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Research on selecting a model to evaluate resources and original gold reserves in Phuoc Son area - Quang Nam - 1


MINISTRY OF EDUCATION AND TRAINING UNIVERSITY OF MINING AND GEOLOGY


LE VAN LUONG

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RESEARCH ON SELECTING A MODEL TO ASSESS RESOURCES AND ORIGINAL GOLD RESERVES IN PHUOC SON AREA - QUANG NAM


Industry: Geological Engineering Code: 62520501


DOCTORAL THESIS IN GEOLOGY


SCIENTIFIC INSTRUCTOR:

1. Assoc.Prof.Dr. TRUONG XUAN LUAN

2. Assoc.Prof.Dr. NGUYEN PHUONG


Hanoi - 2014


INTRODUCTION

1. Urgency of the topic

Phuoc Son area, Quang Nam province has a complex geological structure, with quite rich mineral manifestations; especially primary gold. The results of searching, exploring and exploiting by Phuoc Son Gold Company in recent years show that the area has great potential for primary gold with mineralization manifestations, ore spots, ore mines of different scales, distributed in metamorphic sediments of the Nui Vu formation. The issue of studying mineralization characteristics and selecting a model to assess resources and primary gold reserves in the area has not received due attention. To clarify the characteristics of primary gold mineralization; especially the selection of a suitable resource and reserve assessment model, as a basis for orientation for exploration and exploitation is a necessary task. The thesis for the degree of Doctor of Geology with the topic " Research on selecting a model to assess resources and primary gold reserves in Phuoc Son - Quang Nam area " was selected by the PhD student to contribute to meeting the requirements of the research.

requirements required by reality.

2. Objectives of the thesis

The study clarifies the characteristics of original gold mineralization in Phuoc Son area; Selects a model to evaluate resources, original gold reserves and associated useful components to contribute to perfecting the exploration methodology based on the application of scientific and technological advances.

3. Research object and scope

- Research objects: ore bodies, original gold mineralized zones in Phuoc Son area; especially Dak Sa area.

- Research scope: Phuoc Son area, Phuoc Son district, Quang Nam province.

4. Research content

- Collect, synthesize, systematize, and process mineral geological data; conduct additional research on ore material composition to clarify the characteristics of original gold mineralization in the area.


- Identifying factors controlling primary gold ore as a basis for zoning prospects, contributing to orienting exploration and investment in exploitation.

- Research to clarify the nature and characteristics of changes in key geological parameters of ore bodies to serve the exploration and assessment of resources, gold reserves and associated useful elements.

- Exploiting geographic information system (GIS) applications and specialized software, especially Surpac 5.1 software, to build a database and evaluate resources and original gold reserves in the research area.

- Research on selecting cognitive models and methods for evaluating resources and reserves suitable for Phuoc Son gold ore type.

5. Research methods

To solve research tasks, the researcher uses a combination of the following methods:

- Synthesize and process existing documents, research and supplement mineral geological documents;

- Building a tabular geological mineral database based on Surpac 5.1 software application and GIS database to manage digital maps;

- The study uses statistical mathematical models (one-dimensional, two-dimensional), structure functions (Variogram), mine geometry, and geological cross-sections to model the research object, as a basis for selecting methods to evaluate resources and original gold reserves;

- Research using Kriging method, inverse distance to calculate reserves, identified resources and straight calculation method according to mineralization parameters, regression equation to forecast unidentified resources.

6. Scientific significance and practical value

6.1. Scientific significance

- The thesis contributes additional data to a more comprehensive understanding of the ore material composition, mineralization characteristics and spatial variation of geological parameters of the original gold ore body in the study area;


- The research results contribute to perfecting the exploration methodology; the focus is on researching and selecting suitable models to model and evaluate resources and original gold reserves.

6.2. Practical significance

- Provide managers and businesses with a database of primary gold minerals in Phuoc Son area to ensure reliability and serve as a reference document to guide the search, exploration, and investment in primary gold mining in the area.

- Provide production facilities with a method system to improve reliability in resource and reserve assessment; select an exploration network suitable for Phuoc Son gold ore type and other areas with similar geological and mineral conditions.

7. New points of the thesis

- The original gold in Phuoc Son area is of the typical quartz - polymetallic sulfide - gold type, with two mineral formation stages with a typical mineral symbiotic complex of quartz - pyrite II - gold I and quartz - pyrite II - gold II - galena - sphalerite (possibly with electrum).

- The content of Au and associated elements (Ag, Pb and Zn) in the original gold ore bodies in the study area can be reduced to a log-normal distribution function and there is a relatively strong to strong positive correlation between them.

- The spatial variation characteristics of Au can be modeled by a spherical structure function, the Au content has local variation and weak anisotropy; it can basically be considered isotropic in space. This characteristic is a scientific argument for using square, equilateral triangle, and diamond-shaped exploration networks and at the same time allows the use of the inverse square distance method to calculate the original gold resources and reserves of the research area.


- The research results with the help of Surpac software have confirmed the superiority of the structural function model and the Kriging method in evaluating the resources and original gold reserves of Phuoc Son area.

- The research results have proposed a process for evaluating resources and original gold reserves in Phuoc Son area (Figure 2.11) to ensure reliability and convenience for exploration and mining.

