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The Middle and Lower Yangtze River metallogenic belt is one of the most important polymetallic resource areas in China. Iron oxide-apatite deposits, mainly distributed in Ningwu and Luzong volcanic basins, are a distinct type of iron deposits in this region. These deposits have a close temporal and spatial relationship with Mesozoic dioritic porphyries and are characterised by magnetite-apatite-pyroxene/actinolite_x000D_
anhydrite assemblage and large-scale sodic-calcic alteration.Widespread multiphase inclusions in pre- to main-mineralisation stage pyroxene and garnet in Meishan (in the Ningwu basin), Luohe and Nihe (both in the Luzong basin) iron deposits were trapped at ~780C in extremely saline brines (~90 wt per cent NaCl equivalent), consisting of Na (13-24 wt per cent), K (7-11 wt per cent), Ca (~7 wt per cent), Fe (~2 wt per cent), Cl (19-47 wt per cent) and SO4 (3-39 wt per cent), based on petrologic, microthermometric, Raman spectroscopic studies and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of natural fluid inclusions and synthetic analogues. The high Cl/Br, Na/B and S/B ratios in brine inclusions and the heavy sulfur isotopic values of anhydrite and pyrite (34SAnh = +15.2 to +16.9, 34SPy = +4.6 to +12.1) suggest a significant contribution from both halite- and anhydrite-bearing sedimentary rocks. The involvement of evaporites caused the production of large amounts of high-salinity brines with apparently enhanced capacity to extract iron from the dioritic intrusions.According to their geologic features and the above characteristics, these iron oxide-apatite deposits are considered to be a special type of iron oxide copper gold (IOCG) deposits characterised by high contents of Na, Ca, Cl and SO4 in the ore-forming fluids. Moreover, we believe that evaporite-bearing sedimentary basins are more prospective than evaporite-free ones for these kinds of deposits.CITATION:Li, W T, Audtat, A and Zhang, J, 2015. The connection between evaporites and iron oxide-apatite deposits, Yangtze River, China - laser ablation inductively coupled plasma mass spectrometry analysis of Na, S, Cl and Br in fluid inclusions, in Proceedings PACRIM 2015 Congress, pp 623-630 (The Australasian Institute of Mining and Metallurgy: Melbourne).