Mineralogy, geochemistry and sulfur isotope characterization of Cerro de Maimón (Dominican Republic), San Fernando and Antonio (Cuba) lower Cretaceous VMS deposits: Formation during subduction initiation of the proto-Caribbean lithosphere within a fore-arc
Mineralogy, geochemistry and sulfur isotope characterization of Cerro de Maimón (Dominican Republic), San Fernando and Antonio (Cuba) lower Cretaceous VMS deposits: Formation during subduction initiation of the proto-Caribbean lithosphere within a fore-arc
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DOI：
10.1016/j.oregeorev.2015.09.017
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发表时间：
2016
影响因子：
3.3
通讯作者：
L. Torró;J. Proenza;J. Melgarejo;P. Alfonso;J. F. Pablo;J. Colomer;A. Garcia‐Casco;A. Gubern;E. Gallardo;X. Cazañas-;C. Chavez;R. Carpio;P. León;C. E. Nelson;J. Lewis
中科院分区：
文献类型：
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作者：
L. Torró;J. Proenza;J. Melgarejo;P. Alfonso;J. F. Pablo;J. Colomer;A. Garcia‐Casco;A. Gubern;E. Gallardo;X. Cazañas-;C. Chavez;R. Carpio;P. León;C. E. Nelson;J. Lewis
下白垩纪Maimón组（多米尼加共和国）和Los Pasos组（古巴）火山弧是加勒比岛弧中记录的最古老的岩浆活动的代表，是大安的列斯群岛已知火山成因块状硫化物（VMS）矿床的主要产地。根据新的岩石地球化学资料，将Maimón组的玄武岩分为弧前玄武岩（FAB）、玻安岩和丰度较低的低钛拉斑玄武岩（LOTI）和正常岛弧拉斑玄武岩（IAT），而Los Pasos组的玄武岩分为LOTI和IAT。这两个地层的长英质火山岩在地球化学上相似，具有地幔型（M型）、玻安岩和拉斑玄武岩特征，属于FIV型，是典型的后白垩纪含VMS的幼年火山岩套。岩石地球化学数据表明，形成在前弧环境后，俯冲开始与初始的伸展制度和相关的玻安岩和拉斑玄武岩熔体，起源于浅地幔。在这个构造框架内，洛斯帕索斯组的岩石和相关的VMS矿床可能形成于比Maimón组稍晚的阶段。Cerro de Maimón（Maimón组）、San Fernando和Antonio（洛斯帕索斯组）VMS矿床的原生同生矿石矿物组合相似。它们主要由黄铁矿组成，在基质中有不同比例的黄铜矿、闪锌矿和砷铜矿。然而，不同的变质和变形印上了不同的变形/恢复结构的三个矿床。残留的沉积-成岩硫化物生长物仅以局部framboidal和胶状生长物和微晶结构的形式保存在Antonio矿石中。海绵状结构，占主导地位的安东尼奥存款和稀疏的圣费尔南多矿石，沿着与黄铁矿的过度生长被解释为同沉积热液交代的代表。黄铁矿颗粒之间的退火结构和旋转的黄铁矿碎斑与相邻的不对称压力阴影，结合Cerro de Maimón矿石中的碎裂结构，指示更高的变质等级和更强烈的变形。同变质硫化物的恢复/重结晶导致微量元素的再活化和随后的离散矿物（方铅矿、碲化物、黝铜矿、毒砂/勒灵石、银硫盐和银金矿）的结晶。根据三个矿床层状矿化的闪锌矿成分计算的估计最低喷发流体温度在242至302 °C之间。三个矿床的砷锑铅矿晶体返回低Sb和Ag含量，典型的VMS矿化形成于幼年洋内岛弧环境。San Fernando和Antonio矿床层状矿石中Sb富集的广泛趋势与Cerro de Maimón方铅矿中Se和As的浓度较低以及更不相容的Sb、Te和Bi的含量较高相平行。矿石地球化学中的这些细微差别与Maimón组中VMS矿化形成的稍微更原始的环境非常一致，如火山寄主岩石的岩石地球化学所示。Cerro de Maimón的硫化物显示δ 34 S值为− 1.3至+ 3.0‰，而San Fernando和Antonio矿床则分别为-0.5 ‰ ~+7.0 ‰和0.0 ‰ ~+5.8 ‰。δ 34 S分布较窄，表明成矿流体硫成分均一，成矿物理化学条件相似。
The volcanic-arc Lower Cretaceous Maimón (Dominican Republic) and Los Pasos (Cuba) Formations, representative of the oldest magmatism recorded in the Caribbean island arc, host most of the known volcanogenic massive sulfide (VMS) deposits in the Greater Antilles. On the basis of new lithogeochemical data, basalts of the Maimón Formation are classified as fore arc basalts (FAB), boninites and less abundant low-Ti (LOTI) and normal island-arc tholeiites (IAT), and those of the Los Pasos Formation as LOTI and IAT. Felsic volcanics from the two formations are geochemically analogous and present mantle-type (M-type), boninitic and tholeiitic signatures, classifying as FIV-type, typical of post-Archaean VMS-bearing juvenile volcanic