『Abstract
　The Sekarna Zn-Pb deposit is located in Central Tunisia at the northeastern edge of the Cenozoic Rohia graben. Mineralization comprises two major ore types: (1) disseminated Zn-Pb sulfides that occur as lenses in sedimentary phosphorite layers and (2) cavity-filling zinc oxides (calamine-type ores) that crosscut Late Cretaceous and Early Eocene limestone. We studied Zn sulfide mineralization in the Saint Pierre ore body, which is hosted in a 5-m-thick sedimentary phosphorite unit of Early Eocene age. The sulfide mineralization occurs as replacements of carbonate cement in phosphorite. The ores comprise stratiform lenses each in sphalerite with minor galena, Fe sulfides, and earlier diagenetic barite. Laser ablation-inductively coupled plasma mass spectrometry analyses of sphalerite and galena show a wide range of minor element contents with significant enrichment of cadmium in both sphalerite (6,000-20,000 ppm) and galena (12-189 ppm). The minor element enrichments likely reflect the influence of the immediate organic-rich host rocks. Fluid inclusions in sphalerite give homogenization temperatures of 80-130℃. The final ice melting temperatures range from -22℃ to -11℃, which correspond to salinities of 15-24 wt.％ NaCl eq. and suggest a basinal brine origin for the fluids. sulfur isotope analyses show uniformly negative values for sphalerite (-11.2‰ to -9.3‰) and galena (-16‰ to -12.3‰). The δ³⁴S of barite, which averages 25.1‰, is 4‰ higher than the value for Eocene seawater sulfate. The sulfur isotopic compositions are inferred to reflect sulfur derivation through bacterial reduction of contemporaneous seawater sulfate, possibly in restricted basins where organic matter was abundant. The Pb isotopes suggest an upper crustal lead source.

Keywords: Zn-Pb deposits; Sedimentary phosphorites; Sekarna; Central Tunisia』

Introduction
Geological setting
Analytical methods
Host rock petrography and geochemistry
　Petrography
　Geochemistry
Mineralization
　Saint Pierre deposit
　Saint Eugene（最初のeの頭に｀） deposit
Geochemistry
　Trace elements
　Fluid inclusions
　Sulfur isotopes
　Lead isotope compositions
Discussion
　Diagenetic vs. epigenetic origin
　Diagenetic barite
　Sulfur source(s)
Conclusions
Acknowledgments
References