河北崇礼一带层控金矿床

崇礼-带晚太古代桑干群含金地层,系由-套中-基性火山-沉积岩系组成,其含金丰度高出地壳平均丰度的2～5倍.金矿化主要赋存于桑干群上部变质岩中,具有明显的层控特征.根据成矿特点,提出了四个找矿远景区.

STRATABOUND GOLD DEPOSITS IN CHONGLI AREA, HEBEI

The Sangang auriferous formation in Chongli area of Hebei Province is located at the north margin of the North China platform, consisting chiefly of late Archean intermediate and basic volcanic-sedimentary series, with an isotopic age of 2600 m. y.. This series of rocks has been metamorphosed into hornblende and granulite facies, with rich abundance of Au-Ag, formed a tight linear fold, in which fractures were well developed. Magmatite is mainly composed of basic volcanic rocks and granite. Magmatic eruption is developed in three epoch: Archean; Hercynian movement; and Yenshan movement. Gold deposits are controlled by NW and NNW fracture structurcs. Two types of gold deposits are recognized: auriferous quartz (simple vein and compound vein) and gold-bearing altered rocks.Gold mineralizations occur in metamorphic rocks underiying the Sangang group with distinct stratabound feature. The gold mineralization is of multi-stage. The lead isotope of ores is the ancient weak anomalous lead with a model age of 2.5 - 7 m. y.. The sulfur isotope ratio being as a mean value of -10 per mil indicates that the ore deposits have undergone erosion and weathering and that the mineralization is associated with the surface water. The source material is derived from the Sangang group. The metallogenic pattern is volcanic-sedimentary-regional metamorphic; migmatitic-dilatancy-magmatitic. Four prospects have been suggested by the author.