Cretaceous limestone

With an uncertainty of 0.06, the use of the gaseous phase C02 and the mineral phases calcite, dolomite, and halite (from the Cretaceous limestone), quartz, K-mica, albite, anorthite, and Ca-montmorillonite (from the Quaternary aquifer) as well as Fe(OH)27Clo3 pyrite, pyrolusite (from the crystalline basement) and assuming additionally that halite, K-mica, albite, and anorthite can only be dissolved while Ca-montmorillonite can only precipitate, the following model was found (Table 46). 

Besides the clay mineral Ca-montmorillonite, calcite and Fe(OH)2 7Clo.3 also form. All other mineral phases remain dissolved. The hypothesis that there is a hydrochemical influence from the Cretaceous limestone and from the Quaternary sediments because the spring is located above an apparently hydraulically active fault, seems to be correct. The influence of the crystalline basement results from the general groundwater flow from east to west. The model uncertainty is acceptable with 6%. 

The mineral phases calcite, dolomite, halite, and gypsum for the Cretaceous limestone, as well as albite, quartz, anorthite, K-mica for the sandstone, and the gaseous phase C02 have to be defined. Furthermore it is assumed that dolomite, gypsum, and halite only dissolve, while calcite precipitates and C02 degasses. Under those conditions and with an uncertainty of 4%, two models are obtained (Table 47). 

Longman, M.W. and Mench, P.A., 1978. Diagenesis of Cretaceous limestones in the Edwards aquifer system of south-central Texas A scanning electron microscope study. Sediment. Geol., 21 241—276. 

Fig. 4. (a) Seismic travel-time structure map showing surface of Lower Cretaceous limestone marker in the Hibernia Anticline and location of wells used in this study. From Arthur el a . (1982). (b) Schematic cross-section along line A-A (corresponding to zone 2 in Fig. 3), showing three main reservoir sandstones of Hibernia Field Avalon, B ... 

Cretaceous limestone was deposited in the Cretaceous period 65 to 144 million years ago. 

Calcareous conglomerates consisting of clasts of Upper Cretaceous limestone, scattered over a - Calcareous conglomerates consisting of clasts of Upper Cretaceous limestone, scattered over a sandy-argillaceous matrix, or cemented by carbonates. Interbedded sandstones are usually present, reddish or greenish brown, or cemented by carbonates. Interbedded sandstpnes are usually present. 

Confined aquifer formed by Cretaceous limestone of the Fm. Oviedo with calcareous conglomerates (both show karstification processes). 

The Isca cave (Fig. 27.2), located in the island bearing the same name in the Sorrento Peninsula, developed by karstic processes in the Cretaceous limestone consists of a large cavern ca, 60 m (N-S) long and 30 m wide. Its mouth faces south towards the open sea and is located on a platform at a depth of 14 m, it is 2 m wide and 8 m high. The floor of the cave rises unevenly to —2 m its dome-shaped ceiling is partially above sea level and reaches a height of -h 11 m. 

The raw materials for cement manufacture which are the subject of geological exploration are mainly limestones and clays. In the geological sense both are sedimentary rocks which may occur as hard or dense material (commonly known as "rock") or softer soil deposits. They may be of any geological age. Limestones mostly occur in the form of rock, sometimes constituting whole mountainous formations. In Europe, more particularly the Devonian granular limestones, the Jurassic and Triassic limestones of the Alpine region and the Cretaceous limestone deposits are of importance. 

Sierra Pena Blanca district. Chihuahua, Mexico The Pena Blanca uranium district is about 50 km northeast of Chihuahua, Mexico, on the east side of a large Basin and Range horst block and near the eastern edge of the Caenozoic Sierra Madre Occidental volcanic province. The bulk of the uranium deposits, which total about 5000 ton of reasonably assured U3O8 resource, occur in extracaldera ash-flow tuffs overlying Cretaceous limestones. The source of the tuffs is unknown, but some appear to be related to a large caldera south of Chihuahua. Other tuffs appear to have a western source. 

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 ... 

Important metallic ore deposits include Besshi (Kieslager)-type (strata-bound cupriferous pyritic deposits), strata-bound Mn-Fe-type, skam-type, Kuroko-type and vein-type. Dominant non-metallic deposits are limestone, clay, native sulfur, zeolite, silica and gypsum deposits. The deposits are divisible into three groups, based on their ages of formation Carboniferous-Jurassic, Cretaceous-Paleogene and Tertiary-present. 

The injection zone consisted of multiple Upper Cretaceous strata of sand, silty sand, clay, and some thin beds of limestone (see Figure 20.14). The clay confining layer was about 30 m (100 ft) thick. 

In Gubbio, Italy, a 1 cm layer of clay between extensive limestone formations marks the boundary between the Cretaceous and Tertiary Periods. This clay layer was known to have been deposited about 65 million years ago when many life forms became extinct, but the length of time associated with the deposition was not known. In an attempt to measure this time with normally deposited meteoritic material as a clock, extensive measurements of iridium abundances (and those of many other elements) were made on the Gubbio rocks. Neutron activation analysis was the principal tool used in these studies. About 50 elements were searched for in materials like the earth s crust, about 40 were detected and about 30 were measured with useful precision [26-28]2. 

The Middle Jurassic consists mainly of marls. The Upper Jurassic formations are massive (over 100 m thick) and are made up exclusively of limestones. During Upper Jurassic and Lower Cretaceous the limestone deposits have been uplifted and resulted in a paleo-karst surface that hosts discontinuous bauxite deposits. Lower... 

Cretaceous sedimentation started with the deposition of fresh-water limestones (Hauterivian) followed by successive layers of marine limestones (Barremian), marls (Aptian), marine limestones (Aptian), glauconitic sandstone (Aptian-Albian) and ended with a package of red detritic deposits. 

The Ulsan carbonates (Fig. 1) have long been interpreted as limestone of Paleozoic age or "age unknown" and as the host of a skarn-type iron (magnetite) deposit due to the intrusion of Cretaceous granitic rocks (Park Park 1980 Choi et al. 1999). However, a Paleozoic marine limestone hypothesis fails to explain the spatial association or the relationship between carbonate and ultramafic rocks in a concentric, ellipsoidal shape surrounded by Cretaceous sedimentary, volcanic, and granitic rocks. The sedimentary hypothesis also fails to explain the isolated exposure of a funnel-shaped Paleozoic marine limestone where no marine limestone has been previously observed within the Mesozoic Kyongsang Basin. 

Non-metamorphic equivalents of this Th-free mineralization may be sought in some rare limestone-hosted U-occurences, such as the Jurassic Todilto lacustrine formation in the Grant Uranium Belt (Rawson Richard 1980), the Cretaceous Toolebuc marine formation in Eromanga Basin (Ramsden 1982), the Mesoproterozoic Vempale marine formation in Cuddapah Basin (Sinha et al. 1989), and the Cretaceous Probeer marine formation in the Huab deposit (Hartleb 1988). 

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). 

Figure 16. S18Osc (PDB) versus S13 (PDB) values from marine limestone and paleosol carbonate in the late Cretaceous Takena Formation at the Penbo locality, southern Tibet (Leier 2005). Range of expected marine isotopic values for the late Cretaceous from Veizer et al. (1999).

The Ligurian complex tectonically superimposed on the Tuscan units, consisting of middle to late Jurassic ophiolites and radiolarites plus Cretaceous to Eocene pelagic limestones and flysch sequences. 

Upper Cretaceous or Tertiary, Milburn Table Hill, Otago, New Zealand (limestone) Hutton and Seelye (1941) analyst F.T. Seelye. 

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