Advances in Geosciences: Volume 13: Solid Earth (Se)

A d v a n c e s

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Geosciences Volume 13: Solid Earth (SE)

ADVANCES IN GEOSCIENCES Editor-in-Chief: Wing-Huen Ip (National Central University, Taiwan) A 5-Volume Set Volume 1: Volume 2: Volume 3: Volume 4: Volume 5:

Solid Earth (SE) ISBN-10 981-256-985-5 Solar Terrestrial (ST) ISBN-10 981-256-984-7 Planetary Science (PS) ISBN-10 981-256-983-9 Hydrological Science (HS) ISBN-10 981-256-982-0 Oceans and Atmospheres (OA) ISBN-10 981-256-981-2

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A d v a n c e s

i n

Geosciences Volume 13: Solid Earth (SE)

Editor-in-Chief

Wing-Huen Ip

National Central University, Taiwan

Volume Editor-in-Chief

Kenji Satake

University of Tokyo, Japan

World Scientific NEW JERSEY

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ADVANCES IN GEOSCIENCES A 6-Volume Set Volume 13: Solid Earth (SE) Copyright © 2009 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage and retrieval system now known or to be invented, without written permission from the Publisher.

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(Set) (Set) (Vol. 13) (Vol. 13)

Typeset by Stallion Press Email: [email protected] Printed in Singapore.

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EDITORS Editor-in-Chief:

Wing-Huen Ip

Volume 10: Atmospheric Science (AS) Editor-in-Chief: Jai Ho Oh Editor: Gyan Prakash Singh Volume 11: Hydrological Science (HS) Editor-in-Chief: Namsik Park Editors: Joong Hoon Kim Eiichi Nakakita C. G. Cui Taha Ouarda Volume 12: Ocean Science (OS) Editor-in-Chief: Jianping Gan Editors: Minhan Dan Vadlamani Murty Volume 13: Solid Earth (SE) Editor-in-Chief: Kenji Satake Volume 14: Solar Terrestrial (ST) Editor-in-Chief: Marc Duldig Editors: P. K. Manoharan Andrew W. Yau Q.-G. Zong Volume 15: Planetary Science (PS) Editor-in-Chief: Anil Bhardwaj Editors: Yasumasa Kasaba Paul Hartogh C. Y. Robert Wu Kinoshita Daisuke Takashi Ito v

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LIST OF REVIEWERS

The Editor of Volume 13 (Solid Earth) would like to thank the following referees who have helped review the papers published in this volume: Agustan Giulio Barbieri Jungho Cho Phil Cummins Takashi Furumura Richard Gross Martin Flower Nuraini Rahma Hanifa Hasanuddin Z. Abidin Takahiro Hatano Yukio Hayakawa Kosuke Heki Giulio Iovine Shuanggen Jin Yasuyuki Kano Teruyuki Kato Somboon Khositanont Hamzah Latief Kuo-fong Ma Norio Matsumoto

Ritsuko S. Matsu’ura Irwan Meilano Ki-Bok Min James Mori Hiroshi Munekane Ken T. Murata Danny H. Natawidjaja Jong Uk (James) Park Bill Petrachenko Marco Piras CP Rajendran Lucas Donny Setijadji D. Srinagesh Yuichiro Tanioka Hiroyuki Tsutsumi Yasushi Watanabe Pornsawat Wathanakul Moriaki Yasuhara Jiancang Zhuang Michael Zolensky

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CONTENTS

Editors

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List of Reviewers

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Mineralization Characteristics and Ore Fluid of Huai Kham on Gold Deposit, Northern Thailand Somboon Khositanont, Khin Zaw and Prayote Ounchanum Formation of Hollow Concretions in Northeastern Thailand Prinya Putthapiban and Sutatcha Hongsresawat Investigations on Local Quartz Sand for Application in Glass Industry Pisutti Dararutana, Prukswan Chetanachan, Pornsawat Wathanakul and Narin Sirikulrat Geochemical and Sr–Nd–Pb Isotopic Study of Late Neogene Volcanic Rocks from the Arita–Imari Area (SW Japan): Evidence for Coexisting OIB-Like and Subduction-Related Mantle Sources Nguyen Hoang, Jun’ichi Itoh, Kozo Uto and Akikazu Matsumoto Landslide Hazard Zoning of the Muravera Hillside (Sardinia, Italy) Giulio Barbieri and Paolo Cambuli

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An Integrative Geoscience Data Model by Linking Field-Specific Data Models in Digital Geologic Map, Earth Resource, and Geo-Hazard Lucas Donny Setijadji and Koichiro Watanabe Crustal Deformation Monitoring by GNSS: Network Analysis and Case Studies Marco Piras, Marco Roggero and Maurizio Fantino

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The Global Geodetic Observing System H.-P. Plag, M. Rothacher, M. Pearlman, R. Neilan and C. Ma

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The International Laser Ranging Service Michael Pearlman, Carey Noll, Jan McGarry, Werner Gurtner and Erricos Pavlis

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Earth Rotation Parameters from Very Long Baseline Interferometry and Ringlaser Observables P. J. Mendes Cerveira, H. Spicakova, H. Schuh, T. Kluegel, U. Schreiber and A. Velikoseltsev Toward a New VLBI System for Geodesy and Astrometry J¨ org Wresnik, Johannes B¨ ohm, Andrea Pany and Harald Schuh

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Periodic Station Motion in Gothenburg Observed with GPS — Possibly Related to Hydrological Phenomena? R. Haas, N. Tangdamrongsub, H.-G. Scherneck and J. Johansson

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Evaluation of the Coseismic Pore Fluid Pressure on a Thrust Fault Jeen-Hwa Wang

