Genesis of the Questa Mo Porphyry Deposit and Nearby Polymetallic Mineralization, New Mexico, USA
Genesis of the Questa Mo Porphyry Deposit and Nearby Polymetallic Mineralization, New Mexico, USA
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DOI：
10.5382/econgeo.5011
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发表时间：
2023-03
期刊：
影响因子：
5.8
通讯作者：
S. Gaynor;J. Rosera;D. Coleman
中科院分区：
文献类型：
--
作者：
S. Gaynor;J. Rosera;D. Coleman
新墨西哥州北部渐新世拉蒂尔岩浆中心是一个异常暴露的火山-成矿复合体，拥有各种岩浆-热液矿床，从相对较深的富f斑岩钼矿化到较浅的浅成热液矿床。本文介绍了拉蒂尔岩浆中心深部岩体的全岩化学和同位素数据，包括对Questa斑岩钼矿床侵入岩岩心的大量取样。这些资料记录了与斑岩相关的成矿作用发生在破火山口形成岩浆活动之后和破火山口后岩基组合期间的时间化学趋势。在拉蒂尔岩浆中心的历史上，硅质岩浆多次产生，但很少与矿床的形成有关。整个岩石微量元素比例和Sr、Nd、Pb同位素组成在整个漫长的硅岩浆活动历史中变化。形成破火山口的火成岩和破火山口后侵入体的早期未矿化，高场强元素含量较高，放射性Sr和Pb含量普遍低于后期侵入体，而放射性Nd含量较高。Questa斑岩钼矿床是在岩基最同位素原始阶段组装完成后立即形成的，排除了地幔源壳的简单改造作为成矿岩浆来源的可能性。流纹岩脉与钼矿化后~800 ky侵入的多金属硫化物矿床有关，Nd同位素数据表明，这些脉脉与不同批的岩浆有关，与Questa矿的钼矿化侵入体无关。总之，这些数据表明，岩浆的来源在过去10年中发生了重大变化。岩浆中心的历史。根据这组数据，我们评估了与斑岩有关的岩浆活动的多种成因模型，倾向于下地壳深部杂交带岩浆成因的离散期模型，这些岩浆成因期导致了矿化的间断期。这些观察结果表明，在中央岩浆轨迹内的矿床的形成可能是单个热液-岩浆系统的零碎组合的结果，而在已知斑岩矿床附近常见的远端和较年轻的多金属成矿作用代表了解耦过程。
The Oligocene Latir magmatic center in northern New Mexico is an exceptionally well-exposed volcanoplutonic complex that hosts a variety of magmatic-hydrothermal deposits, ranging from relatively deep, F-rich porphyry Mo mineralization to shallower epithermal deposits. We present new whole-rock chemical and isotopic data for plutonic rocks from the Latir magmatic center, including extensive sampling of drill core samples of intrusive rocks from the Questa porphyry Mo deposit. These data document temporal chemical trends of porphyry-related mineralization that occurred after caldera-forming magmatism and during postcaldera batholith assembly. Silicic magmas were generated multiple times throughout the history of the Latir magmatic center, but few are associated with the formation of a mineral deposit. Whole-rock trace element ratios and Sr, Nd, and Pb isotope compositions vary throughout the protracted history of silicic magmatism. The caldera-forming ignimbrite and early phase of postcaldera intrusions are unmineralized, more enriched in high field strength elements, and generally contain less radiogenic Sr and Pb and more radiogenic Nd than later intrusions. The Questa porphyry Mo deposit formed immediately after the most isotopically primitive phase of the batholith was assembled, ruling out simple reworking of juvenile mantle-derived crust as the source for mineralizing magmas. Rhyolite dikes associated with polymetallic sulfide deposits intruded ~800 k.y. after Mo mineralization, and Nd isotope data indicate that these dikes are associated with different batches of magma and are unrelated to the Mo-mineralizing intrusions at the Questa mine. Together, these data indicate that the source of magmas changed significantly throughout the 10-m.y. history of the magmatic center. We assess multiple genetic models for porphyry-related magmatism against this data set, favoring models with discrete periods of magma genesis from a deep hybridized zone in the lower crust giving rise to the punctuated periods of mineralization. These observations suggest that the formation of mineral deposits within a central magmatic locus is likely the result of the piecemeal assembly of individual hydrothermal-magmatic systems, and that distal and younger polymetallic mineralization commonly observed near known porphyry deposits represents decoupled processes.