火成论的

例句：

1. 1. The mineral deposit is believed to be of volcanic origin.
   这个矿床被认为是火山起源的。
2. 2. The rocks in the area are mostly made up of igneous materials.
   该地区的岩石主要是由岩浆材料组成的。
3. 3. The geological survey revealed that the region was once covered by a vast lava flow.
   地质调查发现，该地区曾经被大量的熔岩流覆盖。