most complete and well-preserved Cretaceous metriorhynchid skull known to date, preserving most of the cranium and mandible, the atlas-axis complex and the first postaxial cervical vertebra. The specimen was previously attributed to the coeval enigmatic metriorhynchid Enaliosuchus (a nomen dubium) and, more recently, to Cricosaurus. Although the specific epithet schroederi has been used frequently in the literature, it has never been formally established. Herein, we demonstrate that the new taxon is distinct from all known metriorhynchids by a unique combination of characters including several autapomorphies such as: the lack of bulbous dorsolateral expansion in the posterior nasal cavity; mediolateral distance between the orbital canals being approximately 1.5 times the diameter of the orbital canals; lacrimal with dorsoventrally deep anterior process ventral to the preorbital fossa being equal to or greater than the depth of the jugal anterior process and the anterodorsal process of the lacrimal; and ascending processes at atlas intercentrum extending far dorsally to level of neural canal. Enalioetes schroederi contributes to the sparse global record of Cretaceous metriorhynchids and represents one of the stratigraphically youngest occurrences of the group. It can thus help to enhance our understanding of the metriorhynchid diversity during the Cretaceous Period. http://zoobank.org/urn:lsid:zoobank.org:pub:5139021C-8E09-4912-BF22-9DDF14A4C895

Рельеф, коррелятные отложения и палеогеография Ольской низменности (Северное Приохотье)

The basic features of the geological and geomorphological structure and paleogeography of the Ola Lowland surface are determined. A wide distribution of heterogeneous Quaternary continental sediments has been established, with the predominant Upper Pleistocene glacial formations, forming a loose cover on the slopes, in river valleys, and on the plains of intermountain depressions. In some places, the lowland surface was formed on Oligocene-Miocene sediments composing the lower part of the sedimentary mass. Separate areas are formed by subhorizontal surfaces of the eroded Late Mesozoic basement of the lowland (leveling surfaces), composed of effusive and intrusive rocks of the Early Cretaceous age. In the Late Pleistocene, two glaciations took place in the territory under consideration: the Zyryan and the Sartan. The former significantly affected the formation of the lowland relief while the latter left moraines only in the narrow strip at its northern boundary. Layers of the Early Holocene volcanic ash are marked in the soil horizon of the lowland.

Cranial anatomy and holotype reconstruction of the Late Cretaceous turtle, Australobaena chilensis from the Quiriquina Formation, Chile

Resolving the phylogeny of fossil turtles is uniquely challenging given the high potential for the unification of convergent lineages due to systematic homoplasy. Equivocal reconstructions of turtle evolution and biogeographic or palaeo-climatic data with phylogenetic hypotheses and new images of the holotype reconstructions of fossil turtles are important for prehistoric turtle fossil remains. Here we describe the cranial anatomy and holotype reconstruction of the Late Cretaceous turtle, Australobaena chilensis from the Quiriquina Formation of the Maastricht Ocean Horizon Chile, which was identified as a new genus and species of Baenidae (an extinct family of para-cryptodiran turtles) in 2002 by Karl and Tichy. The holotype is “SMF R 415”, a partially destroyed skull without a lower jaw, and with a unique cranial plane. This taxon belongs to Baenidae, an extinct freshwater family from the Cretaceous period in North America. This is the first baenid fossil found outside of North America, and we re-describe and reconstruct it with new photographs and illustrations of the cranial anatomy of this material (Holotype).

Primary study of a new dinosaur tracksite from the Lower Cretaceous Matoushan Formation, Yunnan Province, China

ABSTRACT The Early Cretaceous period is characterised by a rapid evolutionary radiation for dinosaurs. Yunnan Province, one of China’s richest regions for dinosaur records, has yielded numerous skeletal and track fossils from the Middle and Lower Jurassic deposits, while the Lower Cretaceous dinosaur records are relatively scarce. This paper reports the discovery of a large dinosaur tracksite from the Lower Cretaceous Matoushan Formation in Huashiban Village, Konglongshan Town, Lufeng City, Yunnan Province. Preliminary analysis has identified at least 418 footprints that are dominated by sauropods, with theropod and ornithopod footprints also present. The track assemblage from the Huashiban main site broadens our understanding of the distribution of Early Cretaceous dinosaurs in Yunnan, which shows greater consistency with the Lower Cretaceous tetrapod track assemblage from the Sichuan Basin.

