Stratigraphic Distribution Research Articles

Laffitteina from the Maastrichtian-Thanetian shallow marine carbonates of the Aures Basin (Northeastern Algeria): microfacies and stratigraphic distribution

The Maastrichtian-Thanetian Ncham Member of the Aurès Basin in northeastern Algeria contains variably lenticular microfossils, which are defined as Laffitteina genera. It is a large benthic foraminifera, studied from three stratigraphic sections. The systematic study of Laffitteina led identification of nine species, four of which, Laffitteina marsicana, L. aff. mengaudi, L. monodi and L. erki were recorded for the first time in the study area. Various species of Laffitteina were used as index fossils to recognize the K/Pg transition in the Aurès Basin. The last occurrence of L. oztuerki marks the end of the Maastrichtian, which was found in association with Omphalocyclus macroporus (Lamarck) in the upper Maastrichtian. The first occurrence of L. erki marks the Thanetian age, while the Danian and Selandian deposits are missing in the field after a general emersion in the early Paleocene, despite the absence of a visible non unconformity. It could therefore be proposed that the K/Pg transition may occurs in the last 10 m of the Ncham Member. Concerning the paleoenvironment, Laffitteina is considered as a resistant foraminifera and thrives in meso- to eutrophic environments (lagoon). Microfacies data from the Upper Cretaceous-Lower Paleogene limestones of the Aurès Basin suggests a carbonate platform with shallowing-up sequential organization, mainly controlled by fluctuations in sea-level.

Implication of middle Eocene to early Miocene ostracodes from the N. El Faras-1X Well, Qattara Depression, Egypt, for paleobathymetry and paleobiogeographic reconstruction

The subsurface middle Eocene - early Miocene succession in the N. El Faras - 1X Well, drilled in the Qattara Depression at the northern part of the Western Desert, Egypt (Southern Tethyan Province, STP), was studied for its ostracode content to infer changes in paleobathymetry as well as paleobiogeographic reconstructions. This succession is composed mainly of three lithostratigraphic units, as the upper part of the Apollonia Formation (middle to late Eocene), the Dabaa Formation (late Eocene and Oligocene) and the lower part of the Moghra Formation (early Miocene). The stratigraphical distribution, paleoenvironmental and paleobiogeographical significance of the ostracode faunas from the Oligocene interval of the study area are documented for the first time. Fifty seven ostracode species belonging to 36 genera were identified in this succession. Among them, two new species were described. The vertical distribution of these ostracode species enabled the recognition of seven local biozones. Qualitative and quantitative statistical analysis of ostracode associations revealed a depositional depth ranging from the inner to outer neritic setting. Considering the CONISS cluster analysis, six ecozones were established. During the middle and late Eocene, the paleobiogeographical affinities of the Egyptian ostracodes from N. El Faras-1X× Well succession with that of the Southern Tethyan countries suggest a direct connection between Egypt and the countries of the Southern Tethyan Province. This connection facilitated the dispersal and exchange within this province. The low ostracode similarity between the STP and the Northern Tethyan Province (NTP) suggests a slight connection and exchange between them. The in common occurrence of these ostracodes with that of Somalia is attributed to the connection between the STP and Somalia via the Tethyan Seaway, which facilitated the dispersal and exchange of the middle Eocene ostracodes. The similarity between the Egyptian ostracodes (STP) and that of South America and the Caribbean Sub-Province indicates a direct connection between those provinces across the Gibraltar Strait and through the North Equatorial Oceanic Water Current during that time. During the Oligocene, the low ostracode similarity between the STP and the NTP may be attributed to a more or less restricted connection. Also, the low similarity indicates a continuation of the mild connection between the STP and the South America and Caribbean Sub-Province across the Gibraltar Strait and through the North Equatorial Current. During the early Miocene, the similarity of the recorded ostracodes of the STP with that of the NTP suggests a continuous connection between the two provinces. Also, there was a connection between the South America and Caribbean Sub-Province and the North American Province through the North Equatorial Current and the warm Gulf Stream within the Caribbean Sea.

