Multi-Stage Mineralization And Prospect Evaluation Of The Mengku Iron Deposit, Altay

Mengku Iron deposit is the largest iron deposit in Xinjiang, west China,whose's structural position is located in the Mazy volcanic sentiment basin whichformed in the late Paleozoic active continental margin, but the genesis of Mengkuiron deposit is a conflict for a long period of time. This thesis is mainly aboutstaging the structural and metamorphosed formation ore-controlling regularity andmetallogenic model systematically based on comprehensive analysis ofmetallogenic background, also with evaluation of the regional exploration. Themain analysing method implicated are mineral geochemistry, chronology,decrepitating method, fluid inclusion microthermometer, Synchrotron radiationX-ray fluorescence microanalysis (μ-SRXRF) and Laser Raman spectroscopy.Achievements of metallogenesis study in this thesis are:1) Clearly definingthat the main enrichment and metallogenic period of Mengku iron deposit areAltay main collision orogeny–reginal metamorphose period, the paleo submarinevolcanism of Early Devonian Epoch only formed the initial material resource ofiron (impregnated structural lean element). The postorogenic hydrothermalmetasomatism mainly related to the copper mineralization;2) Get a relativelycomprehensive consideration about a characteristic of ore mineral, hydrothermalfluid and ore forming material sources based on integrated application of variousanalytical methods. The study result shows that δ¹⁸O_SMOWof magnetite fromMengku iron deposit varies from-2‰to+1.77‰with the average of-0.15‰thatsimilar to sedimentary-metamorphic iron deposits and clearly differs from that oftypical skarn type iron deposits. Content of Rare Earth Elements in magnetite isvery low, the range of ΣREE is0.94ppm to4.46ppm, with the characteristic ofrichen of LEE and right dip rare earth elements patterns which indicate thatsources of metallogenic materialism are closely bound up with volcanic rocks;Value of δCe shows that relatively oxidizing metallogenetic environment turned tobe reducing. Decrepitating of magnetite suggesting overlapping of multistagemetalloginesis. Laser Raman study shows the composition of fluid is mainly ofH₂O and CO₂; μ-SRXRF test shows constent of iron family elements andsulphophile elements in fluid are relativly high, which indicates the contributionof fluid to mineralization; Sm-Nd isotope chronology study indicates the sourceof ore-forming materials is from the ancient continental basement. Rb-Sr radioisotopic tracer study suggesting that charactristics of fluid is the mixed crustand mantle source.3) This thesis gives out a metallogenetic model of MengkuIron deposit based on analyzing the geological background, ore controllinggeological condition and mechanism of multi-stage mineralization, also build upan exploration model based on geochemical marks and geophysical data of theMengku orefield, still evaluated the mineralization prospecting of the Mengkuiron deposit briefly, concluding that blind ore deposit maybe occurs in the deephinge zone, and the detachment structure of Tiemuxiaergun enclosed syncline.4)This thesis applies the geological statistics method of geological variables toevaluate the resource prospecting of Altay area for the first time, raising a thoughtand working method of evaluating resource prospecting and optimizing targetingfor ore prospecting. This thesis also gives out seven prospecting area based ongeological variable's anomaly of regional geological data and regionalgeochemical data which's scale is1:200,000.