subformation
n. 从属形态;单编队;亚群系
例句
The comparison study shows that source the crude oils of the Maling oilfield are derived from Yanchang formation source rocks, especially from Chang-7 subformation.
油源对比表明,马岭油田原油的源岩为延长组烃源岩,特别是长7油层组烃源岩。