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The Water Level Changes of the Aneuklaot Lake, Weh Island after the 2004 Sumatra–Andaman Earthquake Agustan, Djoko Nugroho, Lena Sumargana, Irwan Meilano, Mohd. Effendi Daud, Fumiaki Kimata and Yusuf S. Djadjadihardja Effect of Near-Source Trench Structure on Teleseismic Body Waveforms: An Application of a 2.5D FDM to the Java Trench Taro Okamoto and Hiroshi Takenaka Numerical Modeling of the 2006 Java Tsunami Earthquake Nuraini Rahma Hanifa, Irwan Meilano, Takeshi Sagiya, Fumiaki Kimata and Hasanuddin Z. Abidin Why Many Victims: Lessons from the July 2006 South Java Tsunami Earthquake Hasanuddin Z. Abidin and Teruyuki Kato Earthquake Potential in Myanmar Hla Hla Aung

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Looking into a Sandpile by Photo-Elasticity and Discrete Element Method Naoto Yoshioka and Hide Sakaguchi

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Statistical Properties and Time Trend in the Number of Holocene Volcanic Eruptions A. N. Zemtsov and A. A. Tron

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Advances in Geosciences Vol. 13: Solid Earth (2007) Ed. Kenji Satake c World Scientific Publishing Company


MINERALIZATION CHARACTERISTICS AND ORE FLUID OF HUAI KHAM ON GOLD DEPOSIT, NORTHERN THAILAND SOMBOON KHOSITANONT Geological Sciences, Chiang Mai University, Chiang Mai, 50002 Thailand [email protected] KHIN ZAW CODES ARC Centre of Excellence in Ore Deposits, University of Tasmania, Hobart, TAS, 7005 Australia PRAYOTE OUNCHANUM Geological Sciences, Chiang Mai University, Chiang Mai, 50002 Thailand

Huai Kham On gold deposit is located within the Lampang-Phrae volcanic belt of the Sukhothai Fold Belt in northern Thailand. The gold deposit is hosted by Triassic andesitic tuff and intercalated rhyolitic welded tuff. The host sequence is overlain by sedimentary sequences including Triassic calcareous sandstone of the Wang Chin Formation and Middle Triassic limestone of the Kang Pla Formation. Gold nuggets and electrum were found in quartz-rich veins with associated pyrite, chalcopyrite, galena and bournonite cutting across the andesitic tuff and underlying rhyolitic tuff. Sulfur isotope analyses indicate that the gold-ore forming fluids vary in sulfur isotopic values from −5.3 to −3.5 per mil. Fluid inclusion studies indicate that the ore-forming fluids were typically enriched in CO2 which is evidenced by the occurrence of carbonic (CO2 (L)– H2 O(L)–CO2 (V)) inclusions in quartz adjacent to the gold-bearing sulfide minerals. Three types of fluid inclusions including Type I (L-V) aqueous inclusions, Type II (L-L-V) aqueous–carbonic inclusions, and Type III (V) vapor rich inclusions, were classified in vein quartz. Results from a preliminary microthermometry study of fluid inclusions in ore-bearing vein quartz indicate that the melting temperature of CO2 solid varies from −56.8◦ C to −56.6◦ C and that the homogenization of the carbonic phase varies from 28◦ C to 31◦ C suggesting that the carbonic phase contains pure CO2 . This interpretation is supported by Laser Raman Spectroscopy analyses. The homogenization temperatures of the carbonic inclusions in quartz vary from 280◦ C to 300◦ C Salinities of ore fluids range from 1 to 7 wt.% NaCl equiv. 1

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S. Khositanont, Khin Zaw and P. Ounchanum On the basis of available data such as vein texture, alteration, and fluid inclusion data, the Huai Kham On gold deposit is comparable to orogenic gold deposits.

1. Introduction The Sukhothai Fold Belt in northern Thailand has formed as a result of Indochina–Shan Thai collision.1−4 The formation of N–S trending orogenic belt in conjunction with volcano-plutonism in relation to subduction and collision has produced a large variety of precious and base metal deposits, e.g. tungsten, antimony, copper, and gold. A number of gold deposits which have been discovered within the Sukhothai Fold Belt are also located in the volcano-plutonic aureole including Huai Kham On deposits in Phrae Province. However, the gold mineralization at Huai Kham On deposit has not been well studied. This study reports gold mineralization and fluid inclusion characteristics at Huai Kham On deposit in the Sukhothai Fold Belt.

2. Geology of Huai Kham On Deposit The Huai Kham On deposit is hosted within the NNE-SSW trending Triassic volcanic rocks, named as Lampang-Phrae volcanic belt, and the overlain by Triassic sedimentary sequences of the Kang Pla Formation and Wang Chin Formation of Lampang Group. The lower part of the volcanic sequence at the Huai Kham On deposit is composed mainly of andesite porphyry, andesitic tuff, and breccia. Pyrite and other sulfide minerals are rarely observed in the andesite porphyry. The overlying andesitic tuff contains breccia within a welded matrix. The andesite sequence is overlain by rhyolitic and welded rhyolitic tuff. The rhyolite, composed of angular translucent to transparent quartz and subrounded pink feldspar, is set in the dark reddish brown fine grained groundmass. Some rhyolites are composed of angular to subangular quartz phenocrysts with fragments of subhedral K-feldspar and plagioclase. Large pyrrhotite crystals with fine-grained pyrite replacement are observed elsewhere in this rock. The uppermost successions of volcanic rocks at the Huai Kham On deposit are overlain by middle to late Triassic sedimentary rocks including limestone of Kang Pla Formation (Lst) and clastic rocks (Tr) of Wang Chin Formation.5

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3. Vein Mineralogy and Alteration Quartz veins are found only in the Triassic andesitic tuff and intercalated rhyolite (Fig. 1). The veins are 50 cm to 3 m thick and delineate along

Fig. 1. Geological map showing major rock units and significant geological features at Huai Kham On deposit, Wang Chin District, Phrae Province.

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Fig. 2. Gold and galena association in quartz vein from Huai Kham On deposit. Au: native gold, Gn: galena, Gtz: quartz.

northwest strike. Quartz veins are enclosed within chlorite alteration zone. Most of vein quartz in the gold-bearing quartz veins show cataclastic texture suggesting that the gold-bearing quartz veins were formed in the orogenic environment. Pyrite is the most abundant sulfide mineral, whereas chalcopyrite, galena, and bournornite are much less abundant. Pyrite generally has a reaction rim with galena inclusions. Gold grains are specially associated with galena or included by quartz (Fig. 2). Results from Laser Ablation Inductively Couple Plasma Analyses indicate that pyrite also contains dissolved gold where chalcopyrite is present.

