Mesozoic period

The correlation between oceanic plateau formation and marine environmental catastrophes (characterized by mass extinction, oceanic anoxia and black shale deposition) throughout the Mesozoic period suggests a causal link between oceanic plateau formation and environmental crises. 

The Mesozoic era lasted almost 200 x 10 years and is so called because its fossils attest to substantial changes in the Earth s faima (see Figure 4.3). In contrast to the Proterozoic and Palaeozoic eras when most life forms were small, even microscopic, those of the Mesozoic period included many of the largest (and most popularized) animals, the dinosaurs as well as the emergence of birds. Some of these animals are shown in Figure 4.7. 

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)... 

Section 8.6.2, the Permian period ended with the largest mass extinction event that has yet occurred on planet Earth. As the ocean began a sustained recovery at the beginning of the Mesozoic era, opportunities likely abounded for the survivors to take over empty ecological niches through evolutionary adaptation. Prior to the advent of planktonic... 

The Silver Bell Mine area consists of dipping units that are composed of dacite porphyry, alaskite and monazite. The rock ages span the Paleozoic, Mesozoic and Cenozoic periods. The Paleozoic wall rocks consist of quartzite, siltstone and altered limestone. The carbonate rocks are exposed along the contact between the host rock and intrusions, and host the... 

Red beds are continental or marine sedimentary rocks with an eye-catching red colour which has been responsible for the interest in them. They are widespread all over the world and belong mainly to the Late Palaeozoic, Early Mesozoic, and Late Cenozoic periods. 

Cretaceous The last period of the Mesozoic era, therefore just following the Jurassic and just preceding the Tertiary. 

Cenozoic Era The period of geologic time beginning after the end of the Mesozoic Era 65 million years ago and encompassing the present. Commonly referred to as the age of mammals. 

Jurassic Period Middle period of the Mesozoic Era, between 185-135 million years ago. Characterized by the (possible) origin of angiosperms and the continued split of the worldwide supercontinent of Pangaea. 

Mesozoic Era The period of geologic time beginning 245 million years ago and ending 65 million years ago the age of the dinosaurs and cycads, the Mesozoic falls between the Paleozoic and Cenozoic Eras and includes the Triassic, Jurassic, and Cretaceous Periods. 

Paleozoic Era The period of time beginning 570 million years ago ending 245 million years ago falls between the Proterozoic and Mesozoic Eras and is divided into the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian Periods. 

Triassic Period The first period of the Mesozoic Era between 225 and 185 million years ago. Pangaea began to breakup during this time. The ancestors of dinosaurs were present, as were early mammals and mammal-like reptiles. 

Mass extinctions have been recognized in the fossil record since the middle of the nineteenth century. Levels of mass extinction of species were selected as marker levels in the stratigraphic record because the death of index-fossil species provided a convenient marker to subdivide and correlate strata. The mass-extinction level called the Permian-Triassic boundary is so profound in terms of faunal and floral change that it was early on noted and chosen to represent the transition from Paleozoic to Mesozoic era. The mass-extinction level called the Cretaceous-Tertiary boundary is also quite distinctive in terms of faunal and floral change, and it too was noted early on and chosen to represent the transition from Mesozoic to Cenozoic era. Other less profound, but nevertheless distinctive levels of mass extinction of fossils have been selected to represent marker points in the stratigraphic record at which geological periods, epochs, ages, and other intervals of lesser temporal value are defined. 

The Pi values in different areas appear to have persisted for long periods of time, and there are currently spatial links with the locations of certain Mesozoic CFB and with oceanic basalts with DUPAL isotope signatures. Such long-lived U/Pb variations may therefore correspond to large-scale mantle anomalies, perhaps at relatively shallow levels in the mantle. 

The basin occupied by Long Island Sound is a product of the period of prolonged erosion of eastern North America that occupied the late Mesozoic and the Cenozoic eras. Because the onshore geological record consists of erosion surfaces, and the products of this erosion are now submerged on the continental shelf, reconstruction of a detailed geological history is not possible. However, the main events are well established. 

Norphlet formation waters produced from three Fairway Field wells were analysed for major components and for selected minor cations as part of normal production operations (Table 1). The samples were taken from platform separators during production. Multiple samples from individual wells taken over a period of several years show only minor variations in composition. The waters are extremely saline brines with total dissolved solids between 300 and 373 g/1. Chlorine is the dominant anion in these brines, and sodium (71.6-89.8 g/1), calcium (33.0-41.6 g/1) and potassium (12.9-17.6 g/1) are the major cations. Norphlet formation waters at Fairway are also characterized by relatively high concentrations of Mg, Ba, Sr, Fe, Mn, Li and Pb. Brines of similar composition are produced from deep Norphlet reservoirs and other Mesozoic strata of onshore Mississippi (Carpenter et al. 1974 Kharaka et al. 1987). 

The Silurian and Early Devonian organic matter is typically sapropelic, mixed, and humic (Fig. 5.3). It was intensely generating hydrocarbons in the south of the region in the Paleozoic, and in the areas of the other basins in the Mesozoic. At present, the organic matter may presumably persist either at the end of the oil window, or in the gas window and low-molecular hydrocarbons. The radioactive shales of the Early Silurian are good source rocks in the central and north-eastern areas of the region. The Late Devonian and Carboniferous periods have provided satisfactory source rocks in the south-west and north-east of the region. 

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