柴达木盆地北缘滩间山群的构造属性及形成时代

Tectonic setting and age of the“Tanjianshan Group”on the northern margin of the Qaidam basin

滩间山群在柴达木盆地北缘构造带广泛发育,以浅变质的中基性火山岩为主,可见少量细碎屑岩和碳酸盐岩。该群的成岩背景过去多认为是陆内裂陷槽环境,时代归属晚奥陶世至志留纪。新近绿梁山地区的区调填图研究表明,滩间山群的岩石组合具岛弧背景的建造特点,地球化学特征也显示了火山弧的构造属性,区域地质特征及同位素年龄表明滩间山群很可能是寒武纪—奥陶纪的产物,与超基性—基性岩体一起构成一套早古生代蛇绿杂岩组合。

The“Tanjianshan Group”is widely distributed on the northern margin of the Qaidam basin.It consists dominantly of low-grade metamorphic intermediate-basic volcanic rocks,with small quantities of fine clastic rocks and carbonate rocks.Previously it was considered that this group formed in an intraconti-nental aulacogen during the Late Ordovician to Silurian.Recently,the regional mapping of the Lüliang Mountains indicates that the rock association of the Tanjianshan Group has the characteristics of a forma-tion with the island-arc setting.Geochemical characteristics also indicate the tectonic attribute of an vol-canic arc.Regional characteristics and isotope ages also suggest that this group is very likely to be the Cambrian-Ordovician product and combines with ultrabasic-basic rock to form an Early Paleozoic ophi-olitic complex.