Summary of technical doctoral thesis: Research on the selection of models for mineral resource assessment of lode gold deposits at Phuoc Son – Quang Nam

To study the characteristics of mineralization zone of lode gold in Phuoc Son area; To select resource assessment models for lode gold ores and associated minerals, as a contribution to exploration methods using newly developed scientific and technological advances.

MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF MINING AND GEOLOGY

LE VAN LUONG

RESEARCH ON THE SELECTION OF MODELS FOR MINERAL RESOURCE ASSESSMENT OF LODE GOLD

DEPOSITS AT PHUOC SON – QUANG NAM

SUMMARY OF TECHNICAL DOCTORAL THESIS

Ha Noi - 2014

Petroleum Faculty, Ha noi University of Mining and Geology

Advisors:

1 Prof Dr Truong Xuan Luan

2 Prof Dr Nguyen Phuong

Reviewer 1: Prof Dr Đo Đinh Toat

Reviewer 2: Dr Hoang Van Khoa

Reviewer 3: Dr Bui Tat Hop

The thesis will be defended in Assessment Committee of University level which meeting at Hanoi University of Mining and Geology in time hour date

month year 2014

References to thesis at library: National library or Hanoi University of Mining and Geology library

INTRODUCTION

1 Rationale of research: The Phuoc Son area, of Quang Nam province, has complex geological structures and rich in mineral resources, especially, lode gold deposits However, research issues on mineralization characteristics and the selection of mineral resource assessment (MRA) models are not thoroughly studied To elucidate the characteristics of lode gold occurrences; especially to select the appropriate models for mineral resource assessment and reserve calculations, forming a basis for the exploration and exploitation periods os a necessary task The disertation “Research on the selection

of mineral resource assessment models for lode gold ores at Phuoc Son area, Quang Nam province” is prepared from actual requirements

of mining activities in study area

2 Objectives of the study: To study the characteristics of mineralization zone of lode gold in Phuoc Son area; To select resource assessment models for lode gold ores and associated minerals, as a contribution to exploration methods using newly developed scientific and technological advances

3 Objects and scopes of the study: The ore bodies and mineralization zone of lode gold at Phuoc Son region, especially in the Dak Sa area

4 Research contents: Data collection, investigation of previous studies and data analysis for geological and mineral resource information

Additional research material composition to elucidate the characteristics of the original gold ore Determine the partition base and prospect base area Phuoc Son gold Studies shed light on the nature and characteristics of transformation parameters geological ore body serves exploration, resource evaluation, gold reserves Application of geographic information system (GIS) software dedicated especially Surpac 5.1 software to build a database, resource assessment, the original gold reserves Study selection model awareness mineralization characteristics and change selected resource assessment methods, appropriate reserves root Phuoc Son gold ore types

5 Research methods: Collect, synthesize, geological data processing of minerals; Additional research material composition of ore; Building a database (the database) geological mineral form of tables on the basis of Surpac software applications and databases in GIS to manage digital map; The study used models: statistical (one-way and two-way), the structure function (Variogram), mine geometry, geological cross-sections for modeling objects as the basis for the research methodology selection resource prices, original gold reserves; Research using the Kriging method, inverse distance weighting to calculate reserves, resources and methodology determined according to mineralization straight to forecast resource undetermined

6 Significance scientific and practical values:

- Scientific significance: the thesis contributes additional evidence on a more comprehensive understanding of the material composition of ore, mineralization characteristics and spatial variations of the geological parameters of the original gold ore bodies investigated Research; Contributing to complete exploration methodology; Research focus is on selecting the appropriate model for resource assessment, the original gold reserves

- Practical significance: to give managers and enterprise database geological mineral Phuoc Son Gold root zone to ensure reliability, the references in the search and navigation, exploration and mining; Provide production base methodology to enhance the reliability of resource assessment, reserve; Selecting the appropriate network probe with original style Phuoc Son gold ore and other areas where geological conditions similar minerals

7 New achievements of the disertation:

- Phuoc Son Gold of the original style quartz - sulphide polymetallic - typically yellow, two-stage mineralization with complex symbiosis is characterized mineral quartz - pyrite II - the first gold and quartz - pyrrhotite II - Gold II - galena - sphalerite (possible electrum);

