Other
Scientific paper
Jul 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994e%26psl.125..105m&link_type=abstract
Earth and Planetary Science Letters (ISSN 0012-821X), vol. 125, no. 1-4, p. 105-118
Other
4
Beryllium 10, Cenozoic Era, Chemical Composition, Earth Crust, Geochemistry, Geochronology, Geomorphology, Iron Compounds, Manganese Compounds, Seamounts, Stratigraphy, Strontium Isotopes, Aluminum Silicates, Cobalt, Fossils, Strontium 87, Transport Properties
Scientific paper
To investigate the growth rates and absolute time stratigraphy of marine hydrogenetic ferromanganese encrustations, we performed Be-10 profiling and 'Co chronometry' of crustal layers, as well as Sr-87/Sr-86 and delta(O-18) analysis of phosphatised limestone (francolite) within a approximately 9.5 cm thick ferromanganese crust from Schumann Seamount in the Hawaiian Archipelago. Together with microfossil stratigraphy, our results indicate that some seamount crusts greatly exceed the commonly accepted Miocene maximum age, in this case probably approaching the Cretaceous age of the seamount. In addition to the unconformity at the crust-substrate boundary, at least eight major disconformities are indicated in the Schumann Seamount crust which probably represent depositional hiatuses or episodes of crust erosion. Three of the six upper disconformities can be placed at the Plio-Pleistocene, Middle Miocene and Paleocene-Eocene based on Be-10, microfossil and Co chronometer evidence. Sr-87/Sr-86 and delta(O-18) values of purified francolite from an inclusion-rich layer between the depths of 44 and 49 mm suggest apparent ages that approach those of Eocene-Late Paleocene microfossils reported in overlying layers, whereas francolite vein infillings in the lower part of the crust and in the basaltic substrate yield values that, if interpreted as ages of phosphatization, suggest a minimum Oligocene age. Paleotracking suggests the phosphogenesis observed here and on other Central Pacific seamounts could not have resulted from upwelling enhanced productivity associated with equatorial divergence if the Oligocene and Middle Miocene isotopic ages reported here and elsewhere are correct; however, a maximum Late Paleocene age for the phosphogenesis, consistent with the stratigraphy, would place these seamounts within 10 deg N of the equator. Paleotracking also suggests northeast tradewind transport of aluminosilicates in the Cenozoic, in agreement with other evidence for the antiquity of this ferromanganese crust.
Eisenhauer Anton
Mahoney John J.
McMurtry Gary M.
Vonderhaar D. L.
Yeh Hsueh-Wen
No associations
LandOfFree
Cenozoic accumulation history of a Pacific ferromanganese crust does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Cenozoic accumulation history of a Pacific ferromanganese crust, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cenozoic accumulation history of a Pacific ferromanganese crust will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1254534