55th CCOP Annual Session Proceedings of the Thematic Session
Geosciences for [ Sustainable Development ]
5-6 November 2019, Chiang Mai, Thailand Proceedings of the Thematic Session, “Geosciences for Sustainable Development”, 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Printed in Thailand by: Coordinating Committee for Geoscience Programmes in East and Southeast Asia (CCOP)
Editors-in-Chief: Mr. Chen Schick Pei and Dr. Martin Smith
Editors: Dr. Young Joo Lee CCOP Technical Secretariat Dr. Dhiti Tulyatid CCOP Technical Secretariat Dr. Kong Sitha Cambodia Dr. Rer.nat. Budi Joko Purnomo, S.T., M.T. Indonesia Mr. Kamal bin Daril Malaysia Dr. Toshihiro Uchida Japan Mr. Conrado R. Miranda Philippines Dr. Dhiti Tulyatid Thailand
Copyright: Coordinating Committee for Geoscience Programmes in East and Southeast Asia (CCOP)
Published by: Coordinating Committee for Geoscience Programmes in East and Southeast Asia (CCOP) CCOP Building, 75/10, Rama VI Road, Thung Phayathi, Ratchathewi, Bangkok 10400, THAILAND
December 2020
ISBN (e-book): 978-616-93191-1-5
Picture on cover page: Phutthiseth Thongtae / Getty Images Coordinating Committee for Geoscience Programmes in East and Southeast Asia (CCOP)
Proceedings of the Thematic Session
“Geosciences for Sustainable Development”
55th CCOP Annual Session 5-6 November 2019, Chiang Mai, Thailand
PREFACE
The Thematic Session held at the 55th CCOP Annual Session on 5-6 November 2019 in Chiang Mai, Thailand, was carried out under the theme “Geosciences for Sustainable Development”.
There were a total of 44 papers for oral presentations and 12 papers for poster presentations delivered with approximately 150 participants attended at the Thematic Session.
A total of 21 papers were presented in this proceedings volume. The papers were grouped into three subthemes, which are
1. Geo-resources for the society: Mineral, Groundwater, Fossil Fuel Resources and Geological Conservation Sites; 2. Geo-environments for the Society: Climate Changes, Global Warming, Natural Disasters and Land-use Planning; and 3. Geo-education for the Society: Geopark and Geotourism.
The Thematic Session has successfully provided a venue for the exchange and sharing of updated information, networking and reunion of CCOP delegates of the Member Countries, Cooperating Countries and Organizations, as well as other participants.
We appreciate all the supports kindly provided to CCOP by the Ministry of Natural Resources, Department of Mineral Resources (DMR), Department of Groundwater Resources (DGR), Department of Marine and Coastal Resources (DMCR), Department of Primary Industries and Mines (DPIM, Ministry of Industry), and Department of Mineral Fuels (DMF, Ministry of Energy) on the organizing of the Thematic Session and the preparation and printing of the abstract volume to the Thematic Session.
We hope the readers, researchers, government services and all, find the papers published in this proceedings volume are useful and applicable to the preset-day needs on “Geosciences for Sustainable Development”.
Dr Young Joo Lee Director, CCOP Technical Secretariat
Thematic Session: “Geosciences for Sustainable Development”
I SUB-THEME I: GEO-RESOURCES FOR THE SOCIETY The 3D crust and upper mantle velocity model of South China Sea and surrounding region from joint inversion of ambient noise and event- based surface wave dispersions Liaoliang Wang, Haopeng Chen, Zhiwei Li, Feng Bao, and Guanghong Tu 05 Non-targeted 1H NMR profiling: A novel methodology for multiple- approaches to characteristic analysis of crude oil Kenta Asahina and Tadashi Nemoto 11 Source rock potential of coal and coaly mudstones from the Eocene Urahoro Group in the Kushiro Basin, eastern Hokkaido, Japan Koji U. Takahashi, Takeshi Nakajima, Yuichiro Suzuki, Sumito Morita, Takayuki Sawaki and Yasuaki Hanamura 15 The gravelly sedimentology of the Changcheng System and its petroleum geological significance Yinye Wu, and Jianzhong LiTakayuki Sawaki and Yasuaki Hanamura 21
Geological and geochemical approach for the binary power generation experiment at Matsunoyama hot spring area, Niigata, Japan Norio Yanagisawa, Munetake Sasaki, Hajime Sugita, Akinobu Miyakoshi, Masatake Sato, Kazumi Osato, Sei-ichiro Ioka and Hirofumi Muraoka 31
The Volcanic Facies and their Reservoirs Characteristics in Eastern China Basins Chunshuang Jin, Dewu Qiao, and Wenli Pan 39
The shale gas characteristics of Upper Ordovician Wufeng formation and Lower Silurian Longmaxi formation in Southwestern Sichuan Basin Chao Wang, Wentao Li, Shufang Yu, Xianglin Chen, Tianxu Guo, and Kun Yuan 51
New approaches for the identification of prospective gold mineralization localities in Chukchi and Magadan areas, Artic region by medium-scale geochemical prospecting A.G. Pilitsyn 59
II SUB-THEME II: GEO-ENVIRONMENTS FOR THE SOCIETY
Investigation of acid mine drainage (AMD) with long-term release of arsenic (AS) at Kyaukpahto gold mine, Myanmar Shinji Matsumoto, Akihiro Hamanaka, Thant Swe Win, Hiroto Yamasaki, Takashi Sasaoka and Hideki Shimada 67 Potential contribution of geosciences to Mekong’s environmental problems founded on cooperation of the CCOP member countries Toru Tamura 75 Purification of zeolite from Mae Moe power plants coal fly ashby microwave synthesis from improvement of sulfate removal from wastewater Khamngoen Kiattipong 81
1 2 Thematic Session: “Geosciences for Sustainable Development”
Studying the pH effect for sulfate removal in water by using Electrocoagulation Method Jaturong Kongwutthivech 85 Arsenic and Cadmium: under the DMR Hazardous Elements Project Apsorn Sardsud and Jitisak Premmanee 91 Managed aquifer recharge to ensure sustainable groundwater availability and quality under ongoing climate change and rapid economic development in Vietnam (Viet MAR) Arsenic and Cadmium: under the DMR Hazardous Elements Project Nguyen Thi Ha, Jaana Jarva, Kristiina Nuottimäki, Pham Thanh Long, Dang Tran Trung, Hoang Van Duy, Nguyen Thi Hong, and Nguyen Kim Hung 101 Potential Hazard from the M 8.7 Sunda Strait Megathrust Earthquake: a Deterministic Approach Amalfi Omang, Akhmad Solikhin*, Athanasius Cipta and Supartoyo 111 The Study of Temperature Effect on Q-seam of Mae Moh Mine’s Coal Pyrolysis Nucharin Whangdeeniran, Chatchawan Chaichana, and Suparin Chaiklangmuang 121 Study on Possible Sources of Elevated Arsenic Level in Water, Amphoe Ban Rai, Changwat Uthai Thani Apsorn Sardsud, Onuma Khamphleang and Jitisak Premmanee 125
III SUB-THEME I: GEO-EDUCATION FOR THE SOCIETY How to disseminate geological knowledge: an attempt in the Miné- Akiyoshidai Karst Plateau Geopark Koji Wakita1, Takanori Nakagawa1, Hokuto Obara2 and Tristan Gray2 135 Geological Survey of Japan international training course for CCOP Member Countries, Follow-up training and collaborative research with General Department of mineral Resources in Cambodia Hidetoshi Hara, Tsuyoshi Ito, Sitha Kong, Pagna Lim, and GSJ International Coordination Group1 145 Constructing a comprehensive geoscience database in East and Southeast Asia: CCOP Geoinformation Sharing Infrastructure for East and Southeast Asia (GSi) Project Shinji Takarada, Joel Bandibas and Toshihiro Uchida 147 Formulating Web Processing Service (WPS) and Web Map Service (WMS) for the Processing and Sharing of ASTER Satellite Data Using the GSi Information System Joel Bandibas and Shinji Takarada 157
3 4 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
The 3D crust and upper mantle velocity model of South China Sea and surrounding region from joint inversion of ambient noise and event-based surface wave dispersions
Liaoliang Wang1, Haopeng Chen2,3, Zhiwei Li3, Feng Bao3, and Guanghong Tu1
1Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou, 510075, China 2Institute of Geophysics, School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China 3State Key Laboratory of Geodesy and Earth’s Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan, 430077, China
Abstract
In this study, the vertical component waveforms recorded by 30 seismic stations in the area surrounding the South China Sea from January 2011 to December 2016 were used. The event- based Rayleigh wave phase velocity dispersion curves in the period range of 20 – 120 s measured using the two-station cross-correlation method. Utilizing the ambient noise cross-correlation function obtained by Zhao (2019), the ambient noise Rayleigh wave phase velocity dispersion curves in the period range of 12 – 40 s was also measured. . Then the continuous regionalization of generalized least square inversion scheme to perform the 2D phase velocity tomography by jointly using the ambient noise and event-based phase velocity dispersions was adopted. Lastly, a linear iteration inversion method was used to perform the 1D S-wave velocity inversion at each grid point and obtained the 3D S-wave velocity model in the depth range of 10 – 250 km. In the South China Sea, the results show that it will cause large error if the sea water column is not included in the S-wave velocity inversion. In the depth range of 20 – 60 km, there is a prominent high-velocity anomaly in the South China Sea Basin, which may be related to the thin crust in the basin. In the north of the Kalimantan Island, a prominent low-velocity anomaly is shown in the depth range of 10 – 250 km. This low-velocity anomaly may indicate the upwelling of asthenosphere or the mantle material.
1. Introduction
Since the Cenozoic era, the South China Sea has undergone complex tectonic evolution processes under the combined influence of the Pacific Plate and the Tethyan tectonic area, resulting in a complex area including continental margins, sea basins, oceanic trenches and island arcs (Figure 1). At present, the tectonic evolution process of the South China Sea and surrounding region is still not very clear. The detailed 3D velocity structure model could provide valuable information for the study of the evolution mechanism of the South China Sea and its surrounding region.
In this study the vertical component waveforms recorded by the seismic stations in the area surrounding the South China Sea were used, and the ambient noise and event-based Rayleigh wave phase velocity dispersion curves measured. Then, the 2D phase velocity maps in the period range of 12 – 120 s were imaged and inverted for the 3D S-wave velocity model in the depth range of 10 – 250 km. Finally, the tectonic implications from the 3D S-wave velocity model are discussed.
5 Liaoliang Wang, Haopeng Chen, Zhiwei Li, Feng Bao, and Guanghong Tu The 3D crust and upper mantle velocity model of South China Sea and surrounding region
Figure1. Physiography and bathymetry of the region with locations of seismic stations (red triangles).
The first module is the portal for dataset upload, metadata edit and data transfer. Second one is message queue, for physical dataset description and transfer of the dataset information in the form of message queue, including name, parameters need to be processed by the server and the address of storage. Third one is the message scheduling server, which is mainly act as turnover/transfer and processing of the message, and scheduling balancing amongst distributed node according to executive frequency of the massage queue (Figure 2). The fourth is data service module for the datasets, which is functioned as the module for geoscience data processing. It conducts processing and generates results in OGC’s WMS or WFS format while receiving massage from the scheduling server. And release the access interface code for the portal to access the results data.