4. Sulfur Isotope Study Sulfur isotope study is applied to the sulfide mineral from five vein quartz samples of various depths at the Huai Kham On deposit. Pyrite grains were drilled from gold-bearing quartz veins. Sample preparation for sulfur isotope analyses was carried out using quantitative preparation of SO2

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Mineralization Characteristics and Ore Fluid of Huai Kham Table 1. deposit.

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Sulfur isotope analyses of pyrite from Huai Kham On

Sample ID

[email protected] [email protected] [email protected] [email protected] [email protected]

Mineral

Weight (mg)

d 34 SCDT (permil)

pyrite pyrite pyrite pyrite pyrite

14.2 31.0 12.7 14.0 12.3

−3.4 −4.6 −4.2 −5.5 −5.4

for 34 S/32 S analyses from sulfides by combustion with cuprous oxide technique.6 The sulfur isotope analyses were performed with VG SIRA Series 2 triple-collector mass spectrometer at University of Tasmania. Sulfur isotopes of pyrite from the Huai Kham On deposit show a narrow range from −3.4 to −5.5 per mil (Table 1). The S isotope ranges for magmatic source generally show small positive values or close to 0 per mil and the isotope value for sedimentary source generally shows much greater positive value.7

5. Fluid Inclusion Study Fluid inclusions are observed in quartz. Primary fluid inclusions are observed in crystal growth zones by polarizing microscope (Fig. 3) and by cathodoluminescence — SEM image.

5.1. Classification of fluid inclusions Fluid inclusions in quartz are classified into three types as follows: 1. Type I (L-V) aqueous fluid inclusions are composed mainly of aqueous liquid with a relatively small vapor bubbles (Fig. 4). They generally occur as secondary origin along fractures that cut across the crystal boundaries of quartz. 2. Type II (L-L-V) aqueous–carbonic fluid inclusions show aqueous and carbonic liquids and a gas bubble at the core of the carbonic liquid at a room temperature (Fig. 5). Carbonic gas and carbonic liquid phase separation is observed at temperature below 31.1◦ C (critical point of CO2 ). The presence of CO2 as a major component in the carbonic phase is also confirmed by Laser Raman Spectroscopic Analyses. These

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Fig. 3. Photograph of crystal growth zone (dashed lines) and fluid inclusions in quartz at Huai Kham On deposit.

Fig. 4. Type I fluid inclusions in quartz from Huai Kham On deposit; V = vapor bubble, L = aqueous liquid.

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Fig. 5. Type II (L-L-V) aqueous carbonic fluid inclusions in quartz from Huai Kham On deposit. Low-density CO2 phases are squeezed in the middle, surrounded by aqueous liquid at rim.

inclusions are aligned along crystal growth zones in quartz crystals, suggesting a primary origin. 3. Type III (V-L) aqueous–carbonic inclusions generally show large volumes of carbonic phase including liquid and gas (Fig. 6). The CO2 liquid may not be observed at room temperature due to insufficient CO2 in the fluids. Laser Raman Spectroscopy analysis shows that the carbonic phases are composed only of CO2 . These inclusions are of primary origin due to their appearance along crystal growth zones.

5.2. Microthermometric measurement and P–T–V–X relation Microthermometric measurement was carried out using a Linkamcomputerized fluid inclusion freezing/heating stage. The thermocouple was calibrated from −56.6◦C (melting point of pure CO2 ) to 374.1◦C (critical point of pure H2 O) using Fluid Inc synthetic fluid inclusions. The results can be reproduced within 0.1◦ C for the freezing experiment and 1.0◦ C for heating experiment. The inclusions were cooled down to −120◦C while all phases were frozen. Then they were gradually heated up to −56.6◦ C to observe the

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Fig. 6. Photograph of Type III vapor-rich inclusions in quartz from Huai Kham On deposit. Inclusions contain mainly CO2 gas bubble (dark part inside the inclusions).

melting point of CO2 for Type 2 (L-L-V) inclusions and Type III vaporrich inclusions. The heating experiment was carried on to 10◦ C in order to observe the final melting temperatures of the solid phases including ice and clathrate (mixed CO2 –H2 O solid). Finally, all inclusions were heated up to observe the CO2 homogenization temperature in Type II (L-L-V) and Type III inclusions and the final homogenization temperature. The melting temperature of carbonic ice in Type II (L-L-V) inclusions ranges from −59.2◦ C to −56.6◦C suggesting that CO2 is the major component in the carbonic phase for Type II (L-L-V) inclusions. The homogenization temperatures of CO2 phase range from 25◦ C to 31.1◦ C, which also support CO2 as a major component in the carbonic phase. The clathrate melting temperatures of Type II (L-L-V) inclusions and Type III vapor-rich inclusions range from 5.3◦ C to 9◦ C. It is noticeable that the depression of the clathrate melting temperature from 10◦ C is affected by the amount of salt in the aqueous phase in the Type II (L-L-V) inclusions. The salinity of aqueous fluid ranges from 1–7wt% NaCl eq. (Fig. 7) is obtained from the depression of clathrate melting temperature using the equation of Brown.10

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Fig. 7. Histogram shows salinity variation in Type II and Type III inclusions of quartz from Huai Kham On deposit. The majority of inclusions contain 2–3wt% NaCl equivalent.

Fig. 8. Histogram shows homogenization temperature variation of Type II and Type III fluid inclusions from quartz of Huai Kham On deposit.