Changes in macrofaunal groups before, during and after the Cenomanian–Turonian biotic crisis in north Eastern Desert, Egypt

The stratigraphic distribution of the different faunal groups of the upper Cenomanian–lower Turonian deposits in the north Eastern Desert, Egypt, is investigated. Variations in species richness, faunal diversity, extinction and origination rates before, during, and after the globally known Oceanic Anoxic Event (OAE) 2 are documented. The OAE2 interval is constrained by the first occurrence of the marker ammonite species Vascoceras cauvini and the last occurrence of Vascoceras proprium, along with the positive δ13C excursions, previously identified from the Wadi El-Burga section. A prominent decline in species richness and diversity, high extinction rates, and low origination rates of the recorded macrofaunal elements are reported during the OAE2 interval. Such faunal bottleneck was attributed to the prevailing major palaeoclimatic and palaeoenvironmental perturbations during that time. Besides oceanic anoxia, changes in sea water palaeotemperature and sea level are discussed. It can be concluded that oceanic anoxia, warming, and /or transgressive episodes were the major driving mechanisms of the faunal crisis reported in the present work.

Cladistics and Stratigraphy

Using cladistic phylogenies (cladograms) to evaluate stratigraphy (taxon distributions and correlations) necessitates various assumptions that include all of the assumptions built into the cladogram, assuming the cladogram is “correct” and that new taxa only arise by dichotomous splitting. Ghost lineages extend back the temporal ranges of sister taxa by assuming that both taxa’s oldest records are the time of dichotomous splitting, the only mode of evolution in cladistics. Other modes of evolution require no ghost lineages (anagenesis) or indicate unequal temporal ranges of closely related taxa (punctuation). Evaluating congruence between cladistic branching patterns and stratigraphic distributions reveals much congruence, simply because the cladogram and the taxa in the stratigraphic distribution are overlapping datasets, and the pattern of evolution is to evolve derived taxa after more primitive taxa. Correlating fossil assemblages based on the phylogenetic signals of their included taxa is little more than correlating by stage of evolution. Claiming that paraphyletic taxa are of less biochronological utility than monophyletic taxa is not borne out by examining correlations provided by the actual stratigraphic ranges of the taxa, regardless of their status in an a posteriori cladistic analysis. Thus, using cladistics to evaluate stratigraphy is assumption laden and of questionable value.

A possible turtle swim track from the late Triassic of the Sichuan Basin, China

ABSTRACT A possible turtle swim track from the Third Member of the Late Triassic Xujiahe Formation (Norian-Rhaetian) represents the oldest ichnological evidence of the group from China, supplementing previous reports of more abundant tracks from the Middle Jurassic of the region. The specimen is younger than the known pantestudinate (‘stem-turtle’) body fossils from China but matches the stratigraphic distribution of testudinate skeletons in other regions, for example, in Thailand, Europe and North America. Caution should be used to distinguish turtle swim tracks from those of crocodylomorphs and theropod dinosaurs, especially where only small samples are available. Therefore, we do not completely exclude an affinity with these groups or other archosaurs, such as phytosaurs. Nevertheless, the morphology of the imprints is most similar to turtle tracks, and it is most likely that an early non-crown group representative was the responsible producer. Of interest is also the depositional environment of the track-bearing deposit, which can be considered a deltaic plain marsh.

Gastropods of the genus <i>Sulcoactaeon</i> Cossmann from the Barremian and Hauterivian Deposits of Ulyanovsk Volga Region (Russia)

Eight new species of the genus Sulcoactaeon are described from the Barremian and Hauterivian of the Ulyanovsk Volga region: S. gerassimovi sp. nov., S. fallax sp. nov., S. simbirskensis sp. nov. S. kremenkensis sp. nov. from the Barremian, S. insuetus sp. nov., S. rotundus, sp. nov., S. polivnensis sp. nov., S. shumilkini sp. nov. from the Hauterivian. Information about their geographical and stratigraphic distribution is given.

