云南大姚地区上白垩统马头山组六苴段中亚段

上白垩统马头山组六苴段中亚段(K2ml2)是云南六苴砂岩型铜矿区内含铜层位之一。六苴段中亚段含铜砂岩Mo、Cd、As、Cu等亲硫元素富集。微量元素多富集于浅色砂岩中，向紫色砂岩一侧逐渐亏损，呈现分带特征。铜矿石V/(V+Ni)值大于0.7，反映缺氧环境的特点。稀土元素总量(∑REE)101.71×10-6～157.55×10-6，稀土元素分配模式为Eu、Ce亏损-轻稀土元素富集型。从铜矿石→浅色矿化砂岩→浅色无矿砂岩，随着铜含量的降低，Mo、Cd、As、Hg平均含量逐渐降低，∑REE与高场强元素Nb、 Zr、 Hf、Th平均含量逐渐升高。六苴段中亚段砂岩具“矿源层”的特征，铜矿石与围岩具物源一致性，铜矿石在弱碱性、还原条件下由砂岩经水-岩作用形成，与六苴铜矿床(K2ml1)成矿机理相似。小河地段纵向上从北向南，六苴段中亚段中铜矿化的能力逐渐减弱，推测矿化带在走向上向西(紫色砂岩一侧)发生了偏移。

Trace elements and REE geochemistry of copper-bearing sandstone in the Middle Submember of the Liuju Member of the Upper Cretaceous Matoushan Formation, Dayao County, Yunnan Province, China.

The Middle Submember of the Liuju Member in the Upper Cretaceous Matoushan Formation is one of the copper-bearing horizons in the Liuju sandstone copper district. The sulphophile elements such as Mo, Cd, As and Cu are enriched in the sandstone. Trace elements are enriched in gray sandstone and depleted in purple sandstone. In the copper ore, value of V/(V+Ni) is over 0.7, which indicates that it is formed in oxygen-poor environment. The ∑REE of rocks ranges from 101.71×10-6 to 157.55×10-6. Chondrite-normalized REE distribution patterns show oblique to the HREE side with the poor Eu, Ce and enrichment in LREE. From the copper ore to gray sandstone, and then to purple sandstone, the average values of Mo, Cd, As and Hg reduced gradually, and Nb, Zr, Hf,Th and ∑REE increased gradually. It indicates that the copper ore and wall rock have the similar provenance. The copper ore formed by water-rock interaction of wall rock with weak alkaline and reducing property condition. The metallogenic mechanism is similar to that in the Liuju copper deposit. From north to south in Xiaohe ore block, the weakening mineralization ability of Cu, and the ore belt deflect to west part (purple sandstone).