The majority of final homogenization temperatures (Th ) of Type II (L-L-V) inclusions are 240◦ C to 310◦ C (Fig. 8), whereas the final homogenization temperatures of Type III vapor-rich inclusions are slightly higher (320◦ C–340◦C). The difference between the final homogenization temperatures of Type II and Type III inclusions may be due to a kinetic barrier during the formation of vapor and liquid phases of aqueous– carbonic fluids. Since the majority of inclusions were homogenized at temperature ranging from 280◦C to 300◦ C. These temperature ranges

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Fig. 9. Th -XH2 O plots for Type II and Type III inclusions. The data, which are scattered above 1 kb solvus, suggest that the inclusions were trapped at pressure above 1 kb.8,9

therefore, represented the homogenization of Type II and Type III fluid inclusions. The similarity between the final homogenization temperatures (Th ) of the liquid-rich and vapor-rich inclusions is, therefore, interpreted as the same trapped P –T conditions of 280◦ C to 300◦ C and 1 to 3 kb.

5.3. P–T–V–X relation Homogenization of Type II and Type III inclusions are plotted against molar volume of XH2 O (Fig. 9). The data plotted above the 1 kb solvus indicate that the pressure of entrapment of Type II inclusions and Type III inclusions were higher than 1 kb. It is also noticeable that the salinity– homogenization temperature plots form clusters rather than a mixing trend suggests that the ore-forming fluids were derived from homogeneous fluid (Fig. 10).

6. Gold Mineralization at Huai Kham On Deposit Gold grains that are present as cavity filling and as dissemination in quartz without observable fractures may suggest that they were formed simultaneously with the formation of quartz veins. Therefore, primary fluid inclusions in quartz veins were trapped simultaneously with the formation of gold mineralization.

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Fig. 10. Salinity — Homogenization plots showing composition of fluid inclusions of vein quartz from Huai Kham On deposit.

The presence of Type II (L-L-V) aqueous–carbonic and Type III vapor rich fluid inclusions in gold-bearing vein quartz in conjunction with microthermometric measurements indicate that gold-bearing quartz veins at the Huai Kham On deposit were derived from aqueous–carbonic fluids, which are composed of 2–3wt% NaCl equivalent in the aqueous phase, whereas CO2 is a major component in the carbonic phases. Evidence from fluid inclusion trapping temperature also indicates that the majority of oreforming fluids were trapped at 280◦ C–300◦C at 1 kb–3 kb. These pressure and temperature ranges are similar to those in mesothermal and/or orogenic gold styles of mineralization. The presence of aqueous–carbonic (Type II and Type III) fluid inclusions indicates that the precipitation of ore at the Huai Kham On deposit occurred by fluid effervescence process, which can be only formed under high pressure condition. Fluid effervescence (phase separation of CO2 ) may have resulted in pressure reduction.

7. Conclusions 1. Sulfur isotope characteristics suggest that the ore-forming fluids at Huai Kham On were formed either from magmatic fluids. 2. Fluid inclusion studies indicate that the gold-bearing quartz veins at the Huai Kham On deposit were formed at 280◦ C–300◦C and 1 kb–3 kb. 3. The formation of gold-bearing quartz veins resulted from fluid effervescence which led to rapid pressure reduction in the hydrothermal system.

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4. The pressure–temperature range of ore formation is similar to that of mesothermal or orogenic gold mineralization around the world.

References 1. S. Bunopas, Palaeogeographic history of western Thailand and adjacent part of Southeast Asia: A plate tectonic interpretation, PhD Thesis, Victoria University of Wellington, 1981, 810p. 2. S. Bunopas, P. Vella, H. Fontaine, S. Hada, C. Burrett, P. Haines, S. Potisat, Th. Wongwanich, P. Chaodamrong, K. T. Howard and S. Khositanont, Growth of Asia in the late Triassic continent–continent collision of Shan Thai and Indochina against South China, J. Gonwana Res. 4(4) (2001) 584–586. 3. S. M. Bar, S. A. Macdonal, G. R. Dunning, P. Ounchanum and W. Yaowanoiyothin, Petrochemistry, U-Pb (zircon) age and the palaeotectonic setting of the Lampang volcanic belt, northern Thailand, J. Geol. Soc. London 157 (2000) 553–563. 4. I. Metcalfe, Permian tectonic framework and palaegeography of SE Asia, J. SE Asian Earth Sci. 20 (2002) 551–566. 5. P. Chaodamrong, Stratigraphy, sedimentology and tectonic implications of the Lampang Group, central north Thailand, PhD Thesis, University of Tasmania, 1992, 230p. 6. B. W. Robinson and M. Kasakabe, Quantitative preparation of SO2 for 34 S/32 S analyses from sulphides by combustion with cuprous oxide, Anal. Chem. 47(7) (1975) 1179–1181. 7. H. Ohmoto and R. O. Rye, Isotope of sulphur and carbon, Geochem. Hydrothermal Ore Deposits (1979) 509–567. 8. E. Roedder, Fluid inclusion, Rev. Mineralogy 12 (1984) 646. 9. T. S. Bowers and H. C. Helgeson, Calculation of the thermodynamic and geochemical consequences of nonideal mixing in the system H2 O-CO2 -NaCl on phase relations in geologic systems: Equation of state for H2 O-CO2 -NaCl fluids at high pressure and temperatures, Geochim Cosmochim Acta 47 (1983) 1247–1275. 10. P. Brown, Flincor Software (1989).

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Advances in Geosciences Vol. 13: Solid Earth (2007) Ed. Kenji Satake c World Scientific Publishing Company


FORMATION OF HOLLOW CONCRETIONS IN NORTHEASTERN THAILAND PRINYA PUTTHAPIBAN∗ and SUTATCHA HONGSRESAWAT Geoscience Programme, Department of Physics, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand ∗ [email protected]

The mysterious rocks “Naka’s eggs” commonly found in Northeastern Thailand are hollow concretions derived from clastic rocks of the Khorat Group. The concretions appear in different shapes, such as spheroidal, ellipsoidal, and irregular with sizes varying from a few cm up to 60 cm. Their dark brown outer shells are much harder than the hosted rocks, and the inner surfaces of the hollows are rugged and occasionally contain remnants of pyrite (FeS2 ) minerals indicating incomplete oxidation processes. The result of extensive examinations of these hollow concretions suggests that their formation involves subsurface water that penetrates through fractures of rocks and the boundaries of sand grains forming several species of iron solutions. Due to their exothermic nature, these solutions sieve outward to the region with lower temperature and pressure where chemical reactions can continue. When equilibrium is reached, reddish brown iron oxide sediments remained as hard shells of the concretions. The hollow is then created in situ as a result of these chemical processes. The size and shape of these hollow concretions clearly depend on the quantity of pyrite crystals and the morphology of the pyrite nodules. As an external erosion process subsequently takes place, the outer shells which are more resistant and have a smaller porosity due to the secondary cemented iron oxides survive with shapes of sphere, ellipsoid and others, whereas other sandy parts of the host were eroded away. Because it is evidently clear that the reddish-brown color of the clastic rocks in our study areas is secondary in origin, parts of chemical reactions discussed here are promising candidates for actual chemical alterations responsible for the reddish color of the Khorat Group red beds in Thailand.