Bivalves from the Changhsingian (upper Permian) Bellerophon Formation of the Dolomites (Italy): ancestors of Lower Triassic post‐extinction benthic communities

AbstractDiverse shallow marine fossil assemblages from the Changhsingian Bellerophon Formation (Dolomites) record late Palaeozoic marine life immediately before the end‐Permian mass extinction. We classified c. 6500 bivalves from western Dolomites localities, identifying 26 species including one new family (Ladinomyidae), three new genera (Ladinomya, Lovaralucina, Gardenapecten) and 10 new species: Acharax frenademezi, Bakevellia (Bakevellia) preromangica, Edmondia hautmanni, Etheripecten stuflesseri, Ladinomya fosteri, Lovaralucina covidi, Palaeolima badiotica, Promytilus merlai, Tambanella? stetteneckensis and Volsellina carinata. The occurrence of three Eumorphotis species with different stratigraphic distributions, leads us to propose an upper Permian ‘Lower Eumorphotis Zone’, divided into E. praecurrens, E. striatocostata and E. lorigae subzones, and distinct from the existing Lower Triassic Eumorphotis Zone (here renamed ‘Upper Eumorphotis Zone’). Palaeoecological analysis produced six biofacies and four ecofacies, based on richness, dominance and ecological lifestyle. The bivalves inhabited lagoonal to nearshore environments affected by stressed conditions: high temperatures, high salinity, shallow water depths, low oxygen and high terrigenous input. The upper Bellerophon Fm is characterized by increasingly fully marine conditions, although eurytopic taxa still suggest stressed conditions. Bivalve richness of the upper Permian Bellerophon and Lower Triassic Werfen formations was compared to estimate the genus‐level extinction rate. The disappearance of almost half (47%) of Bellerophon Fm genera is remarkably low compared with other, coeval bivalve faunas. Pre‐extinction bivalve faunas were dominated by stress‐adapted taxa (Unionites, Eumorphotis, Bakevellia, Towapteria) able to thrive in extreme environmental conditions, survive the end‐Permian mass extinction, and become the dominant biotic component of Lower Triassic benthic communities globally.

The first Late Permian fish fossils from Leszczyna quarry in South-West Poland

ABSTRACTPermian fishes and their isolated microremains are known from many localities in the Zechstein Basin. However, up to date the vertebrates have never been revealed in the southeasternmost part of this ancient sea. The new material consists of euselachian-type dermal denticles,?Listracanthus sp. dermal denticle,?Omanoselache sp. tooth, actinopterygian scales and actinopterygian teeth. Here, the detailed study of euselachian and actinopterygian remains, their stratigraphic distribution and geographical contexts is presented. Based on the qualitative analysis of teeth shapes several ecomorphotypes were described as well as the probable dietary preferences of fishes were reconstructed. These finds confirmed existence of small predators who fed on soft bodied prey as well as durophagous forms which were feeding on small shelly crustaceans or molluscs. The analysis of stratigraphic distribution of microremains, and their comparison with neighbouring sections revealed a spatially correlatable trend in increasing abundance of fishes in the more clayey parts of sections, interpreted to be positively associated with a sea level transgression event.

Uranium-bearing celestine and barite in the Upper-Paleocene deposits of the Siouf-Cherahil sector: stratigraphic distribution, geochemical, and mineralogical characterization

Uranium-bearing celestine and barite in the Upper-Paleocene deposits of the Siouf-Cherahil sector: stratigraphic distribution, geochemical, and mineralogical characterization

Стратиграфический объем тоупуголъегартской толщи (нижний-средний девон, Полярный Урал)

We refined the age of carbonate and clastic volcanomictic rocks of the Toupugol'egart Formation (D1–2tg) of the Voikar Belt of the Polar Urals, which formed at the final stage of the Polar Ural Island arc development. The analysis of the stratigraphic distribution of fossils of the Toupugol'egart Formation was based on a revision of previously published data and new collections of the authors (algae, tabulatomorphic corals). The stratigraphic range of the Toupugol'egart Formation was extended up to the Karpinsky-Langur regional stages of the Emsian Eifelian of the Devonian. The similarities of the structure, lithological composition and paleontological associations of carbonate sequences of the Toupugol'egart Formation and the upper part of the Malyj Ural Formation (Voikar Belt of the Polar Urals), as well as the Terrigenous-Volcanogenic Formation (eastern slope of the Middle Urals) were noted. The accumulation of these deposits took place in the Late Emsian Early Eifelian, probably during joint sedimentary-volcanogenic cycle within a single extended island-arc system. We assumed a similar evolution of the Polar Ural and Tagil island arcs at the final stage of their formation.

