Добірка наукової літератури з теми "Fluviolacustrine"

The Quaternary sediments deposited in the Indo-Gangetic, Brahmaputra and adjoining smaller inland basins and Duns formed after the Middle Pleistocene Himalayan Orogenic Movement (HOM-4), are fluvial-fluviolacustrine and or lacustrine in nature. A synthesis of the available data in the Brahmaputra Basin and its comparison with that of the Indo-Gangetic Basin and Duns suggests two cycles of sedimentation, separated by a period of erosion and non-deposition and continuous in inland basins, such as Bhimtal-Naukuchia Tal, Hawalbagh in Kumaun region in Uttar Pradesh and Loktak Lake in Manipur. The sediments of the first cycle which terminated in late Upper Pleistocene are, in general, oxidised and referred to as the Older Alluvium, while that of the second assigned to Holocene, is unoxidised grey in color and constitutes the Newer Alluvium.

The coarsening-upward clastic sequence at Tebch, Inner Mongolia, China, containing the dinosaur Psittacosaurus mongoliensis, comprises the remains of a fluviolacustrine system deposited in an extensional tectonic setting.The presence of Asteropollis sp. cf. Asteropollis trichotomosulcatus (Singh) Singh, 1983 in conjunction with the absence of tricolpate pollen indicates a Barremian or possibly early Aptian age. The overlying Tebch basalt, dated by the 40Ar/39Ar laser step-heating method, yields a mid-Aptian age of 110 ± 0.52 Ma.This chronology supports the argument that the Juifotang Formation of the Jehe Group in western Liaoning is Early Cretaceous, with the Jurassic–Cretaceous boundary very low within, or below, the base of the Jehe Group. Our data also suggest that the Berriasian–Hauterivian (Neocomian) age suggested for the one known Russian locality that has yielded P. mongoliensis (Shestakovskaya Svita at Gorno-Altayaskaya, Avtonomnaya Oblast) may be excessively old.

The Middle to Upper Jurassic Walloon Coal Measures of eastern Australia host petroleum resources mostly in the form of coal bed methane. The coals accumulated at a high-latitude (>75°S) during a greenhouse epoch and occur in regionally extensive fluviolacustrine successions. Previous studies have described the spatial relationship of facies using a variety of (and sometimes ambiguously defined) stratigraphic frameworks. This was complicated by the absence of marker beds or published radiometric dates. The coal beds are thin and laterally discontinuous and their origin, which has been poorly understood, has implications for consistent stratigraphic correlations. Improved correlation techniques and an understanding of the controls on coal bed geometry should allow better prediction of: 1) the location and architecture of prospective reservoirs, and 2) gas drainage patterns around individual wells. This study aims to address these questions by building upon pre-existing notions on the evolution of eastern Australia during the Middle to Late Jurassic using an integrated approach with new sedimentologic and palynologic data, combined with precise U-Pb dating of volcanic sediments and basin subsidence studies. Zircon from twenty-eight tuffs in 12 wells across the Surat and Clarence- Moreton Basins were dated using the high-precision chemical abrasion thermal ionization mass spectrometry (CA-TIMS) technique to within an error margin of ±40 ka. In addition, two volcanogenic sandstones from one well that intersected the Birkhead Formation in the Eromanga Basin were dated using the same methodology to within ±50 ka. On a 1237 km transect, five regional datums <420 ka in duration were defined for a chronostratigraphic framework using UPb dates. The dated zircons indicate that the Walloon Coal Measures that had previously been considered as Middle Jurassic (Aalenian-Callovian) are largely of Upper Jurassic age (Oxfordian-Tithonian). The new dates also reveal the diachroneity of coal-bearing facies across eastern Australia and inconsistencies in the correlation of lithostratigraphic units. Jurassic spore-pollen units of Price (1997) were also calibrated to the geologic time-scale using the same U-Pb dates to enable chronostratigraphic horizons to be correlated between basins where volcanic sediments are absent. The first occurrences of key taxa maybe younger than originally estimated, possibly by as much as ~4.2 Ma. These interpretations require further palynological analyses to confirm the age of first occurrences in wells to due to the rarity of key spore-pollen taxa. A high-resolution investigation on the roles of accommodation creation and climate on coal bed geometry suggest that, although subsidence was important in determining the abundance of coal, the climatic patterns contributed towards their thin, discontinuous character. Although the Walloon Coal Measures were deposited at high latitudes (>75°S), the coals originated from peats that accumulated in mires that experienced a warm temperate climate. Rapid and frequent climate change in the polar region may have limited the window of opportunity for thick, widespread coals to develop. New sedimentological and palynological data from the Surat Basin substantially revises interpretations of the environments of deposition. Sedimentary facies and spore-pollen assemblages confirm deposition in a predominately fluviolacustrine setting. However, the identification of tidally-influenced facies, acritarchs and dinoflagellate cysts (a first for Jurassic-aged strata in the basin) indicate periods of brackish water conditions. Marine incursions may have come from the north and the east during time of high eustatic sea-level during the Jurassic. Palaeogeographic reconstructions over 13 Ma reveal extensive fluviolacustrine systems draining from an eroding orogenic belt into proximal estuarine complexes. Allocyclic controls revealed by incised valleys and the deposition of transgressive estuarine facies strongly suggests the accumulation of coal (peat) was unlikely to be coeval with clastic sedimentation because of frequent changes in base level. This study illustrates that a multidisciplinary approach (notably the acquisition of precise U-Pb dates from volcanic sediments and the recognition of subtle indicators of marine influences) can be used to elucidate complex continental successions over large geographic areas. These type of studies will help in the search for subtle oil and gas reservoirs and better calculation of resource and reserve numbers. They may also be of use in better understanding sedimentary mineral resources and groundwater aquifer systems.
Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2018