1. Introduction The continental Mesozoic rocks of the Khorat Group in northeastern Thailand have been intensively studied by many researchers.1−5 These rock ∗ Corresponding

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sequences vary in age from Upper Triassic to Cretaceous-Tertiary.6−9 The rocks of the Khorat Group are subdivided into nine formations listed from the oldest to the youngest as follows: Huai Hin Lat, Nam Phong, Phu Kradung, Phra Wihan, Sao Khua, Phu Phan, Khok Kruat, Maha Sarakham, and Phu Thok Formations.10,11 In this study, we present evidences of the formation of mysterious rocks, “Naka’s eggs” or hollow concretions which are found in the low hills with gentle slopes and flat land within the terrain covered by the clastic rocks of the Phra Wihan and Sua Khua Formations (Study Area 1) and of the Phu Kradung Formation

Fig. 1. Geologic map of Southeastern Khorat Plateau showing locations of the hollowed concretions Study Area 1 (filled circle) Phu Phrao near the Ban Chong Meg border town, Sirinthorn District, and Study Area 2 (open star in a filled circle) Ban Palai, Amphoe Po Sai, Ubon Ratchathani Province (filled star) Pak Moon Dam Site (modified after Sattayarak and Suteethorn, 1983).

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(Study Area 2), shown in Fig. 1. Consequently, we propose, for the first time, the mechanisms responsible for the creation of the hollow concretions.

2. General Geology of the Study Areas The Khorat Group clastic rocks in the southeastern corner of the northeastern plateau are generally flat lying beds, and slightly dip west toward the center of the Khorat basin (Fig. 1). The study areas predominantly contain three major rock formations. The first formation is classified as the Middle to Upper Jurassic Phu Kradung Formation normally distinguished by brown to grayish siltstones and fine-grained sandstones. This rock formation is mainly observed in the Study Area 2. Two additional formations observed in the Study Area 1 are Upper Jurassic to Lower Cretaceous Phra Wihan Formation containing mostly quartzitic sandstones and siltstones and the Lower Cretaceous Sua Khua Formation. This last formation is recognized as the rock unit where most vertebrate fossils were excavated in Thailand. Typical rocks in the Sao Khua ranging from most to least abundant are reddish brown sandstones, siltstones, conglomeratic sandstones, conglomerates, and intercalated shale, respectively.

3. Physical Descriptions of the Hollow Concretions Most spaces of hollow concretions’ cores are empty with minute amounts of loose sand, silt, or clay particles or detached hard lumps of clay materials resembling nuts. These concretions appear in various sizes and shapes. Their average sizes vary from a few cm up to 60 cm in lengths and greatly depend on the grain sizes of the pre-existing clastic rocks of the formation (Fig. 2). The typical shapes of these concretions are spheroidal, ellipsoidal, distorted cylindrical, and irregular (Fig. 3). While embedded in the strata, these hollow rocks do not show any uniform patterns of distribution. The outer shells are significantly harder than the surrounding rocks in which they are buried. When viewing the cross section, the inner part near the hollow has a reddish brown color, and such color fades outward making the outermost crust relatively pale. The inner surface of the hollows is usually rugged showing distinct corroded features. In some cases, there are remnants of pyrite crystals (FeS2 ) observed at the inner surfaces. We will explain in the next section that several species of iron solutions react as additional cementing media which hold the mantle of hollow concretions tighter than the sand grains farther away in the rock formations.

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Fig. 2. The sizes of the hollow concretions are larger in the coarser-grained clastic rocks comparing to those of the finer-grained one, (a), (b), and (c) show the concretions from the Study Area 1 and (d) shows the concretions from the Study Area 2.

Fig. 3. The adopted shapes of the hollow concretions showing their dependence on the pre-existing pyrite nodules. (a) and (b) are from the Study Area 1, and (c) and (d) are from the Study Area 2.

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4. Formation Processes Extensive examinations performed on hundreds of samples of the hollow concretions collected from and observed in the fields lead to the conclusion that the most suitable processes responsible for their formation are sedimentary depositions followed by a series of chemical reactions and ended with weathering and erosion processes. From our present information, the best formation scenario is chronologically described as follows. 4.1. Lithified stage The first stage is the formation of clastic sedimentary rocks, siltstone, sandstone, shale, and conglomerate present in the Phu Kradung, Phra Wihan, and Sao Khua Formations by meandering and braided stream deposits. The existence of pyrite (FeS2 ) occurring as individual crystals, clusters of combined crystals or pyrite nodules, the existence of coal jets and carbonaceous materials suggest that these rock formations were formed under significantly reducing conditions. These crystalline pyrites distribute unevenly throughout the rock formations. The gray to greenish gray color of the rock formations also indicates reducing environment of depositions. This color can only be observed when the rocks are not subjected to prior chemical weathering processes, fresh rocks. 4.2. Subsurface chemical reaction stage The second stage involves activities of subsurface water which sieves through fractures and grain boundaries of these pyrite-bearing rocks upon being exposed above the water table. The effectiveness of this water transmission is mainly regulated by the porosity and permeability of the rocks; therefore, properties such as grain size, primary rock structures, and the complexity of fracture system are important. The presence of water and oxygen gradually converts the system into oxidizing environment. As a result, several chemical reactions are triggered and often release heat and pressure to the system where reactions occur. The following four chemical equations show the general accepted sequence of pyrite reactions12,13 : + 2FeS2 + 7O2 + 2H2 O → 2Fe2+ + 4SO2− 4 + 4H

4Fe2+ + O2 + 4H+ → 4Fe3+ + 2H2 O 4Fe3+ + 12H2 O → 4Fe(OH)3 + 12H+ + FeS2 + 14Fe3+ → 15Fe2+ + 2SO2= 4 + 16H .