Palynomorph Biostratigraphy of VIC 97 Well, Nothern Depo Belt, Niger Delta, Nigeria

Palynological and sedimentological studies were conducted on sixty ditch cutting rock samples from interval 460 to 4550 feets of VIC-97 well, located at OML 38, Northern Depo-belt, Niger-Delta, to delineate lithofacies units and the age of the rock succession. Standard methods of palynological sample analysis were used to disaggregate the palynomorphs from the rock matrix. Log signatures, sand/shale ratios, textural attributes, and accessory mineal compositions of ditch cutting rock samples were used as lithologic parameters to establish two lithofacies units; the transitional unit having a sand/shale ratio of 80:20 and the continental Unit having a 98:2 ratio ascribed to upper Agbada and Benin formation respectively. Palynological analysis revealed that the retrieved palynomorphs were numerous and reasonably diversified, particularly in the lower portion of the sample interval. Palynological zonation was based on the palynofloral assemblage of important species and their stratigraphic distribution. Thirteen informal biozones were recognised on the basis of their first and last downhole occurences and compared with P 560, P580 and P624 to delineate an early to late Oligocene age for the studied interval.

An Uncertainty-driven Peak-integration (UP) Strategy for 3D Borehole Layout Planning

Equal-spaced borehole drilling is commonly adopted in practice for site investigation, which ignores spatial uncertainty and might result in insufficient site characterization. Model-driven precise drilling is regarded as a potential solution. In this study, an uncertainty-driven peak-integration (UP) strategy is proposed to improve decision-making in 3D borehole planning. The UP strategy consists of stratigraphic uncertainty modelling and peak-integration method. The random field-based uncertainty modelling approach has been improved by employing stratum-informed Scales of Fluctuation and a novel site division method to capture the site-specific uncertainty distribution with sufficient interpretation. The peak-integration method is proposed to consider the uncertainty around peaks, as improvement of existing peak uncertainty-based borehole planning strategy. To provide an objective evaluation for borehole layout planning, a new index “Contribution of Borehole” (CoB) is proposed for the first time, using the Earth Mover’s Distance, to quantify the net changes of stratigraphic distribution revealed by additional boreholes and offer validation for every decision-making. The feasibility and practicability of the proposed strategy are demonstrated by applying to an artificial geological model created based on real borehole data. The superiority of the proposed strategy is elucidated by comparing with equal-spaced strategy, via both CoB and conventional entropy reduction with detailed discussion.

Three-Dimensional Geological Modeling of the Shallow Subsurface and Its Application: A Case Study in Tongzhou District, Beijing, China

Three-dimensional (3D) geological models are currently needed and used independently for urban development. The main difficulty in constructing a 3D geological model of a shallow subsurface is to determine the stratigraphic distribution. Highly variable properties and geometries of geological units beneath lead to difficulty. It is key to find a practicable and efficient way to construct a model in practical work. This study takes Tongzhou District (Beijing) as a case; 476 boreholes (40 newly drilled and 436 existing engineering boreholes) were utilized combined with the cross-section method to construct an integrated 3D geological model. The framework and analyses contributed to the following applications: (1) High-quality information from new boreholes and existing engineering boreholes were used to define stratigraphy and build cross-sections. (2) The resulting geological model (up to 50 m beneath Tongzhou area) shows many details of the shallow subsurface. This includes 10 major layers which were grouped into three cyclothems representing cyclic sequences of clay, interbedded silt, sand, and gravel with variable quantities of lenses. (3) The new model was used as a tool to visualize the depth and geometry variations below ground and to characterize a large variety of properties (for example, the compression modulus analyzed in this paper) that each unit contains, and then to evaluate the underground geological conditions. (4) An analysis of a dynamic monitoring model based on the resulting 3D model indicated that the geological units (sand and silty clay) at depths between 30 m and 40 m, with an average vertical deformation of 0.97 mm, from July 2019 to September 2020, are suitable for underground construction, from the perspective of vertical stability in the study area. Monitoring models that take time into consideration based on a 3D framework will be further explored.

