Glauconites from New Jersey–Maryland Coastal Plain: Their K-Ar Ages and Application in Stratigraphic Studies

Owens, James Patrick; Sohl, Norman F.

doi:10.1130/0016-7606(1973)84<2811:gfnjcp>2.0.co;2

Cited by 37 publications

(13 citation statements)

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“…The 64.8-m.y. age obtained from the Denver flora and fauna (Evernden and James, 1964) is considerably older than any of the radiometric ages (all on glauconite) obtained from lower Paleocene marine rocks in either the Atlantic Coastal Plain (Owens and Sohl, 1973) or in the Mississippi Embayment (Ghosh, 1972). If these ages are valid, the Denver type of flora may, at least in part, be of latest Cretaceous age; on the other hand, the work of Butler and others (1977) indicates that the Puercan is indeed of Paleocene age, which indicates that the 64.8-m.y.…”

Section: Denver and Fort Union Typesmentioning

confidence: 86%

A chronologic framework for Cenozoic megafossil floras of northwestern North America and its relation to marine geochronology

Wolfe

1981

Geological Society of America Special Papers

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Collection and analysis of fossil plants in several stratigraphic sections have produced a chronologic framework for plant-bearing rocks of the northwesternNorth American province. The geographic extent of this province varied during the Cenozoic, but the stage framework can generally be applied to the region west of the Rocky Mountains (including Alaska) during the Paleogene and Miocene. The occurrence of some plant megafossils in dominantly marine sections of Paleogene age provides only a general concept of relation to the marine geochronology. Numerous Neogene floras have been radiometrically dated and can thus be more accurately related to the marine geochronology. The changes in the floral assemblages are largely the result of major climatic changes. If these changes are assumed to represent secular phenomena, the provincial chronology can also be related to the Cenozoic terminology in those Northern Hemisphere regions where paleobotanical data indicate that a similar series of climatic changes occurred. Inferences based on a combination of radiometric ages, correlations of West Coast benthic foraminiferal stages to the planktonic chronologies, and marine-nonmarine correlations of West Coast units indicate that the Eocene/Oligocene boundary may be as young as 32 m.y.

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Section: Denver and Fort Union Typesmentioning

confidence: 86%

A chronologic framework for Cenozoic megafossil floras of northwestern North America and its relation to marine geochronology

Wolfe

1981

Geological Society of America Special Papers

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“…Glaucony facies are usually present in open marine distal shelf and upper slope settings of the modern ocean in low to intermediate latitudes, in areas with low sedimentation rates where available iron is derived from weathering of adjacent continental landmasses that do not provide high amounts of siliciclastics to the basin (Owens & Sohl, 1973; Nikolaeva, 1977; Giresse et al. , 1980, 2004; Odin, 1985, 1988, etc.).…”

Section: Discussionmentioning

confidence: 99%

Depositional controls on glaucony texture and composition, Upper Jurassic, West Siberian Basin

et al. 2007

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This study examines textural inhomogeneity and variable chemical composition of Upper Jurassic glaucony in relation to small-scale synsedimentary and postsedimentary authigenic processes controlled by the palaeonvironmental and palaeogeographical context. Four glaucony types with complex textural and compositional features have been recognized in cores of the Georgiev Formation of the West Siberian Basin. Samples exclusively made of light green type 1 glaucony (K 2 O < 6AE5%: the less mature type, richer in glauconite-smectite mixed layer) formed under dysoxic conditions in the deepest distal marine environments of the northern sectors of the West Siberian Basin. Dark green type 2 glaucony is the most mature (richest in glauconitic mica: K 2 O up to 8AE5%), is sometimes associated with type 1 glaucony, and is typical of high bottom areas with a low sedimentation rate within the central sectors of the basin. Type 3 glaucony is formed by brown grains, poorer in K and Fe but richer in Al and Si than type 2 glaucony, and is only present in strongly condensed successions of the central-eastern sectors of the West Siberian Basin. Type 4 glaucony is much richer in Fe than any other type, shows fresh yellowish green cores slightly less mature than type 2 glaucony, and brown rims and cracks with composition similar to that of type 3 grains; it was formed in western sectors of the West Siberian Basin, close to Urals. Weathering under a subtropical to temperate climate, and erosion of badly drained peneplaned lowland areas around the basin, provided Al-rich terrigenous clays as substratum for glauconitization, which explains Al and Si enrichment in Siberian glaucony. Maturation from glauconite-smectite to glauconitic mica is monitored by a change from light to dark green colour related to decrease in Al, Si, Mg, Ca and Na, and to increase in K and Fe. Brown rims of type 4 glaucony, and brown type 3 grains formed after leaching of Fe and K from mature glauconite, with formation of clays and Fe oxyhydroxides as reaction products, as a result of free oxygen exposure related to a hydrodynamic regime and temporary sea-level fall. Glauconitization stopped and diagenetic pyrite formed due to basin deepening and burial under black shales during the latest Jurassic-earliest Cretaceous transgression. This study demonstrates that, due to the complex nature of glaucony, the authigenesis of glauconitic minerals in the rock record cannot be correctly understood if the 1 Deceased. 1365 palaeoenvironmental context and the palaeogeographical context of glauconybearing sediments are not considered.

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“…Squares: recalculated from Hardenbol and Berggren (1978) by Ness and others (1980) and used for calibration of geomagnetic reversal sequence by Lowrie and Alvarez (1981). Open triangle: from Owens and Sohl (1973). Anomaly numbers are indicated below bar graph of geomagnetic reversal sequence (fiUed for normal, open for reversed polarity).…”

Section: Comparison To Biochronologymentioning

confidence: 99%

Cenozoic geochronology

Berggren

Kent

Flynn

et al. 1985

Geol Soc America Bull

1,008

801

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We present a revised Cenozoic geochronology based upon a bestfit to selected high-temperature radiometric dates on a number of identified magnetic polarity chrons (within the Late Cretaceous, Paleogene, and Neogene) which minimizes apparent accelerations in seafloor spreading. An assessment of >200 first-order correlations of calcareous plankton biostratigraphic datum events to magnetic polarity stratigraphy yields an improved correlation of the standard magnetostratigraphic, standard biostratigraphic (zonal) and chronostratigraphic boundaries, as well as improved resolution in marinecontinental stratigraphic correlations. The time scale presented here has been accepted by the Committee on Geochronology as the standard time scale for the Cenozoic for the Decade of North American Geology (DNAG).

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Glauconites from New Jersey–Maryland Coastal Plain: Their K-Ar Ages and Application in Stratigraphic Studies

Cited by 37 publications

References 0 publications

A chronologic framework for Cenozoic megafossil floras of northwestern North America and its relation to marine geochronology

A chronologic framework for Cenozoic megafossil floras of northwestern North America and its relation to marine geochronology

Depositional controls on glaucony texture and composition, Upper Jurassic, West Siberian Basin

Cenozoic geochronology

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