(1) (2) (3) (4)

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In Eq. (1), FeS2 which is stable under the previous reducing condition starts to react with oxygen and water to form ferrous iron (Fe2+ ), sulfate (SO2− 4 ), and acid (H+ ). Later, Fe2+ is transformed to ferric iron (Fe3+ ), as shown in Eq. (2). Fe3+ ions can undergo two different reactions, either hydrolyzed with water to form the solid ferric hydroxide (ferrihydrite) (Fe(OH)3 ) shown in Eq. (3) or further consume more FeS2 releasing additional + Fe2+ , SO2− 4 , and H , as shown in Eq. (4). These subsequent oxidation reactions of the pyrite crystals cause the textural failure; consequently, the individual sand grains (mainly quartz) previously held in the sedimentary rock matrix fall off becoming loose sand and silt particles. The Fe2+ /Fe3+ solution percolates outward seeking appropriate environments with lower temperature and pressure for chemical reactions to continue. This radiallyoutward percolation ceases at the outer shell of the concretion after the system reaches equilibrium leaving behind the rusty color of iron oxide. In the presence of alkaline minerals such as feldspars, the H+ and water from the above equations will be naturally neutralized by presumably, the following chemical reactions: 4KAlSi3 O8 + 4H+ + 18H2 O → 4K+ + 2Al2 Si2 O5 (OH)4 + 8Si(OH)4 2CaAl2 Si2 O8 + 4H+ + 2H2 O → 2Ca2+ + Al4 Si4 O10 (OH)8

(5) (6)

The end product of both Eqs. (5) and (6) is mainly a kaolinite clay. This clay mineral can further react with SiO2 and water yielding the solution of silica and silicic acid (H2 SiO4 ). These iron oxide and silicic solutions which disperse throughout the mantle additionally strengthen the crust of the hollow concretions. If carbonate minerals such as calcite are present, the neutralized process can be described by the following equations, and the chemical weathering product will be the mineral gypsum: CaCO3 + 2H+ + SO2− 4 + H2 O → CaSO4 · 2H2 O + H2 CO3

(7)

− CaCO3 + H+ + SO2− 4 + H2 O → CaSO4 · 2H2 O + HCO3

(8)

The embedded FeS2 crystals and nodules in the rock formations are evidently the essential starting materials for these chemical reactions to persist. Final size and shape of the hollow concretions are directly derived from the quantity of FeS2 and the orientation of the FeS2 nodules (Fig. 4).

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Fig. 4. Successive developments of the hollow concretions. (a) is gray to greenish gray, fresh sandstone with pyrite and carbonaceous materials of the Phra Wihan Formation excavating from the river bed near the Pak Moon Dam site; (b) shows the alteration of the similar rocks shown in (a) after being exposed to air for some years. Rusty spots and banded circles evidently ascertain the validity of chemical reactions caused by weathering; (c) shows the rugged inner surface of the hollow previously underwent severe chemical reactions; (d) shows trapped loose sand, silt, and clay particles which are always observed in the undisturbed hollows.

4.3. Post-chemical erosion stage The last stage is the prolongation of weathering and erosion processes undertaking well after maturation of chemical reactions of the previous stage. The portions of the rock farther away from the crust of the concretion are subjected to erosion process much more severely and are easily removed. Without surrounding materials, some hollow concretions become free and can be transported to new depositional sites by various means. The remaining partially free hollow concretions are left embedded in situ within the outcrop exposures (Fig. 5).

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Fig. 5. The outcrops containing partially free hollow concretions embedded in situ at Phu Phrao, the Study Area 1.

5. Conclusion The origin of hollow concretions can be summarized by the lithified stage, the subsurface chemical reaction stage, and the post-chemical erosion stage. The lithified process of the clastic rocks occurs under significantly reducing condition as indicated by the existence of pyrite nodules. Later on, the environment becomes more oxidized due to the presence of subsurface water and oxygen. Several chemical reactions take place forming hollows and strengthening outer shells of the concretions. The final post-chemical erosion stage explains the mobility and the distribution of the hollow concretions observed in the rock outcroups.

Acknowledgments Mahidol University, Faculty of Science and Mahidol University, Kanchanaburi campus are thanked for their support and encouragement. The authors are grateful for the provision of basic geological information

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by The Royal Thai Department of Mineral Resources. Sirot Sulyapongse, Manop Raksaskulwong, Apichat Lumjuan, and Nopadol Chaikum are thanked for offering valuable discussions. The provisions of research facilities and necessary supports from Nakorn Hamah, Vice President for Campus Development, Mahidol University and Tanakorn Osotchan, Director of the Physics Department, Faculty of Science, Mahidol University are appreciated.

