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墨西哥西北部谢拉西马德雷山脉(Sierra Madre Occidental)的巴托皮拉斯地区(Batopilas)有两套大陆弧岩浆岩。时代较老的有晚白垩纪至早新生代的花岗岩类,年轻的是中第三纪安山岩至流纹岩系列,大部分以大规模出露的火山碎屑流堆积为代表。火山岩类岩石的SiO_2含量从54%变化至78%,花岗岩类岩石的SiO_2含量则限于57—68%。两套岩石的主要元素通常极相似,然而,较老的花岗岩类与火山岩相比具低的Zr/Nb值和高的Nb/Y和K/Rb值。此外,花岗
There are two sets of continental arc magmatic rocks in the Batopilas region of Sierra Madre Occidental in northwestern Mexico. Older Cretaceous to Early Mesozoic granitoids of the younger age are in the Tertiary andesite to rhyolite series, most of which are represented by large-scale deposition of volcanic debris flow. The SiO 2 content of volcanic rocks changes from 54% to 78%, while that of granite rocks is limited to 57-68%. The major elements of the two sets of rocks are usually very similar, however, older granites have lower Zr / Nb values and higher Nb / Y and K / Rb values than volcanic rocks. In addition, granite