Along the boundary between the Precambrian basement and the Permo-Mesozoic sedimentary basin of northernmost Madagascar, an extensive network of epigenetic quartz-barite veins can be found. The veins are extensional in nature and show a polyphase paragenesis. Some of the veins, especially in the northern part of the district, hold some minor Zn-Pb sulfides and erratically distributed, native gold mineralization. The latter has been exploited in the past and is currently subject to artisanal mining activity. Saline aqueous fluid inclusions in the various quartz and barite vein generations indicate involvement of a relatively cool (<100 °C), high-salinity (~24 eq. wt% NaCl) fluid and a hotter fluid (>160 °C) of lower salinity (~5 eq. wt% NaCl). Analyses of fluid inclusion leachates suggest that the high-salinity end member was a bittern brine, residual to seawater evaporation, whereas the low-salinity end member was a hydrothermal, metal-bearing fluid that had been sourced from the crystalline basement. Sporadic aqueous-carbonic fluid inclusions possibly represent involvement of a third fluid component of metamorphic or magmatic affinity that might have been responsible for the minor gold mineralization. The δ³⁴S composition of the barites averages 20.6 ± 2‰ V-CDT and is indicative for a seawater origin of sulfur. Sulfate was sourced either from evaporite minerals (e.g., gypsum) present in the Early Mesozoic sedimentary sequence or was originally concentrated in the bittern brine. While the timing of mineralization remains enigmatic due to the lack of reliable radiometric age determinations, the metallogenic constrains support vein formation during or shortly after the establishment of evaporitic conditions, likely around the Middle Jurassic, in the intracratonic rift basin that developed between the East African and Madagascar-Seychelles-India plates.

沿着前寒武纪基底和马达加斯加最北端的二叠纪-中生代沉积盆地之间的边界，可以发现广泛的后生石英重晶石脉网络。静脉本质上是伸展的并且表现出多相共生。一些矿脉，特别是在该地区的北部，含有一些少量的锌铅硫化物和分布不规则的原生金矿化体。后者过去曾被开采过，目前正在进行手工采矿活动。各种石英和重晶石脉中的含盐水溶液包裹体表明涉及相对较冷（<100°C）、高盐度（~24 eq. wt% NaCl）流体和较低温度的较热流体（>160°C）。盐度（~5 eq. wt% NaCl）。对流体包裹体渗滤液的分析表明，高盐度端部成分是卤水，海水蒸发的残留物，而低盐端元是来自结晶基底的热液、含金属流体。零星的水-碳酸流体包裹体可能代表了变质或岩浆亲和力的第三种流体成分的参与，这可能是造成少量金矿化的原因。δ^{重晶石的34} S 成分平均为 20.6 ± 2‰ V-CDT，表明硫源自海水。硫酸盐要么源自早中生代沉积序列中存在的蒸发岩矿物（例如石膏），要么最初浓缩在卤水中。虽然由于缺乏可靠的辐射年龄确定，成矿时间仍然是个谜，但成矿约束支持蒸发条件建立期间或之后不久的矿脉形成，很可能在中侏罗世附近，在东非和东非之间发育的克拉通内裂谷盆地中。和马达加斯加-塞舌尔-印度板块。