concretion forms是什么意思

用法例句

The sedimentary environment and genesis of Middle Ordovician nodular limestones in Keping,Xinjiang;

新疆柯坪中奥陶统结核状灰岩的沉积环境及成因

A sedimentary copper deposit was discovered in Upper Permian (P_2x) Xuanwei Formation of Emeishan basalts in northeastern Yunnan Province, and the nodular copper mineralization and disseminated copper mineralization were recognized in the ore district.

研究表明,区内沉积型铜矿床主要有两种矿化类型:结核状铜矿化和浸染状铜矿化,矿石矿物以辉铜矿、斑铜矿、铜蓝等为主;成矿受上二叠统宣威组沉积地层控制,与峨眉山玄武岩喷溢形成的古火山构造和古地形以及火山期后的热泉活动关系密切,有机质在成矿过程中可能发挥了作用;成矿过程可能从沉积成岩阶段一直延续到成岩期后。