Figure 2. The seismic events used in this study 2. Data and Method
Thirty seismic stations in the South China Sea and adjacent area are used in this study. Seismic records from January 2011 to December 2016 were used to obtain the Rayleigh wave group phase velocities. Figure 1 shows the distribution of the seismic stations. Eevents with magnitude between Mw 5.5 and 7.5, depth of less than 50 km and distance between 15-120º were selected. The signal-noise-ratio is set to be greater than 5.0 and the cross-correlation method to measure the event-based phase velocity in the period range of 20 – 120’s was used. The two-station method 6 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand is based on the great circle approximation and requires that the event is approximately located on the great circle path of the station pair. The ambient noise phase velocity in the period range of 12 – 40’s was measured using the cross-correlation function from Zhao et al. (2019). Finally, the Rayleigh wave phase velocity dispersion in the period range of 12 – 120 s was obtained.
The continuous generalized least square inversion method (Tarantola and Valette, 1982; Tarantola and Nercessian, 1984; Montagner, 1986) was used to image the Rayleigh wave phase velocity distribution. The choices of the correlation length and the priori model error are very important for the use of this inversion method (Montagner, 1986; Yao et al., 2008). The S-wave velocity structure of the study region was inverted with a grid spacing of 1.0º×1.0º using the linear iteration inversion method of Herrmann and Ammon (2004).. Since it is a non-linear problem to invert the S-wave structures from surface wave dispersion, the choice of initial model is quite important. The South China Sea is very deep and after many tests, it was found that a sea water column should be added in the initial model. If the sea water column is not added layer, the short period dispersion curve could not be well fitted.
3. Results
Based on the methodology described above, the 3D S-wave velocity model of South China Sea and adjacent region in the depth range of 10 – 250 km was obtained (Figure 3). In the depth range of 20 – 60 km, there is a prominent high-velocity anomaly in the South China Sea Basin. In the north of the Kalimantan Island, a prominent low-velocity anomaly is shown in the depth range of 10 – 100 km and the S-wave velocity remains relatively low i n the depth range of 200 – 250 km. An obvious low velocity anomaly is also shown at 200 km in the north of Indo-China Peninsula.
4. Discussion and conclusions
In this study, the 3D S-wave velocity model of the crust and upper mantle in the South China Sea and adjacent region was developed by joint inversion of ambient noise and event-based Rayleigh wave phase velocity dispersions. As the South China Sea is very deep, the results show that it will cause large error if the sea water column is not taken into consideration in the S-wave velocity inversion. In the depth range of 20 – 60 km, there is a prominent high-velocity anomaly which may be related to the area of thin crust in the South China Sea Basin, . In the north of the Kalimantan Island, a prominent low-velocity anomaly is shown in the depth range of 10 – 250 km. This low-velocity anomaly may indicate the upwelling of asthenosphere or the mantle material.
7 Liaoliang Wang, Haopeng Chen, Zhiwei Li, Feng Bao, and Guanghong Tu The 3D crust and upper mantle velocity model of South China Sea and surrounding region
Figure 3 The 3D S-wave velocity model
8 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Acknowledgements
This study is supported by China-ASEAN Marine Geoscience Research and Disaster Prevention Program (121201002000150022), National Natural Science Foundation of China (41804061, 41674065), National Key Research and Development Project (2018YFC1504202) and China Geological Survey Geological Survey Program (DD20160191).
References
Herrmann, R. B., and Ammon, C. J., 2004. Computer Programs in Seismology. 3.30, http://www.eas.slu. edu/eqc/eqccps.html.
Huang, Z. X., and Xu, Y., 2011. S-wave velocity structure of South China Sea and surrounding regions from surface wave tomography. Chinse Journal of Geophysics (in Chinese), 2011, 54 (12): 3089- 3097.
Montagner, J. P., 1986. 3-dimensional structure of the Indian Ocean inferred from long period surface waves. Geophys. Res. Lett., 13, 315-318.
Tarantola, A., and Valette, B., 1982. Generalized nonlinear inverse problems solved using the least squares criterion. Reviews of Geophysics, 20, 219-232.
Tarantola, A., and Nercessian, A., 1984. Three-dimensional inversion without blocks, Geophys. J. Int., 76, 299-306.
Yao, H., Beghein, C., and Van Der Hilst, R. D., 2008. Surface wave array tomography in SE Tibet from ambient seismic noise and two-station analysis–II. Crustal and upper-mantle structure. Geophysical Journal International, 173(1): 205-219.
Zhao, J. Z., Li, Z. W., Lin, J. M., Hao, T. Y., Bao, F., Xie, J., Wang, L. L., and Tu, G. H., 2019. Ambient noise tomography and deep structure in the crust and mantle of the South China Sea. Chinese Journal of Geophysics (in Chinese), 62(6): 2070-2087
9 10 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Non-targeted 1H NMR profiling: A novel methodology for multiple-approaches to characteristic analysis of crude oil
Kenta Asahina and Tadashi Nemoto
National Institute of Advanced Industrial Science and Technology, Japan
E-mail: [email protected]
Abstract
Molecular indicators provide useful information for petroleum system studies. This is typically performed by gas chromatography-mass spectrometry (GC-MS) in combination with silica-gel column chromatography or pyrolysis. ; However, these techniques are time consuming and have difficulties in identifying the difference among similar samples. To speed up the analysis, nuclear magnetic resonance-metabolic profiling (NMR-MP) was applied and tested. The utility of NMR- MP methodology has been demonstrated in food and medical studies as metabolomics. Nemoto et al. (2007) reported the difference between healthy and hypertensive rats using urines by principal component analysis (PCA). In the same way, NMR data from crude oils were directly visualized and evaluated.
In this study, crude oil samples were obtained from oil and gas fields in Japan. The source rock type of these samples has been firstly investigated by conventional methods. Then, the samples were directly dissolved in NMR solvent without any separation and/or purification. Proton NMR spectra at 500 MHz were obtained and then bucket-integrated to produce numerical data. Consequently, the dataset was subjected to statistical pattern recognition by PCA.
The resulting variable of 1.26 corresponding to methylene signals remarkably contributed to the alignment of the data points along the PC1 axis. The resulting 2D scatter plot shows whether the type of source organic matter is marine or terrestrial. The study result confirmed that the NMR-MP results were consistent with those of the conventional analysis. Two step PCA was carried out by removing variable of 1.26, the resulting score plot suggested locality of producing areas. Contributing variables in the resulting score plot were 0.86, 0.90 and 2.30 corresponding to aliphatic/aromatic methyl groups.
In this paper, the “NMR-Petro analysis” is presented as a rapid and easy approach to elucidate the characteristics of crude oil.
Keywords: Source rock evaluation, NMR spectral profiling, Principal component analysis, Non-target analysis
1. Introduction
Various organic compounds are contained in crude oils. They are suggested to be mostly originated from organism. Organic compounds found in geological samples, known as biomarkers, can provide useful information, such as source organic matter, maturity and sedimentary environment (van Aarssen et al., 1999). Chromatography-based techniques are widely used as a conventional analytical method of biomarkers. The general procedure of these methods requires sample preparation by silica-gel column chromatography. The measurement using gas chromatography also requires much more time.
11 Kenta Asahina and Tadashi Nemoto, Non-targeted 1H NMR profiling: A novel methodology for multiple-approaches to characteristic analysis of crude oil
Nuclear magnetic resonance (NMR) spectrometer is widely used in organic chemical studies to determine the chemical structure. NMR measurement has many advantages: no preparation needed, short acquisition time, sample recovery and free from contamination. NMR-Metabolic profiling (NMR-MP) has been used in medical science and food chemistry (Lindon et al., 2007). Nemoto et al. (2007) reported the difference of healthy/hypertensive rats using urines by principal component analysis (PCA). This method can determine the difference between each sample.
In this study, a non-targeted PCA based on NMR-derived data was employed to clarify the contributions of signals that characterize the oil samples. The results of NMR profiling were compared with results from gas chromatography and mass spectrometry analysis.
2. Results and Discussion
Seventeen (17) crude oil samples were collected from oil and gas fields in Japan. The source rock type of these samples was first investigated by the conventional methods followed by the NMR spectrometry method.
Outline of the non-targeted NMR profiling is shown in Figure 1. Samples were directly dissolved in chloroform-d. 1H-NMR spectra were recorded at 500 MHz to obtain the numerical data. The NMR spectra from 0.5 to 10.0 ppm were calculated by bucket-integration with each 0.04 ppm step to give 238 variables. The dataset was visualized by statistical pattern recognition using PCA. The first (PC1) and second (PC2) principal components explained 95.3% and 2.1% of the variance, respectively. The methylene signals remarkably contributed to the alignment of the data points along the PC1 axis. Resulting PCA suggested that PC1 shows wax content of crude oil. The alignment shows the type of source organic matter is marine or terrestrial. This study confirmed that the NMR profiling results were consistent with those of conventional analysis. The second PCA was carried out by removing the variable of 1.26. The PC1 and PC2 were 71.4% and 13.9%, respectively. The result shows the locality of oil producing area. The remarkable variable of PC1 were 0.86, 0.90 and 2.30. These variables correspond to aliphatic/aromatic methyl group.
This study demonstrated that the NMR-Petro analysis is a good approach to elucidate the characteristic component of crude oil. This method is also an exploratory analysis for grouping by multiple viewpoints, finding novel indicators and suggesting important factor.
Figure 1 Outline of non-targeted NMR profiling.
12 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
References van Aarssen, B.G.K., Bastow, T.P., Alexander, R., and Kagi, R.I., 1999. Distributions of methylated naphthalenes in crude oils: indicators of maturity, biodegradation and mixing. Organic Geochemistry 30, 1213–1227.
Lindon, J. C., Nicholson, J. K., and Holmes, E., 2007. The Handbook of Metabonomics and Metabolomics, First Edition. Elsevier. 561p.
Nemoto, T., Ando, I., Kataoka. T., Arifuku, K., Kanazawa, K., Natori, Y., and Fujiwara, M., 2007. NMR metabolic profiling combined with two-step principal component analysis for toxin-induced diabetes model rat using urine. Journal of Toxicological Science 32, 429-435.
13 14 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Source rock potential of coal and coaly mudstones from the Eocene Urahoro Group in the Kushiro Basin, eastern Hokkaido, Japan
Koji U. Takahashi1, Takeshi Nakajima1, Yuichiro Suzuki1, Sumito Morita2, Takayuki Sawaki2 and Yasuaki Hanamura3
1Research Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Japan 2Geoinformation Service Center, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Japan 3JX Nippon Oil & Gas Exploration Corporation, Japan
E-mail: [email protected]
Abstract
Cenozoic coal and coaly sediments have the potential to generate oil because their hydrogen and aliphatic structures are more abundant compared with Carboniferous coal. Therefore, the Cenozoic coal is an important source rock for oil and gas. Previous study (Takahashi et al., 2020) has revealed the hydrocarbon generation potential and the thermal maturity of the coal and coaly mudstones from the Eocene Urahoro Group in the Kushiro coal basin (Kushiro Basin) of eastern Hokkaido, Japan. In this study, preliminary maceral analysis was carried out to investigate the relationship between hydrocarbon potential and maceral composition in coal samples from the Kushiro Basin.
According to Takahashi et al. (2020), the coal samples were classified as subbituminous or high volatile C bituminous, characterized by high hydrogen content. The hydrogen index (HI: mg hydrocarbon/g total organic carbon) and random mean vitrinite reflectance (VRr %) indicated that the coal and coaly mudstones were gas- and oil-prone or oil-prone. Preliminary results of this study on maceral analysis suggest that the oil-proneness of the Kushiro coal samples can be related to the abundance of detrovitrinite and liptodetrinite.
