罗布泊坡北基性—超基性侵入岩体航磁特征及其成矿规律

Aeromagnetic Characteristics and Metallogenic Regularity of Pobei Basic-ultrabasic Rock in Lop Nor

罗布泊坡北基性-超基性侵入岩体主要是辉长岩、辉橄岩及橄榄岩构成的多期次复式岩体,其航磁特征表现为内部叠加有多个较弱小尖峰状正磁异常的强烈尖峰状负磁异常区,异常区形态与岩体完全吻合。从航磁特征、实测磁化率、剩磁定量测试和正演拟合计算分析可以得出,基性-超基性侵入岩对应的负磁异常由辉长岩剩磁引起,内部叠加正异常则与辉长岩体内后期侵入的橄榄岩-橄榄辉长岩有关。航磁地质解译表明,坡北岩体具有三次岩浆侵入活动发生,分别形成了磁性差异较大的辉长岩主体及其中呈正常磁化的橄榄岩、橄辉岩等超基性小岩体,在超基性小岩体周边及切割岩体的次级断裂构造部位具有良好的成矿前景。

The northern Lop Nor basic-ultrabasic intrusive rock mass is mainly a multi-stage compound rock mass composed of Gabbro,pyroxenite and peridotite.The aeromagnetic characteristics shows that there are multiple weaker spike-like positive magnetism superimposed inside.In abnormal strong spike-like negative magnetic anomaly area,the shape of the anomaly area is completely consistent with the rock mass.From the aeromagnetic characteristics,measured magnetic susceptibility,quantitative test of remanence,and forward fitting calculation analysis,it tums out that the negative magnetic anomaly corresponding to the basic-ultrabasic intrusive rock is caused by the remanence of the gabbro and the peridotite-olivine gabbro invaded later in the feldspar is related.Aeromagnetic geological interpretation shows that there are three magmatic intrusions in the Pobei Pluton.The main bodies of gabbro with large magnetic differences and the ultra-basic small intrusions such as peridotite and olivine pyroxene with normal magnetization are formed respectively.It has good mineralization prospects around the ultra-basic small rock mass and the secondary fracture structure of the cutting rock mass.