suites. This lithogeochemical data is indicative of formation in a fore-arc environment just after subduction initiation in association with initial extensional regimes and associated boninitic and tholeiitic melts that originated in the shallow mantle. Within this tectonic framework, rocks of the Los Pasos Formation and associated VMS deposits likely formed at a slightly later stage than those of the Maimón Formation.Primary syngenetic ore mineral assemblages from VMS deposits in the Cerro de Maimón (Maimón Formation), San Fernando and Antonio (Los Pasos Formation) are similar. They are composed mainly of pyrite in a matrix with variable proportions of chalcopyrite, sphalerite and tennantite. However, variable metamorphism and deformation have imprinted distinct deformation/recovery textures on the three deposits. Relict sedimentary-diagenetic sulfide growths are preserved only in Antonio ore in the form of local framboidal and colloform growths and microcrystallite textures. Spongy texture, dominant in the Antonio deposit and sparse in San Fernando ores, along with overgrowths of pyrite are interpreted as representative of syn-depositional hydrothermal replacement. Annealing texture among pyrite grains and rotated pyrite porphyroclasts with adjacent asymmetric pressure shadows, combined with cataclastic textures in Cerro de Maimón ore denote higher metamorphic grade and more intense deformation. Syn-metamorphic sulfide recovery/recrystallization led to the remobilization of trace elements and subsequent crystallization of discrete minerals (galena, tellurides, tetrahedrite, arsenopyrite/löllingite, Ag-sulfosalts and electrum).The chemical composition of sphalerite from the three deposits suggests ore formation in a sediment-starved environment. Estimated minimum venting fluid temperature calculated from the composition of sphalerites from stratiform mineralization in the three deposits is in the range of 242 to 302 °C. Tennantite crystals from the three deposits returned low Sb and Ag contents, typical of VMS mineralization formed in juvenile intraoceanic island-arc settings. A broad trend towards Sb enrichment in stratiform ores in the San Fernando and Antonio deposits parallels lower concentration of Se and As and higher contents in the more incompatible Sb, Te and Bi in galena with respect to Cerro de Maimón. These nuances in ore geochemistry are in good agreement with the slightly more primitive setting of formation of VMS mineralization hosted in the Maimón Formation, as indicated by the lithogeochemistry of the volcanic host rocks.The sulfides from Cerro de Maimón display δ34S values of − 1.3 to + 3.0‰, whereas those from the San Fernando and Antonio deposits were in the range of − 0.5 to + 7.0‰ and of 0.0 to + 5.8‰ respectively. The relatively narrow scatter of δ34S suggests homogeneous fluid sulfur composition and similar physico-chemical conditions during the ore forming processes …