The Searchlight pluton (SLP) and coeval Highland Range volcanic sequence (HRV) have been suggested to represent intruded and erupted counterparts, and the 15 km tilted crustal section in which they are exposed has been presented as an illustration of the anatomy of a large, upper crustal, intermediate to silicic magmatic system. We summarize herein three decades of published and unpublished research on this system, emphasizing new work on its final silicic products that verifies direct connections between SLP and HRV and provides insights about storage, extraction, transport, and eruption processes in the waning stages of the system.

Circumstantial evidence strongly suggests that volcanic and plutonic SLP-HRV products were directly linked for one million years (~17–16 Ma). For most of this period the system produced primarily intermediate rocks: dominantly quartz monzonite in the lower and upper SLP and trachyandesite-trachydacite lavas of the HRV (~58–70 wt% SiO₂). Over the final ~0.2 million years of the evolution of the system, silicic magma (70–78 wt% SiO₂) constructed the youngest part of the pluton (middle SLP granite) and the coeval volcanic sequence (silicic HRV: rhyolite lavas and tuffs). Throughout the system's history, subordinate mafic magma accompanied the more silicic magmas.

New results reveal that the youngest silicic rocks exposed in both the middle SLP and the silicic HRV are distinctive rhyolite porphyries (RP) that are essentially identical in texture, mineral assemblage, and elemental compositions. This lithology is phenocryst-rich (40–50%), with large quartz, alkali feldspar, plagioclase, as well as biotite, amphibole, titanite, apatite, Fe-Ti oxides, zircon, and chevkinite. RP dikes emanate from the middle SLP and crosscut the upper SLP and the pluton's roof (Proterozoic basement and lower HRV); small plugs intrude the upper part of the silicic HRV, and identical RP lava is part of a composite lava flow that is the last silicic material erupted in the HRV sequence. This terminal lava also includes basaltic trachyandesite and mechanical mixtures of basaltic trachyandesite and RP. In all environments in which it is exposed, RP is extensively mingled with mafic magma. RP is also very similar in composition, mineralogy, and texture (except for its aphanitic groundmass) to the coarse low-silica granite that dominates the middle SLP. The RP connection provides strong evidence for direct connection between SLP and HRV.

A second highly plausible connection between SLP and HRV is strengthened by the RP correlation. Phenocryst-poor high-silica rhyolite (HSR) dikes in the upper SLP and roof that are cut by RP dikes are very similar in mineralogy, texture, and composition to HSR lavas and tuffs that dominate the silicic HRV. The HSR dikes emanate from leucogranite that forms the upper part of the middle SLP; though differing in texture, the fine- to medium-grained leucogranite is compositionally almost identical to the HSR dikes and volcanic rocks. Though more variable and less distinctive than RP, the similarities among the HSR rocks (dikes, lavas, tuffs) and the leucogranite also suggest a direct SLP-HRV connection.

Rhyolite-MELTS phase-equilibria and amphibole geobarometers indicate that crystal-poor HSR was stored directly above the crystal-rich RP, consistent with RP derivation from lower middle SLP and HSR from upper-middle SLP. Trace-element modeling suggests that the HSR and leucogranite magmas were produced through ~10–50% fractional crystallization of low-silica rhyolite/granite melt that fed the middle SLP. Together, these results suggest that the HSR and leucogranite represent the extracted melts derived from middle SLP mush. Texture and composition of RP indicates that it was derived almost en masse from the middle SLP; its ubiquitous association with mafic magma and thermometry within mingled materials indicate that final mobilization of SLP magma was a consequence of mafic recharge.

The silicic portion of the SLP-HRV system documents important processes and distinctive products of magmatic systems that are active in the upper crust: (1) production of granitic mushes (cumulates) and extraction of fractionated melt; (2) resultant “filtering:” preferential eruption of the fractionated melt, retention of the cumulate (the HRV silicic section is mostly HSR, the middle SLP mostly low-silica granite [cumulate]); (3) bulk extraction of mush (RP) facilitated by hot mafic recharging; (4) eruption of both crystal-poor, highly-evolved magmas (HSR) and crystal-rich, less evolved magma similar to “monotonous intermediates” (RP).

