研究人员提出了一个地震层析模型，该模型对整个岩浆柱进行了成像，清楚地揭示了间歇泉—清湖地区下方的多层次跨地壳岩浆系统。来自地幔的上升流熔体穿过壳幔边界，并在清湖东南部下方的下地壳中积聚，形成热莫霍面。
由于西部的伸展作用和上覆刚性蛇绿岩碎片的物理屏障作用，镁铁质熔体主要向西上升，最终形成下伏和加热间歇泉地热田的浅层硅质岩浆储层。此外，本研究还将大陆背景下成分多样的火山作用与多层次跨地壳岩浆体系的分异联系起来。
据悉，第四纪清湖火山区(CLVF)的岩浆活动，其最近一次的喷发仅发生在大约c.10ka年前，通常被认为是世界上最大的商业地热储层—位于加利福尼亚北部的间歇泉的热源。研究人员在地壳中上部发现浅硅质岩岩浆库已有一段时间，但对其潜在的深部镁质岩浆储层的位置和形成机制的研究还止步不前。
附：英文原文
Title: Multilevel transcrustal magmatic system beneath the Geysers-Clear Lake area
Author: Li, Tianjue, Wu, Shucheng, Tong, Ping
Issue&Volume: 2024-3-11
Abstract: Magmatism in the Quaternary Clear Lake volcanic field (CLVF), with its youngest eruption having only occurred c. 10 ka ago, is commonly invoked as the heat source for the world’s largest commercial geothermal reservoir, The Geysers, in northern California. A shallow silicic magma reservoir in the upper-middle crust has been discovered for some time, but the location and mechanism of a potential deep mafic magma reservoir have remained elusive. Here, we present a seismic tomographic model that images the entire crustal column, clearly revealing a multilevel transcrustal magmatic system beneath the Geysers-Clear Lake area. Upwelling melts from the mantle traverse across the crust-mantle boundary and accumulate in the lower crust underneath the southeastern part of Clear Lake, resulting in a hot Moho in between. Mafic melts primarily ascend westward due to the extensional regime in the west and physical barrier effect from the overlying rigid ophiolite fragment, ultimately forming a shallow silicic magma reservoir underlying and heating The Geysers geothermal field. In addition, this study also links compositionally diverse volcanism in a continental setting to differentiation in a multilevel transcrustal magmatic system.
DOI: 10.1073/pnas.2317809121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2317809121