21 D5. Economic Geology and Energy Geology (Posters)

Sunday, 18 March 2018
1:30 PM - 5:30 PM
Lake Champlain Exhibition Hall

ZONATION OF LEAD AND SULFUR ISOTOPIC COMPOSITIONS AND TRACE ELEMENTS OF ORE SULFIDES IN THE MOROCCAN HIGH ATLAS MVT ORE PROVINCE: IMPLICATIONS FOR ORE EXPLORATION

Paper number: 21-2
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

The ore sulfides of the Moroccan High Atlas metallogenic province display lead and sulfur isotopic compositions zonation. Sulfide ores show concrete sulfur composition zonation with heavy sulfur isotopic composition ( δ34S ~ +12.2‰) in the center of the High Atlas basin, negative δ34S values (avg. ~ –12.5 ‰) at the northern and western borders of the basin, and intermediate sulfur isotopic signature (avg. ~ +2.3‰) at the southern border. This zonal distribution of sulfur isotopic composition reflects different sulfate reduction mechanisms. Bacterial Sulfate Reduction (BSR) induced the negative δ34S values at lower temperature whereas Thermochemical Sulfate Reduction (TSR) yielded positive δ34S values at higher temperature. The intermediate sulfur isotopic composition reflects the mixing of sulfur-derived TSR and bacteriogenic sulfur.

The west part of the High Atlas near the Precambrian-Paleozoic paleohigh "Le massif ancien" is characteristically more radiogenic (206Pb/204Pb= 18.709 207Pb/204Pb= 15.658 and 208Pb/204Pb = 38.808) than the rest parts of the basin (206Pb/204Pb = 18.358 to 18.377, 207Pb/204Pb= 15.636 to 15.668 and 208Pb/204Pb=38.476 to 38.606). LA Q-ICP-MS analysis of galena samples reveals that galena with radiogenic Pb isotope in the West border are distinguishably rich in silver. The Pb and Zn concentrations respectively in galena and sphalerite are overall similar regardless of the location of the ore deposits.

On the basis of the available data, the grade of the orebodies is independent of the lead and sulfur isotopic compositions. The large size orebodies, however, seem to be generally associated with TSR-derived heavy isotopic sulfur. The center of the High Atlas, characterized by heavy sulfur isotopic signature, is a potential and promising area for ore exploration.

Geological Society of America Abstracts with Programs. Vol. 50, No. 2

doi: 10.1130/abs/2018NE-310408

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