A salt diapir-related Mississippi Valley-type deposit: the Bou Jaber Pb-Zn-Ba-F deposit, Tunisia: fluid inclusion and isotope study

Abstract

The Bou Jaber Ba-F-Pb-Zn deposit is located at the edge of a Triassic salt diapir in the Salt Diapir Cenomanian. The limestone host rock is hydrothermally altered to ankerite proximal to and within the ore 6 bodies. Quartz as fine-grained bipyramidal crystal formed during hydrothermal alteration of the host rocks. 7The ore mineral assemblage is composed of barite, fluorite, sphalerite and galena in decreasing abundance. 8The ore zones outline distinct depositional events: sphalerite-galena, barite+ankerite and fluorite. Fluid 9 inclusions, commonly oil-rich, have distinct fluids salinities and homogenization temperatures for each of 10 these events: sphalerite-galena (17 to 24 wt% NaCl eq., and Th from 112° to 136°C; ankerite+ barite (11 to 11 17 wt% NaCl eq., and Th from 100° to 130°C); fluorite (19 to 21 wt% NaCl eq., Th from 140° to 165°C). 12The mean temperatures of the ore fluids in the events decreased from sphalerite (125°C) to barite (115°C) and 46

C–O Stable Isotopes Geochemistry of Tunisian Nonsulfide Zinc Deposits: A First Look

“…The ores are hosted in carbonate rocks of various ages, ranging from Triassic to Mio-Pliocene. In terms of tectonic setting, host rock ages and paragenesis, the sulfide deposits in this part of Tunisia are subdivided into five sub-types [1,3,5,39]:…”

“…Lead, silver and zinc were initially exploited in this deposit, while barite and fluorite were mined only later [5]. The mineralization (hosted in late Aptian carbonates, along the flanks of a northwest-dipping salt diapir) consists of several small-to medium-size bodies, which are fault and unconformity controlled.…”

“…The rich ores form three roughly vertical bodies in the central part of the deposit. From the outer part to the core, most orebodies have a sulfide-rich zone, a mixed barite/sulfide zone and a late barite-rich zone [5].…”

“…In this mountain belt, Triassic to upper Miocene carbonate rocks host numerous Zn-Pb sulfide deposits, which genetically represent varieties of the typical Mississippi Valley-type (MVT) ores [1][2][3][4][5]. The nonsulfide Zn-Pb deposits of Tunisia have not been investigated since the pioneering works of [6][7][8][9].…”

“…Hydrothermal alteration of the carbonate host rock includes silicification, dolomitization and ankeritization and may vary within a single deposit. These common features allowed classifying the Tunisian sulfide deposits as Mississippi Valley-type mineralizations [1,[3][4][5]39,41]. Since the Tunisian Zn-Pb ores replace and crosscut Triassic to Mio-Pliocene host-rocks, they are considered to be genetically associated with the Alpine tectonic activity [8,39], which started in the Late Cretaceous in this region and reached its maximum with two successive phases in the middle Miocene and late Miocene-Pliocene [48,49].…”