Evolution of a complex isolated dome system, Cerro Pizarro, central México
Evolution of a complex isolated dome system, Cerro Pizarro, central México
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墨西哥中部皮萨罗山复杂的孤立圆顶系统的演变
DOI：
10.1007/s00445-003-0313-y
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
G. Carrasco‐Núñez
中科院分区：
文献类型：
--
作者：
N. Riggs;G. Carrasco‐Núñez
皮萨罗山（Cerro Pizarro）是一个孤立的流纹岩圆顶，位于东墨西哥火山带东部的塞尔登-东方山间盆地。大约在220 ka时，Cerro Pizarro喷发了约1.1 km 3的岩浆。皮萨罗山的活动始于一定深度的排气孔清理爆炸;由此产生的沉积物含有当地基底岩石的碎屑，包括白垩纪石灰岩，~0.46 Ma的焊接凝灰岩和玄武质熔岩。在最早的圆顶生长过程中，随后的爆炸性喷发从推断的小圆顶产生了一系列交替的浪涌和沉降层。随着圆顶的垂直和横向生长，由于快速冷却，它形成了外部玻璃壳。在就位过程中，圆顶的不稳定性导致其侧翼的部分重力坍塌，产生各种块状和灰流沉积物。经过短暂的休息期，岩浆的重新注入导致形成了一个隐穹窿，玻璃斑状穹窿和下面的单位明显变形，以接近垂直的方向陡峭。这一阶段开始显然是一个气体贫乏的喷发，没有爆炸阶段伴随着隐穹的就位。然而，在隐穹顶就位后不久，建筑物的西侧灾难性地倒塌，造成碎片雪崩。火山喷发活动中断的标志是火山锥的侵蚀和来自Cerro Pizarro北部破火山口的熔结凝灰岩的就位。穹隆的最后增长形成了它现在的形状;这种增长伴随着多次喷发，产生了浪涌和沉降物沉积物，覆盖了Cerro Pizarro周围的地形。塞罗皮萨罗圆顶的演变与经典圆顶模型和更大的成层火山系统有共同之处。我们认为，模型，预测一个简单的进化圆顶未能占进化路径的可能性。特别是，在穹丘形成的早期阶段形成隐穹丘可能比一般认识的要普遍得多。同样，圆顶的扇形倒塌虽然很少见，但也是一种必须认识到的潜在危险，必须进行规划。
Cerro Pizarro is an isolated rhyolitic dome in the intermontane Serdán-Oriental basin, located in the eastern Trans-Mexican Volcanic Belt. Cerro Pizarro erupted ~1.1 km3of magma at about 220 ka. Activity of Cerro Pizarro started with vent-clearing explosions at some depth; the resultant deposits contain clasts of local basement rocks, including Cretaceous limestone, ~0.46-Ma welded tuff, and basaltic lava. Subsequent explosive eruptions during earliest dome growth produced an alternating sequence of surge and fallout layers from an inferred small dome. As the dome grew both vertically and laterally, it developed an external glassy carapace due to rapid chilling. Instability of the dome during emplacement caused the partial gravitational collapse of its flanks producing various block-and-ash-flow deposits. After a brief period of repose, re-injection of magma caused formation of a cryptodome with pronounced deformation of the vitrophyric dome and the underlying units to orientations as steep as near vertical. This stage began apparently as a gas-poor eruption and no explosive phases accompanied the emplacement of the cryptodome. Soon after emplacement of the cryptodome, however, the western flank of the edifice catastrophically collapsed, causing a debris avalanche. A hiatus in eruptive activity was marked by erosion of the cone and emplacement of ignimbrite derived from a caldera to the north of Cerro Pizarro. The final growth of the dome growth produced its present shape; this growth was accompanied by multiple eruptions producing surge and fallout deposits that mantle the topography around Cerro Pizarro. The evolution of the Cerro Pizarro dome holds aspects in common with classic dome models and with larger stratovolcano systems. We suggest that models that predict a simple evolution for domes fail to account for possibilities in evolutionary paths. Specifically, the formation of a cryptodome in the early stages of dome formation may be far more common than generally recognized. Likewise, sector collapse of a dome, although apparently rare, is a potential hazard that must be recognized and for which planning must be done.