- Content of Au and associated elements (Ag, Pb and Zn) in the root zone of gold ore bodies may inductive study of the standard

logarithmic distribution function, we have the relationship between correlated from relatively tight to close tightly

- Characteristics of Au transformed space can function modeled by model type bridge structure, Au concentrations have local variability and weak anisotropy, can basically see as isotropic in space This feature

is the scientific foundation for network exploration using squares and equilateral triangles, rhombus

- The results of the study with the help of software Surpac Vietnam confirmed the superiority of the model structure and function Kriging method in resource assessment, the original gold reserves Phuoc Son

- The study results suggested resource assessment process, the original gold reserves Phuoc Son ensure reliability, utility and mining exploration

8 Theoretical points of dissertation:

Thesis 1: Using modeling solution components reflected by the quality of the original gold complex statistical models (one-dimensional, two-dimensional) structure and function (Variogram) has contributed to a more comprehensive awareness of mineralization characteristics; Au content in two dimensions (in strike and dip of ore body) local variation, weak anisotropy, can be considered as isotropic This is a scientific foundation for network application suitable for ore exploration area Phuoc Son gold original

Thesis 2: Resource Assessment, the original gold reserves according to the research proposed in the thesis (Figure 2:11); Kriging method which is key to ensure the reliability and utility for use in planning material exploration and mining

9 Basis Document

The work geologic mapping area ratio 1:200.000, 1:50,000; Report the results of exploration, gold mining and the original subdivision Bai Bai Dat Type the Phuoc Son; Documents in the thematic studies, surveys, original gold exploration in the region; The resources of gold and foreign origin

10 Place this research

The thesis was completed at the Department Search and Exploration, Department of Geology, University of Mining and Geology under the scientific guidance of Prof Truong Xuan Luan, Prof Nguyen Phuong NCS is pleased to express deep gratitude for the guidance and help of the dedicated science instructor NCS received attention, facilitated by the Department of exploration, backroom University, University of Mining and Geology, Office Leadership Board of Assessment national mineral reserves The teachers, scientists in and outside the University of Mining and Geology NCS would like to express gratitude!

CHAPTER 1 OVERVIEW OF THE STUDY AREA 1.1 STRUCTURAL CHARACTERISTICS OF REGIONAL GEOLOGY PHUOC SON

1.1.1 Position in the scheme of the study area structure

Phuoc Son region has an area of approximately 100km2, located north of Kontum massif, terrane of South Asia Ngai

1.1.2 History of geological and mineral research

- Before 1975: Geological studies document the left is a representative profile Fromaget, JH Hofet (1933-1941), La Croix A, Tran Huynh Anh (1932-1968)

- After 1975: Works geological mapping and mineral ratio of 1:500.000 Tran Duc Luong and Nguyen Xuan Bao co-editor (1976) Geological and mineral maps Bana ratio 1:200.000 sheets are vetted Nguyen Duc Thang 2006; The East team to Tam Ky - German Association of Koliada A A et al (1990); A group of northern forms of Bui The Vinh Hoi et al (2011); To the south is the newspaper group Dak Glei - Do Kham Duc Van Chi et al (1997)

The search for the 1:10,000 scale gold Phuoc Son has done in 7 areas: Banana Beach, K7, Longjing Tea - Spring Tree, Butterfly Beach, Golden Light, Wind and Mountain Gold Beach Sa Dak area has been explored

1.1.3 An overview of the stratigraphy

NCS uses geological map scale 1: 25,000 of Le Van Hai et al, combined with vetted results geological and mineral maps 1:200.000

sheets Bana rate of Nguyen Duc Thang et al, topographic maps mineral ratio 1:50,000 sheets A group of Bui The Vinh Hoi et al include the following formations:

+ Kham Duc Formation, middle tier module (PR2-3kd2) consists of quartz-biotite schist, quartz-chlorite, quartz-biotite schist containing garnet

+ Breast Mountain Formation, the upper sub (PR3-€ 1nv2) occupies the largest area distribution center in the study area Lithological composition includes quartz schist - biotite, actinolite - albite, actinolite - chlorite, limestone and shale of lime blossom The rocks are strongly modified, common slope angle 30-500 During the oral argument breaks, fractures of the quartz schist - biotite, calcareous shale, distribution of ore bodies of gold polymetallic sulfide quartz vein, network circuit, circuit lens Thickness of about 1,300 meters floor modules