References 1. T. Kobayashi, F. Takai and I. Hayami, On some Mesozoic fossils from the Khorat Series of East Thailand a note on the Khorat Series, Geol. Palaeontol. SE Asia 1 (1964) 119–133. 2. D. E. Ward and D. Bunnag, Stratigraphy of the Mesozoic Khorat Group in Northeast Thailand, Department of Mineral Resources of Thailand Report of Investigation 6 (1964) 95pp. 3. R. Ingavat and P. Taquet, J. Geol. Soc. Thailand 3 (1978) 1–6. 4. N. Sattayarak, Review of the continental Mesozoic stratigraphy of Thailand, Proc. Workshop on Stratigraphic Correlation of Thailand and Malaysia, ed. P. Nutalaya (Had Yai, Thailand, 1983), pp. 127–148. 5. E. Buffetaut and V. Suteethorn, The biogeographical significance of the Mesozoic vertebrates from Thailand, in Biogeography and Geological Evolution of Southeast Thailand, eds. R. Hall and J. D. Holloway (Backbuys, 1998), pp. 83–90. 6. A. Meesook, V. Suteethorn and T. Wongprayoon, Early Cretaceous nonmarine bivalves of the Sao Khua Formation, Khorat Group, Northeastern Thailand, 3rd Symposium IGCP 350, Manila, Philippines, Program and Abstract Volume (1995), pp. 10–11. 7. A. Meesook, V. Suteethorn, P. Chaodumrong, N. Teerarungsigul, A. Sardsud and T. Wongprayoon, Mesozoic rocks of Thailand: A summary, Proc. Symposium on Geology of Thailand, eds. N. Mantajit and S. Potisat (2002), pp. 82–94. 8. E. Buffetaut, V. Suteethorn, H. Tong, Y. Chaimanee and S. Khunsubha, New dinosaur discoveries in the Jurassic and Cretaceous of Northeastern Thailand, Proc. Int. Conf. Stratigraphy and Tectonic Evolution of Southeast Asia and the South Pacific (GEOTHAI 1997), eds. P. Dheeradilok, C. Hinthong, P. Chaodumrong, P. Putthapiban, W. Tansathien, C. Uthaaroon, N. Sattayarak, T. Nuchanong and S. Techawan, Vol. 1 (1997), pp. 177–187. 9. A. Racey, J. G. S. Goodall, M. A. Love, S. Polachan and P. D. Jones, New age data for the Mesozoic Khorat Group of Northeastern Thailand, Proc. Int. Symp. Stratigraphic Correlation of Southeast Asia, eds. P. Angsuwathana, T. Wongwanich, W. Tansathien, S. Wongsomsak and J. Tulyatid (Department of Mineral Resources, 1994), pp. 245–252.

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10. L. S. Gardner, H. F. Howarth and P. Na Chiangmai, Salt resources of Thailand, Department of Mineral Resources, Report of Investigation 11 (1967) 100pp. 11. N. Sattayarak and V. Suteethorn, Geological Map of Thailand 1:500,000 (Northeastern Sheet) (Geological Survey Division, Department of Mineral Resources, Thailand, 1983). 12. W. Stumm and J. J. Morgan, Aquatic Chemistry: An Introduction Emphasizing Chemical Equilibria in Natural Waters, 3rd edn. (John Wiley and Sons, New York, 1996). 13. K. B. Krauskopf, Introduction to Geochemistry, International Series in the Earth and Planetary Sciences (McGraw-Hill Book Company, 1967).

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Advances in Geosciences Vol. 13: Solid Earth (2007) Ed. Kenji Satake c World Scientific Publishing Company


INVESTIGATIONS ON LOCAL QUARTZ SAND FOR APPLICATION IN GLASS INDUSTRY∗

PISUTTI DARARUTANA The Royal Thai Army Chemical Department, Phaholyothin Road, Chatuchak, Bangkok, 10900 Thailand; The Glass and Glass Products Research and Development Laboratory, Institute for Science and Technology Research and Development, Chiang Mai University; The Graduate School of Chiang Mai University [email protected] PRUKSWAN CHETANACHAN National Institute of Health, Department of Medical Sciences, Nonthaburi 11000, Thailand PORNSAWAT WATHANAKUL Department of Earth Sciences, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand NARIN SIRIKULRAT Department of Physics, Faculty of Science, Chiang Mai University, Muang, Chiang Mai, 50200 Thailand; The Glass and Glass Products Research and Development Laboratory, Institute for Science and Technology Research and Development, Chiang Mai University

Silica or glass sand is a special type of quartz sand that is suitable for glassmaking, because of its high silica content, and its low content of iron oxide and other compounds. In Thailand, deposits of quartz sand are found as the beach and the river sands in many areas; eastern, southern, northeastern and northern. In this work, grain-size distribution and chemical analyses were carried out on 10 sand samples taken from various localities in Thailand such as Chanthaburi, Trat, Rayong, Chumphon, Nakhon Si, Pattani, Phuket, Songkhla, Nong Khai, and Tak provinces. The geological resources show that most of them are the surface-to-near-surface glass sand deposits. The sand grains in most deposits were mainly angular-to-rounded, except in some areas of either angular or rounded grains. Chemical analysis showed that the sands

∗ Work partially supported by The Graduate School of Chiang Mai University and The Office of the National Research Council of Thailand.

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contained more than 95wt% silica and low content of Fe, Al, Ca, Mg, Na, and K. The concentration levels of these components in the samples confirm with internationally acceptable standard for glass production. The quartz sand dressing plants that used the spiral classifier to improve the properties of the quartz sands to meet the standard specifications are mostly located in the eastern area. It can be concluded that most of the quartz sand deposits in Thailand investigated show well-sorted grain-size with considerable purity, i.e. high-grade quality. The advanced works resulted in that these raw quartz sands can be used as raw material for fabrication of soda-lime, lead crystal, and lead-free high refractive index glasses. The colorless and various colored glass products have been satisfactorily used in the domestic art and glass manufactures.

1. Introduction Glass is one of the oldest artificial materials known to man. The major raw materials of the most common glasses are the same as the oldest known glass recipe, and the process of glass making was recorded on clay tablets from the Royal Library of Assur-bani-pal at Nineveh (Iraq) in the seventh century BC. Silica, lime, and alkali are the bases of oxide glasses, which are of great importance, both historically and technologically. The source of silica is quartz sand.1−3 Sand consists of small grains or particles of minerals and rock fragments. Although these grains may be of any mineral composition, the dominant component of silica sand is the mineral quartz. Glass sand is a special type of sand that is suitable for glass making because of its high silica content and its low conduct of iron oxide and other compounds. It may be produced from both unconsolidated sands and crushed sandstones.4 The glass sand standards that was fixed by the US Bureau of Standard fixed the Sand Class Conditions for glass making,5 and the British standard methods for sampling and analyzing of glassmaking sand6 (Table 1). In Thailand, deposits of glass sand are found to be of both the beach and the river sands; most of them are beach sand,8 located in many areas; eastern, southern, northeastern, and northern.7 The geological Table 1. Standard

USA British

The standard of glass sand. Composition (%wt)

SiO2

Fe2 O3

Al2 O3

CaO + MgO

95 (min) 98.5 (min)

1 (max) 0.30 (max)

4 (max) —

0.5 (max) —

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resources show that they are mainly the surface-to-near-surface glass sand deposits. The previous works indicated that the other local raw materials including zircon sand and basalt rock also met the requirements for the glass industrial process.9,10 The local quartz sand from Trat area was satisfactory for the lead crystal glass fabrication.11 In this work, the physical structure, grain-size distribution, and chemical analyses of quartz sand samples taken from various localities in Thailand were investigated.

