Eocene

Koch, P.L., Zachos, J.C. and Gingerich, P.D. 1992 Correlation between isotope records in marine and continental carbon reservoirs near the Paleocene/Eocene boundary. Nature 358 319-322. 

Blow, W.H. (1969) Late middle Eocene to Recent planktonic foraminiferal biostratigraphy 1st International Conference on Planktonic microfossils. Proceeding, 1, 199 21. 

Keller, G. (1986) Stepwise mass extinction and impact events Late Eocene to early Oligocene. Marine Micropaleontology, 10, 267-293. 

Montanari, A., Asaro, F., Michel, H.V. and Kennett, J.P. (1993) Iridium anomalies of late Eocene age at Massignaro (Italy), and ODP Site 689B (Mand Rise, Antarction). Palaios, 8, 420-437. 

Budyko et al. (1987) pointed out that Eocene and Miocene volcanisms and related CO2 fluxes have been large. 

Roberts, D.G., Mortin, A C. and Backmann, J. (1984) Late Paleocene-Eocene volcanic events in the northern North Atlantic ocean. Washington, D.C. U.S. Gov. Printing Office. Initial Report Deep Sea Drilling Project, 81, 913-923. 

Eocene/Oligocene boundary. This shift is thought to reflect an increase in DSi delivery to the ocean associated with the evolution of grasses and grazing ungulates. 

Paleocene eocene thermal maximum (PETM) A hyperthermal period, 55.8mybp, during which average global temperatures increased by 6°C for a period of 20,000 years. 

The phosphatic series, about 50 m thick, and of Paleocene-Eocene age, consists of ten phosphatic layers (Sassi 1974) Interbedded with non- or poorly phosphatized strata with various facies... 

Three intrusions occur in the QB open pit and drill core. These consist of (/) Carboniferous diorite that was intruded by (/ /) Late Eocene granodiorite, and (///) later quartz-feldspar porphyry dykes of granodiorite composition. 

Unconsolidated cover at Pebble consists of 0-50 m of a variety of glacial deposits over Pebble West, where the deposit is partially exposed. At Pebble East, the deposit was partially eroded and is unconformably overlain by an eastward thickening wedge of post-mineralization Late Cretaceous to Eocene volcanosedimentary rocks, up to 600 m in thickness, which in turn are overlain by the glacial deposits. 

Haeussler, P.J. Saltus, R.W. 2004. 26 KM of offset on the Lake Clark Fault since Late Eocene time. U.S. Geoiogicai Survey Professionai Paper 1709A, 4. 

The major rock units in the East-Kahang are made up of andesite, volcanic breccia, dacite, quartz-diorite, diorite and locally mineralized hydrothermal breccia (Fig. 2). Eocene andesite and volcanic breccias showing propylitic alteration are the oldest units in the area. They have been intruded by dacite, mostly showing phyllic alteration associated with weak copper mineralization. Quartz-diorite and dioritic... 

The Pebble Cu-Au-Mo porphyry deposit contains one of the largest resources of copper and gold in the world. The Pebble West Zone, partially covered by glacial deposits up to 50 m thick, extends from the surface to 500 m depth (Lang et al. 2007). The East Zone, which extends to at least 1700 m depth, was partially eroded and is concealed by an eastwardly thickening wedge (300-600 m thick) of Late Cretaceous to Eocene volcanic and sedimentary rocks (Bouley et al. 1995 Lang etal. 2007). 

Fig. 2. West to east plot of vanadium by enzyme leach in soils on top of a cross section showing vanadium in drill core. Dashed line shows the subcrop of Cretaceous, granitic rock of Pebble East beneath the Palaeozoic/Eocene volcanic and sedimentary rock cover.

The boron isotope approach to pC02 estimation relies on the fact that a rise in the atmospheric CO2 concentration will increase pC02 of the surface ocean which in turn causes a reduction of its pH. By measuring the boron isotope composition of planktonic foraminifera Pahner et al. (1998) and Pearson and Palmer (2000) have reconstructed the pH-profile of Eocene sea water and estimated past atmospheric CO2 concentrations. However, Lemarchand et al. (2000) argued that 5 B records of planktonic foraminifera partly reflect changes in the marine boron isotope budget rather than changes in ocean pH. 

As has been proposed by numerous studies (e.g., Rohl et al. 2000 Dickens 2003) the massive release of gas hydrates could modify climate. The best example for this hypothesis are sedimentary rocks deposited at around 55 Ma during the Paleocene-Eocene thermal maximum, where a decrease of 2-3%c in carbonate-carbon is interpreted as a consequence of an abrupt thermal release of gas-hydrate methane and its subsequent incorporation into the carbonate pool. 

Figure 3.49 summarizes the oxygen isotope curve for the last 65 Ma. The most pronounced warming trend is expressed by a 1.5%o decrease in 8 0 and occurred early in the Cenozoic from 59 to 52 Ma, with a peak in Early Eocene. Coinciding with this event is a brief negative carbon isotope excursion, explained as a massive release of methane into the atmosphere (Norris and Rohl 1999). These authors used high resolution analysis of sedimentary cores to show that two thirds of the carbon shift occurred just in a few thousand years, indicating a catastrophic release of carbon from methane clathrates into the ocean and atmosphere. 

Fig. 3.49 Global deep-sea isotope record from numerous DSDP and ODP cores. PETM Paleocene-Eocene Thermal Maximum (Zachos et al. 2001)...

Pearson PN, Palmer MR (1999) Middle Eocene seawater pH and atmospheric carbon dioxide. Science 284 1824-1826... 

TERTIARY /Pliocene Miocene Oligocene Eocene Palaeocene... 

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