Sediments referred to the Trias outcrop at intervals over a distance of 105 miles (157 km) along the northwestern seaboard of Scotland. A detailed description is given of the field occurrences and successions, and the stratigraphy revised. Important rod sediments in Westor Ross, previously mapped as Trias, are shown to be Torridonian and their significance is discussed. The Trias is very variable in thickness ranging from negligible to over 300 m (1000 ft). Lithological units show rapid lateral variation, and it is impossible to draw detailed comparisons between successions in different areas. The sediments mainly consist of conglomerates and sandstones which are compared of materials derived from formations, known in the area at the present time. The study of textures and sedimentary structures shows that the sediments are fluviatile. Piedmont deposits and sediments which accumulated in an environment intermediate between piedmont and valley-flat are common true valley-flat deposits also occur, represented by thin fine-grained said-stones and siltstones, Concretionary limestones occur throughout the area, except in one locality, find are interpreted as pedocals. The sediments probably, accumulated in a series of partially isolated basins. Sedimentation was influenced early on by a chain of upland area consisting of n sequence, of Torridonian and Cambro-Ordovician sediments which extended from Loch Broom to Iona, west of the present outcrop of the Hoine Thrust. Source areas to the east became dominant later. The climate was probably hot and semi-arid, with seasonal rainfall.

A Dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the Degree of Master of Science Johannesburg, 2015 / The Chiniquodontidae is a family of Triassic carnivorous cynodonts well represented in the Middle-Upper Triassic of Argentina and Brazil. Chiniquodontids were more recently discovered in Madagascar and central Namibia, representing the only record of the family outside South America. The Namibian specimen was discovered in the Upper Omingonde Formation and is represented by the skull and a partial skeleton. The new chiniquodontid was identified as Chiniquodon and is diagnosed by the postcranial characteristics identified; a strong bend in the proximal portion of thoracic ribs, reduced curvature of the clavicle, although this may be due to deformation, robustness of the neck of the ilium, differences in the angulation between the edge of the posterior lamina of the ilium and the margin of the neck, and a large ischium, which is more than twice the size of the pubic plate. The postcranial material of the chiniquodontid from Namibia is described and compared with that of South American chiniquodontids. Chiniquodontids lack costal plates on ribs, show a tall and slender scapular blade, a large acromion process positioned well above the scapular neck and absence of disc-like phalanges in the autopodium. The Namibian Chiniquodon provides the first evidence of elements from the pes in chiniquodontids, and one of the few for non-mammaliaform cynodonts. Sedimentological studies confirm that the Upper Omingonde Formation of Namibia represents fluvial deposits of braided and meandering rivers formed in a predominately arid climatic regime during the Middle Triassic.

"February 2001" / Bibliography: p. 335-349. / xxix, 394 p. : ill. (some col.), maps (some col.), plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, National Centre for Petroleum Geology and Geophysics, 2004

The rocks of the Upper Triassic Nicola Group represent the altered broken remnants of a volcanic island archipelago. About 23,000 feet of Upper Triassic sediments and volcanic rock are present in the thesis area. The group is the product of two cycles of deposition distinguishable on the basis of relative abundance of phenocrysts in the volcanic members. Rocks of the lower cycle (P), characterized by abundant feldspar phenocrysts, are separated into a lower, 6,000 foot thick assemblage of flows, breccias, and tuffs composed mainly of basaltic andesite; and an upper, heterogeneous, 8,000 foot thick assemblage composed of andesitic and rarer basaltic or dacitic agglomerates, breccias, tuffs, flows, and associated sediments as well as coral reef bodies. Rocks of the upper cycle (A), characterized by abundant augite phenocrysts, are separated into a lower assemblage about 7,500 feet thick composed of flows, breccias, tuff, and greywacke with rare limestone; and an upper assemblage about 1,600 feet thick composed of tuff, argillites, and cherts. During the Lower Jurassic, the group was gently folded, variably fractured, and intruded by a sequence of plutons culminating in the near-surface emplacement of huge batholiths. Metamorphism and metasomatism associated with batholiths altered the rocks so that they are now composed of low-grade metamorphic mineral assemblages. By mid-Mesozoic time, the plutons were exposed and a conglomerate laid down. Faulting along previous zones of weakness affected area during late Mesozoic time. Eocene deposits formed in an environment of hills and swamps. By late Miocene, after some jostling of faults blocks, the main topographic features of the Interior Plateau were fixed. Subsequent outpouring of Plateau and Valley basalts as well as glacial erosion and deposits have only mildly affected the main topographic features. The Nicola Group provides a chapter on the evolution of the Cordillera. The relationships provide certain limits to events that occurred outside the thesis area. Equally, relationships within the thesis area cannot all be answered without reference to larger areas. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

