Chatree Gold Mine

Akara Mining Limited

Paleo-Stress Evolution in the A and K-East Pits of Chatree Gold Mine, Phichit-Phetchabun Provinces,

Central Thailand

Worawong Sirisookprasert 1, Sarawute Chantraprasert 2

and Suphanit Suphanunthi 1

1 Akara Mining Limited 2 Department of Geological Sciences, Chiang Mai University

Kinematic & Dynamic Analyses Using FaultKin® 4.3 by Allmendinger, R.W., Marrett, R.A., and Cladouhos, T.

Topic

Introduction

Problem

Methodology

Result

Conclusion & Discussion

Application

Chanthaburi

Sra Kaew Bangkok CAMBODIA

THAILAND

THE LAO PEOPLE’S DEMOCRATIC REPUBLIC

VIETNAM

THE UNION OF MYANMAR

Loei

Phetchabun

Nakhon Sawan

Tak

Nan

Phrae

Chiang Rai

Chaing Mai

Lampang

98oE 102oE 106oE

12oN

16oN

20oN Chiang Khong

Phai Sali

0 100 200km

Li

Chiang Rai – Chiang Mai volcanic belt Chiang Khong – Tak volcanic belt

Sra Kaew – Chanthaburi volcanic belt volcanic belt

Loei – Phetchabun – Nakhon Nayok volcanic belt

Nakhon Nayok

Lamphun

Mae Ping Fault Zone

N

Nan - Uttaradit volcanic belt

Uttaradit

Mae Hong Son

Mae Sariang

Portions of any volcanic belt to the north

Mae Sariang Fault Zone

Modified from Kosuwan, 2004 and Panjasawatwong, et al, 2006

Chatree Gold Mine

Introduction

A Pit

K-East Pit

Geology & Problem

N10E / 80NW : RL / LL look NW

Superimposed Structure

Selected 84 fault slip data from 2,000 structural data for kinematic & dynamic analyses.

Problem

Methodology

Kinematic Analyses Changes in Dimension of Rock Body after Fault Movement

Kinematic Axes Plot

Four Fault Sets & Two Tectonic Mechanism with

Distinct Kinematic Axes

Extension Mechanism 1.1 Extension 1.2 Conjugated Extension

Compression Mechanism 2.1 Conjugated Compression (inverse) 2.2 Compression

NNW-SSE trending (N20W/50E) Normal Fault

Extensional Fault

Field evidence of fissure quart - carbonate - chlorite banded vein intrude along with normal fault plane.

FAULTS & STRIAE (n=22) arrow shows the movement of the hanging wall

Shortening (P) Axis

Extension (T) Axis

Maximum Principal Stress

Intermediate Principal Stress Minimum Principal Stress

1

2

3

The stereographic plot shows pre-mineralized NNW-SSE normal fault present ENE-WSW extension mechanism.

Andesitic dyke crosscut in damage zone (stockwork replaced on hanging wall of normal fault)

Extension Tectonic Mechanism

1

2

3

Pre-mineralized extensional stage is represented as NNW-SSE trending normal fault plane on great circles with scattering sub-horizontal extension kinematic axes (T) and sub-vertical shortening kinematic axes (P). They indicate ENE-WSW extension and generate NNW-SSE trending pre-mineralized normal faults.

N=22

Shortening (P) Axis

Extension (T) Axis

Maximum Principal Stress

Intermediate Principal Stress Minimum Principal Stress

1

2

3

Field evidence of fissure quart - carbonate - chlorite banded vein intrude along with normal fault plane.

FAULTS & STRIAE (n=22) arrow shows the movement of the hanging wall

Shortening (P) Axis

Extension (T) Axis

Maximum Principal Stress

Intermediate Principal Stress Minimum Principal Stress

1

2

3

The stereographic plot shows pre-mineralized NNW-SSE normal fault present ENE-WSW extension mechanism.

Andesitic dyke crosscut in damage zone (stockwork replaced on hanging wall of normal fault)

Field evidence of fissure quart - carbonate - chlorite banded vein intrude along with normal fault plane.

Andesitic dyke crosscut in damage zone (stockwork replaced on hanging wall of normal fault)

Extension Tectonic Mechanism

Conjugated Extension

Tectonic Mechanism

1

2

3

Post-mineralized Extensional Mechanism The E-W trending left lateral faults were crosscut by andesitic dykes and were closely associated with two extensional conjugate sets of steeply dipping strike-slip and oblique faults with scattered shortening (P) and extension (T) kinematic axes. they correspond to N-S trending sub-horizontal maximum principal stress (σ1) and E-W trending sub-horizontal minimum principal stress (σ3).

N=30

Shortening (P) Axis

Extension (T) Axis

Maximum Principal Stress

Intermediate Principal Stress Minimum Principal Stress

1

2

3

T A

Right Lateral Fault (N50W / 70NE)

cross-cutting in andesitic Dyke

(N20E / 85NW)

Look SW

Conjugated Extension

Tectonic Mechanism

Younger conjugate compressional fault set crosscutting relationship of younger NE-SW trending dyke intruded along of NW-SE trending left-lateral and NNE-SSW trending right-lateral strike-slip faults. The scattered plot of shortening and extension kinematic axes present ENE-WSW trending sub-horizontal maximum stress (σ1) and sub-vertical minimum stress (σ3) represented E-W compressional tectonic mechanism.

1

2

3 N=28

Shortening (P) Axis

Extension (T) Axis

Maximum Principal Stress

Intermediate Principal Stress Minimum Principal Stress

1

2

3

Conjugated Compression

Tectonic Mechanism

Late NE-SW dyke crosscut older NE-SW & NW-SE trending dykes

Conjugated Compression

Tectonic Mechanism

Shortening (P) Axis

Extension (T) Axis

Maximum Principal Stress

Intermediate Principal Stress Minimum Principal Stress

1

2

3

The E-W compressional tectonic mechanism was

generated to the latest NNW-SSE trending complicated reverse faults present ENE-WSW trending sub-horizontal maximum principal stress (σ1) with N-S trending sub-vertical minimum principal stress (σ3).

N=4

Compression

Tectonic Mechanism

Compression

Tectonic Mechanism

Conclusion • Outcrop evidence was used to determine the timing and

relationship of the faults to mineralization and regional tectonics.

• NNW-SSE trending normal faults developed in response to E-W extension prior to or during mineralization in the Early Triassic(ca. 250 Ma). Back-arc extension?

• Transient stress systems during the transition between extension to compression resulted in two sets of conjugate strike-slip faults associated with andesitic dyke intrusion (ca. 244 Ma).

• N-S trending reverse faults were likely related to Triassic collision.

Application

H Pit & Gosowong Comparisons Model

H-central & cutback

H-west & J

Look SW

Application

Released face-1 : J1 (85/225)

Released face-2 : J2 (85/135)

3D Solid Model By Surpac Software

Geological & Geotechnical Pit Mapping

Akara Environmental Care Mining

Toward - Sustainable

On Resource & Production