Isotopic Characteristics of Mesozoic Au-Ag Polymetallic Ore Deposits in Northern Hebei and Their Ore-Forming Materials Source

摘要

It has long been a controversy about the source of ore-forming materials of Au-Ag polymelallic deposits both in metallogenic theory and in ore-searching practice. In terms of a large wealth of the isotopic statistics data from Indosinian-Yanshanian endogenic ore deposits in northern Hebei ( generally referring to the areas along the northern part of Taihang Mountains and northern Hebei, the same below) , it is considered that the ore-forming materials came from the deep interior of the Earth, which had migrated through plumes to the Earth surface while experienced multi-stage evolution and then emplaced progressively in favorable structural loci to form ores. Their isotope data show that 559 sulfur isotopic data from 40 ore deposits are, for the most part, within the range of ― 5per thousand ― 5per thousand, with a high degree of homogenization, indicating that the sulfur is derived mainly from magma; 200 lead isotope data from 37 ore deposits indicate that the ore-forming materials are principally of mantle source though some crust-source material was involved; 96 oxygen, hydrogen and carbon isotope data from 34 ore deposits illustrate that the ore-forming fluids are dominated by magmatic water while other sources of water would be involved. It may therefore be seen that the formation of endogenic deposits has nothing to do with the strata .