According to Takahashi et al. (2020), the vitrinite reflectance of the coal samples from the Kushiro Coal Mine is inversely proportional to the HI value although each coal seam has the identical thermal history. This suggests that their vitrinite reflectance is suppressed. Based on the corrected vitrinite reflectance, the coal maturity increases towards the north in the Kushiro Basin.The corrected vitrinite reflectance of the samples from the northernmost part of the basin (Hokuyo Area) is approximately 0.8%, which falls within the oil window. The maturity of the coal-bearing strata in the northern area of the basin could have been affected by volcanic activity along the volcanic front. In the Hokuyo Area, the Urahoro Group overlies a sequence of Cretaceous–Eocene marine clastic rocks (Nemuro Group), suggesting that the maturity of the organic matter in the subsurface Nemuro Group should have reached the oil window (> 0.8%) in the northern Kushiro Basin.
Keywords: Cenozoic coal, Kushiro Basin, Maceral composition, Source rock assessment, Japan
15 Koji U. Takahashi, et al., Source rock potential of coal and coaly mudstones from the Eocene Urahoro Group in the Kushiro Basin, eastern Hokkaido, Japan
1. Introduction
The Paleogene Kushiro sedimentary basin (the Kushiro Basin) in eastern Hokkaido is one of the most important coal-bearing basins in Japan. The abundant coal seams in the sedimentary basin have been exploited as the Kushiro Coal Field since the 19th century. The Urahoro Group comprises the major coal-bearing stratigraphic succession in the Kushiro sedimentary basin, and was deposited during the middle to late Eocene 40 to 34 Ma (Kaiho, 1983; Editorial Committee of Hokkaido, 1990; Geological Society of Japan, 2010; Katagiri et al., 2016). However, the hydrocarbon potential of coal and coaly mudstones of the Urahoro Group is still unclear. In the previous study, the maturity and source rock potential of the coals and coaly mudstones from the Urahoro Group was evaluated based on Rock-Eval pyrolysis, elemental composition (atomic H/C and O/C), ultimate analysis and vitrinite reflectance measurements (Takahashi et al., 2020). In this study, Preliminary maceral analysis was also carried out to investigate the relationship between hydrocarbon potential and maceral composition in the Kushiro coal samples.
2. Coal characterization and hydrocarbon potential of the Urahoro coal
The coal samples of the Urahoro Group are classified as subbituminous or high volatile C bituminous, characterized by high hydrogen content (Takahashi et al., 2020). The Urahoro coal samples fall between Type II and Type III pathways on the van Krevelen plot of atomic H/C versus O/C. The TOC and Rock-Eval S2 values of the samples range from 29.1 to 70.6 wt.%, 52.3 and 278.2 mg HC/g rock, respectively, corresponding to excellent hydrocarbon potential (Peters and Cassa, 1994). The high hydrocarbon potential is partly due to unusual scarcity of inertinite macerals, except for a small amount of sclerotinite (funginite), and abundant degradinite (detrovitrinite) (Takahashi and Aihara, 1989; Suzuki and Fujii, 1995).
Vitrinite is divided into telovitrinite, detrovitrinite, and gelovitlinite (ICCP, 1998). Detrovitrinite consists of finely fragmented vitrinitized plant remains occurring either isolated or cemented by amorphous vitrinitic matter (ICCP, 1998). Detrovitrinite is divided into vitrodetrinite and collodetrinite (ICCP, 1998). In Japanese coal, detrovitrinite is often associated with liptinite macerals (oil-prone) (Suzuki and Fujii, 1995). Actually, detrovitrinite associated with liptinite macerals such as liptodetrinite and sporinite is observed in the Urahoro coal samples (Fig. 1). Preliminary result of maceral analysis for several coal samples shows that the coal having the high hydrocarbon potential (HI=400) is rich in detrovitrinite and liptodetrinite (Dv+Ld > 50 vol.%). In contrast, the coal having the medium hydrocarbon potential (HI=200) is relatively poor in detrovitrinite and liptodetrinite (Dv+Ld < 20 vol.%). According to Fujii et al. (1978), the degradinite contents in the Kushiro coal range from 20 to 60 vol.%. These results suggest that the hydrocarbon potential of the Urahoro coal samples can be related to the abundance of detrovitrinite and liptodetrinite.
3. Thermal maturity trend of the Urahoro group in the Kushiro Basin
The random mean vitrinite reflectance (VRr %) of the Urahoro samples ranges from 0.42 to 0.56%. The vitrinite reflectance of coal samples from the Kushiro Coal Mine (KCM) is inversely proportional to the HI value, although each coal seam has the identical thermal history. The VRr and HI values of the KCM samples show a good linear relationship (R2 = 0.82, n=9). This result suggests that the vitrinite reflectance of coal samples in the KCM is suppressed. To investigate the thermal maturity trend of the Urahoro Group in the Kushiro Basin, the effect of vitrinite reflectance suppression in each sample is corrected by the slope of linear regression equations for the VRr (%) and HI values. The corrected vitrinite reflectance (VRc %) in northern part of the study area showed slightly higher values than those in other locations. 16 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 1. Photomicrographs of coal samples from the Eocene Urahoro Group. Images (a) and (c) were taken in reflected white light and (b) and (d) in fluorescence mode (blue light excitation), oil immersion. Vitrodetrinite (Vd), collodetrinite (Cd), semifusinite (Sf), inertdetrinite (Id), funginite (Fg), sporinite (Sp), cutinite (Cu), liptodetrinite (Ld), alginite (Ag). Image (b) is the same field of views as (a), and image (d) is the same field of views as (c).
The boreholes drilled to assess coal resources of the Urahoro coal-bearing strata in the Hokuyo Area are located in about 15 km northwest of the study area (New Energy Development Organization, 1983, 1984, 1985, 1986). These previous surveys reported the mean maximum vitrinite reflectance (Rmax %) of the Urahoro coal-bearing strata in the Hokuyo Area. These Rmax values were converted to VRr using the equation, Rmax (%) = 1.07*VRr - 0.01 (Diessel and
McHugh, 1986), and further corrected to VRc values (Takahashi et al., 2020). The VRc values of the Urahoro coal-bearing strata in Hokuyo area are higher than those in the study area. The VRc in the Kushiro Basin coal shows that the maturity increases towards the north. The higher maturity of the coal-bearing strata in the northern area could be explained by the influence of volcanic activity along the volcanic front. The maximum VRc (%) in the Hokuyo coal falls within the oil window (Takahashi et al., 2020).
Moreover, the lower unit of the Urahoro Group rests unconformably on the Upper Cretaceous– Eocene Nemuro Group (Matsui, 1962; Naruse, 2003). The Nemuro Group is a marine clastic sequence (about 3,000–4,000 m thick) that is mainly composed of hemipelagic mudstones, turbidites and submarine slump deposits (Kiminami, 1978; Editorial Committee of Hokkaido, 1990). The organic matter maturity of the Nemuro Group in the subsurface of the northern Kushiro Basin can be higher than that of the Urahoro Group since the former burial depth is greater. This suggests that the organic matter maturity in the subsurface Nemuro Group from the northern Kushiro Basin should have reached the oil window. 17 Koji U. Takahashi, et al., Source rock potential of coal and coaly mudstones from the Eocene Urahoro Group in the Kushiro Basin, eastern Hokkaido, Japan
4. Conclusions
The hydrocarbon generation potential of coal samples from the Eocene Urahoro Group in the Kushiro coal basin is examined by maceral analysis. The hydrocarbon potential (e.g., HI value) of the Urahoro coal samples can be related to the abundance of detrovitrinite and liptodetrinite. It is also related to vitrinite suppression. Maceral analysis is, therefore, crucial for the assessment of thermal maturity by vitrinite reflectance.
References
Diessel, C.F.K. and McHugh, E.A., 1986. Fluoreszenzintensität und Reflexionsvermögen von Vitriniten und Inertiniten zur Kennzeichnung des Verkokungsverhaltens. Glückauf-Forschungsh, 47, 60–70 (in German).
Editorial Committee of Hokkaido (eds.), 1990. Regional Geology of Japan, Part 1 Hokkaido*. Kyoritsu Shuppan, Tokyo, 337p (in Japanese).
Fujii, K., Sasaki M., Goto, S. and Higashide, N., 1978. Maceral and vitrinite reflectance in relation to some coal properties of low rank coal in Kushiro coal field, Hokkaido, Japan. J. Geol. Soc. Japan 84, 539–547 (in Japanese with English abstract).
Geological Society of Japan (eds.), 2010. Bulletin of the Regional Geology of Japan, Part 1 Hokkaido*. Asakura Shoten, Tokyo, 631p (in Japanese).
ICCP, 1998. The new vitrinite classification (ICCP System 1994). Fuel, 77, 349–358.
Kaiho, K., 1983. Geologic ages of the Paleogene of Hokkaido, Japan based upon planktonic foraminifera – The relationship between the hiatuses and sea-level movements. Fossils (Kaseki), 34, 41–49 (in Japanese with English abstract).
Katagiri, T., Naruse, H., Hirata, T. and Hattori, K., 2016. U-Pb age of the tuff bed in the Urahoro Group, eastern Hokkaido, northern Japan. J. Geol. Soc. Japan, 122, 495–503 (in Japanese with English abstract).
Kiminami, K., 1978. Stratigraphic re-examination of the Nemuro Group. Chikyu Kagaku (Earth Sci.), 32, 120–132 (in Japanese with English abstract).
Matsui, M., 1962. Sedimentological study of the Paleogene basin of Kushiro in Hokkaido, Japan. J. Fac. Sci., Hokkaido Univ. Series 4, Geology and Mineralogy, 11, 431–480.
Naruse, H., 2003. Cretaceous to Paleocene depositional history of North-Pacific subduction zone: reconstruction from the Nemuro Group, eastern Hokkaido, northern Japan. Cretac. Res., 24, 55– 71.
New Energy Development Organization, 1983. Report of Hokuyo Area. Fundamental Survey for domestic coal resource development*, 13p (in Japanese).
New Energy Development Organization, 1984. Report of Hokuyo Area. Fundamental Survey for domestic coal resource development*, 19p (in Japanese).
New Energy Development Organization, 1985. Report of Hokuyo Area. Fundamental Survey for domestic coal resource development*, 11p (in Japanese).
New Energy Development Organization, 1986. Report of Hokuyo Area. Fundamental Survey for domestic coal resource development*, 9p (in Japanese).
18 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Peters, K. E. and Cassa, M. R., 1994. Applied source rock geochemistry. The petroleum system – from source to trap (Magoon, L. B. and Dow, W. G., eds.), 93–120, American Association of Petroleum Geologists, Tulsa.
Suzuki, Y. and Fujii, K., 1995. Source rock potentials of coal based on coal properties. J. Jap. Assoc. Petroleum Tech., 60, 520–529 (in Japanese with English abstract).
Takahashi, R. and Aihara, A., 1989. Characteristic nature of sedimentation and coalification in the Tertiary system of the Japanese Islands. Int. J. Coal Geol., 13, 437–453.
Takahashi, K.U., Nakajima, T., Suzuki, Y., Morita, S., Sawaki, T. and Hanamura Y., 2020. Hydrocarbon generation potential and thermal maturity of coal and coaly mudstones from the Eocene Urahoro Group in the Kushiro Coalfield, eastern Hokkaido, Japan. Int. J. Coal Geol., 103322.
* English translation from the original written in Japanese.
