【摘要】 对青藏高原北部柴达木盆地西北缘红三旱地区古近系高精度的磁性地层研究表明,下干柴沟组的磁极性带对应标准地磁极性年表C16n—C18极性时熏相应的磁性年代为大于40Ma至35.5Ma,其地质时代属于始新世早、中期;上干柴沟组的磁极性带对应C8.2n—C15极性时,相应的磁性年代为35.5～26.5Ma,地层的地质时代属于始新世晚期和渐新世早、中期。上、下干柴沟组的界线位于C16n顶部,其年代约为35.5Ma。上干柴沟组顶部的砂砾岩或砾岩层,以及沉积速率的大幅增加可能是该地区在27.9～26.5Ma期间规模隆升的结果。更多还原

【Abstract】 A highly precise magnetostratigraphic study was carried out on the Paleogene in the Hongsanhan area on the northwestern margin of the Qaidam basin. The magnetic polarity zone of the Lower Gancaigou Formation corresponds to subchrons C16n-C18 of the recommended international geomagnetic polarity timescale (GPTS) with a corresponding age of >40 to 35.5 Ma, indicating an early-mid Eocene geologic age. The magnetic polarity zone of the Upper Gancaigou Formation can correspond with subchrons C8.2n-C15 with a corresponding age of 35.5 to 26.5 Ma, indicating a late Eocene-early-mid Oligocene geologic age. The boundary between the Upper and Lower Gancaigou formations is located at the top of subzone C16n, with an age of ～35.5 Ma. The accumulation of sandy conglomerate or conglomerate layers on the top of the Upper Gancaigou Formation and the marked increase in sedimentation rate are probably the result of large-magnitude uplift of the area at 27.9-26.5 Ma.更多还原