Gallophilous theory of cyclical parthenogenesis in aphids (Homoptera, Aphidinea).

The paper elaborates theoretical basis of the origin of aphid cyclical parthenogenesis in view of the original life of these insects in strobiloid galls on Picea spp. The period of gall opening is greatly extended in time, which prevents normal panmixia and creates a selective advantage for parthenogenetic reproduction. Migration of aphids to secondary host plants, on which closed galls never form, parthenogenetic reproduction on these plants, and the subsequent simultaneous return of "remigrants" to the main host plant make it possible to synchronize the development of the bisexual generation and achieve mass panmixia at the end of the life cycle only; it coincides with the end of summer growth shoots or the autumn end of the vegetation period as a whole. The evolutionary transition of aphids from conifers to angiosperms in the Cretaceous period in parallel meant the possibility of development in more spacious galls accommodating several consecutive parthenogenetic generations, the transition to viviparity and telescopic embryonization, significantly accelerating the propagation.

Late Cretaceous turbidite systems of southern Belgrade outskirts: Constraints on the Santonian convergence onset, evidence from the Sava Suture Zone (Guberevac-Babe, northern Šumadija, Serbia)

As ancient depositional systems associated with active continental margins, turbidites may provide crucial information on orogenic evolution. This paper offers new stratigraphic and structural data on one of the late Alpine turbidite systems of the Late Cretaceous age (Guberevac-Babe-Ropočevo area; Serbia). The two opposite yet juxtaposed tectonic systems were initially deposited within the Sava Suture Zone and East Vardar Zone, whereby the former experienced Upper Cretaceous contractional- and extensional-type deformations. The new biostratigraphic dating constrains the age of mapped compressional structures, which indicates their Santonian age. This deformed segment of the newly dated Santonian clastic-carbonate turbidite sequence near the Guberevac site exposes new important compressional structures. The folds, reverse faults, and tectonic stylolites are allocated several kilometers from the primary deformation (Bela Reka thrust fault), positioned within the crustal footwall of the overriding East Vardar Zone. The complexity of the geological processes in the Guberevac-Babe-Ropočevo area is further revealed by the previously mapped layering of Upper Cretaceous strata, exposed within the wider investigated area. Our combined field study provides a new statistical analysis of structural elements such as faults, folds, and bedding planes, adding to the depth of the understanding of the Sava Suture Zone. The observed contractional structures, mesoscopic folds, thrust faults, two-generation cleavage planes, as well as the produced statistical structures, are mostly imprinted into the out-of-deformation front or within the mixed clastic-carbonate turbidites of the Sava Suture Zone (Guberevac-Babe area). The composite study shows that the investigated footwall segment, represented by the deformed Sava Suture Zone turbidites, underwent tectonic shortening during Santonian (convergence onset). After the main crustal thickening event ceased, the Guberevac-Babe-Ropočevo suture segment was reactivated several times (post-orogenic extension). The investigated segment of the Neotethyan Vardar paleosuture experienced a total of four deformation stages spanning Late Cretaceous to Miocene times. These include the Late Oligocene reactivation and emplacement of the Glavčina-Parlozi Late Oligocene subvolcanic body and the slightly younger Stenička bara Miocene igneous system.

Thermochronological Constraints on the Tectonic History of the Arabian–Nubian Shield’s Northern Tip, Sinai, Egypt

The effects of different regional tectonic events on the Neoproterozoic basement rocks of the Arabian–Nubian Shield in Sinai, as well as the Egyptian unstable and stable shelves, remain uncertain. Coupling fission-track thermochronometry findings with the modeling of the time–temperature history has proved to be an effective method for tackling these issues. The obtained zircon fission-track ages were differentiated into two groups from the Ediacaran–Cambrian and the Ordovician–Carboniferous periods, while the apatite fission-track data revealed two separate groups of cooling ages of the Carboniferous–Triassic and Late Cretaceous ages. The integration of these cooling ages and modeling of the time–temperature history revealed four discrete cooling pulses during the Neoproterozoic, Devonian–Carboniferous, Cretaceous, and Oligocene–Miocene eras. After integrating our findings with the regional tectonic historical and sedimentological records, these could be identified as cooling/exhumation pulses activated in response to the post-accretional event of erosion, Variscan tectonism, the disintegration of Gondwana, and the Gulf of Suez rifting, respectively. Furthermore, the southern border of the Egyptian unstable shelf was found to extend southward to South Sinai and south of the Bahariya depression.