+ A Great Formation (€ 2-O1av) consists of schist quartz - biotite, quartz - biotite-chlorite, sericite - quartz, slate coal-rich material

1.1.4 Overview of intrusive

Mainly granodiorit, granite - biotite phase 2 complexes Ben Giang - Que Son distributed in the west of the original gold-related areas, less than olivinit rock, pyroxenite Hiep Duc complex, in addition to the majority circuit unknown age

1.1.5 An overview of structural features, tectonic

The west fault Kham Duc, Dak Po Ko, K7, K7 which faults and anticlines Song Giang distribution of quartz - sulphide polymetallic - gold on the southwest side These are favorable conditions for root in the area, looking for gold

In a nutshell: the Phuoc Son geological structure complicated, distributed mainly metamorphosed sedimentary Breast Mountain Formation, upper level modules The sulfide ore bodies of gold in quartz schist quartz - biotite, alternating calcareous shale files related to faulting K7 and distribution wing Giang River anticline This is the basis

of delimitation, the area of the original gold prospects in the region

1.2 Features gold mineralization awkward angle Phuoc Son

8 areas identified primary gold ore distribution includes: Dak Sa, Banana Beach, K7, Longjing Tea - Spring Tree, Butterfly Beach,

Golden Light, Wind and Mountain Gold Beach In which the Dak Sa has been explored in two zones (2 mines), the other new zones meticulous search

1.2.1 Characteristics of the mineralization zone

The gold mineralization zone containing the main northeast - southwest, longitude, northwest - southeast, length 200 - 1,500 mm, width 5 - 30 m depth is estimated at 45 - 100m On the Au: 0.1 to 98.16

g / t; deep, Au: 0.1 to 69.7 g / t, averaging 0.5 to 3.27 g / T

1.2.2 Characteristics of ore bodies

Sa Dak region, including two sub-areas and grounds timber yard

- Beach Land Division Main orebody (BDMQ) accounting reserves mainly in zones, quartz schist in practice - biotite Small ore bodies (BDUQ) located on a thickness small, discontinuous distribution, of little value

- Classification Type Beach area have been 6 beam control including SERP itself, BGUQ, SC2, MB2, BGLQ, QTZ4 and 02 single body SC3, MB1 In particular ore body QTZ3 (under the beam itself BGLQ) accounts for the reserves in subdivisions distributed in quartz schist episode - biotite calcareous shale alternating sets

Comment: in the Dak Sa, the original gold ore bodies form circuits, network circuits, circuit lenses, fill the cup surface layer of the developing northeast - southwest, is the less than or west longitude north - SE Part of the wall is often distributed collection of flowers limestone, calcareous shale alternating quartz schist episode - biotite, usually cylindrical quartz schist - biotite, the boundary between the rocks surrounding the ore body

is relatively clear

1.2.3 Characteristics of material composition

The thesis focused research, describe, calculate parameters Sa Dak mineralization zones, as the basis of interpretation of ore characteristics and model selection evaluation resources reserve

- Mineral components: Beach Land subdivision mainly pyrrhotite, pyrite, galena, sphalerite and native gold (electrum can be) filled cracks form, accounting for 1 ÷ 65% In that little sphalerite from 50% to 12% less galena, pyrite from less to 2%, from less than 1% pyrrhotite; Subdivision consisting of pyrrhotite timber yards,

pyrite, sphalerite, galena and native gold (electrum can be); total sulfide minerals 2 ÷ 15%, locally up to 45%

+ Main mineralogical characteristics: native gold (Au) exist are varied and plentiful including 2 generations scattered disseminated in quartz; IC form filling cracks; and disseminated sphalerite and gelenit (image 1.3, 1:16) Gold particle size from 0.01 to 0.2 mm, from relatively isometric (photo 1.3) to the distorted grain (photo 1.5) or granular particles to form larger neighbor (photo 1:16), in the form spontaneous encounter Au system flat contact with galena, sphalerite (Image 1.3); with galena, sphalerite and pyrite II (picture 1:16)