2. Experiment The geological explorations of silica sand were carried out in 10 various localities in Thailand such as Chanthaburi, Trat, Rayong, Chumphon, Nakhon Si, Pattani, Phuket, Songkhla, Nong Khai, and Tak provinces. The sand samples of about 10–100 k from each locality were taken to analyze their properties. The samples were prepared using standard metallographic technique prior to other specific experimental investigations. The physical structure investigations of the samples were determined using scanning electron microscope (SEM); Jeol JSM-5910, operated at 20 kV. The chemical compositions were determined by the wavelengthdispersive X-ray fluorescence spectrometer (WDXRF), Phillips MagixPro PW 2400, operated with LiF 200 crystal, scintillation and flow proportional detectors, with the Rh-tube at 60 kV 125 mA. The neutron activation analysis (NAA) was used to determine the trace elements. The grain distributions of the sand samples from each locality were analyzed by using the particle size analyzer, Malvern Instrument Mastersizer, using polydisperse analysis, and operated with a beam length of 240 mm and range lens 300 RF mm.

3. Results and Discussion The geological explorations showed that most of the sand resources from 10 localities in Thailand (Chanthaburi, Trat, Rayong, Chumphon, Nakhon Si, Pattani, Phuket, and Songkhla provinces) were the surfaceto-near-surface glass sand deposits, except at Nong Khai site that was the subsurface deposit. Most of them were the beach sand, except that of Nong Khai site that was the river sand, and at Tak deposit was the by-product from the feldspar floatation plant. The beach sands were

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Fig. 1.

The micrographs of the local sands studied.

deposited as lenses, of more than 100 m2 and approximately 0.2–2.0 m thick each, covering the wide area possibly about 1–3 km2 in each locality. Scanning electron microscope investigation (Fig. 1) revealed that the grain shape of the older beach sands (Chanthaburi, Trat, and Pattani) were angular to rounded. The present beach sands of Rayong, Chumphon, and Nakhon Si, showed the angular grain, whereas the Songkhla and Phuket sites were the rounded and the angular-to-rounded grains, respectively. The river sand from Nong Khai site was the angular-to-round grain, mixed with

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calcium carbonate in composition. The smaller grain sizes and angular grain were found at Tak site. Most of the older beach sand showed fine-grain, and also most of the present beach sand, except the Nakhon Si site showed fine to coarse grain. The fine grain was founded from Nong Khai and Tak sites. The color of the older beach sand was pink–gray, except the one from Rayong site that was orange–gray. Most of the present beach sands were pink–gray, but those at Phuket site were gray in color. Both the river sand from Nong Khai and the feldspar-floated sand from Tak sites showed white color. The origin, grain shape, and color of the local sands are shown in Table 2. Results of the grain-size analysis showed that the sizing of the sand particles was between 20 to 510 µm, as shown in Table 3, that fall within the ideal sand fraction range used for the glass production. Chemical analysis showed that the sands contain more than 95wt% silica and low content of Fe2 O3 , Al2 O3 , CaO, MgO, Na2 O, and K2 O, as shown in Table 4. Because of its origin of occurrences, the quartz glass sand from Tak site contained high silica and low impurities due to being the product of feldspar floatation. The concentration silica and the minor components in most of the samples confirmed with the internationally acceptable standards for glass production. Moreover, the trace elements using neutron activation analysis showed the presence of Hf, Os, Ti, Yb, and Se in the beach sand. All of these differential properties may be caused from the chemical and the physical weathering, and the biotic effect that erode the original source rocks. The quartz sand dressing plants that used the spiral classifier to improve the properties of the quartz sands to meet the wanted specifications were mostly founded in the eastern area. Table 2. Sites Rayong Chanthaburi Trat Chumphon Songkhla Phuket Pattani Nakhon Si Nong Khai Tak

The origin, grain shape, and color of the local glass sands. Origin

Grain shape, texture

Older beach Older beach Present beach Present beach Present beach Present beach Old beach Present beach River By-product

Angular-to-rounded, fine Angular-to-rounded, fine Angular, fine Angular, fine Rounded, fine Angular-to-rounded, fine Angular-to-rounded, fine Angular, fine-to-coarse Angular-to-rounded, fine Angular, fine

Color Orange–gray Pink–gray Pink–gray Pink–gray Pink–gray Gray Pink–gray Pink–gray White White

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The distribution of local quartz sands. Grain size, µm

Sites D(V , 0.1)

D(V , 0.5)

D(V , 0.9)

132 138 168 150 140 201 155 54 185 20

191 250 248 219 222 331 241 224 252 38

264 395 344 308 322 510 349 477 423 139

Rayong Chanthaburi Trat Chumphon Songkhla Phuket Pattani Nakhon Si Nong Khai Tak

Table 4.

Specific area m2 /g

0.148 0.138 0.166 0.146 0.119 0.212 0.140 0.118 0.158 0.026

0.043 0.057 0.046 0.043 0.055 0.040 0.050 0.050 0.031 0.474

The composition of local quartz sands.

Sites

Rayong Chanthaburi Trat Chumphon Songkhla Phuket Pattani Nakhon Si Nong Khai Tak

Concentration %vol

Composition SiO2

Fe2 O3

Al2 O3

CaO + MgO

Na2 O + K2 O

97.5 98.8 98.8 99.1 96.9 97.0 96.0 95.2 97.6 99.2

0.31 0.05 0.05 0.03 0.12 0.37 0.10 0.70 0.14