Rocks Cretaceous-Tertiary

The historical background is presented for the asteroid-impact theory that is based on the iridium anomaly found in rocks frm the Cretaceous-Tertiary boundary. Recent measurements of Ir, Pt, and Au abundances from such rocks in Denmark have shown that the element abundance ratios are different from mantle-derived sources and agree with values for chondritic meteorites within one standard deviation of the measurement errors (7-10%). Rare-earth patterns for these rocks are... 

Fullerenes are rather easily oxidized, which explains the fact that, despite their commonplace occurrence in soots, they had escaped detection for so long. Fullerenes have now been found in Precambrian carbonaceous rocks from Karelia, Russia in breccias associated with the 1.85-billion-year-old Sudbury impact structure in Canada and in a sooty layer (believed to be due to fires from the asteroid impact that is thought to have killed off the dinosaurs) marking the Cretaceous-Tertiary boundary in New Zealand.8... 

R. Brett, The Cretaceous-Tertiary extinction a lethal mechanism involving anhydrite target rocks, Geochim. Cosmochim. Acta 56, pp. 3603 - 3606 (1992). 

Gas reserves are less easy to associate with their source rocks because gas is able to migrate more easily and over greater distances than oil. Consequently, conventional reserves (existing as gas in reservoirs) are dominated by contributions from coal and kerogen sources of Cretaceous-Tertiary age (Bois et al. 1982).The largest proven gas reserves are in the Middle East and the former Soviet Union, each of which accounts for c.35% of the... 

Fig. 4. C28/C29 sterane ratios for crude oils generated from marine source rocks (stippled area) generally increase from the Paleozoic to the present due to increasing phytoplankton diversity (Grantham and Wakefield, 1988). The six Algerian oil samples have C28/C29 sterane ratios in the range 0.38-0.44 (solid bar), consistent with Paleozoic source rock. G, O, S, D, C, P, Tr, J, K, T, Cz—Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Tertiary, and Cenozoic, respectively.

The known oil and gas reservoirs on the North Slope fields are shown in Figure 3. Oil and gas occurs over a wide area at various horizons. Source rock was abundant in Paleozoic and Upper Cretaceous/Tertiary to generate sufficient quantity of hydrocarbons to fill traps of various resrvoirs. Gas from Paleozoic Package occurs in Triassic Sadlerochit Formation near Barrow In the east. In Kemik and Kavik in the west, and In Seal Island, and Gwydyr Bay in the north. Lower Cretaceous gas have been observed in Prudhoe Bay complex, Kuparuk, Milne Point, Point Thomson and the Beaufort-Mackenzie areas, Canada in the east. 

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. 

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. 

Geology of the studied area was derived from 1 250,000 scale geologic maps of the Lake Clark and lliamna quadrangles (Wilson et al. 2006). These data contain attribute information that identifies lithologic units and their ages. Subsets were made of all igneous rock types from Late Cretaceous through Tertiary. 

Between 80 Ma and 50 Ma, the Namib rocks were eroded to a smooth peneplain (the Namib Unconformity). Namib Group Tertiary and Quaternary sedimentary debris was deposited in east-west to southwest trending paleochannels incised into Karibib marbles and schists on that Cretaceous age unconformity. From mid Tertiary to present, the central Namib region has maintained profoundly arid climatic conditions for the last 50 or more million years. Uplift initiated the post African erosion surface that filled valleys and channels with poorly sorted angular... 

The reservoir rocks that yield crude oil range in age from Precambrian to Recent geologic time but rocks deposited during the Tertiary, Cretaceous, Permian, Pennsylvanian, Mississippian, Devonian, and Ordovician periods are particularly productive. In contrast, rocks of Jurassic, Triassic, Silurian, and Cambrian age are less productive and rocks of Precambrian age yield petroleum only under exceptional circumstances. 

Conway (1942) and Smulikowski (1954) have interpreted the potassium-distribution data to indicate that there is a potassium deficiency in Tertiary and Recent seas. However, Spiro and Gramberg (1964) made analyses of the composition of cations adsorbed on argillaceous rocks of northern Siberia and concluded that ... the highest content of potassium is inherent in marine water of the Permian Period. In Triassic seas the content of the potassium dropped significantly, and reached a minimum in seas of the Jurassic Period. Beginning with Cretaceous, the amount of potassium in sea water increased again, and during the Quaternary Period its level approached that of the Permian seas. These ideas are extremely speculative. 

Bouse, R. M., Ruiz, J., Tidey, S. R., Tosdal, R. M., and Wooden, J. L. (1999). Lead isotope compositions of Late Cretaceous and Early Tertiary igneous rocks and sulfide minerals in Arizona Implications for the sources of plutons and metals in porphyry copper deposits. Econ. Geol. 94, 211-224. 

Aagaard P., Egeberg P. K., Saigal G. C., Morad S., and Bj0rlykke K. (1990) Diagenetic albitization of detrital K-feldspars in Jurassic, Lower Cretaceous, and Tertiary clastic reservoir rocks from offshore Norway 11. Formation water chemistry and kinetic considerations. J. Sedim. Petrol. 60, 575-581. 

Meissner F. F. (1984) Cretaceous and lower Tertiary coals as sources for gas accumulations in the Rocky Mountain area. In Hydrocarbon Source Rocks of the Greater Rocky Mountain Region (eds. J. Woodward, F. F. Meissner, and... 

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