Publication Type:

Journal Article

Authors:

Davies, James F.; Prevec, Stephen A.; Whitehead, Robert E.; Jackson, Simon E.

Source:

Chemical GeologyChemical Geology, Elsevier, Amsterdam, Netherlands, Volume 144, Number 1-2, p.99-119 (1998)

ISBN:

0009-2541

Keywords:

alkaline earth metals, Antilles, Carbonates, Caribbean region, chemical ratios, Cuba, exhalative processes, gangue, geochemistry, Greater Antilles, ICP mass spectra, isotope ratios, Isotopes, laser methods, lead-zinc deposits, mass spectra, metal ores, metals, mineral deposits, genesis, rare earths, spectra, Sr-87/Sr-86, Stable isotopes, strontium, Trace elements, West Indies

Abstract:

Abundances of REEs and Sr, the magnitudes of the positive Eu anomalies (Eu/Eu (super *) ) and (super 87) Sr/ (super 86) Sr values in carbonate gangue of the Late Jurassic Castellanos SEDEX Zn-Pb deposit vary both laterally and, to a lesser extent, vertically. At the vent-distal site Sr, La and Eu/Eu (super *) , determined by laser ablation microprobe analyses of individual grains, increase slightly from the base of the deposit upward. The La/Lu ratio only increases significantly in the upper part of the section. Both Sr/(Sr+Ca) and La/(La+Ca) in total carbonate, determined by ICP spectrometry, remain relatively constant or increase slightly from the base upward at the vent-distal location. Values of Sr/(Sr+Ca) correlate reasonably well with La/(La+Ca) throughout most of the vent-distal section. The Sr content and Eu/Eu (super *) are higher and La much lower at the vent-proximal location and all three exhibit very large within-sample variations. La does not correlate with Sr at the vent-proximal site. The (super 87) Sr/ (super 86) Sr values at both distal and proximal sites lie between that for Jurassic (Oxfordian) seawater and that of a hydrothermal fluid with a (super 87) Sr/Sr (super 86) value estimated from (super 87) Sr/ (super 86) Sr in the carbonate gangue of Cu mineralization in a nearby feeder channel beneath a small Zn-Pb deposit similar to Castellanos. Mixing of the REE- and Sr-enriched hydrothermal component with seawater in proportions calculated from the Sr-isotope data will explain the small vertical variations throughout most of the vent-distal section. However, the very low La abundances, the decoupling of the La from Sr and Eu/Eu (super *) and the extreme micro-scale heterogeneity of REE distribution at the vent-proximal site suggest extensive leaching, redistribution and removal of REEs from early-stage carbonates by late-stage hydrothermal fluids at that location. Abstract Copyright (1998) Elsevier, B.V.

Notes:

GeoRef, Copyright 2018, American Geological Institute.<br/>1998-032858<br/>Castellanos Deposit<br/>SEDEX<br/>western Cuba