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得克萨斯州西部丰里措(Carrizo)山群1270百万年的辉绿岩床具有与现代洋中脊玄武岩相似的不活动元素丰度。卡里措山群厚层陆源沉积岩和超铝流纹质火山灰流凝灰岩的存在排除了辉绿岩形成于典型的现代洋中脊玄武岩环境的可能。野外的、岩石学和地球化学证据指示卡里措山群沉积在早期大陆边缘弧后盆地。该盆地向北东方向延伸到得克萨斯州柄状狭长地区。上覆的阿兰莫雷(Allamoore)组由沉积岩和堆聚在成熟边缘弧盆地的玄武岩组成。该边缘弧盆地位于拉诺(Llano)区以拉斑玄武岩为主的岛弧后面。
The 1270 million diabase bed of the Carrizo Mountains, western Texas has similar abundances of inactive elements to modern mid-oceanic basalts. The existence of the thick terrigenous sedimentary rocks and the ultra-Allulite volcanic ash tuffs in the Kaluruo Mountains excludes the possibility that diabase is formed in the typical modern mid-oceanic ridge basalts. Field, petrological and geochemical evidences indicate that the Kalimoyama group was deposited in the back-arc basins of the early continental margin. The basin extends north-east to Texas Shallows. The overlying Allamoore Formation consists of sedimentary rocks and basalts that accumulate in mature marginal arc basins. This marginal arc basin is located behind the island arc in the Llano area that is dominated by tholeiite basalts.