Triassic

For example, the many deepwater fields located in the Gulf of Mexico are of Tertiary age and are comprised of complex sand bodies which were deposited in a deepwater turbidite sequence. The BP Prudhoe Bay sandstone reservoir in Alaska is of Triassic/ Cretaceous age and was deposited by a large shallow water fluvial-alluvial fan delta system. The Saudi Arabian Ghawar limestone reservoir is of Jurassic age and was deposited in a warm, shallow marine sea. Although these reservoirs were deposited in very different depositional environments they all contain producible accumulations of hydrocarbons, though the fraction of recoverable oil varies. In fact, these three fields are some of the largest in the world, containing over 12 billion barrels of oil each ... 

Mesozoic Triassic 245 Myr Continents begin to drift apart. Early dinosaurs first mammals gymnosperms become dominant diversification of marine invertebrates. Moss extinction at end of period (ca. 75% of all species disappear)... 

Isozaki and Itaya (1990) suggested from biostratigraphic data that the age of Minawa Formation is Triassic to Jurassic, indicating Besshi-subtype (mostly Group A) formed at these ages. 

Age of formation of Group B of Besshi-subtype are variable, early Cretaceous (Shimokawa), late Early Cretaceous to early Late Cretaceous (Makimine) and Triassic to Jurassic (Minenosawa, Kune). 

Sandstone The tertiary, Jurassic and Triassic sandstones of the western Cordillera of the United States account for most of the uranium production in that country. Cretaceous and Permian sandstones are important host rocks in Argentina. Other important deposits are found in carboniferous deltaic sandstones in Niger in Permian Lacustrine siltstones in France and in Permian sandstones of the Alpine region. The deposits in Precambrian marginal marine sandstones in Gabon have also been classified as sandstone deposits. 

The Ebro headwaters flow on calcareous substratum, specifically sandstone and calcium marls, from the Triassic, Cretacic, and Jurassic. During the Quaternary, at the plain of La Virga (Reinosa), a shallow lake accumulated the deposits of siliceous sandrocks. This old highland lake is now the Embalse del Ebro reservoir. From that point downstream to Conchas de Haro the main channel flows on calcareous rocks from the Cretacic, highly resistant to the erosion. 

Bath, A. H., Edmunds, W. M., Andrews, J. N., Palaeoclimatic trends deduced from the hydrochemistry of a Triassic sandstone aquifer, United Kingdom, In Isotope Hydrology 1978, Internat. Atomic Energy Agency, Vienna, Vol. 2, p. 545-568, 1979. 

If the asteroid-impact theory is correct, the extinctions should be repetitive and the Ir anomaly should be observed in other geological stratigraphic levels corresponding to known extinctions. About five other massive extinctions (besides the one at the end of the Cretaceous Period) have been noted [25]. These come at the end of the Cambrian ( 500 MY ago), the Ordovician (M35 MY age), the Devonian ( 345 MY ago), the Permian ( 230 MY ago) and the Triassic ( 195 MY ago) Periods. 

Central and Eastern England is almost entirely underlain by sedimentary rocks that young from west to east. Four major geological sub-divisions are presented in Figure 1. Permian and Triassic mudstone and sandstone dominate the East Midlands and parts of Yorkshire Jurassic clays crop out within the centre of the study area and Cretaceous chalk underlies most of Central East Anglia. 

The basement is made up of crystalline schists of the meso-metamorphic Somes Series. Sedimentation started during Permian with detritic deposits interbedded with rhyolites. The overlying Triassic deposits are unconformable and include detritic formations (Lower Triassic) and massive layers of carbonate rocks (Middle Triassic). The absence of the Upper Triassic is due to the uplift of the region during the Kimmeric tectonic phase. 

New Brunswick s bedrock geology is well mapped and largely well understood. Because of NB s mineral wealth, a great deal of mineral exploration work has been carried out since the 1950s. The bedrock in NB is also diverse in age. The oldest Precambrian rocks can be found in the Saint John area, whereas some of the younger ones, in the form or Triassic basalts, occupy more than half of the Island of Grand Manan. Most of NB s rocks are of Middle Paleozoic age. The triangle between Moncton, Fredericton, and Bathurst is occupied by a thick sequence of Carboniferous rocks that host... 

Moldowan, M.J., J. Dahl, S.R. Jacobson, B.J. Huizinga, F.J. Fago, R. Shetty, D.S. Watt, and K.E. Peters. 1996. Chemostratigraphic reconstruction of biofacies Molecular evidence linking cyst-forming dinoflagellates with pre-Triassic ancestors. Geology 24 159-162. 

Baker JC, Kassan J, Hamilton PJ (1995) Early diagenetic siderite as an indicator of depositional environment in the Triassic Rewan Group, southern Bowen Basin, eastern Australia. Sedimentology 43 77-88 Barghoom ES (1981) Aspects of Precambrian paleobiology the early Precambrian. Paleobot Paleoecol Evolution 1 1-16... 

This deposit is located in the north-east of Russia and belongs to a gold-arsenic type of low-sulphide formation (Abramson et al, 1980). It lies within a carbonaceous terrigenous rock of Triassic age and is associated with a dome-shaped uplift in a node of intersecting faults of various directions. The ore bodies consist of zones of silicification and kaolinization with veinlet-disseminated sulphide mineralisation. Gold is present in the form of finely-dispersed dissemination in arsenopyrite and pyrite. As an example. Figure 1 illustrates the distribution of Au and Mn in connection with commercial ore... 

Munizaga, F., Maksaev, V., Fanning, C.M., Giglio, S., Yaxley, G., Tassinari, C.C.G. 2008. Late Paleozoic-Early Triassic magmatism on the western margin of Gondwana Coiiahuasi area. Northern Chile. Gondwana Research, 13, 407-427. 

The Pinguino veins, occupy more than 30 fault controlled structures. They have a NW and ENE strike and are hosted in Triassic continental sedimentary rocks and lower Jurassic epiclastic and volcaniclastic rocks, and are spatially related to lower Jurassic subvolcanic dioritic intrusions, basaltic sills and andesitic porphyries (Jovic etal. 2005). 

The Late Cretaceous Pebble deposit is located within the southern part of the Late Jurassic to Early Cretaceous Kahiltna terrane, which is bounded to the southeast by the Peninsular terrane (Late Triassic to Late Jurassic) and to the northwest by flysch of the Kuskokwim Group (middle to Late Cretaceous) (Fig. 1). The southern Kahiltna terrane consists predominately of Jurassic to Cretaceous turbidite deposits and can be divided into two major lithologic units the Koksetna River sequence and the Chilikadrotna Greenstone (Wallace etal. 1989). The... 

Carboniferous to Permian redbeds of the Pictou Group (Bell 1929). In the area surrounding the Bay of Fundy, there was also a Jurassic-Triassic sedimentary basin (Fundy Group) developed in which sandstones, shales, basalts and minor limestone were deposited. During the Cretaceous fluvial quartz sands and kaolin of the Chaswood Formation were deposited throughout the Maritimes, but only a few outliers have been preserved (Stea Pullan 2001). 

---