The Study On The Geological And Geochemistry Characteristics Of Isua BIF Iron Ore Deposit, Greenland

Greenland is famous for its’ oldest gneissAm tsoq gneiss) and the Isua supracrustal belt(ISB)(more than4000Ma) in the world. on the island, the mineral resources is very rich, and theiron ore is the highest economic value in all the resources. Isua iron deposit in west ofGreenland, and in the distance of150kilometers, northeast of Nuuk-the capital of Greenland. Doresearch about the geological characteristics, geochemical characteristics of the Isua iron oredeposit and other important aborad ore deposit, which are essential for us to maintenance ofmineral resources security, implement the strategy of "going out", seek and establish some stableoverseas mineral resources base, maintain the national economic sustainable, realize the greatrejuvenation of the "Chinese dream".Guided by the modern regional metallogenic theory, using of mineralogy, microscopy,chronology and geochemistry method, in this thesis, the geological and geochemicalcharacteristics of Isua iron deposit were mainly focused. This study are mainly based on theachievements of predecessors, geological, mineral exploration and scientific researchachievements of predecessors in Isua were summarized, then,we gather proper samples fromthe outcrop in Isua, August2012, to check the result obtained and wish getting new discovery.The main achievements are as follows:Mineragraphy of BIFs shows that: the textures of the majority of these materials range fromfine-grained to medium-grained, in bedded structure or banded structures, All assemblagescontain quartz as a major constituent as well as magnetite in most cases. This is same in GongChang Ling, And metamorphisms in Gong Chang ling are more complex than that in Isua.Isua’s total iron content (49.7%) was lower than those of Gong Chang Ling iron ore(49.9%), while, the Isua iron ore smaple can be above67%, after magnetic separation. The BIFshave been studied for major and trace element, On the primitive mantle-normalized diagram,Both BIFs are enrich in U,P, Sm, and more strongly depleted in Sr, Ti. Isua BIFs is more rich inY,Yb,Lu and more depleted in Ba、Nb、Zr、Hf、Sm than that in Gong Chang Ling BIFs. TheLREE and HREE patterns of both BIFs, They display U-shaped chondrite-normalized REEpatterns, with variably positive Eu and negative Ce anomalies, both the LREE part difference isbigger than HREE. And the Isua‘s chang range is bigger, while abnormal degree less than thatGong Chang Ling’sThe Isua supracrustal belt conglomerate rocks give yields of (commonly40-120μm long),prismatic, oscillatory-zoned zircons with less common, somewhat rounded zircons of volcanicand/or detrital origin.The ages of these zircons are different in two periods,one ages is3570Ma-3739Ma, the other ages is2709Ma. that means, duing the times we obtained, at leasttwo episodes of metamorphism occurred in the Isua supracrustal belt.Based on the Geochemical, isotope systematics study, scholars argued that BIFs werederived from volcanogenic sources by seafloor hydrothermal alteration, after series of structurereform and metamorphism.During the Isua iron deposite exploration process, based on aeromagnetic, electromagnetic,airborne hyperspectral scanning and radiometric surveys, new methods have been introduced andused.Additional targets in the southwest and south regions of the Isua existing orebody have beenrecongnized.