Eocene formation

Otto A, Simoneit BRT, Ghemosystematics and diagenesis of terpenoids in fossil conifer species and sediment from the Eocene Zeitz Formation, Saxony, Germany, Geochim Gosmochim Acta 65 3505—3527, 2001. 

Pocknall DT (1987) Paleoenvironments and age of the Wasatch Formation (Eocene), Powder River Basin, Wyoming. Palaios 2 368-376... 

The geology of the Scripps cliff has been discussed previously by Carter (44) and by Karrow and Emerson (45). The cliff is composed of Pleistocene alluvial and colluvial sediments overlying the Ardath Shale and Scripps Formation which are Eocene in age. There is a marine fossili-ferous terrace deposit at the contact between the Pleistocene sediments and the Eocene conglomerate. Shells obtained from this terrace, 40-50 m north of the area where the cliff collapsed, have been analyzed by amino acid racemization and corresponded in age to a period of high sea level during the last interglacial, i.e., 120,000 years B.P. (46,47). This... 

Limestones (Knauth and Epstein, 1976), the maximum 5 0 values of all Precambrian cherts are lower than those of Phanerozoic marine cherts (Figure 2). Representative S Osmow values of Phanerozoic cherts are +35%o for fibrous quartz from Eocene deep-sea chert (Knauth and Epstein, 1976) and + iQ%c to +34%o for Devonian Arkansas novaculite chert precipitated at shallow depth (Jones and Knauth, 1979). In contrast, the maximum 5 0 of chert in Paleoproterozoic iron formation is +2A.Wcc to +24.7%o (Winter and Knauth, 1992 Becker and Clayton, 1976 Perry et al., 1973), and 5 0 values for Archean chert are even lower, - -22%o for 3,400 Myr Onverwacht formation chert (Knauth and Epstein, 1976) and +20%c for metachert in 3,700 Myr Isua iron formation (Perry et al., 1978). 

In the Guff of Mexico, the increase in Pqq occurs to a greater degree (up to 16 mol.%) and at shallower depths in Eocene units (Wilcox formation) that contain smaller quantities of less-reactive detrital feldspars (of plutonic as opposed to volcanic provenance) (Lundegard and Land, 1986). Apparently, as the detrital feldspar supply is exhausted, pH buffering shifts to the carbonate assemblage. The FcOo rises... 

Figure 13 Quartz on silt grains in Wilcox Formation shale, Eocene, Texas Gulf Coast (a) secondary electron image and (b) panchromatic cathodoluminescence image.

Awwiller D. N. (1993) Illite/smectite formation and potassium transfer during burial diagenesis of mudrocks a study from the Texas Gulf Coast Paleocene-Eocene. J. Sedim. Petrol. 63, 501-512. 

The primary source of the selenium is believed to have been pyrite in shales, particularly the Upper Cretaceous-Paleocene Moreno Shale and the Eocene-Oligocene Kreyenhagen Shale. Concentrations of selenium in these formations range up to 45 mg kg median concentrations being 6.5 mg kg and 8.7 mg kg respectively (Presser, 1994). The concentration of selenium in the surface sediments (0-0.3 m depth) of the old playas is in the range l-20mgkg reflecting the historical accumulation of selenium from the selenium-rich drain water. Deeper sediments... 

The Late Jurassic Spekk Formation represents the major source rock, charging the structure, during Eocene to Recent. 

Leckie, D. A. Cheel, R.J. (1990) Nodular silcretes of the Cypress Hills Formation (Upper Eocene to Middle Miocene) of Southern Saskatchewan, Canada. Sedi-mentology 37, 445-454. 

One well-known example is the Lower Permian Karniowice travertine of Poland, where a rich fossil flora and fauna has been uncovered (Szulc and Cwizewicz, 1989). There is evidence that tufas date back to at least the Tertiary within the Barkly karst area of Queensland, Australia (Carthew et al., 2003b), and they have also been recorded in the Eocene Chadron Formation in South Dakota (Evans, 1999), the middle Miocene Barstow Formation in the Mojave Desert of California, USA (Becker et ah, 2001), and in the Miocene Ries crater basin in Germany (Pache et ah, 2001). 

Evans, J.E. (1999) Recognition and implications of Eocene tufas and travertines in the Chadron formation, White River group, Badlands of South Dakota. Sedimentology 46, 771-789. 

Evidence is accumulating that the oil shale deposits considered in this paper at least, are co-eval, now that the microfloral assemblages in Australia have been tied into the marine succession preserved around the southern margins of the continent. Foster (14 and pers. comm.), in studying additional material supplied from the current exploration activity, has been able to review earlier interpretations and it appears that most, if not all, of the Condor, Duaringa, Byfield, Rundle and Stuart oil shale sequences are confined to the middle and late Eocene. The unique conditions favouring formation of the oil shale deposits may have ended at this time. 

The oil shales of the Green River Formation in Colorado, Utah, and Wyoming formed from sediments deposited in Eocene lakes... 

In northwest Colorado, the Parachute Creek Member of the lacustrine Green River Formation (Eocene) contains thick sequences of rich oil shale that were deposited in ancient lake Uinta. The richest sequence and the richest oil-shale bed within the Parachute Creek Member are called the Mahogany zone... 

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