Natural history of cyclical parthenogenesis of aphids (Homoptera: Aphidinea)

The article puts forward and argues the hypothesis of the emergence of cyclical parthenogenesis in aphids as a consequence of their ancestral habitation in closed strobiloid galls on coniferous trees. The period of gall opening is greatly extended in time, which prevents normal panmixia in the population and creates a selective advantage for parthenogenetic reproduction. Migration of aphids to secondary host plants, on which closed galls never form, parthenogenetic reproduction on these plants, and the subsequent simultaneous return of “remigrants” to the main host plant make it possible to synchronize the development of the bisexual generation and achieve mass panmixia only at the end of the life cycle, which coincides with the end of summer growth shoots or the autumn end of the vegetation period as a whole. Due to the fact that the development of the bisexual generation always necessarily occurs in the second half of the year, when the conditions for aphid feeding on arboreal plants become unfavorable, small size of sexual individuals and their reduced fertility (often only one egg per female), in comparison with parthenogenetic generations of the first half of the year, are understandable. The evolutionary transition of aphids from conifers to angiosperms in the Cretaceous period in parallel meant the possibility of development in more spacious galls accommodating several consecutive parthenogenetic generations, the transition to viviparity and telescopic embryonization, significantly accelerating the change of generations. The loss of ovipositor in Phylloxeridae and in hypothetically descended from them Aphidoidea can be explained by the initial life in galls, where egg laying does not require specialized ovipository organs. The evolutionary transition from oviparity of parthenogenetic generations to viviparity probably occurred in the ancestors of modern Eriosomatidae, as evidenced by the plesiomorphic features of the reproductive biology of the latter.

Interpretation of a 3D Magnetotellurics Model of the Aceh and Seulimeum Segments of the Sumatran Fault Zone

The Sumatran Fault runs from the southeast (SE) to the northwest (NW) of Sumatra Island, with the highest slip rates reaching about 3.0 cm per year in the northwestern part. There is a seismic gap along this fault, including the northern Aceh domain, which consists of the Aceh and Seulimeum fault segments. Previous studies have used various methods to investigate the Sumatran Fault system, including seismic, geoelectric, gravity anomaly, and magnetotellurics (MT). The MT method has proven advantageous as it can non-destructively image a wide range of depths. However, previous studies using the two-dimensional (2D) MT inversion did not represent realistic information of the subsurface conditions. Therefore, a three-dimensional (3D) MT data inversion was used in this study to obtain more realistic information about the resistivity structure of the Aceh and Seulimeum segments. The results confirmed that the Sumatran Fault is a strike-slip fault, with a relatively northwest (NW)–southeast (SE) direction of conductivity strike with an angle of S 71.61° E from Groom–Bailey decomposition of MT data. The 3D resistivity distribution model from 33 stations showed that the Aceh Fault Segment is 20–30 km away, while the Seulimeum Fault Segment is 55–60 km away based on the MT data. The results also indicated a creeping zone at a depth of 2 km beneath the Aceh Fault Segment. Different rock formations were identified beneath the fault system, with the western part of the Aceh Segment dominated by high-resistivity metamorphic rocks (150–1000 Ωm) from the Triassic–Cretaceous age. The zone between the Aceh and Seulimeum fault segments exhibited low resistivity, characterized by volcanic rocks (1–15 Ωm) from the Lam Teuba Volcanic Formation and the Indrapuri Formation. Beneath the eastern part of the Seulimeum Fault Segment was found to consist of low-resistivity quaternary volcanic rocks (1–15 Ωm) and high-resistivity andesite rocks (4.5 × 104–1.7 × 105 Ωm). These findings correlated well with the geological map.

