Минералогия (Sep 2017)
MICROTOPOCHEMISTRY OF MARCASITE-PYRITE NODULE IN ILLITE-HEMATITE GOSSANITES OF THE LAHANOS MASSIVE SULFIDE DEPOSIT (PONTIDES, TURKEY): LA-IСP-MS DATA
Abstract
In addition to black shales, the sulfide nodules can occur in red-colored aposulfide deposits, e.g., illite-hematite gossanites of the Lahanos massive sulfide deposit (Pontides, Turkey), where the marcasite-pyrite nodules are located at the base of the layer. The nodules have zonal structure: the nucleus of the poikilite pyrite (zone A) is successively surrounded by zones of metacrystalline pyrite (zone B) and marcasite (zone C). Each zone is characterized by own mineralogical features, which are reflected in the results of LA-ICP-MS images («microtopochemistry») of the surface of the nodule. It is assumed that, at the first stage, the matter source for the nodule growth was related to the products of the halmyrolysis of sulfide-bearing hyaloclastites. Diagenetic nucleus of the nodule contains the chemical elements typical of illite (Si, Al, K, Mg, V, Cr), rutile (Ti, W), apatite (Ca, Mn, U), galena (Pb, Bi, Sb, Ag), bismuth sulfosalts (Bi, Cu, Pb), bornite (Cu, Bi, Ag), tetrahedrite-tennantite (Cu, As, Sb), chalcopyrite (Se, Te, Cu), native gold (Au, Ag, Hg ) and barite poikilites. Pyrite is characterized by high Co and Ni contents, which are tentatively associated with Bi tellurides. Zone B, probably formed at the early catagenetic (anadiagenetic) stage, is depleted in most trace elements, except for Cu, Pb, and Ag. The formation of zone C, probably during the stage of late catagenesis (anadiagenesis), was accompanied by saturation of marcasite with some elements (Cd, In, Tl, As, Sb, Mo, Ni) from pore solution at the early stage of catagenesis.
