摘要
通过华北地台北缘两侧超基性岩带Sm-Nd同位素等时线测定,首次获得位于燕山南岩带的放马峪岩体为2010±155Ma,属于燕山中岩带的罗匠沟岩体为881±29Ma,属于西拉木伦岩带的柯单山岩体为665±46Ma。华北地台北缘内外两侧超基性岩带(体)侵位由老到新的演化关系,与该区构造演化关系是一致的。
Three EW-extending ultrabasic rock belts occur along the northern margin of the North China Platform, i.e., the Yanshan South Belt, the Yanshan Middle Belt and the Xilamulun Ophiolite Belt in going from south to north, respectively.The emplacement ages of the ultrabasic massives have been determined by the Sm-Nd method and the whole-rock Sm-Nd isotopic isochron ages are 2010 + 155 Ma (Fangmayu massif, Yanshan South Belt), 881±29Ma (Luojianggou massif, Yanshan Middle Belt) and 665±46 Ma(Kedanshan massif, Xilamulun Ophiolite Belt). Chronology data for the ultrabasic massives indicate that the emplacement evolution of the three ultrabasic rock belts shows a trend of becoming younger from south to north, in consistence with the evolution of geotectonics there.Samples from the three ultrabasic massives were dated at (143Nd/144Nd)0 = 0.510004, 0.511506 and 0.511726, with εNdt=-0.25, 0 and -0.95, respectively, demonstrating that the magma was derived from the upper mantle.
出处
《地球化学》
CAS
CSCD
北大核心
1991年第2期128-133,共6页
Geochimica
基金
国家自然科学基金(4870186)