The Late Tremadocian (Ordovician) Graptolite Kiaerograptus from Central Hunan, China: Taxonomy and Biostratigraphy

AbstractWell‐preserved graptolites of the genus Kiaerograptus are first reported from the upper Tremadocian Yinchupu Formation in the Nanba section, Yiyang, Hunan Province, South China, including four species, i.e., Kiaerograptus lauzonensis (Erdtmann, 1966), Kiaerograptus stoermeri (Erdtmann, 1965), Kiaerograptus cf. supremus? Lindholm, 1991, and Kiaerograptus sp., which are robust in form. Based on these new specimens, the Kiaerograptus biozone is established for the first time in South China, increasing the late Tremadoc graptolite biozones in South China from four to five, in ascending order as follows: the Adelograptus tenellus biozone, the Aorograptus victoriae biozone, the Kiaerograptus biozone, the Sagenograptus murrayi biozone, and the Hunnegraptus copiosus biozone. A review of the occurrence records for robust Kiaerograptus species worldwide reveals that the distribution is restricted to the Aorograptus victoriae biozone and Kiaerograptus biozone in the late Tremadocian. This limited stratigraphical distribution makes Kiaerograptus a valuable taxon for precise biostratigraphical correlation at both the regional and global scales.

The Lower Silurian (Hot Shale) Source Rocks of Western Iraq: Depositional Model and Stratigraphic Distribution

The Hoseiba Member, an Early Silurian basal mature hot shale of the Akkas Formation (Silurian) consists of about 80% of the Paleozoic hydrocarbon potential system, it is organic-rich with total organic carbon up to 16% as the main source for the Paleozoic gas resources in Iraq. The hot shale is the main source of rocks that are penetrated in deep wells in the western Iraqi desert such as Akkas-1, Qaim-1, and Khleisia -1, which are distributed due to paleo uplift in the restricted regional basin in the west, south, and northwest Iraqi desert and wedged to north thrust zone in Ora area of extreme northern Iraq, Ora subbasin to Aljezira NW and in the west where the approved source rocks of ‘Hot shale” Akkas -Widyian subbasin (Rephrase). The Hoseiba Member, basal hot shale in the Akkas Formation in Iraq and their correlative units are extended within neighboring countries Jordan, Syria, Saudi Arabia, Iran, Oman, and south Turkey. Qualitative and quantity of Hot Shales source rocks Silurian are Excellent in Akkas well -1 (0.95-16.62%) TOC in Akk-1 Akkas sub-basin west Iraq and an average thickness (30 m.) with 1-9.94% TOC in Kh-1 Al-Jezira sub-basin NW Iraq. The hot shale distribution was controlled by the Caledonian uplift that created paleo-high in northern Iraq and moderately deep to the northwest, and deep depression deposition in west and south desert Iraq. The hot shale expulsion and migration of hydrocarbon are controlled by the underlying main reservoir of the Khabour Formation K1 sandstone ember by block faulting

Systematic composition of the middle Jurassic flora and its stratigraphic distribution (Ustyurt region, Uzbekistan)

The article presents the systematic composition and stratigraphic distribution of the Middle Jurassic flora of Ustyurt (Uzbekistan). In the Middle Jurassic sediments, three plant complexes of different ages are distinguished, corre-sponding to aalen, bayos and bath, differing from each other by the unequal species composition of Coniopteris ferns and Nilssonia cicadas. The change of complexes during the Middle Jurassic occurred gradually. The vegetation reached its greatest dawn in the Bajocian and Bata centuries.

Extending the stratigraphic range of Nummulites bormidiensis Tellini in the Neo-Tethys (Zagros basin, SE Iran) through biometry and calcareous nannofossil biostratigraphy

A biometrical study on four reticulate Nummulites populations from the lower part ofAsmari Formation of the Vazag section (Zagros zone) is carried out. The biostratigraphy obtained by studing the succession points to the Early Oligocene (Rupelian), indicating shallow benthic zones SBZ21 and SBZ22A by the occurrence of Operculina cf. complanata, Eulepidina formosoides, Nephrolepidina sp. The age assignment is calibrated with calcareous nannofossils biostratigraphy indicating the NP22-NP23 (=CNO2-CNO3) Zones.We have observed a stratigraphic trend related to Nummulites bormidiensis Tellini 1888 that results to be characterized by two populations composed of transitional Nummulites fichteli/bormidiensis with values of mean inner proloculus that exceeds by very little the boundary commonly established at 300 um. Such a populations, indicated as Nummulites ex interc. bormidiensis et fichteli, span through the lower Rupelianwhere classically just N. fichteli is reported so far. The stratigraphic distribution of Nummulites bormidiensisis and related transitional forms is here stretched to the Rupelian (SBZ21 and SBZ22A), encompassing older ages than previously recorded throughout the Neo-Tethys Ocean.

