Geology of Gold Mineralization In Qeissan Country Blue Nile State ,South Eastern Sudan

Abstract

Acknowledgement I would like to thank the Minister ofMinistry ol“;\/Iinerals Mr. Kamal Abdel Laticf and the Director General of GRAS. Dr. Yusuf F.l Sammany for their financial supports. 'l‘ltz1nks also due to colleagues; Radwan Ahmed for his helps in Remote Sensing interpretations, Mohamed i7edeeu and Fatinia El Badawe in microscopic studies. Also thanks to Dr. A. Kodi Bttkhit, Dr. E. M. Abedl Rahainan. Wad Tan Nour and El Nour Koko for their comments. I am greatly indebted to Dr. Siddig Mahmud El Lain; associate professor in University of El Nelziin, Collage of Mineral and petroleum, Department of Geology for his supervision. and Dr. Mohammed Yahya for his critical reviews and valuable comments. l greatly acknowledge Dr, Ando Fzshulie, the exploration manager ofllyat for Mining and the general ntanager of Eyat Company for their supports in l-‘ield work and sample analysis. My thanks lo all nty colloquics in (IRAS and Eyat Company who are support me in this work. l am also pafliculml)-' indebted to the staff of GRAS, specially my colleagues in the Arlministration of Mineral Resources and Ms. Nagat in information Center for her helps in printing, thanks for their help, comments, discussion and suggestions. xiv

Abstract Higli-grade gneisses and low grade volcano-sedimentary rocks underlain the Queissan area. They have been sheared. folded and faulted extensively. Orogenie plutons and anorogcnie ring complexes have intruded these successions. A mylonitie quartz fcldspathie gneiss (politic). trending northeast to southwest and highly sheared rneta-volcanic rocks hosting the auriferous quartz veins. Detailed geochemical study (grid soil sampling. rock chip sampling) has been carried out to determine the anomalous area. Also a few alluvial samples have been taken to trace alluvial gold mineralization. All samples, (soil 8:. rock) are prepared, analyzed and the results are interpreted using different sol'tware’s (Minpet, Statislictf/. and Surferl0). The gold concentration in soil is rather low grade ranging from .001 to 0.92ppm comparing with those of quartz vein ranging from 0.01 lo 4.27ppm (Appendexl &Z).'l‘he mean calculated for Au in soil was tJ.l5ppm. while for rock was ().0357ppm. The background and threshold values for gold in soil were 0.15 and ().609pp1Tl, while for rock were 0.0337 and (J. l 39ppm respectively. Statistical and geochemical analysis (correlation coefficient, factor analysis and cluster analysis) has been used for evaluating the soil and rock data, from the evaluation, the following are obtained: >Ni, C0, Cu, are forming one phase as they show correlations patterns extremely similar to each other (Fig.S.36].

>The relation between Au and Ag is positive in rock samples while the it is negative in the soil samples, this may be clue to high solubility of silver or silver is amenable to mobilization by weathering. >Au path findei"s in rock samples are Ni, Pb, Ag, and Co as they slightly positively correlated [the same cluster; Fig.5.36]. Au correlations with the other trace elements is negative; Zn, and Cu. That means Au grew at their expense.