Geochemical Characteristics of Rare Earth Elements in the Dolomite of Longjiayuan Formation and Its Indicative Significance on the Southern Margin of the North China Craton
The dolomite of Longjiayuan Formation in the southern margin of the north China is a special set of sedimentary strata in the region.Its tectonic evolution process,diagenesis and mineralization characteristics have always been the focus of regional geological research.Through the test and analysis of rare earth elements in the dolomite and its surrounding rock samples in the area,the ∑REE value of Guandaokou Group dolomite is significantly lower than that of the andesite or rhyolite of Xiong'er Group,which is related to the dripping effect of atmospheric fresh water during the original deposition.It is confirmed that the origin of the dolomite in this area is a sedimentary type.The distribution pattern of rare earth elements in dolomite presents a flat shale standardized curve shape,which indicates that the dolomite in this area has experienced a similar depositional environment and diagenetic process.The dolomite in the area shows obvious positive Eu anomaly,negative Ce anomaly and enrichment of light rare earths,which reflects the reducing and weakly acidic depositional environment.This may be related to the transformation of the tectonic thermal events since the Proterozoic in the southern margin of the north China Craton,which made the dolomite REEs evolve towards the enrichment of light rare earths and positive Eu anomaly,accompanied by the widespread development of lead polymetallic mineralization in the dolomite.
North China CratonDolomiteRare earth elementsGeochemistryIndicative significance
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