Science Advances ( IF 13.6 ) Pub Date : 2020-09-23 , DOI: 10.1126/sciadv.aba7940 Fabian B Wadsworth 1 , Edward W Llewellin 1 , Jérémie Vasseur 2 , James E Gardner 3 , Hugh Tuffen 4
Silicic volcanic activity has long been framed as either violently explosive or gently effusive. However, recent observations demonstrate that explosive and effusive behavior can occur simultaneously. Here, we propose that rhyolitic magma feeding subaerial eruptions generally fragments during ascent through the upper crust and that effusive eruptions result from conduit blockage and sintering of the pyroclastic products of deeper cryptic fragmentation. Our proposal is supported by (i) rhyolitic lavas are volatile depleted; (ii) textural evidence supports a pyroclastic origin for effusive products; (iii) numerical models show that small ash particles ≲10−5 m can diffusively degas, stick, and sinter to low porosity, in the time available between fragmentation and the surface; and (iv) inferred ascent rates from both explosive and apparently effusive eruptions can overlap. Our model reconciles previously paradoxical observations and offers a new framework in which to evaluate physical, numerical, and geochemical models of Earth’s most violent volcanic eruptions.
中文翻译:
烧结引起的爆炸性火山喷发转变。
长期以来,人们一直将硅质火山活动定义为猛烈爆炸或轻度冒出。但是,最近的观察表明,爆炸性行为和喷射行为可以同时发生。在这里,我们提出流纹岩浆供给的地下喷发通常在上升通过上地壳的过程中破碎,而喷发性喷发是由于导管堵塞和深部隐裂碎片的火山碎屑产物的烧结所致。我们的建议得到以下方面的支持:(i)流纹岩熔岩中的挥发物被耗尽;(ii)质地证据支持散发性产品有火山碎屑起源;(三)数字模型显示,小灰颗粒≲10 -5在碎裂和表面之间的时间间隔内,m可以扩散脱气,粘附和烧结至低孔隙率;(iv)从爆炸性喷发和显然是喷发性喷发推断出的上升率可能重叠。我们的模型调和了先前矛盾的观察结果,并提供了一个新的框架来评估地球上最猛烈的火山喷发的物理,数值和地球化学模型。