A Comparative Geophysical Study of Major Basins in the Pranhita–Godavari Rift, India and Rio Grande Rift, USA

ABSTRACT In this study, we compare and contrast two major sub-basins in the Pranhita-Godavari rift in eastern India (Chintalapudi subbasin) and the Rio Grande rift in the western United States (Albuquerque basin) using bouguer gravity data analysis and integrated profile modeling constrained with seismic, drilling, and geological data. The Chintalapudi sub-basin formed during the break-up of Gondwana around 350 Ma, while the Albuquerque basin formed much later (30–35 Ma) in the interior of North America approximately synchronous with extension in the Basin and Range province. The Chintalapudi sub-basin is narrow and deep; and associated with a −60 mGal (low) gravity anomaly that is mostly due to Gondwana fluvial sediments of late Carboniferous (~350 Ma) to early Cretaceous age (~120 Ma). The negative gravity anomaly associated with the Albuquerque basin is −55 mGals (low) and the Cenozoic sediments were deposited on Mesozoic and Palaeozoic strata with Precambrian crystalline rocks being exposed along the basin flanks. This sub-basin is wide and shallow. Major faults which bound these basins were delineated by gravity modeling that integrated all of the available constraints, and the average depth to the basement at the basin centers calculated from gravity modeling is 4–5 km. However, for Chintalapudi sub-basin, if the residual gravity anamoly is considered, it may be reduced to about 3.5 km.

An Integrated Geological Model of Selective Carbonate Reservoir Wells, in Mishrif Formation in the Ratawi Oilfield, Southern Iraq

The majority of petroleum studies have traditionally focused on rocks that store hydrocarbons due to their economic significance, particularly in a period where oil is the primary global energy source. In the Cretaceous period, Iraq, and the Middle East, in general, are of particular interest due to the presence of formations that are significant for hydrocarbon storage and generation. The Mishrif Formation, dating to the Cenomanian-Early Turonian period, is a notable oil reservoir in southern Iraq. This formation’s distinctive features and extensive surface area make it a significant hydrocarbon repository, ranking second economically after the Zubair Formation in the region. This study analyzed six oil wells from the Mishrif Formation using various well logs (gamma ray, density, neutron, spontaneous potential, acoustic and resistivity) to extract petrophysical properties. The study identified rock types, layer boundaries, thicknesses, formation depths, and hydrocarbon-bearing zones. Through qualitative interpretation of these logs, the reservoir's characteristics were evaluated, including porosity, shale distribution, water and oil saturation. The results were visualized in three-dimensional models using the Petrel software, showing the distribution of these characteristics across the study wells. The Mishrif Formation is composed of four units (MA, CR-1, MB-1, and MB-2), with varying properties that were detailed in this study. Shale volume, averages between 0.04 % and 0.16%. Effective porosity ranges from 0.09% to 0.19%, indicating good reservoir quality; permeability ranges from 0.001 to 10 MD. Hydrocarbon saturation varies from 0.1to 0.7, while water saturation ranges from 0.3 to 0.9. The distribution of effective porosity in the Middle Mishrif reservoir unit is good throughout the field. In the Lower Mishrif reservoir unit, the effective porosity distribution is good in the central part of the field but poor in the northern and western parts. The formation thickness is homogeneous, indicating stable deposition. Hydrocarbon accumulations are present in both the Lower and Middle Mishrif reservoir units.

Tectono-sedimentologic and lithostratigraphic control in Aures Region: Case study Djebel Metlili, Batna, Algeria

