Palynostratigraphy and Paleoenvironment of Bukit Tigapuluh Area in the Jambi Subbasin from Oligocene to Miocene

The Oligocene-Miocene trajectory exposed at the Lubuk Lawas and Lubuk Bernai Stratigraphic Tracks in Bukit Tigapuluh, Jambi Subbasin, Indonesia, archives remnants of equatorial vegetation during extreme global warming and near the beginning of the East Java-Eurasia microcontinent collision, and was carried out using mapping surface analysis, petrological analysis, sedimentology, stratigraphy and palinology. The rock units were deposited during one sedimentation phase, that is the continental deposition phase, which consists of conglomerates, gravel sandstones and sandstones that fill the basin followed by transgressive deposits associated with the deepening of the basin environment. Three palynozones Meyeripollis naharkotensis (Oligocene), Florschuetzia trilobata (Early Miocene) and Florschuetzia meridionalis (Middle Miocene) were identified stratigraphically on the basis of these pollen. The rock layers are deposits from the Early Oligocene to Middle Miocene from bottom to top. The depositional environment changed over time, passing from a narrow, steep-sided tectonic basin, during the Early to Late Oligocene, followed by a lacustrine basin to a palustine with oceanic influence, as a result of distensive E-W movement between the Jambi Fault and the Sunda Fault in the Late Oligocene to the Middle Miocene. Occurrence of taxonomically highly diverse angiosperm pollen in all three palynozones attests to an extremely rich inland and nearshore tropical flora under a strong seasonal rainfall regime. The climate remained warm and became increasingly humid towards the end of the Miocene. The nature of the environment is related to the dynamics of the opening of the basin opening.

Palynostratigraphy of Upper Cretaceous and boundary Paleogene deposits in West Siberian Plain

The article presents the results of many years of studies of the Upper Cretaceous and Paleogene sediments in the territory of West Siberian Plain. The heterogeneous structure of these sediments in different regions of the plain is shown. The lithological and palynological characteristics of a number of studied wells drilled in different years in Omsk and Kulunda Depressions, in Baraba Lowland and Bakchar Basin are given. The obtained palynological data allowed to substantiate the age of the deposits and to make suggestions concerning their depositional environment, and to clarify the subdivision of geological section into formations. The sections of the Upper Cretaceous and Paleogene deposits in different lithofacial regions of the Western Siberia differ from each other in completeness, genesis, and paleontological characteristics. The Upper Cretaceous sediments in Western Siberia are represented by formations of both marine(Pokur, Kuznetzovo, Ipatovo, Slavgorod and Gan'kino Formations) and continental genesis(Lenkovo and Sym formations). The Paleogene sediments, with the exception of Oligocene, mostly have a marine genesis-these are Talitsa-, Marsyat-, Lulinvor-, Tavda-and Yurki formations, but there are also continental sediments(Ostrovnoje Formation). A large stratigraphic break in the Upper Cretaceous and Paleogene boundary deposits, covering a significant part of the Maastrichtian, Paleocene, Ypresian, and Lutetian stages of the Eocene, was established in the sourheast of the West Siberian Plain(Bakchar Basin, Baraba Lowland and Kulunda Depression). The most complete sections are located in the Omsk Depression, where the Upper Cretaceous Gan'kino Formation is covered by Talitsa and Lulinvor Formations of Paleogene age. The most important events occurring at the boundary of the Cretaceous and Paleogene in Western Siberia can be traced currently in a few sections located in the Trans-Ural area, since there was no sedimentation in the rest of the territory at that time.

Preliminary Palynostratigraphic Data on the Middle Albian-Lower Cenomanian of the Tarfaya Basin, Southwest Morocco

The Tarfaya-Laayoune-Boujdour basin is of great interest to oil exploration;on this aspect, there has been exploration by the Moroccan National Office of Hydrocarbons and Mining, which has shown indices of oil and/or gas recorded in most wells drilled in the Moroccan Atlantic margin. FD-1 well, object of this study, is one of these wells located in the offshore Tarfaya-Laayoune-Boujdour basin. A palynological examination of the processed samples revealed the existence of organic palynomorphs, well conserved and rich in dinoflagellate cysts. The latter are composed of worldwide marker taxa of high stratigraphic resolutions. Thus, the middle upper Albian (3408 - 3408.5 m) is determined by the presence of Cribroperidinium tensiftense, Tehamadinium coummia, Spiniferella cornuta, Chichaouadinium vestitum, Dinopterygium alatum and Litosphaeridium arundum. The upper Albian (3406.5 - 3408 m) is characterized by the FOs of marker taxa: Cyclonephelium chabaca, Cribroperidinium auctificum and Chichaouadinium vestitum. Lastly, the upper Albian-lower Cenomanian transition is defined between 3404 m and 3406.50 m, as suggested by the FOs of Chichaouadinium boydii, Dinopterygium tuberculatum, Sepispinula ancorifera, Litosphaeridium conispinum, Prolixosphaeridium conulum and Xenascus ceratioides.

Stratigraphy of southeastern flanks of Raichikhinsk brown coal field (Zeya-Bureya sedimentary basin)

The results of the palynologic and paleobotanic analyses have allowed determining the Paleocene (including Danian) and Eocene deposits in the series of coal-bearing sediments of southeastern flanks of the Raichikhinsk brown coal field. Their age was corroborated by the palynologic and paleobotanic data. The detailed biostartigraphic data were obtained in the area"Pioneer"for the first time. The coal-bearing strata were correlated with those from the sections of the Arkhara-Boguchan brown coal field and the stratotype of the Tsagajan Formation of the Bureya Belogor’ye.