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对洛川黄土、古土壤和红粘土中磁性矿物组成、成因和相关系进行了研究。结果表明:黄土磁性矿物以风尘磁铁矿为主,少量的成土赤铁矿和成土磁赤铁矿;古土壤磁性矿物以成土磁赤铁矿为主,成土赤铁矿次之,少量的风尘磁铁矿和赤铁矿;红粘土磁性矿物以成土赤铁矿为主,风尘磁铁矿和成土磁赤铁矿次之,少量风尘赤铁矿。黄土、古土壤和红粘土磁性矿物组成差异,反映了其形成期不同的古气候特性以及不同气候条件下生物地球化学作用强度的差异。干冷的冰期,黄土弱成土作用形成了以粗颗粒的风尘磁铁矿核+赤铁矿边的磁化率载体。间冰期的温暖湿润的古气候最有利于生物活动,强烈生物活动导致古土壤中大量纳米超细磁赤铁矿/磁铁矿产生,形成以磁赤铁矿为主,风尘磁铁矿核+赤铁矿边为辅的磁化率载体。红粘土成壤期,强降雨强蒸发的长干短湿的高温炎热的古气候使得红粘土化学风化强烈,生物地球化学活动较弱,形成以磁铁矿核+赤铁矿边和磁赤铁矿核+赤铁矿边的磁化率载体。黄土、古土壤和红粘土磁性矿物组成、磁性矿物相关系是其形成期独特的古气候指示。
The composition, origin and facies of magnetic minerals in Luochuan loess, paleosol and red clay were studied. The results show that the loess magnetite is dominated by aeolian magnetite and a small amount of hematite and earth maghemite. The ancient soil magnetite is mainly composed of hematite and hematite , A small amount of dust magnetite and hematite; red clay magnetic minerals to hematite hematite, dust magnetite and laterite magmatite followed by a small amount of dust hematite. The differences in the composition of magnetic minerals of loess, paleosol and red clay reflect the different paleoclimate characteristics during their formation and the difference of biogeochemical intensities under different climatic conditions. During the dry and cold glaciations, loessial loess formation formed a magnetic susceptibility carrier at the dust-core magnetite + hematite side with coarse particles. The warm and humid paleoclimate during the interglacial period is most conducive to biological activities, resulting in a large number of nanometer ultrafine maghemite / magnetite in the ancient soil resulting from intense biological activities, forming mainly maghemite, and the dust-magnetite + Hematite carrier complemented by hematite. In the clay-forming period of red clay, the hot and humid climate with strong dryness and long wet with strong rainfall and strong rainfall makes the red clay chemically weathered strongly and the biogeochemical activity is weaker, and the magmatic rocks with magnetite + hematite and maghemite Magnetic nuclei + hematite side of the magnetic susceptibility carrier. Loess, Paleozoic and red clay magnetic minerals, the magnetic mineralogy is a unique paleoclimatic indicator during its formation.