Photo 1.3 Model LV1, floor furnace 1, China BDMQ Native gold, isometric particles in contact with galena and sphalerite Picture Flat 1.5 Model LV2-2, 2-story fireplace, China BDMQ Extends native gold grains disseminated in accordance with the microchip micro cracks 1:16 Picture: BG 7.3 (oven 1) China QTZ3, native gold (Au) (≈ 0.2 mm) created THCSKV with sphalerite, galena, pyrrhotite II

Non-ore minerals are mainly quartz, dolomite, calcite (less sericite and chlorite)

- Chemical composition of ore

+ Key Element

In the mineralization zone, on the Au concentration: 0.1 to 98.16

g / T (K7); deep Au: 0.1 to 69.7 g / T; zone average 0.5 to 3.27 g / T

In Au grade ore bodies BDMQ: 0.13 ÷ 76g / t (sample handling characteristics were high), average 18.65 g / t; levels of change are extremely uneven (Vc = 267%); QTZ3 relative Au concentration: 0.11

÷ 48g / t (sample handling characteristics were high), average: 9.57 g / T; levels of change are extremely uneven (Vc = 206%)

+ The accompanying elements including Ag, Pb and Zn recovery value

- Composition characteristics, architecture ore: in the main drive form, fill cracks, chips form The ore mineral particles to form larger tha picture, particle lasts, sometimes relatively isometric particles, angular

- Mineral Complex symbiotic stage mineralization

In the region there are 3 main stages of ore formation; with the mineralogical characteristics:

Stage 1: quartz, pyrrhotite I, pyrite I;

Stage 2: quartz, pyrite II, gold I;

Stage 3: quartz, pyrrhotite II, II gold, galena, sphalerite (possible electrum)

In this present gold mineralization in two phases 2 and 3

- Feature change surrounding rocks

Transform ice thickness around 0.1 ÷ 0.3 m, disseminated gold at low levels, fail to achieve the industry Mineralization accompanying phenomenon mainly of quartz, dolomite is less of goods and calcite Slate quartz - biotite quartz is the mineral of ore containing up to 10% (Bai Dat and Bai Go), dolomite chemical, chemical calcite mineral ore containing less than 2% of, (K7, Tra Long - Stream Tree) , chlorite chemical (Long Tea - Spring Tree, Bai pump), sericitization phenomenon is limited

Picture 1:22 Quartz biotite schist are quartz ore Picture of 1:23 Quartz biotite schist are quartz, dolomite, chemical, ore 1:24 Image

Of dolomite rock is talc, magnesite of disseminated ore

- Identify the source of the original gold ore

From the results of additional studies, combined with previous literature (Tran Trong Hoa, Le Van Hai, Vinh Bui et al) allow to draw: original gold zones Sa Dak derived average temperature hydrothermal , medium low (300-1800)

1.3 DIVISION REGIONAL PERSPECTIVE

1.3.1 Establishments partition prospects

- Premise: is the collective slate quartz - biotite, calcareous shale

of Breast Mountain Formation, the upper sub; Phase 2 complexes Ben Giang - Que Son; tectonic breccia zones related to faults and anticlines K7 Giang River

- Signs of search: the ore outcrop, handmade exploitation work, the alteration zones of dolomite, quartz and calcite of goods; Geochemical dispersion haloes of primary Pb, Zn and Ag, the boulder zone containing sulfide minerals, geophysical anomalies

1.3.2 Promising Results partition

Results were divided: very promising area (A) as follows: Sa Dak area: 0.5 km2 (outside the area explored); Banana Beach: 0.112

km2; Tea - Spring Tree: 0.59 km2; Beach Wind: 0.13 km2; Prospect area (B) include: parks K7: 0.173 km2; Butterfly Beach: 0.28 km2; Light Gold 0.185 km2; The area of unknown prospects (C) is the Gold Mountain: 0.16 km2

CHAPTER 2 STUDY METHOD AND MODEL SELECTION FOR NATURAL

RESOURCES, RESERVES ACCESSMENT 2.1 Overview geochemical, mineralogy characteristics and types origin of industrial gold mine

Gold mineralogy is quite simple, native gold and tellus gold has main industrial value Most native gold contains impurities such as

