Clusters of early central volcanoes in the mid-Cenozoic Southern Rocky Mountain volcanic field (SRMVF; southwestern Colorado, USA) record sites of initial magmatic focusing that led to assembly of sizable upper-crustal magma bodies capable of generating large ignimbrites. Peak growth at precursor andesitic volcanoes was followed by extended periods (0.5 to >2 m.y.) of reduced eruptive activity during inferred prolonged incubation of the crustal reservoir prior to eruption of ignimbrites at the San Juan magmatic locus, as exemplified by the 5000 km3 Fish Canyon Tuff and associated La Garita caldera. After a magma system became thermally mature and compositionally evolved, additional large ignimbrites could erupt more rapidly from polycyclic calderas. In contrast, incubation times for smaller ignimbrite magmas, as at Crater Lake, Oregon, were briefer than for San Juan systems. Plutonic counterparts to the temporal-compositional assembly of arc-ignimbrite magmas are exemplified by incrementally emplaced granitoid intrusions like the Mesozoic Tuolumne complex in the Sierra Nevada.

中文翻译：

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大型火成岩岩浆体的早期孵化和长期成熟：来自美国科罗拉多州南落基山火山场的证据

中新生代南部落基山火山场（SRMVF；美国科罗拉多州西南部）的早期中央火山群记录了初始岩浆聚集的地点，这些地点导致了相当大的上地壳岩浆体聚集，能够产生大型点火岩。前体安山质火山的峰值增长之后，在圣胡安岩浆部位的火成岩喷发之前推断地壳储层的长时间孵化期间，喷发活动减少了长时间（0.5 到 > 2 米），例如 5000 平方公里的鱼峡谷凝灰岩和相关的拉加里塔火山口。在岩浆系统变得热成熟和成分演化之后，额外的大型火成岩可以从多环火山口中更快地喷发。相比之下，较小的火成岩岩浆的孵化时间，如俄勒冈州的火山湖，比圣胡安系统更简短。与内华达山脉的中生代 Tuolumne 杂岩这样的渐进式花岗岩侵入体为例，与弧燃岩岩浆的时间组成组合的深成相对应物。