Petrologic constraints on the development of a large-volume, high temperature, silicic magma system: The Twin Falls eruptive centre, central Snake River Plain
Petrologic constraints on the development of a large-volume, high temperature, silicic magma system: The Twin Falls eruptive centre, central Snake River Plain
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DOI：
10.1016/j.lithos.2010.09.008
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发表时间：
2010-12
期刊：
影响因子：
3.5
通讯作者：
B. Ellis;T. Barry;M. Branney;John A. Wolff;I. Bindeman;Rob Wilson;B. Bonnichsen
中科院分区：
文献类型：
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作者：
B. Ellis;T. Barry;M. Branney;John A. Wolff;I. Bindeman;Rob Wilson;B. Bonnichsen
爱达荷州南部和内华达州北部的桂皮山脉记录了与黄石热点相关的爆发性火山活动，时间跨度约为 11.3 至 9 Ma，被认为是从双子瀑布喷发中心喷发的。地层包含强烈熔结的流纹岩 (SiO269–76wt.%) 熔结岩，具有无水矿物：斜长石、透长石、石英、辉长石、辉石、钛铁矿、钛磁铁矿、副锆石和磷灰石。几种不同的温度计表明存在高温流纹岩浆 (>900°C)。所有决明山熔凝岩都显示出 δ18OVSMOW 的显着损耗，岩浆长石值在 1.7 至 3.0‰ 之间，反映了热液蚀变原岩的并入。在单个火凝灰岩中可能会出现变辉石 (Mg# 30–46) 和辉石 (Mg# 17–53) 的多种成分，而晶体聚集体仅包含每种成分的单一成分。火凝结岩内的成分异质性反映了一个复杂的岩浆系统，岩浆在喷发前被分成多个较小的房间。
Explosive volcanism associated with the Yellowstone hotspot spanning ~11.3 to 9Ma, thought to have erupted from the Twin Falls eruptive centre, is recorded in the Cassia Mountains of southern Idaho and northern Nevada. The stratigraphy contains intensely welded, rhyolitic (SiO269–76wt.%) ignimbrites with an anhydrous mineralogy: plagioclase, sanidine, quartz, pigeonite, augite, ilmenite, titanomagnetite, accessory zircon and apatite. Several different thermometers indicate high temperature rhyolitic magmas (>900°C). All Cassia Mountain ignimbrites show a significant depletion in δ18OVSMOWwith magmatic feldspar values between 1.7 and 3.0‰, reflecting incorporation of a hydrothermally altered protolith. Multiple compositions of both pigeonite (Mg# 30–46) and augite (Mg# 17–53) may occur within an individual ignimbrite while crystal aggregates contain only a single composition of each. The compositional heterogeneity within the ignimbrites reflects a complex magmatic system whereby magma was segregated into multiple smaller chambers prior to eruption.