Ag, Cu and Fe; sometimes Bi, Pd and Rd

Gold has main industrial value includes: high-temperature hydrothermal; average temperature hydrothermal; low temperature hydrothermal; The helmet of the sulfide deposits; Mine type metamorphic origin conglomerate contains gold

2.2 Study Methods

2.2.1 To survey, collect, synthesize material: geological route in lines associated with exploration and exploitation, establishing the additional detail sections at the Dak Sa area

2.2.2 Studying on building database of geological minerals including: digital database tables; Database of geographical information systems (GIS)

2.2.3 Modelling

- The concept of modelling: Modelling is a solution to study, search, test and evaluate with the purpose of understanding, interpretation, prediction and selection of mineral explore and exploration methods Mines model or the critical features of the mineral deposits are usually done by the method of inductive or simulation Products of the modeling process can be a specific pattern observed with the naked eye (resolution map blocks, the plan, section, etc.) or inductive model as a mathematical formula (abstract model)

- The model:

+ Model based on mine geometry theory includes: To geometrize the features of ore body, analysis Trend and model the two-way or

three-way Fourier series The dissertation uses geometric patterns mining (contours) for modeling orebodies

+ Statistical model includes: One-way, two-way and multi-way to determine the statistical distribution laws, the statistical characteristics and the relationship between the elements in the ore body

+ Mathematical model based on the theory of stochastic processes including: content structure, linear algebra theory, autocorrelation analysis, wave analysis harmonic oscillator Postgraduate focus on studying structure function model (Variogram)

Structure function model  (h): to guide on interpreting exploration network, layout exploration works, sampling and help to choose shape and size of block for resources reserves assessment by Kriging methods The theoretical models can be spherical, exponential, Gauss, hole effects, etc

Variogram is not only the unit of change measure, but also shows clearly structural properties and spatial variations of the studied parameters, is the key to perform the Kriging methods in particular and geo-statistical methods in general In geostatistics, some authors also considered Variogram as a basis for calculating and decentralization (reliability) resource reserves

2.2.4 Method of Mineral resource reserves Assessment

- Method of forecast undetermined-resource

Forecast value of area; Forecast for a region or specific area with similar approach; Estimating the abundance of regional natural resources based on empirical formula; forecast mine type according to area with certain reliability; Professional method; Aggregate forecast regional links; Calculation method based on the straight vertical mineralization parameters

- The method of calculating identified resources reserves

Geological block method; Geological cross-sections; exploitation Block; Polygons; Triangles; Inverse distance weight, Kriging The thesis uses Kriging method, inverse distance weighting and geological block method (for comparison)

Common Kriging method known as Kriging unknown average value, based primarily on the theory of stable random function (stop) really

Today, with the help of computers, geostatistical methods are considered as key method in spatial forecasting The method has closely algorithmic, ability to forecast reliability, is not affected by the shape, size of probe network, overcoming the drawbacks that other methods can not calculator such as remove the local errors in calculation Input data volume is large enough, the result is high reliability; on the other hand the method also shows the error in calculation according to the Kriging variance By Kriging we could calculate reserves, resources each block of small size even if no work

in block, and very useful for design mining engineering, mining directing, supporting for the other methods such as establishing contour maps, etc

2.2.5 Research Surpac software application

5.1 Surpac software to handle geological data, modeling ore body and calculator resource reserves of deposit

Design, establishment and database management geology - mining, modeling and evaluate original gold resources reserves

2.3 Select model and method for resources and reserves original gold accessment in Phuoc Son area

2.3.1 The factor affect model sellection

Factors of mineralization controlling; shape, size of ore bodies; distribution of beneficial components in the ore body; shape exploration networks affect model selection

2.3.2 Select model

+ The search: document is preliminary, Postgraduate use vetically calculation method based on mineralization parameters for forecasting Au resource, correlation function model (regression) to predict useful accompanied element (Ag, Pb and Zn)

+ The exploration zone

* Controlling mineralization factor: Bai Dat zone, the main ore body (BDMQ) distributes in the surface separated-layers of shale quartz - biotite Bai Go zone, QTZ3 ore body distributes in the surface separated-layers of quartz - biotite shale, calcareous shale

* Ore body shape and size: BDMQ ore body extends to the north-east - south-west about 250m, plug direction to the Northwest