This research delves into the geological features of the western section of the Aures Basin, with a primary focus on Djebel Metlili. The geological characteristics span Mesozoic and Tertiary deposits, ranging from the Triassic to the Quaternary epochs. Notably, the higher Cretaceous period stands out for its substantial carbonate-rich sequence. The research relied on geological maps, field observations, core samples, and laboratory analyses, including lithostratigraphic examinations (cross-section) and thin section. Structural features show that is formed by large regular folds of ENE-WSW or E-W direction. Anticlines and synclines are often affected by transverse accidents at the axes of the folds. In its northern part is located immediately south of the Belezma-Batna mountains. Structural analysis highlights significant tectonic disturbances, oriented in a northwest-southeast direction. A detailed lithostratigraphic examination reveals marly formations interspersed with limestone-rich layers containing Inoceramus. The southern part of Dj. Metlili, particularly the Santonian-Campanian series, unveils three distinct meso-transgressive sequences, linked to sea-level fluctuations associated with sedimentary basin subsidence. The studied area exhibits three distinct facies: one characterized by gray phosphate limestone with crisscrossed stratifications and agitated bioclastic sand, another featuring a mollusk-rich bioclastic limestone indicating a turbulent intertidal environment, and a third presenting a clay limestone bank with fine to medium grains and lumachels rich in oysters and gastropods. The associated grainstone texture in the microfacies suggests an internal platform environment marked by dissolution, bioturbation, and ferruginization. This comprehensive exploration provides valuable insights into the geological history of the region, significantly contributing to our understanding of its evolution over time.

Investigation of Geological Structures between Acıpınar-Hanobası-Altınkaya (Aksaray-Türkiye) About Satellite-Based Tectonic Lineaments

The region between Aksaray, Central Anatolia, and Altınkaya (Turkey) is included in the study area. The area's basement comprises ophiolites, igneous rocks from the Late Cretaceous period, and metamorphic rocks from the Palaeozoic to Mesozoic ages. Late Cretaceous-Quaternary sedimentary units were formed in the area called Tuzgolü Basin. The Late Cretaceous-Mio-Pliocene sedimentary rocks in the study area have undergone polyphase deformation under compressive and extensional tectonic regimes. As a result of these deformations, the rocks in the area have developed folded, faulted and fractured structures. These structures have formed lineations. In this study, the relationship between the tectonic lineaments identified in the field and those obtained by computer processing of Landsat 8 images was evaluated. It was found that the lineaments belonging to the Tuzgölü fault and the structural geological structures determined in the field are in significant agreement.

A new division of late Cretaceous Erlian Basin tectonic units based on differential basement characteristics

The Erlian Basin, a significant continental sedimentary basin in northeastern China, is renowned for its abundant hydrocarbon resources. Extensive research has been conducted on its sedimentary sequences, hydrocarbon accumulation, and geodynamic background. However, previous tectonic units classifications of the Erlian Basin predominantly reflect its post-Cenozoic tectonic framework, neglecting the Early Cretaceous period. This oversight fails to explain recent petroleum discoveries in the Wulanhua area of the Ondor Sum Uplift. In this study, geological, well log, seismic, gravity, and magnetic data, along with large, deep fault distributions and the regional geology of the Erlian Basin, were utilized to analyze its basement characteristics and propose a new tectonic division. Our findings reveal that the Erlian Basin's basement exhibits composite characteristics, resulting in a north-south zonation of basin depressions. Consequently, the basin's tectonic units were divided into northern, central, and southern depressions, delineated by two major deep faults: Xilinhot and Chifeng–Kaiyuan. This revised tectonic division clarifies the Early Cretaceous tectonic framework, enhances the basin's hydrocarbon exploration potential, and will guide future exploration efforts. Our study identifies nine favorable sags within the Erlian Basin with significant hydrocarbon potential.

Detrital zircon provenance links between outcrop and subsurface, Rocas Verdes and Magallanes-Austral Basins, Patagonia