19 20 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
The gravelly sedimentology of the Changcheng System and its petroleum geological significance
Yinye Wu*, and Jianzhong Li
Research Institute of Petroleum Exploration and Development, CNPC, Beijing, China
E-mail: [email protected]
Abstract
The Proterozoic Changcheng System comprises Changzhougou formation, Chuanlinggou formation, Tuanshanzi formation and Dahongyu formation from the base to the top. These formations mainly comprise a set of shallow marine clastic rocks and carbonate rocks with a wide range of distribution. From geological observation of the Changcheng System at the Changzhou Village in Jixian County of Tianjin, Shanxi and around Beijing, combined with the thin section study, it is considered that the base of the Changcheng System is generally composed of gravelly shoreline facies, partly influenced by tidal action and paroxysmal river injection at the coastal margin, and that the sedimentary microfacies are gravel beaches, small tidal channels braided river channel and sand-gravel in foreshore deposition. They exhibit the following sedimentary characteristics: 1) two-way wedge-shaped and trough-like cross-bedding gravel-bearing coarse sandstone sedimentary sequences; 2) fish-bone-like cross-bedding sedimentary sequences of double clay layers and tidal bundle bodies; 3) the gravels have the characteristics of progressive normal grain sequence in the wedge-like interbedded gravel-bearing sandstone sedimentary sequence; 4) the gravels with good roundness have the characteristic of progressive reverse- grain sequence, and the thickness of the gravelly bed is about 1 ~ 2 m extended widely in striped conglomerate depositional sequences; and 5) Massive bedding is mainly developed in gravel foreshore and low angle scouring bedding seen in sandstone, the shoreface sedimentary sequence composed of multi-stage mudstone and sandstone parasequence in the upper part. The understanding of the gravel shoreline facies is of great significance to the exploration of deep and ultra-deep oil and gas and the study of conglomerate reservoir.
Keywords: gravelly foreshore facies, sandy conglomerate reservoir, Proterozoic Changcheng System, Para sequence, sequence stratigraphy
1. Introduction
The International Commission on Stratigraphy has set the age of the Mesoproterozoic bottom boundary as 1,600 Ma, and from 1,600 to 1,400 Ma as Calymmian, indicating the formation period of the global platform cap-rocks. The consolidation time of the basement of the North China platform is 1,800 Ma, and the cap-rock filling in the crack- internal crack trough of the craton happened around the bottom boundary of 1,800 Ma. The tectonic properties of the Middle Proterozoic basin on the North China platform are completely different in different periods: 1,800~1,600 Ma was a rifting trough; 1,600~1,400 Ma developed into an epeiric sea; 1,400~1,300 Ma was s transformed into a back-arc basin. The 1,800 Ma, 1,600 Ma and 1,400 Ma represent the period of three important regional tectonic transformations in Mesoproterozoic. The age of the basal boundary of Changzhougou formation of the Changcheng system in Miyun area, Beijing can be determined as 1650 Ma (Qiao and Wang, 2014). From the base to the top, the Middle Proterozoic is divided into Changcheng system and Jixian system, among which the Changcheng system is the most widely distributed in the North China craton (Pan et al., 2013). According to the study of outcrop and chrono-stratigraphy in the field, the North China craton developed four rifting valleys in the Middle and Neoproterozoic; the Qionger, the northern margin, Yanliao 21 Yinye Wu, and Jianzhong Li, The gravelly sedimentology of the Changcheng System and its petroleum geological significance and Xuhuai. The Changcheng System is composed of Changzhougou formation, Chunlinggou formation, Tuanshanzi formation and Dahongyu formation from the base to the top (Table 1). It is mainly composed of a set of shallow sea clastic rock and carbonate rock combination with thickness of more than 2,600 m distributed widely. The Changzhougou formation at the base is an uncomformity over the gneiss of Qianxi Group of Archean age. It is considered that the scour surface is widely developed in lowest section of Changzhougou formation, and the gravel deposited have the characteristics of progressive fining-upward, which reflects the change of crustal uplift rate. A large number of wedges cross bedding and tabular cross bedding can be seen in this lower section, reflecting the early fluvial sedimentary characteristics of Changzhougou formation. Two-way wedge cross bedding, fish-bone cross bedding, double clay layer and tidal fasciculate sediments are developed in the upper second member horizon, which reflect the characteristics of marine deposition. In the gravel-bearing coarse sandstone at the base of Changzhougou formation in Jixian outcrops, the frequent development of bi-directional cross bedding and scour surface indicate that it has tidal sedimentary characteristics. This understanding negates the erroneous concept of “river transgression” for the extensive development of rivers in the early stages of transgression. On the other hand, it is shown that the North China craton was not stable in the early Mesoproterozoic crust and did not have a river sedimentary background of more than 400 m thick. It is considered that it should belong to the inshore tidal sand beach deposit in the early stage of transgression. From geological observation of the Changcheng system in Changzhou Village, Jixian County, Shanxi, and around Beijing, combined with the thin section study, it is found that the following scientific problems need to be further considered: 1) how is the transition from the basal river phase to the upper shore (shoreface) with no deltaic deposit?; and 2) there is a great difference between gravel accumulation and fluvial distribution. The analysis in this paper shows that the Changzhougou formation at the base of the Changcheng system has a complete sedimentary sequence from the backshore, foreshore to shoreface, and there is a local river injection and/or tidal activity during the backshore sedimentary period.
The significance of this study are: 1) the petrographic study and reconstruction ofthe paleogeography of the Changcheng system provide scientific basis for deep and ultra-deep oil and gas exploration (Hu et al., 2009); 2) provides reference for the distribution of oil and gas reservoirs in the same type of sedimentary environment; and 3) outlining potential areas for exploration of mineral resources, especially rare-earth minerals in ancient marine strata. The authigenic monazite and other phosphate and silicate rare-earth minerals were found in Changzhougou formation, Chunlinggou formation and Dahongyu formation of the Middle Proterozoic Changcheng system in Beijing (Song et al., 2004).
2. Sedimentary sequence and facies of gravelly sandstone in the lower part of Changzhougou formation of Changcheng system
Changzhougou formation refers to clastic rock strata, which has an unconformity on Archean metamorphic rocks at the base, comprising mainly sandy conglomerate and quartz sandstone, with minor siltstone and mud-shale strata. A set of gravel sequences is developed at the base of Changzhougou formation in Lingyuan area, Liaoning Province. The gravel is composed mainly of quartz rock, the content of gravel is more than 70%, the degree of sorting and roundness are good, and it has high compositional and structural maturity, indicating that it is marine in origin. The grain size gradually becomes finer upwards, and it transitioned into two-way cross bedding gravel-bearing quartz coarse sandstone. Some fish-bone cross bedding, double clay layer and tidal bundle body can be explained as high energy tidal flat deposition. In Yongji area of Shanxi Province, the massive quartz sandstone of the Changcheng system has an inverse rhythmic phase sequence structure, which forms a number of shoreface-foreshore sedimentary cycles with gray- green thin siltstone and argillaceous siltstone.
22 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Table 1 Chronostratigraphy of the Changcheng system of the Proterozoic
Chronostratigraphy Lithostratigraphy Erathen System
Jixian system
Gaoyuzhuan Fm.
Dahongyu Fm. Middle Proterozoic Changcheng system Tuanshanzi Fm. (1800~1400Ma) Chunlinggou Fm.
Changzhougou Fm. Quinxi Group System. Lower Proterozoic
Note: the latest research results classify Gaoyuzhuan Fm. into Jixian
In Jixian County, Tianjin, 7 outcrops were observed at locality 40°13′12″N, 117°30′49″E, over 460 m and described as follows:
Observation point 1 at the Mesoproterozoic / Archean boundary point, the upper and lower strata show unconformity contact, and the surface of bottom scour is obvious. In the upper part of the boundary, the third member of the Changzhougou formation has fining upward grain size cycle, gravel-coarse sandstone, trough cross bedding and good gravel roundness.
Observation point 2 is Archean basement rock, including hornblende plagioclase gneiss, plagioclase hornblendite, granulite, magnetite, and quartzite.
Observation point 3 shows the cycles of multiple fining -upward grain size cycles, and the particle size becomes finer than that at Observation point 1. The sea level has relatively risen, with lithology of fine and medium-sandstone and argillaceous strips of gravelly coarse sandstone with plate-shaped cross bedding (oblique bedding) (Figure 1).
Observation points 4 and 5 show fining-upward grain size cycle, gravel-coarse sandstone-fine- medium sandstone, gravel size commonly 2~3 cm with good roundness, directional arrangement, and plate-shaped cross bedding in sandstone.
Observation point 6 shows reverse grain size sequence, gravel coarse sandstone-gravel; gravel roundness is excellent.
Observation point 7 shows the following grain size sequence; gravel-bearing coarse sandstone- fine-medium sandstone, development of trough cross bedding, obvious sedimentary disconnection surface can be seen.
23 Yinye Wu, and Jianzhong Li, The gravelly sedimentology of the Changcheng System and its petroleum geological significance
Figure 1. Characteristics of sedimentary sequence in the lower part of Changzhougou formation of Changcheng system in Jixian, Tianjin (Zhang Ziyun, revised and supplemented by Wu Yinye, 2019, private communication) To sum up, the sedimentary sequence and facies of Changzhougou formation of Changcheng system exhibit the following sedimentary characteristics:
1. two-way wedge-shaped and trough-like cross-bedding gravel-bearing coarse sandstone sedimentary sequences, 2. fish-bone-like cross-bedding and sedimentary sequences of double clay layers and tidal bundle bodies; 3. the gravelly grains have the characteristics of progressive normal grain size sequence, with the wedge-like interbedded gravel-bearing sandstone sedimentary sequence, 4. the gravel grains with good roundness have the character of progressive reverse-grain sequence, and the thickness of the gravelly bed is about 1~2 m extended in a series of striped conglomerate depositional sequences; and 5. Massive bedding is mainly developed in gravel foreshore and low angle scouring bedding is seen in sandstone. The shoreface sedimentary sequence is composed of multi-stage mudstone and sandstone parasequence in the upper part (Octavin Catuneanu, Translated by Wu et al., 2009).
The sedimentary facies is interpreted as gravel shoreline deposit, which is partly affected by tidal action and paroxysmal river injection on the coastal margin. Sedimentary microfacies include gravel beach, tidal channel (small tidal channel), paroxysmal braided river channel and sandy gravel foreshore deposit.
3. The parasequence sets and sedimentary facies in Lower Part of Changcheng System
3.1 The parasequence sets and sedimentary facies in upper and middle Changzhougou formation of Changcheng System
In the middle part of the Changzhougou formation due to the strong structural action and slight metamorphism, the quartzite-like sandstone and bedding structure cannot be recognized, and only the massive and thick bedded characteristics can be observed, and It is presumed to be the product of the sedimentary environment of the foreshore to the backshore.
24 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
A number of parasequence sets is very obvious in the upper part of Changzhougou formation. The stacked pattern shows the three parasequences (PS 1-3) with boundary of the flooding surface (FS), the upward increase in argillaceous rock and the reflection of the transgression system tract. The predicted parasequence PS1 is about 2 m thick, PS2 is about 4 m, and PS3 is about 3 m (Figure 2).
Figure 2. The stacked pattern of parasequence sets in the Upper Chang cheng System: The stacked pattern shows the three parasequences (PS) with boundary of the flooding surface (FS), the upward argillaceous increase, the reflection of the transgression system tract. Attention to the scale of the automobile, about 4 m long.
From the point of view of sedimentary facies migration, it is mainly the lower shoreface sedimentary environment dominated by quartz sandstone. The increase of mud, indicates the upward transition to the lower shoreface from upper shoreface.