The First Finding of the Genus <i>Megalovis</i> (Artiodactyla, Bovidae) in the Lower Pleistocene of the Taurida Cave in the Crimea

The presence of Megalovis latifrons Schaub, 1923 is discovered in the composition of the Early Pleistocene fauna (1.8–1.5 Ma) of Taurida Cave in the Crimea. A fragment of the frontal bone with a part of the horn core, the incomplete upper and lower jaws, the metacarpus and metatarsus of M. latifrons are described. This large fossil representative of Ovibovini has been known only by the very rare finds from the Lower Pleistocene of the south of Western and Central Europe. Megalovis inhabited Eurasia in the late Early Pleistocene and a very beginning of the Middle Pleistocene. In Russia this species is found for the first time. The data obtained are important for clarifying the morphological features and geographic and stratigraphic distribution of this species.

New agglutinated Foraminifera from Early Eocene deposits of Mahallat region, Central Iran: implication on biostratigraphy and paleoecology

This paper describes the foraminiferal associations along with the presentation of three new agglutinated conical foraminiferal species to the construction of the biozonation framework in the Mahallat region of central Iran. The stratigraphic distribution of benthic foraminifers is used to characterize three assemblage zones that are in ascending order: rotaliids-valvulinids Assemblage Zone, alveolinids-coskinolinids Assemblage Zone, and nummulitids-discocyclinids Assemblage Zone. These associations are characterized by marker fossils and localized from the inner ramp to the proximal outer ramp depositional environments. Their biostratigraphic range is assigned to the middle Cuisian to early Lutetian. In addition, three new agglutinated conical foraminiferal species: Daviesiconus mahallatensis sp. nov., Barattolites arghadehensis sp. nov., and Coleiconus minimus sp. nov. are described and figured for the first time from the lower Eocene shallow-water limestone in the studied area. These new species have common characteristics such as eccentric conical test with a low number of comparably coiled chambers in the early stage and uniserial chambers in the adult stage, but they differ in size, the form of test, and radial subepidermal partitions (beams, intercalary beams, and rafters). They are associated with the index Alveolina fauna and their biostratigraphic range is assigned to middle–late Cuisian (Ypresian, Early Eocene). Keywords: biostratigraphy, Early Eocene, new taxa, Mahallat, Iran.

Geological prerequisites for the search for rocks with increased reservoir properties in domanic type sediments on the territory of the Republic of Tatarstan

Domanic type deposits generally is abundant in Tatarstan Republic and other territories. They are feature with oil-source rocks (black shales), which partly generated hydrocarbons. However, due to their high hydrocarbon contain, domanic type deposits construing as unconventional reservoir rocks, that may be commercial significant. Based on Russian and foreign experience in the development of such deposits, the prospects for their exploitation are associated with the searching for formations with increased reservoir properties and light oil. In this work we are analyzed the stratigraphic distribution of domanic type deposits in the Kama-Kinel system of depressions and beyond them. It is shown that such deposits in the Kama-Kinel system of depressions have a thickness about 300 m and cover the stratigraphic range from semiluk horizon of the Frasnian stage to Tournaisian stage. But out of depressions these rocks occurred only in semiluk horizon. The reason of it is high dissection of the bottom of the Domanic sedimentation basin in the Late Frasnian-Tournaisian ages due to the evolution of the Kama-Kinel system of depressions in the east of the Russian Plate. The results of our own research show that carbonate and carbonate-siliceous rocks enriched in organic matter are the most common lithotypes in the Domanic type deposits. Also, we constantly found carbonate breccias and less secondary dolomites in the studied geological columns. In the last two types of rocks, we found higher values of porosity, openness, and a lighter composition of hydrocarbons. Based on the results of the author’s research and the literature observation, it follows that the development of carbonate breccias and secondary dolomites will be in the sides of the Kama-Kinel system of depressions. We consider that they are as the most promising objects for the search for industrial profit in the Domanic type deposits.