8. Thesis defense arguments

Thesis 1: Using the solution of modeling the composition reflecting the original gold quality by combining statistical mathematical models (one-dimensional, two-dimensional) and structure functions (Variogram) allows a more comprehensive understanding of the mineralization characteristics; Au content in two-dimensional space (according to the direction and slope of the ore body), local variation, weak anisotropy, can be considered as isotropic. This is a scientific argument for applying a suitable exploration network for the original gold ore type in Phuoc Son area.

Thesis 2: Evaluate the resources and original gold reserves of the research area according to the process proposed in the Thesis (Figure 2.11); in which the Kriging method is the main method, ensuring reliability and convenience for using documents in planning exploration and exploitation of mines.

9. Documentation

- Projects to measure and map regional geology at scales of 1:200,000 and 1:50,000.

- Report on the results of gold exploration and exploitation in Bai Dat and Bai Go subdivisions, Phuoc Son region.

- Documents in specialized research projects, surveys, searches, and exploration of primary gold in the region.

- Domestic and foreign sources of documents on assessment of resources, solid mineral reserves in general and primary gold in particular.

- Documents collected by NCS from 2009 to present.


10. Place of thesis implementation

The thesis was completed at the Department of Exploration, Faculty of Geology, University of Mining and Geology under the scientific guidance of Assoc. Prof. Dr. Truong Xuan Luan, Assoc. Prof. Dr. Nguyen Phuong. The PhD student would like to express his deep gratitude for the guidance and enthusiastic help of the scientific supervisors.

The author received attention and support from the Department of Exploration, the Graduate School, the University of Mining and Geology, and the leaders of the Office of the National Mineral Reserves Assessment Council. The author also received encouragement, help, and enthusiastic comments from Dr. Nguyen Tien Dung, Dr. Luong Quang Khang, Associate Professor, Dr. Nguyen Van Lam, Associate Professor, Dr. Nguyen Quang Luat, Prof. Dr. Dong Van Nhi, Associate Professor, Dr. Dang Xuan Phong, Associate Professor, Dr. Le Thanh Me, Associate Professor, Dr. Tran Thanh Hai, Dr. Do Van Nhuan, Dr. Nguyen Mai Quan, Dr. Dang Van Lam, Dr. Tran Van Mien, Dr. Hoang Van Khoa, Dr. Quach Trong Tin, Dr. Bui Hoang Bac, Dr. Khuong The Hung, Dr. Nguyen Quoc Phi and scientists inside and outside the University of Mining and Geology. The author would like to express his sincere gratitude to the leaders of the above agencies and scientists.

The author sincerely thanks the scientists, geologists and colleagues for allowing the use and inheritance of documents to complete this thesis.


CHAPTER 1

OVERVIEW OF THE STUDY AREA

1.1. GEOLOGICAL STRUCTURE CHARACTERISTICS OF PHUOC SON AREA

1.1.1. Location of the study area in the regional structural map

Phuoc Son area has an area of ​​about 100km2 , located to the north of Kon Tum block, belonging to Nam Ngai subterrane [24] (Figure 1.1). Nam Ngai subterrane has a curved and folded structure forming two branches: sub-latitude and sub-longitude formed in the early Paleozoic, corresponding to the late Pan-African or early Caledonian tectonics, located between Ngoc Linh subterrane and Da Nang - Se Cong orogenic belt [24].

1.1.2. History of geological and mineral research

1.1.2.1. Period before 1975

Geological research documents in the area are very sketchy. According to local people, the first people to discover and exploit gold in the area were the Tram people, then the French. Initial research on geology and minerals in the area was conducted by JH Hofet (1941), Fromaget (1952) who measured and drew the Indochina Geological Map at a scale of 1:2,000,000 and 1:500,000. In addition, there are a number of specialized research works on stratigraphy, tectonics and magma by La Croix A, Tran Huynh Anh (1932-1968); isotopic age research by TCV Hilde (1967); C. Faure (1969).

1.1.2.2. Post-1975 period

Systematic geological research and mineral exploration in the region have been conducted by Vietnamese geologists since 1980, including: Surveying and drawing a geological map of Vietnam at a scale of 1:500,000 co-edited by Tran Duc Luong and Nguyen Xuan Bao (1988); Geological and mineral map of Hue - Quang Ngai sheet group (1986) at a scale of 1:200,000 by Nguyen Van Trang and others; Geological map at a scale of 1:200,000 of Ba Na sheet group by Nguyen Duc Thang and others.


revised in 2006. Geological map of Vietnam - Laos - Cambodia scale 1:

1,000,000 by Phan Cu Tien et al. (1989).


Figure 1.1. Diagram of Phuoc Son area in the geological structure of South Central Vietnam, printed scale 1:3,500,000 “Source: Tran Van Tri and Vu Khuc 2010” [24]

Geological mapping project at scale 1:50,000, in the East there is the Tam Ky - Hiep Duc sheet group of Koliada A. A et al (1990); in the North there is the A Hoi sheet group of Bui The Vinh et al (2011); in the South there is the Dak Glei - Kham Duc sheet group of Do Van Chi et al (1997).

In the above works, Bui The Vinh's work classified metamorphic sediments distributed mainly in Phuoc Son area into the Nui Vu formation.

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