The Changcheng system can be divided into two corresponding first-order cycles or first-order sequences, and from the point of view of biosphere evolution, there are significant changes of the biota. The lower clastic rocks are developed in the rift stage, and the upper part is mainly epicontinental sea sedimentation with the development of carbonate platform.. Changzhougou formation is mainly composed of gravel and sandstone, which can be divided into three parts: the lower member is gravel and gravel-bearing coarse sandstone, and the middle section is white, light purplish red quartz sandstone. The upper member is composed mainly of quartz sandstone and thin sandy shale interbeds. The total thickness is about 860m. Therefore, the development order of the facies zone of Changzhougou formation is the backshore with paroxysmal river injection, foreshore and shoreface.
The predominant rock type in the overlying Cunlinggou formation is shale, and the sedimentary facies is the coastal shelf or the local lagoon-tidal flat environment. It can also be divided into three segments: the lower and upper segments are composed of black, gray-green and yellow- green shale developed in the intertidal zone of coastal phase, and silty illite shale with sandstone lenses. Some carbonaceous dolomite is also found in the upper part. The middle part is deposited
25 Yinye Wu, and Jianzhong Li, The gravelly sedimentology of the Changcheng System and its petroleum geological significance in the subtidal zone comprising green, black illite shale, often containing carbon fragments. The total thickness of this formation is about 890 m.
3.2 Parasequence sets and sedimentary facies of Tuanshanzi formation of Changcheng System
The Tuanshanzi formation of Changcheng System belongs to the carbonate platform sedimentary belt subdivided into two members. It is made up mainly of iron dolomite. The lower member is composed mainly of dark gray, siliceous mudstone, muddy dolomite and iron dolomite deposited in the subtidal zone (lagoon facies). The upper member is composed of silty sand and mudstone with retrogression sequence from dolomite to dolomitic fine sandstone. The thickness is about 520 m. It is in continuous contact with the upper and lower strata. The Tuanshanzi formation in Jixian, Tianjin, is comparable to the Changcheng clastic rock profile in Yongji, Shanxi Province. Both of them are marked by sandy dolomite and dolomitic sandstone, purplish red in color and rich in iron deposited in the supratidal zone and intertidal zone.
(1) Thick layer dolomite/thin argillaceous dolomite/laminated stromatolite dolomite rhythm.
The rhythmic assemblages of thick dolomite, thin muddy dolomite and stromatolite dolomite have been observed in the lower part of Tuanshanzi formation (Mei and Meng, 2016). The underlying rocks are the lithologic assemblages of gray dolomite-sandstone and sandy gravel dolomite which was formed after tidal action breaks the formed dolomite and deposited the injected terrestrial clastics. The difference in distribution between the rhythmic dolomitic combination and the underlying rock shows that the injection of clastic material becomes less, the dolomite deposition becomes more prominent and the tidal flat environment is inferred. The thick dolomite is developed in the intertidal zone, the thin layer of argillaceous dolomite in the supertidal zone, and the laminated stromatolite in the subtidal zone. The sedimentary column is shown in Figure 3. The thickness of the sequence decreases from the bottom to the upper cycle. Sedimentation was mainly in the intertidal and the supertidal zones but the lower tidal zone.
Figure 3 Characteristics of tidal flat sedimentary cycle profiles of Tuanshanzi formation of the Changcheng System (Zhang Ziyun, modified by Wu Yinye, 2019, private communication).
26 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
(2) Columnar stromatolite dolomite
The gray columnar stromatolite is also known as Gruna stromatolite. The cylinder part is made up of siliceous mud, which is often dense and symbiotic with each other. The cross section of the cylinder is subcircular to oval, with a thin and gentle dome. The geological age is about 1,680 Ma.
(3) Mud cracks
Muddy or plastic sediments are prone to shrinkage when exposed to a dry environment, resulting in development of reticulated tortoise shaped cracks which are filled. In general, the Tuanshanzi formation is deposited in different sedimentary environments based on lithology as follows: a) Sandstone-dolomite mixed section: sediment maturity is low, tidal structure is developed. Tidal action breaks the formed dolomite and dolomite accumulates together with land-injected clastics, represented by the mixture of dolomite and dolomitic sandstone (Figure 4).
Figure 4. Characteristics of the mixed rock profile of the Tuanshanzi formation of the Changcheng system (Zhang Fenglian, revised by Wu Yinye, 2019, personal communication). b) Carbonate section: extensive columnar stromatolites have been developed in a number of regular superimposed tidal flat cycles with the strata become thinner upwards, the muddy matter and flint contents increase, and the development of stromatolites retarded. The sedimentary environment becomes shallower as a whole.
To sum up, the mixed rocks of Tuanshanzi formation are composed of intercalated sandstone of different thicknesses from the basal to the upper dolomite parts: the sand content gradually increased, the mud content gradually decreased, and the purple lamellar sandy mudstone dolomite appears at the top. which belongs to the retrogression series.
4. The significance of petroleum geology
The gravel shoreline sedimentary characteristics of the Changcheng system are of great significance to the study of oil and gas gravelly reservoirs and the deep and ultra-deep oil and gas exploration, mainly manifested in the understanding of source rocks and reservoirs (Wu et al., 2016) and to the. The Cuizhuang formation and Chenjiajian formation in Yongji and Ruyang areas and
27 Yinye Wu, and Jianzhong Li, The gravelly sedimentology of the Changcheng System and its petroleum geological significance
Chenjiajian formation in Luonan area arev the most important source rocks of the Changcheng system in the southern margin of North China craton. The cumulative thickness of black shales in Cuizhuang formation is about 30 m in Yongji area. In the source rock samples, the distribution range of TOC content in 21 blocks is 0.2~1.21%, with an average of 0.51% (Wang et al., 2018). It is concluded that the deep and ultra-deep reservoir-source forming combination of the North China Craton is still likely. However, in the case of the reservoir property of the gravelly sandstone of the Changcheng clastic rock, it is likely to be a compact reservoir due to the geological age, not conducive for the accumulation of oil and gas. For example, the gravel-bearing iron quartz sandstone in Figure 5 under microscope (Yongji, Shanxi Province, Changcheng 0055 sample) has only a small number of micropores, and the reservoir quality is poor. However, carbonate rocks may form dissolution pores or fractured reservoirs.
The oil and gas reservoirs in gravel and gravelly sandstone have been found in Xinjiang area, and superimposed contiguous gravel reservoir groups have been formed in the slope-center area of the lake basin in the depression (Wu et al., 2015). It is widely distributed in Junggar Basin, Songliao Basin, Bohai Bay Basin and Erlian Basin in China. This type of reservoir is also known in the United States, Canada, Brazil, Argentina, Chile, Russia and the North Sea Basin of Europe. The large-scale conglomerate oil field has been found in Hemlock in the United States, and in Brazil, which resemble the stratigraphic and lithological conglomerate reservoir in the Baikouquan Formation, the slope area of the Mahu depression in the Junggar basin. Conglomerate means a rock consisting of more than 30% of granular debris larger than 2 mm in diameter. The breccia may be formed by the cementing of the gravel and the cobble with better sphericity or by cementation of the angular gravel and the crushed stone. The clastic components in gravel are mainly rock cuttings, with only a small amount of mineral debris, and the fillers are sand, silt, clay and chemical precipitates. The gravel size i classified into drifting gravel (> 256 mm), big gravel (64~256 mm), pebble (4~64 mm) and fine gravel (2 ≤ 4 mm). The vicinity of the shore line is a favorable and the ancient sea (or lake) shoreline has obvious control on the distribution of sandy gravel mass and oil and gas pools.
Figure 5 The gravel-bearing iron quartz sandstone appears under microscope (Yongji, Shanxi Province, Changcheng 0055 sample). Note that the left picture is mainly iron cement (black purple), the right picture in addition to iron, there is calcium cement (red).
28 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
5. Conclusions
There are significant changes in the sequence of sedimentary facies of Changcheng system: the development of clastic rocks in the lower part during rift trough deposition stage, and the carbonate deposition in the upper part of the platform type in epicontinental sea.
1) The base of the Changcheng System is generally gravelly shore facies sedimentation, which is partially affected by tidal action and paroxysmal river injection at the coastal zone. The sedimentary microfacies include gravelly beach, tidal channel , paroxysmal braided river channel and gravel foreshore sedimentation. The gravelly foreshore is mainly developed with massive bedding, and low-angle scouring bedding is seen in sandstone. The upper part is a shoreface para-sequence sediments composed of multi-phase mudstone and sandstone. The main development order of the facies belts of Changzhougou formation are as follows: from backshore with paroxysmal river injection to foreshore and to shoreface
2) The overlying Cunlinggou formation is composed mainly of shale and mudstone, and the sedimentary facies is the coastal shelf or the local lagoon-tidal flat.
3) The Tuanshanzi formation which overlies the Cunlinggou formation developed as the carbonate platform sedimentary facies zone in the sedimentary environment of the supertidal and the intertidal zones. The mixed rocks of Tuanshanzi formation are developed, and there are many intercalated sandstone of different thicknesses from the bottom to the upper dolomite sequence, the sand content increases and the muddy content decreases gradually, and the purple color lamellar sandy argillaceous dolomite appears at the top of this group as the retrogression series.
The sedimentary characteristics of the gravelly shore facies of Changcheng System have important geological significance for deep and ultra-deep hydrocarbon exploration and research of conglomerate oil and gas reservoir. The vicinity of the shore line is a favorable location for the development of lithological and stratigraphic oil and gas accumulation, and the ancient sea (lake) shoreline has obvious control on the distribution of sandy gravel mass and oil and gas pools.
Acknowledgements
This work was financed by the China National Petroleum Corp. Science Foundation (research project No. KT2019-09-01). We are also grateful to arrangement of field survey by the organizing committee of the 4th International Palaeogeography Conference, sample analysis by laboratory center of Zhejiang University, as well as other helps from RIPED and related oil companies.
29 Yinye Wu, and Jianzhong Li, The gravelly sedimentology of the Changcheng System and its petroleum geological significance
References
Hu, J.Y., Wu, Y.Y., Zhang, J., 2009. Discussion on petroleum geology theory for high-elevation and ultra- deep formations. Acta Petrolei Sinica, 30(2), 159–167 (in Chinese with English abstract).
Mei, M.X., Meng, Q.F., 2016. Composition diversity of modern stromatolites: A key and window for further understanding of the formation of ancient stromatolites. Journal of Palaeogeography (Chinese Edition), 18(2), 127–146 (in Chinese with English abstract).
Octavin Catuneanu, Translated by Wu Yinye, et al., 2009. Principle of sequence stratigraphy[M](in Chinese).
Pan, J.G., Qu, Y.Q., Ma, R., Pan, Z.K., and Wang, H.L., 2013. Sedimentary and tectonic evolution of the Meso-Neoproterozoic strata in the northern margin of the North China Block. Geological Journal of China Universities, 19(1), 109–122 (in Chinese with English abstract).
Qiao X.F., and Wang Y.B., 2014. Discussion on the age of the middle Proterozoic bottom boundary and the properties of the basin in the North China craton. Acta Geologica Sinica, 88(09):1623-1637(in Chinese with English abstract).
Song T.R., Wan Q.S., and Chen, Z.Y., 2004. The characteristics and significance of authigenic rare-earth minerals in the Proterozoic sedimentary rock in the northern part of China _ as an example in Beijing and Dalian [J]. Acta Geologica Sinica, (06):822-828 and 883-884.
Wang K., Wang T.S., Wang Z.C., and Luo P., 2018. Characteristics of Great Wall Rift Valley and Petroleum Geological conditions in the Southern margin of North China Craton [J]. Acta Petrolei Sinica, 39(05):504-517.