Analyzing how provenance signatures of tectonically complex ancient sedimentary basins vary between the outcrop and the subsurface provides a more complete sediment provenance history. The 500+-km-long outcrop belt of the Rocas Verdes and the Magallanes-Austral Basins in southern Patagonia and its subsurface to the east allow us to constrain relationships between longitudinal and transverse sediment sources feeding the basin. New detrital zircon U-Pb ages (n = 2558) from nine subsurface core samples from the Springhill, Piedra Clavada, and La Anita Formations along a 140 km E-W seismic reflection transect (50°S, 71.5°W–69.5°W) reveal the provenance of the basin’s eastern subsurface extent and the influence that tectonic activity can have on sediment capture. Detrital zircon ages (n = 1068) were also collected from four outcrop Springhill Formation samples 140 km NW from the transect near Lago San Martín. Maximum depositional ages (MDAs) from the Springhill Formation cores range from 159 to 157 Ma, which are older than correlative outcrop ages of 151–148 Ma. MDAs from the Piedra Clavada and La Anita Formations range from 93.7 to 91.5 Ma and from 79.3 to 78.3 Ma, respectively, and overlap in age or are slightly younger than outcrop ages. The unimodal Late Jurassic age distribution from the Springhill Formation suggests that it almost exclusively was sourced by recycling of the underlying El Quemado Complex. Early–Middle Jurassic ages in the Early Cretaceous Piedra Clavada Formation samples suggest the basin was either sourcing from the North Patagonian Massif to the N-NE and from the Deseado Massif to the NE or recycling exhumed volcaniclastic sequences in the northern margin of the basin. By the Late Cretaceous, the basin fill was more locally sourced, as suggested by the muted abundance of Early–Middle Jurassic ages in La Anita Formation samples and a second mode of Late Jurassic–Early Cretaceous ages locally derived from recycling of the exhumed El Quemado Complex from the Patagonian fold-and-thrust belt. We suggest that the latitudinal and local transverse drainages that sourced the Magallanes-Austral Basin outcrop belt also fed the eastern, subsurface extent of the basin. Results of this work highlight the importance of using several types of provenance methods and a three-dimensional approach to study the erosional history of sedimentary basins.

Paleolatitudinal movements of the eastern Sakarya Zone from Jurassic to Eocene

The study area covers a region oriented north-south from the Black Sea coastline in the north to the Kelkit Basin in the south within the eastern Sakarya Zone in northern Türkiye. The objective of this study is to investigate the paleolatitudinal movements of the eastern Sakarya Zone during the Jurassic-Eocene time interval through paleomagnetism. Various volcanic and sedimentary units (e.g., the Şenköy, Berdiga, Mescitli, Çatak, Kızılkaya, and Çağlayan Formations) spanning the time interval from the Early Jurassic to Middle Eocene were identified. A total of 98 locations belonging to Early/Middle Jurassic to Eocene volcanic and sedimentary units were selected for paleomagnetic core sample collection. The samples were subjected to demagnetization through thermal and alternating field methods. Characteristic remanent magnetization directions (ChRM) were obtained. Isothermal remanent magnetization (IRM) and high temperature susceptibility (HTS) measurements were made to identify the minerals responsible for magnetization. To ascertain whether magnetization was acquired through rock formation or as a consequence of subsequent tectonic processes, conglomerate and fold tests were performed. The results showed that magnetization was acquired before folding, i.e., the rocks have primary magnetization. Polarity tests were also conducted using coeval normal and reverse polarity sites. The results indicate that the mean magnetization direction for the Early-Middle Jurassic is 18.1°/55.2° (D/I) and 3.3°/51.5° (D/I) for sedimentary and volcanic rocks, respectively, and 348.7°/46.7° (D/I) for Late Jurassic/Early Cretaceous sedimentary rocks. In the Late Cretaceous period, the mean magnetization direction is 8.0°/49.3° (D/I) and 9.1°/47.0° (D/I) for sedimentary and volcanic rocks, respectively. In the case of the Early/Middle Eocene, the mean magnetization direction is 348.6°/52.7° (D/I) and 5.9°/48.8° (D/I) for sedimentary and volcanic rocks, respectively. In this study, the E/I correction was applied to the Late Jurassic/Early Cretaceous sedimentary rocks, and paleolatitude data obtained from sedimentary rocks were also utilized. Our paleomagnetic results indicate that the eastern Sakarya Zone was situated at latitudes spanning from 27.9° to 35.7° during the Early Jurassic - Middle Eocene time interval. In consequence, the eastern Sakarya Zone constituted a portion of the southern margin of the Eurasian continent during the Late Jurassic and Middle Eocene periods.

