* This research was supported by a grant from the National Science Foundation, Earth Science Division. 1 Radiative transfer theory has been applied extensively to problems in hydrologic optics by R. W. Preisendorfer. See, for example, Jour. Mar. Res., 18, 1-9 (1959); also U. S. Govt. Reports PB 153995, PB 153994, PB 153993, PB 153987, PB 153992, and PB 153990. 2Holmes, R. W., "Surface Chlorophy...

Over the last decades, determination of ages in monazite using Electron Probe Microanalysis (EPMA) has progressed to the point that it is now considered as a routine procedure within several laboratories worldwide [1,2]. Nevertheless, the typical age errors of individual electron probe spots reported in the literature are an order of magnitude larger than attainable by Secondary Ion Mass Spectr...

Abstract This communication reports novel geochemical and geochronological data of granite from the southeastern part Bastar Craton, Central India. The studied samples are leucocratic in appearance composed quartz, K-feldspar, plagioclase feldspar, biotite decreasing order abundances. Apatite, sphene, zircon occur as accessory minerals. SiO2 Al2O3 content sample varies between 61 69 wt.% 13 15 ...

A U-Pb SHRIMP zircon geochronological study was carried out in the Nico Pérez Terrane central-eastern portion of Uruguay with aim constraining its geological evolution and cratonic affinity. is made up by a mosaic tectonic blocks diferente lithologies sizes. This terrane limited to west Piedra Alta through Sarandí del Yí shear zone, east, contact Retamosa thrust Dom Feliciano Belt (Brasiliano o...

The Omai intrusion-centred Au-quartz vein system, the largest Au producer presently operating in the Guyana Shield, was sampled for detailed U-Pb and Pb-Pb geochronology and petrological investigation. The age of a metavolcanic/sub-volcanic unit in the host rock sequence is 212092 Ma. Zircon analyses from the main body dioritic rocks give U-Pb ages of 209496, 2092911 and 2096+11/−10 Ma. Magmati...

The Upper Ordovician Trenton Group of New York State is one of a number of Appalachian limestones which yields paleomagnetic poles suggesting disturbance in the late Paleozoic. Calcite fractions dissolved from samples of a 238U 206pb a e of 454+8 Ma the Trenton Limestone define g (MSWD = 12.8) in excellent agreement with 40Ar-39Ar and U-Pb ages for the deposition of the underlying Diecke Benton...

The influence of different oxygen concentrations on the bioenergetics parameters, osmoregulatory capacity and O:N atomic ratio of the blue shrimp, Litopenaeus stylirostris (Stimpson), was determined under laboratory conditions; shrimp were acclimated at 28 oC and 25psu and exposed to three different oxygen concentrations 2, 4 and 6 mg L -1 . The critical oxygen level (COL) was determined at 5.5...