Wu, Y.Y., Gu, J.Y., Guo, B.C., et al., 2015. Petroleum Sequence Stratigraphy — Prediction Method of High-quality Reservoirs (Edition II). Petroleum Industry Press, Beijing.
Wu, Y.Y., Liu, W., Liu, Y., Fang, X., and Ma, K., 2016. The underlying deposition of Cambrian of Gondwana in China and its petroleum geological significance. Acta Petrolei Sinica, 37(9), 1069– 1079 (in Chinese with English abstract).
30 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Geological and geochemical approach for the binary power generation experiment at Matsunoyama hot spring area, Niigata, Japan
Norio Yanagisawa1, Munetake Sasaki1, Hajime Sugita1, Akinobu Miyakoshi1, Masatake Sato2, Kazumi Osato2, Sei-ichiro Ioka3 and Hirofumi Muraoka3
1Geological Survey of Japan, AIST, Japan 2Geothermal Energy Research & Development Co., Ltd. (GERD), Japan 3Hirosaki University, Japan
E-mail: [email protected]
Abstract
More than twenty small-scale binary power generation systems have been installed in high temperature hot spring areas in Japan in the past several years. A capacity of less than 200 kWe is suitable for utilisation of a small hot spring water for a resort. To investigate the process of early stage assessment of the hot spring water for power generation, we carried out a study of a small binary system of about 50 kWe at Matsunoyama hot spring resort, Niigata Prefecture between 2010 and 2016. The study funded by the Ministry of Environment included geological and geochemical studies, in order to assess the applicability of such type of power generation.
The experiment was conducted using the fluid from the Takanoyu #3 hot spring well with a flow rate of about 200 L/min, temperature of 100ºC and Cl concentration of 10,000 mg/L. The hydrogen isotope ratio was about -20%, and oxygen isotope ratio was about 1.8‰ and higher than that of the meteoric water. The origin of the Takanoyu #3 hot spring water was therefore interpreted as derived from fossil saltwater with methane gas trapped within a geo-pressured structure.
From the geochemical composition, we estimated the possibility of chemical scaling in the system by calculating the equilibrium of silicate and carbonate minerals using Solveq-Chiller. During the cooling process from 100ºC to 40ºC, dolomite, amorphous silica, talc and tremolite were under- saturated in the heat exchanger. We therefore concluded that the scale problem is not a major issue for the Takanoyu #3 well.
A geochemical monitoring was carried out at the Takanoyu #3 well and the surrounding three hot spring wells to examine the influence of the power generation on the geothermal system. We found that the pH, EC, temperature and Cl concentration of surrounding hot spring wells were approximately constant in spite of the change of the flow rate at the Takanoyu #3 well. This highlights the importance of geochemical monitoring in the sustainable operation of the power generation system and its impact on the surrounding hot spring wells.
Keywords: geology, geochemistry, geothermal energy, hot spring, binary power generation system, isotope, monitoring
1. Introduction
Recently in Japan, several owners of hot springs and power generation companies have developed small binary power plants using hot spring fluids (Muraoka et al., 2008). After the nuclear power plant accident in 2011, more than twenty binary power generation systems with a total capacity of 20 MWe were installed. One of the motivations for this development is the high Feed-in Tariff
31 Norio Yanagisawa, et. al, Geological and geochemical approach for the binary power generation experiment at Matsunoyama hot spring area, Niigata, Japan
(FIT) system started by the government in 2012. Electricity generated by a small geothermal power plant can be sold with a price of 42 JPY/kWh.
At the early stage of the utilization of the hot spring water for power generation, the Ministry of the Environment (MOE) of Japan provided support to a research project, entitled “Development and Demonstration of Small-Grid Power Generation System using Hot Spring Heat Source” in 2010. This project was managed by the Geothermal Energy Research & Development Co., Ltd. (GERD), the Institute for Geo-Resources and Environment of AIST, and Hirosaki University. Under this project, a power generation experiment of a 50kWe Kalina cycle system (Figure 1) was conducted using 100°C fluid from the Matsunoyama hot spring in Niigata Prefecture, central Japan. To estimate the potential and sustainability of the hot spring reservoir in the geo-pressured field at the Matsunoyama area, it was necessary to assess the geochemistry data of the wells drilled in the hot spring area.
Figure 1. Conceptual diagram of hot spring power generation with a Kalina cycle binary system (Yanagisawa et al., 2012). 2. Hot springs in Japan
Enjoying hot springs is one of the Japanese traditional cultures, and there are approximately 27,500 hot spring venues in Japan. The high temperature hot springs are distributed over the whole country and especially in Hokkaido, Tohoku and Kyusyu regions. If these hot spring resources can be used for power generation, then a micro-grid binary system could be used as a dispersive type power source.
In these areas, the temperature of many hot springs is higher than 42°C. Kimbara (2005) collected the temperature data of 4,536 hot springs in Japan. According to this data, the temperature of about 650 hot springs is higher than 60°C and the temperature of about 180 hot springs is higher than 90°C. Based on these data, Muraoka et al. (2008) estimated about 700 MWe of the electricity potential of hot spring binary generation in Japan (Figure 2).
The origin of high-temperature hot springs (about 100°C) suitable for a binary system can be classified into 4 types as shown in Figure 3. In Type 1, the meteoric water is heated by a shallow heat source; this type of hot springs exists mainly inside a volcanic body. In Type 2, the meteoric 32 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand water is heated by a deeper thermal source than in Type 1 and the hot spring fluid typically comes from a depth of about several hundred meters. In some cases, the fluid flows up along faults and/or fractures. Type 3 is a geo-pressured type often found in oil and gas fields for example at the Gulf Coast in USA (Esposito and Augustine, 2012) and the Cooper Basin in Australia, the Matsunoyama hot spring field is a Type 3 reservoir. Type 4 is a hot sedimentary aquifer where due to the regional geothermal gradient, high temperature fluids exist in a deep reservoir even in a non-volcanic environment.
Figure 2. Hot spring resources for power generation in Japan (Muraoka et al., 2008).
Figure 3. Several types of origins of high temperature hot springs (about 100°C). 33 Norio Yanagisawa, et. al, Geological and geochemical approach for the binary power generation experiment at Matsunoyama hot spring area, Niigata, Japan
3. Geo-pressured Matsunoyama hot spring field
The Matsunoyama hot spring field, located in the Tokamachi city in the middle of the Niigata Prefecture (about 200 km NW from Tokyo), occurs in a non-volcanic area. A geological map of central Japan, which includes the Matsunoyama area, is shown in Figure 4 (Takeuchi et al., 2000). The area near the Matsunoyama hot spring field is tectonically pressured by the Izu Peninsula. In the Matsunoyama geo-pressured region, there is a large dome structure with natural gas fields located in Tertiary sedimentary formations.
Figure 4. Geological map of central Japan including Matsunoyama region (modified from Takeuchi et al., 2000). Generally, geo-pressured reservoirs in this region have the following characteristics: 1) the source of the hot fluid is sea water, captured when the sedimentary basin was formed at depth; 2) the hot fluid exists at a depth of 2 to 7 km; 3) the pressure of the formation is much higher than the hydrostatic pressure; and 4) the hot fluid contains methane gas (CH4).
Table 1. The geochemical composition of Matsunoyama hot spring wells.
Na K Mg Ca Cl HCO3 SO4 Si
Takanoyu #3 3700 140.3 0.6 2070 9400 27.3 85.5 66.7
M1 3392 83.4 15.7 1882 8764 19.3 81.1 20.1
M2 3708 103.3 7.7 1980 9252 23.0 80.0 36.7
M3 5680 30.7 44.1 205 8661 316.6 2.6 11.5
(mg/l)
In the Matsunoyama area, several hot spring wells are recorded including the power generation well Takanoyu #3. All wells are located within 2 km from each other as shown in Figure 5. Table 1 shows the fluid composition of Takanoyu #3 and three monitoring wells as measured in November 2012. All wells are methane rich and show high Cl concentrations of about 10,000 mg/l. 34 Thematic Session “Geoscience for Future Earth: Beyond History Toward Mystery” 54th CCOP Annual Session, Busan, Republic of Korea, 30 October 2018
Figure 5. The site of Takanoyu #3 for power generation experiment and three monitoring wells (M1 - M3).
Table 2 shows the steam/gas flow rates and gas composition of Takanoyu #3 relative to wellhead pressure change as measured in November 2012 (Yanagisawa et al., 2013). The steam/gas flow rates have increased as the wellhead pressure decreases. The ratio of gas composition however remained constant, with about 95% methane, 1.8% N2 and 0.5% CO2. The methane rich condition is one of the properties of a geo-pressured field.
Table 2. Gas ratios and flow rates relative to wellhead pressures at Takanoyu #3.
Ratio of gas from Takanoyu #3 Wellhead Steam Gas Pressure Flow Flow (Vol%) (MPa) (ton/h) (ton/h)
CH4 CO2 H2S H2 N2 O2
0.6 1.24 0.06 94.9 0.38 0.05 0.02 1.82 0.31
0.55 1.40 0.10 94.4 0.53 0.05 0.02 1.86 0.29
0.35 1.63 0.17 94.6 0.39 0.06 0.02 1.48 0.21
Figure 6 shows the isotopic composition of hot spring fluid of Takanoyu #3 and Monitoring well-3 (M3), sea water of the nearby sea, and river water from a creek that runs through the Matsunoyama hot spring, plotted in the 18O and Deuterium isotope diagram. The data of the river water is plotted along the Japanese mean meteoric water line. The fluids from Takanoyu #3 and M3 are enriched in both 18O and Deuterium isotopes, and thus plot to the right of the meteoric water line and the below that for sea water. This indicates that the origin of the hot spring fluid is not the meteoric water but the captured sea water, as is characteristic of geo-pressured reservoirs.
35 Norio Yanagisawa, et. al, Geological and geochemical approach for the binary power generation experiment at Matsunoyama hot spring area, Niigata, Japan
Figure 6. Isotope diagram of hot spring fluid in the Matsunoyama area. 4. Estimation of scaling at Takanoyu #3
We estimated the possibility of scaling in this system at Takanoyu #3 by calculating chemical equilibrium of silicate and carbonate minerals using Solveq-Chiller method as described by Reed (1982). The diagram of mineral equilibrium is shown in Figure 7. During the cooling process of hot spring fluid from 100ºC to 40ºC in the heat exchanger, quartz (SiO2) and calcite (CaCO3) are supersaturated, but other minerals including dolomite (MgCaCO3), talc (Mg3Si4O10(OH)2), tremolite (Ca2Mg5Si8O22(OH)2) and amorphous silica (SiO2) are under saturation (Yanagisawa et al., 2012).
To prevent scaling, it is important to prevent the fluid from evaporating and to study the pH change in the heat exchanger. The data plotted on Figure 7, suggest that the scaling problem at Matsunoya #3 is not serious because silica scaling usually occurs as amorphous silica is under saturated at temperatures over 40ºC and the degree of super saturation of calcite is decreases as the temperature decreases.
Figure 7. Estimation of equilibrium of scale minerals of Takanoyu #3.
36 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
5. Monitoring of hot spring wells
The geochemical and flow condition monitoring was also carried out at the Takanoyu #3 well and the surrounding three hot spring wells before and during the power generation experiment in order to examine the influence of power generation on the surrounding wells. The monitoring was carried out from October 2010 to October 2016, with an interruption between February 2013 and to October 2013 due to operational reasons and also, for wells M1 and M2 wells during the winter seasons due to deep snow. Figures 8 and 9 show the change of temperature and Cl concentration, respectively. From these figures, the temperature and Cl concentration of the surrounding hot spring wells were almost constant in spite of the change of the flow rate at the Takanoyu #3 well for the power generation experiment from December 2011 to February 2013 and from December 2013 to February 2015 (Figure 10). It suggests that the geochemical monitoring is important for the sustainable operation of the power generation system as well as the surrounding hot spring wells.
