Middle Ordovician Epoch的意思|示意

That a: The Mn-deposits of Middle Ordovician Epoch in central Hunan were high grade Mn-ores with low-P, low-Fe and high basicity;

提出：①湘中地区中奥陶世锰矿是低磷、低铁、高碱度优质锰矿石；

Comprehensive researches have concluded that the Heishan ophiolite was formed in Nanhua Ordovician period and its structural location in Silurian period early Middle Devonian epoch.

综合研究得出黑山蛇绿岩形成于南华—奥陶纪，构造就位于志留纪—早中泥盆世。