A new palynological assemblage of the Nantun Formation in the Huhehu Sag, Hailar Basin, NE China: Implications for paleoenvironments

The Cretaceous period, recognized as one of the warmest in Earth's geological timeline, is crucial for understanding paleoclimatic conditions. Palynological analyses, focusing on spores and pollen, play a vital role in reconstructing paleoenvironmental. This study emphasizes the relationship between climate and plant distribution through detailed palynological analyses. It reports the first discovery of abundant and diverse palynomorphs from the lower Nantun Fm in the Hailar Basin, Inner Mongolia, China. The identified palynological assemblage, termed the Protoconiferus flavus—Pinuspollenites sp.—Quantouendinium sp. (PPQ) assemblage, provides significant insights into the Early Cretaceous flora of northeastern China. The PPQ assemblage can be chronologically attributed to the Hauterivian–early Barremian interval, consistent with the LA–ICP–MS zircon U–Pb isotope ages of the Nantun Fm volcanic rocks. Paleovegetation reconstruction reveals a prevailing dominance of coniferous vegetation in the region represented by the PPQ assemblage, indicative of a characteristic of mid-to high-latitude mountain coniferous forest landscape. The climatic was mainly humid or semi-humid. This conclusion is supported by the abundance of freshwater dinocyst and green algae fossils, suggesting that sedimentation occurred in a shallow, freshwater hydrostatic environment with an estimated water temperature of approximately 20–25 °C. The environment was also nutrient-rich, which facilitated the proliferation of green algae such as Scenedesmus, Pediastrum, and Tetraedron. Identifying this assemblage is important for determining the age of the lower Nantun Fm, reconstructing paleovegetation and paleoclimate, and analyzing the lacustrine water conditions during the sedimentary period in the Hailar Basin.

Using PySpark to accelerate batch data point rotation for paleogeographic reconstruction

ABSTRACT Batch paleogeographic point rotation (BPPR) is a PySpark-based extensible batch data point rotation method that accelerates rotation during paleogeographic reconstruction. Data point rotation is an important part of paleogeographic reconstruction and a significant tool for exploring the co-evolution of Earth and life. However, current point rotation techniques have challenges with processing speeds when handling extensive paleogeographic data. Therefore, this study introduced a parallel-computing framework to construct a BPPR. This method combines PySpark and PyGPlates, which can partition points and compute them simultaneously in multiple threads. The rotation of 232,277 fossil occurrences from the Cretaceous Period in the Paleobiology Database (PBDB) was completed within 26 s. By contrast, an alternative GPlates method completed the same task within 96 s. The proposed method supports CSV, EXCEL, SHP, and other data formats, thereby avoiding possible software switching requirements when using methods associated with GPlates. Using synthetic and real paleontological data as experimental datasets, BPPR proved to be nine times more efficient than GPlates when rotating 900,000 points. This efficiency improvement significantly enhanced data-driven paleogeographic analysis. The parallel strategy employed can be broadly applied to massive data analysis in geoscience.

Emplacement and landscape controls on ancient submarine volcanism: 3D seismic geomorphological analysis of Cretaceous volcanic activity in the Browse Basin, Australian North West Shelf

Ancient submarine volcanic systems preserved within sedimentary basins provide opportunities to investigate the time and spatial distributions of intrusive and extrusive rocks, though existing work has largely focused on the geometrical features of submarine volcanic products, with limited interrogation of their interactions with sedimentary processes. This study investigates a buried submarine volcanic system within the Browse Basin, Australian North West Shelf. Through the integration of three-dimensional seismic reflection survey with borehole data, our study reveals intricate geometric features of a submarine volcano and lava channels, and their relationship to an associated intrusive network of Early Cretaceous age that has been preserved beneath ∼3.5 km of sedimentary overburden. In planform, the volcano has a diameter >4.5 km with a preserved height reaching 650 m. Meandering lava flow channels extend ∼20 km southward of the volcanic edifice, forming lava lobes with pressure ridges at the flow termini. Abundant sheet intrusions, identified within underlying Jurassic and older strata, indicate a magma transport from the north. The localised accumulation of sills led to variations in paleo-seafloor topography, influencing the direction of lava flows and post-volcanic sedimentation patterns. Our findings have a broad range of implications encompassing submarine volcanism and their impacts on basin dynamics.