Figure 8. Temperature change in four wells during the power generation experiment.
Figure 9. Change of Cl concentration in four wells during the power generation experiment.
37 Norio Yanagisawa, et. al, Geological and geochemical approach for the binary power generation experiment at Matsunoyama hot spring area, Niigata, Japan
Figure 10. Change of flow rate for the binary test line separated from Takanoyu #3 well. Black bars indicate the periods of the power generation experiment.
8. Conclusions
The geological and geochemical surveys were carried out at the Matsunoyama hot spring resort as part of an assessment for a hot spring binary generation project. The Matsunoyama hot spring is a geo-pressured hot spring with high Cl and high methane gas concentration. The oxygen isotope ratio was about 1.8‰ and was higher than that of the meteoric water. The project results show that the scale problem is not serious and the composition of the hot spring water is constant, and therefore the system is favorable for the stable operation of a binary power system.
References
Esposito A., and Augustine C., 2012. The influence of reservoir heterogeneity on geothermal fluid and methane recovery from a geopressured geothermal reservoir. Proc. 37th Workshop on Geothermal Reservoir Engineering, Stanford University. 1310-1323.
Kimbara, K., 2005.Distribution Map and Catalogue of Hot and Mineral Springs in Japan (Second Edition), CD-ROM.
Muraoka, H., Sasaki, M., Yanagisawa, N., and Osato, K., 2008. Development of small and low-temperature geothermal power generation system and its marketability. Asia. Proc. of 8th Asian Geothermal Symposium (CD-ROM).
Reed, M.H.,1982. Calculation of multicomponent chemical equilibria and reaction process in systems involving minerals, gasses and an aqueous phase. Geochimica Cosmochimica Acta, 46, 513-528. Takauchi, K., Yoshikawa, T., and Kamai, T., 2000. Geology on the Matsunoyama onsen district with Geological Sheet Map at 1:50000 (in Japanese). Geol. Surv. Japan, pp.1-76.
Yanagisawa, N., Sasaki, M., Sugita, H., Muraoka, H., Sato, M., and Osato, K., 2012. Scale and corrosion of a Kalina power generation system using hot spring water. Proc. 34th New Zealand Geothermal Workshop.
Yanagisawa, N., Muraoka, H., Sasaki, M., Sugita, H., Sato, M., and Osato, K., 2013. Geochemical properties of Geo-pressured reservoir for binary system. Proc. 35th New Zealand Geothermal Workshop. 38 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
The Volcanic Facies and their Reservoirs Characteristics in Eastern China Basins
Chunshuang Jin1, Dewu Qiao2, and Wenli Pan3
1Oil and gas Investigation Center, China Geological Survey, China 100083 2Strategic Research Center of Oil & Gas Resources, Ministry of Land & Resources, China 100034 3Geophysical Exploration Research Insitute of HuaBei Oilfield Company, Hebei, 062552
Abstract
In recent years, increasing number of volcanic oil and gas fields have been discovered and developed. The volcanic rocks have revealed great petroleum potential in eastern basins of China. There are five volcanic facies identified in the study area, which include volcanic conduit facies, explosive facies, effusive facies, extrusive facies and volcanogenic sedimentary facies. The subaerial eruption usually happened in Mesozoic and Paleocene, and subaquatic eruption in Eocene. The upper sub-facies and top autoclastic brecciation of subaquatic effusive volcanic rocks, and pyroclastic flow sub-facies of subaerial explosive volcanic rocks are the most favourable volcanic reservoirs. The intermittent belt formed between two episodes of volcanic eruptions is the most favourable for reservoirs both in subaquatic and subaerial volcanic rocks. Their main porosity types are interclast porosity, interflow laminar porosity, vesicular and gas pipes porosity, inter-crystalline sieve of moldic porosity, secondary dissolution porosity and tectonic fracture. Developed between pre-emplacement stage and final cooling, the primary porosity may lead to high porosity and permeability, and the secondary porosity usually developed upon them. The porosity of volcanic rocks was less influenced by the compaction and the burial depth.
Keywords: Volcanic facies, Volcanic reservoirs, Porosity, Eastern China
1. Introduction
Volcanic rock reservoirs are increasingly important recently as more unconventional oil and gas fields have been discovered and developed in the world. After more than 50 years of exploration in volcanic rocks, a number of important volcanic oil and gas fields were found in Eastern China. In these years, the Upper Jurassic and Early Cretaceous andesitic volcanic reservoirs in Erlian Basin (Yu and Tang, 1988; Wang et al., 1991), the Lower Cretaceous rhyolitic volcanic reservoirs in Songliao Basin (Chen et al., 2000; Liu et al., 2003; Liu, 2004; Feng et al., 2006; Zhou et al, 2007; and Wu et al., 2007,), the Cretaceous rhyolitic, and the Paleogene basaltic and trachytic volcanic reservoirs in Bohai Bay Basin (Jin et al., 1999; Zhang et al., 2004; Zhao et al., 2006; Liu, 2001; Luo and Zhang, 2002; Xiao, 1999; and Xiao et al., 2004), and basaltic volcanic reservoirs in Subei Basin (Tao et al., 1998) were discovered. With more and more volcanic oil and gas fields being discovered and developed, the volcanic rocks reveal great petroleum potential in China. By the end of 2006, CNPC has reported about 478 million tons of proved oil reserves and 125 billion m3 of proved gas reserves in volcanic rocks in China (Zhou et al., 2008)
2. Geological Settings
From Late Jurassic to Early Cretaceous, the East Asia tectonic environment, induced by westward subduction of the Paleo-Pacific Plate beneath the Asia continent and together with asthenosphere upwelling, transited to intensive intracontinental extension and lithospheric thinning from strong intracontinental compression and lithospheric thickening (Zhang et al.,2004; Duan et al., 2007,), large scale rifting resulted in broad rift basins development (Liu, 2001; Liu et al., 2000; Wu et al., 2007) (Figure 1), during which volcano erupted strongly in Eastern China. Neutral-acid volcanic
39 Chunshuang Jin, Dewu Qiao, and Wenli Pan, The Volcanic Facies and their Reservoirs Characteristics in Eastern China Basins rocks, such as andesite, rhyolite, and volcaniclastic rocks, spread widely in Eastern China. During Late Cretaceous, the vast area of North China west of Tancheng-Lujiang fault zone and almost all peripheral basins of Northeast China were denudated, and only Songliao Basin entered into the stage of intracraton depression.
Since Paleogene, the Paleo-Pacific Plate subduction turned to WNW, which induced the second rifting of Eastern China. In Northeast China, rift basins developed along Yishu and Dunmi fault zones. In North China, Bohai Bay Basin entered its second rifting basin stage, which led to basalt and trachyte development in the Basin. From Neogene, Bohai Bay Basin entered into the stage of depression.
Large scale volcanic activities occurred in Early Cretaceous and Paleogene and a lot of oil and gas were found in the volcanic strata developed in these two rifting stages (Table 1).
3. Volcanic facies
Usually defined as the volcanic activity architecture at given environments, volcanic facies affect the porosity and permeability of volcanic reservoirs directly and become the main reason of reservoirs heterogeneity. The categorizations of volcanic facies by different authors are not uniform (Qiu et al., 1996; Yang et al., 2007; Liu and Zhu, 2005; and Shu et al., 2007). In this paper, volcanic facies is categorized as volcanic conduit facies, explosive facies, effusive facies, extrusive facies and volcanogenic sedimentary facies in Eastern China Basins.. The subaerial eruption usually happened in Mesozoic and Paleocene, and subaquatic eruption in Eocene.
Figure 1. Structural outline of the late Mesozoic- Cenozoic rift basins in Eastern China and adjacent region (modified from Zhang et al., 2004): 1-Songliao Basins Group, 2-Zhangqiang Basin, 3-Liaoxi Basins Group, 4-Erlian Basins Group, 5-Hailar Basin, 6-Genhe Basin, 7-Liebuya Basin, 8-Xialiaohe Basin, 9-Huanghua Basin, 10-Shijiazhuang Basin, 11- Linqing Basin, 12-Huimin-Dongying Basin, 13-Wuhaozhuang Basin, 14-Middle Tanlu Fault Basin, 15-Jiaolai Basin, 16-Zhoukou Basin, 17-Sanjiang Basin, 18-Boli Basin, 19-Hulin Basin, 20-Jixi Basin, 21-NinganBasin.
3.1 Volcanic conduit facies
Locating underneath and near the center of the whole volcanic edifice, volcanic conduit facies are the combination of retention and backfill of volcaniclastic rocks (Figure 2a) and/or lava after magma transited to surface through the conduit (Qiu et al., 1996). The reservoirs significance of volcanic conduit facies is not predominant for their localization. However, it is useful to recognize the volcanic edifice in basin. 40 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Table 1. Generalized volcanic stratigraphical column with oil and gas producing horizons in Eastern China
Volcanic Produced oil/gas in Eastern China Basins Age Lithology Erli Songliao Davangsh Bohai Subei Pliocene Miocene ┌ ┌ ┌ Oligocene ┌ ┌ ┌ ● ┌ ┌ ┌ ● ● Eocene T T T ● Paleocene ┌ ┌ ┌ ● Lata Cretaceous
~ v v ▲ o
Early x x x ▲ o Cretaceous
v v v ● x x x ● x x x Late Jurassic ~ ⌂ ~ ●
Volcaniclastic v v v andesite ┌ ┌ ┌ basalt x x x rhyolite ~ ⌂ ~ Rock
T T T trachyte ● oil ▲ gas o oil shows
3.2 Explosive facies
Explosive facies consists of multi-type of volcaniclastic rocks formed from the volcanic explosion of high viscidity magma. The volcanic explosion may take place in different stages of volcanism but is most developed in early and climax of the volcanic eruption, i.e., the nearer to the volcanic conduit, the coarser the volcaniclastics are. Considering the volcanic eruption style, magma composition, emplacement feature, the explosive facies is classified in three sub-facies as pyroclastic surge, pyroclastic flow and pyroclastic fall.
41 Chunshuang Jin, Dewu Qiao, and Wenli Pan, The Volcanic Facies and their Reservoirs Characteristics in Eastern China Basins
a b
c d
e f Figure 2. The volcanic rocks of volcanic conduit facies and explosive facies. (a) Rhyolitic breccias of diatreme (Wang and Feng, 2008). (b) The base surge subfacies in Songliao Basin (Wang and Feng, 2008.) (c) The ground surge subfacies character in Yandang Mountain. (d) Welded volcanic breccia, Erlian Basin. (e) Ignimbrite, Songliao Basin. (f) The pumice clasts in the upper pyroclastic flow (Yandang Mountain)
3.2.1 Pyroclastic surge subfacies
Pyroclastic surges are low-density flows of pyroclastic material. The reason they are low density is that they lack a high concentration of clastics and contain a lot of gases. These flows are very turbulent and fast. They overtop high topographic features and are not confined to valleys. There are three types of pyroclastic surges: (1) base surge, (2) ash cloud surge, and (3) ground surge. A base surge is usually formed when the volcano initially starts to erupt from the base of the eruption column as it collapses (Figure 2b). It usually does not travel more than 10 km from its source. A ground surge (Figure 2c) usually forms at the base of a pyroclastic flow. An ash cloud surge forms when the eruption column is neither buoying material upward by convection nor collapsing.