探照灯深成岩 (SLP) 和同时代的高地山脉火山序列 (HRV) 已被建议代表侵入和喷发的对应物，并且它们暴露在其中的 15 公里倾斜地壳部分已作为大型解剖学的说明呈现，上地壳，中间至硅质岩浆系统。我们在此总结了三十年来关于该系统的已发表和未发表的研究，强调了对其最终硅质产品的新工作，这些产品验证了 SLP 和 HRV 之间的直接联系，并提供了有关系统衰弱阶段的储存、提取、运输和喷发过程的见解.

间接证据强烈表明，火山和深成岩 SLP-HRV 产物在一百万年（~17-16 Ma）中直接相关。在这一时期的大部分时间里，该系统主要生产中间岩石：在 SLP 的下部和上部主要是石英二长岩，以及 HRV 的粗安岩-粗面英安岩熔岩 (~58–70 wt% SiO 2 ₎。在该系统演化的最后约 20 万年中，硅质岩浆 (70–78 wt% SiO ₂ ) 构成了深成岩的最年轻部分（中间 SLP 花岗岩）和同时代的火山序列（硅质 HRV：流纹岩熔岩和凝灰岩). 在整个系统的历史中，次级镁铁质岩浆伴随着更多的硅质岩浆。

新结果表明，在 SLP 中部和硅质 HRV 中暴露的最年轻的硅质岩石是独特的流纹岩斑岩 (RP)，它们在结构、矿物组合和元素组成方面基本相同。该岩性富含斑晶 (40–50%)，含有大块石英、碱长石、斜长石，以及黑云母、角闪石、钛铁矿、磷灰石、Fe-Ti 氧化物、锆石和 chevkinite。RP 岩脉从 SLP 中部发散并横切 SLP 上部和深成岩的顶板（元古代基底和下部 HRV）；小栓塞侵入硅质 HRV 的上部，相同的 RP 熔岩是复合熔岩流的一部分，它是 HRV 序列中最后喷出的硅质物质。该末端熔岩还包括玄武质粗面安岩和玄武质粗面安岩与 RP 的机械混合物。在其暴露的所有环境中，RP 都广泛地与镁铁质岩浆混合。RP 在成分、矿物学和质地（除了其隐晶质基质）上也与主导中层 SLP 的粗糙低硅花岗岩非常相似。RP 连接为 SLP 和 HRV 之间的直接连接提供了强有力的证据。

RP 相关性加强了 SLP 和 HRV 之间的第二个高度合理的联系。上部 SLP 和屋顶中被 RP 堤坝切割的贫斑晶高硅流纹岩 (HSR) 堤坝在矿物学、质地和成分方面与主导硅质 HRV 的 HSR 熔岩和凝灰岩非常相似。HSR 堤坝源自形成中 SLP 上部的淡色花岗岩；尽管质地不同，但细粒至中粒淡色花岗岩的成分与 HSR 岩脉和火山岩几乎相同。HSR 岩石（岩脉、熔岩、凝灰岩）和淡色花岗岩之间的相似性虽然比 RP 变化更大且更不明显，但也表明 SLP-HRV 之间存在直接联系。

流纹岩-MELTS 相平衡和角闪石地质气压计表明，结晶贫乏的 HSR 直接储存在富含晶体的 RP 之上，这与从中下层 SLP 推导 RP 和从中上层 SLP 推导 HSR 一致。微量元素模型表明，HSR 和淡色花岗岩岩浆是通过供给中层 SLP 的低硅流纹岩/花岗岩熔体的约 10-50% 的分步结晶产生的。总之，这些结果表明 HSR 和淡色花岗岩代表从中 SLP 糊状物中提取的熔体。RP 的结构和成分表明它几乎是从中层 SLP 衍生而来的；它与镁铁质岩浆的普遍联系以及混合材料中的测温表明，SLP 岩浆的最终流动是镁铁质补给的结果。

SLP-HRV 系统的硅质部分记录了在上地壳中活跃的岩浆系统的重要过程和独特产品：(1) 花岗岩糊状物（堆积物）的产生和分馏熔体的提取；（2）合成“过滤”：分馏熔体优先喷发，滞留堆积（HRV硅质段多为HSR，中SLP多为低硅花岗岩[堆积]）；(3) 热镁铁充电促进糊状物 (RP) 的大量提取；(4) 贫晶、高度演化的岩浆(HSR)和富含晶体、演化程度较低的岩浆的喷发，类似于“单调中间体”(RP)。