No description available.

The Dolomite Alps of northern Italy are a classic field locality in the development carbonate stratigraphic theory. Included in the many discoveries rooted in the geology of the Dolomites is the concept of a hierarchy of stratigraphic forcing in the Alpine Triassic. The hierarchy states that carbonate sedimentation is dominantly a record of eustasy, resulting in organized stacking patterns, and that these stacking patterns reflect the interplay between low frequency (1-10 my) eustatic cycles and their component bundled high-frequency (100 & 20 kyr) eustatic cycles. The overall aim of this study is to further investigate the validity of the hierarchical model after recent dating of Anisian and Ladinian successions called the Milankovitchian periodicity and/or allocyclicity of the cyclic series into question. The study was completed using four sub-studies, 3 based on data collected in the field and a fourth based in cycle theory and computer modeling. First, it can be shown that allocyclic forcing exists in the Anisian/Ladinian platforms of the Dolomites by comparing the stratigraphic sections measured from 2 time-equivalent, independent carbonate platforms, the Latemar and Mendola Pass. Second, computer modeling of Anisian/Ladinian carbonate platform stratigraphy using Milankovitchain solar insolation as a proxy for high-frequency eustasy shows that both pure Milankovitch forcing and mixed Milankovitch/sub-Milankovitch forcing will produce synthetic carbonate platforms with stratigraphic successions comparable to those of the Anisian/Ladinian platforms of the Dolomites. Third, it can be shown that the while the Norian Dolomia Principale (a regional carbonate shelf) was affected by differential subsidence, megacycles systematically increase in their number of component cycles from 2-3:1 in the eastern Dolomites (updip) to 5-6:1 in the western Dolomites (seaward). In conclusion, the concept that carbonate platform stratigraphy is a record of an interplay between eustasy, subsidence, and sedimentation is upheld, while the validity of Milankovitchian forcing acting on all Alpine carbonate cycles is questioned. Instead, cyclic carbonates with sub-Milankovitch periodicities were common in the early and mid-Triassic, while cycles with Milankovitchian periodicities were common in the late Triassic. / text

No description available.

No description available.