42 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Pyroclastic surges deposits consist mainly of tuff and show partly good layering, cross bedding, partly mantle, partly infill topography. They are usually only of small volume and close to source. The primary porosity may be high, but the secondary porosity is usually not as good because the pyroclastic surges subfacies is not at the top of cooling unit, and subjected less to weathering and dissolution.
3.2.2 Pyroclastic Flows subfacies
Pyroclastic flows subfacies are distributed broadly and they are usually in explosive facies. Pyroclastic flows are mixtures of hot gas, ash and other volcanic rocks travelling very quickly down the slopes or under the water, and are deposited as the velocity of flow decreases. The flat top surface of the poorly sorted volcaniclastic rocks infill topography may be very thick. Pyroclastic fragments comprise blocks, lapilli (Figure 2d) and ash.
The deposits mainly consists of ignimbrite (Figure 2e), and the non-welded to moderately welded deposits. Sometimes, there is rich pumice lithic at the top of the pyroclastic flow deposits. The high vesicular, and possible dissolution porosity superimposed by weathering make pyroclastic flow deposits the most effective reservoirs with high porosity and permeability. In addition, with an abundance of pumice, the primary porosity of tuff in the upper pyroclastic flow deposits will be much higher (Figure 2f).
3.2.3 Pyroclastic fall subfacies
Pyroclastic fall subfacies is uniform accumulation of material which has been ejected from an eruption plume or eruption column and deposited under the action of gravity. The pyroclastic fall deposits include volcanic blocks, volcanic bombs and lapilli from volcanic explosions, but tuffs are the main pyroclasts. Th show good laying, often graded and decreasing grain size and thickness with increasing distance away from the source.
3.3 Effusive facies Effusive facies is the lava characterized by an outpouring of low viscosity magma which has a fairly low volatile content. The distribution of lava is controlled by volcanic architecture topography, which may encircle the crater or may extent along one direction.
For one lava flow unit, or one cooling unit caused by one magma effusion, often 4 belts, under belt, middle belt, upper belt and top belt can be found. Because of the different cooling conditions, the structure of the volcanic rocks, petro-tectonic and other physical property are distinct in these 4 belts. Autobreccia was developed in the top belt, with rich interclast fracture. The vesicular lava in upper and under belts has rich vesicular and quench fracture, but the vesicular lava in the under belt is often thinner. The compact lava in the middle belt is not an effective reservoir.
With different magma property and eruption environments, the structures of lava flow units are different. The autobreccia belt in acid lava flow unit is not as good as that in neutral-basic lava flow unit. For example, broken forth in water, the trachyte and basalt in the third member of Shahejie series in Bohai Bay Basin are autobrecciated strongly and extensively (Figure 3a), which made them excellent reservoirs. However, the vesicular and interflow laminar may be more developed in the upper belt of acid lava unit than that in neutral-basic lava flow unit (Figure 3b).
With their special characteristics, the lava in different parts of lava flow unit has different reservoir potential. Therefore, it is very important to recognize the top surface, base surface, attitude, and inner belts of lava flow unit for researching volcanic reservoir characteristics. 43 Chunshuang Jin, Dewu Qiao, and Wenli Pan, The Volcanic Facies and their Reservoirs Characteristics in Eastern China Basins
3.4 Extrusive facies
Extrusive facies are mainly found in acid and neutral volcanic activity occurring in the late phase of a volcanic eruption cycle. The lava was squeezed out from the earth and when it had solidified, a lava dome formed. Figure 3c shows the right part of the rhyolite dome in Yandang Mountain. Three belts can be differentiated in the dome (Qiu et al., 1996), there are the autobreccia belt in the margin; the lava alike belt with rich interflow laminar and sometimes with vesicles in the middle; and the dense massive lava in the center. The margin and middle belts may be effective reservoirs.
3.5 Volcanogenic sedimentary facies
After a distance of transport, the volcanic ash and clasts deposit in normal sedimentary environment, which can formed in every stage of volcanic activity. They may be interbedded with sedimentary rocks (Figure 3d). Volcanogenic sedimentary facies are deposited both in the far end of volcanic apparatus and caldera lake.
4. Reservoirs Characteristics
4.1 Types of Porosity
Volcanic rocks develop primary and secondary porosity and permeability, depending on both their lithology, the sequence and processes involved in their formation (Ren et al., 1999, Sruoga et al., 2007). Primary porosity is caused by primary volcanic processes, which are defined as those that are active between the pre-emplacement stage and the final cooling of volcanic rocks under closed-system conditions. Primary processes include welding, deuteric crystal dissolution, gas release, flow fragmentation, which developed the inter-shard (Figure 4a) and intra-pumice (Figure 4b), intercrystalline sieve or moldic (Figure 4c), vesicular and gas pipes (Figure 4d), interflow laminar (Figure 4e), inter-clast and shattered crystal (Figure 4f) porosities. Primary porosity may lead to high porosity and permeability, and the secondary porosity usually developed upon them.
a b
c d Figure 3. The volcanic rocks of effusive facies, extrusive facies and volcanogenic sedimentary facies. (a) Autobreccia, Liaohe Depression. (b) The vesicular and interflow laminar of rhyolite, Yandang Mountain. (c) The rhyolite dome in Yandang Mountain. (d) The volcanogenic conglomerate and mudstones, Liaohe Depression. 44 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Secondary porosity which results from the interaction between a rock and its environment broadly includes two different types; namely, fracture (Figure 5a) and alteration porosities (Figures 5b, 5c, 5d). Secondary processes (different types of alteration) tend to decrease primary porosity. However, certain secondary processes, such as dissolution and hydraulic fracturing may contribute to enhanced total porosity and permeability.
Primary and secondary processes are significant in generating and modifying the petrophysical character of the rock. Their effects may be cumulative, or alternatively, the primary process may cancel out the effect of the secondary process.
4.2 Porosity Features
Since the diagenesis mechanism for volcanic reservoir generally is condensing consolidation, the porosity of volcanic rocks was less influenced by the compaction and the burial depth compared with sedimentary rocks (Figure 6). The capacity of volcanic reservoir will exceed the sedimentary reservoirs when the buried depth is greater than the threshold depth. For instance, the threshold depth is 3500m in Songliao Basin, over this buried depth, the sedimentary reservoirs changed into tight sand conglomerate reservoirs, while the volcanic reservoir remain dominant (Wang and Feng, 2008).
a b
c d
e f Figure 4. The primary porosity of volcanic rocks in Eastern Basins. (a) Inter-shard porosity, Songliao Basin (from Zhao, 2008). (b) Intra-pumice porosity, Liaohe Depression. (c) Intrastalline sieve, Liaohe Depression, Bohai Bay Basin. (d) Vesicular and gas pipes, Dayangshu Basin. (e) Interflow laminar, Songliao Basin. (f) Inter-clast porosity, Erlian Basin.
45 Chunshuang Jin, Dewu Qiao, and Wenli Pan, The Volcanic Facies and their Reservoirs Characteristics in Eastern China Basins
4.3 Favorable volcanic reservoirs
The subaerial eruption usually happened in Mesozoic and Paleocene, and subaquatic eruption in Eocene. In rhyolite and rhyolitic volcaniclastic rocks, the upper subfacies of effusive facies, and pyroclastic flow subfacies of explosive facies are the most favorable volcanic reservoirs. Their main porosity types are vesicular and gas pipes porosity, inter-shard and intra-pumice porosity, interflow laminar porosity, secondary dissolution porosity and tectonic fracture.
a b
c d Figure 5. The secondary porosity of volcanic rocks in Liaohe Depression. (a) Tectonic fracture. (b) Secondary sieve porosity. (c) Dissolution fracture in the groundmass. (d) Quench porosity.
Figure 6 The correlation between the buried depth and the porosity of volcanic reservoirs in Liaohe and Songliao Basins 46 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
In andesite and basalt and related volcaniclastic rocks, the upper subfacies and top autoclastic brecciation of effusive facies, and pyroclastic subfacies of explosive facies are the most favorable volcanic reservoirs. The main porosity types are vesicular and gas pipes porosity, inter-clast porosity, inter-crystalline sieve of moldic porosity, secondary dissolution porosity and tectonic fracture.
In subaquatic eruption trachytic volcanic deposits, the top autoclastic brecciation and upper subfacies of effusive facies are the most favorable volcanic reservoirs, and the interclast porosity, secondary dissolution porosity and tectonic fracture are main porosity types.
5. Conclusions
(1) Early Cretaceous and Paleogene are the two stages of basins rifting in Eastern China, and the companied volcanic rocks established the reservoir for oil and gas pools. With enough oil and gas source, a lot of oil and gas fields were found in Early Cretaceous, Eocene and Paleocene volcanic rocks. In the Bohai Bay Basin, there may be a great potential in Early Cretaceous and Paleocene volcanic rocks for exploration in these strata.
(2) In the five volcanic facies, the most favorable volcanic reservoirs are mainly in the top and upper subfacies of effusive facies and pyroclastic flow subfacies of explosive facies. Furthermore, the lower subfacies of effusive facies, the pyroclastic surge of explosive facies and outer belt of extrusive facies may also be effective reservoirs. In fact, the intermittent belt formed between two episodes of volcanic eruptions is the most effective reservoirs.
(3) The most effective porosity types are interclast porosity, interflow laminar porosity, vesicular and gas pipes porosity, and the inter-crystalline sieve of moldic porosity, secondary dissolution porosity and tectonic fracture. Primary porosity may lead to high porosity and permeability, and the secondary porosity usually developed upon them. The primary process is very important for reservoirs porosity in volcanic rocks and is less influenced by the compaction and the burial depth.
47 Chunshuang Jin, Dewu Qiao, and Wenli Pan, The Volcanic Facies and their Reservoirs Characteristics in Eastern China Basins
References
Chen, J., Wang D., Zhang X., and others, 2000. Analysis of volcanic facies and apparatus of Yingchen formation in Xujiaweizi faulting depression, Songliao basin Northeast China. Earth Science Frontiers. 7(4): 371-379 (in Chinese with English abstract).
Duan, Q., Tan, W., Yang, C., and others, 2007. A review on the late Mesozoic extensional tectonics on the eastern North China Craton. Progress in Geophysics, 22(2): 403-410 (in Chinese with English abstract).
Feng, Z., 2006. Exploration potential of large Qingshen gas field in the Songliao basin. Natural of Gas Industry, 26(6): 1-5 (in Chinese with English abstract).
Jin, C. and Zhao, C., 1999. The volcanic rocks geochemical features of South of Western Sag in Liaohe basin. Journal of the University of Petroleum, China, 23(6): 17-19 (in Chinese with English abstract).
Liu, H., 2001.Geodynamic scenario of coupled basin and mountain system. Earth Science—Journal of China University of Geosciences, 26 (6):581-96 (in Chinese with English abstract).
Liu, H., Liang, H., Li, X., and others, 2000. The coupling mechanisms of Mesozoic-Cenozoic rift basins and extensional mountain system in eastern China.Earth Science Frontiers (China University of Geosciences, Beijing), 7(4): 477-486 (in Chinese with English abstract).
Liu, S., 2001. Characteristics and favorable reservoir forming conditions of igneous reservoir in Liaohe basin. Special Oil and Gas Reservoirs, 8(3): 6-9 (in Chinese with English abstract).
Liu, W., Wang, P., Men, G., and others, 2003. Characteristics of deep volcanic reservoirs in northern Songliao Basin[J]. Oil & