* 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...

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...

In this paper we report U-Pb zircon and titanite data and interpreted ages for sixteen rocks (Figure 1) sampled in support of regional mapping projects conducted by the British Columbia Geological Survey Branch during the midto late-1990s. Each sample is reported with geological context, interpretation of U-Pb data and significance of the date. The U-Pb results are also displayed on standard co...

The probable sources of some of the famous Indian diamonds are the 1.2 Ga old Krishna lamproites of Southern India, a rare Proterozoic occurrence of lamproites which are usually Cretaceous or younger in age. In this study we report Nd, Sr, Pb and Hf isotopes and multiple trace element concentrations of the Krishna lamproites. The goals are to evaluate mantle-processes and the petrogenesis of th...