Upper Triassic and Jurassic rocks in the central Graham Island area comprise shale, siltstone, sandstone, and conglomerate of the Kunga, Maude, and Yakoun Groups. Volcanic rocks are common in the Middle Jurassic Yakoun Group. The oldest unit exposed within the study area is the Lower Jurassic Sandilands Formation of the Kunga Group, a more than 250 metre thick sequence of interbedded organic-rich shale, tuff, siltstone, and sandstone. The Lower Jurassic Maude Group conformably overlies the Kunga Group and is divisible into four formations. The Ghost Creek Formation is an organic-rich black fissile shale, and is overlain by calcareous sandstone of the Fannin Formation. The Whiteaves Formation consists of fissile calcareous grey shale that grades upwards into fossil-rich medium- to coarse-grained, sandstone of the Phantom Creek Formation. The base of the Middle Jurassic Yakoun Group is marked by an angular unconformity. The unit is more than 1500 metres thick and is divided into four lithofacies. The lowermost shale and tuff lithofacies is a sequence of interbedded shale, tuff, siltstone, and sandstone, with shale dominating. The sandstone lithofacies overlies and partly interfingers with the shale and tuff lithofacies and comprises medium- to thickly-bedded lithic arenite interlayered with thinly-bedded shale. The conglomerate lithofacies exists within the sandstone lithofacies and consists mostly of thickly-bedded pebble and cobble conglomerate. The volcanic lithofacies interfingers with, and overlies the sedimentary rocks of the Yakoun Group, and includes lava flows, pyroclastic rock deposits, and lahars. The Kunga and Maude Groups record several relative changes in sea level. They formed in a progressively deepening basin. In Pliensbachian time, the basin shallowed and deposition, represented by the upper Fannin Formation of the Maude Group, was near-shore. Toarcian time is marked by an abrupt transgression. The upper part of the Whiteaves Formation and the Phantom Creek Formation of the Maude Group indicate a subsequent regression. The sedimentary rocks of the Yakoun Group were deposited in local shallow marine basins. Volcanic rocks are most abundant in the eastern parts of the map area, and indicate that an igneous source is located in that direction. All rock units in the map area are deformed by major northwest-trending faults and folds, reflecting at least four northeast-southwest oriented deformational events. The angular unconformity at the base of the Yakoun Group restricts one compressional phase to mid-Jurassic time. Abundant southwest-verging folds suggest development of northeast-dipping thrust faults during this compressional event. Northeast-trending normal faults cut through the thrust faults, postdating them and indicating a period of extension. Rocks of the Sandilands Formation are observed thrust on top of the Yakoun Group, thus indicating a second compressional event. Several small-scale strike-slip faults cut through all described rock units and overlying Tertiary sections, suggesting a late Tertiary deformational event. The Middle Jurassic compressional event may be a result of collision of Wrangellia with North America, or could have been caused by changes in relative plate motion between the North American and Pacific plates during the break-up of Pangaea. Lithologic similarities between the Jurassic and older units of Wrangellia on the Queen Charlotte Islands and coeval rocks of the Alexander terrane in southeastern Alaska suggest that there are no clear differences between the two, and that they were contiguous since Upper Paleozoic time. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

A review of all available surface and subsurface data on Triassic and Lower Jurassic rocks in northeastern Arizona has revealed the following information. The Moenkopi Formation, the Chinle Formation, and the Glen Canyon Group of Triassic and Early Jurassic age are present throughout most of the study area. These units form a sequence of continental and transitional marine origin that shows notable vertical and lateral facies changes. The Moenkopi Formation thickening west and northwestward with a maximum thickness of 134 meters. The unit comprises sandstone and shale, and shows more shaley facies westward. The Chinle Formation shows minimum thickness to the north and thickens toward east and south with a maximum thickness toward west. This unit dominantly consists of sandy shale, but contains more sandstone westward and north westward. The unit contains some limestone in north and northern region. The Chinle Formation is overlain by the Glen Canyon Group, which in ascending order comprises the Wingate Sandstone, the Moenave Formation, the Kayenta Formation, and the Navajo Sandstone. The Wingate Sandstone shows its maximum thickness in the central and southcentral region of the study area and thins west and eastward. This unit mainly comprises sandstone, particularly in its upper part. The Moenave Formation displays its zero thickness, in the eastern region and shows its maximum thickness, 198 meters, in the west-central part. The unit mainly consist of sandstone. The Kayenta Formation attains its greatest thickness, 204 meters, in the southwestern part of the region and thins east and northward. This formation contains high percentages of sandstone. Within the area of this study, the Navajo Sandstone is the thickest formation in the Glen Canyon Group. This unit almost entirely consist of sandstone pinches out toward the south and east, and displays its maximum thickness, 300 meters, northward.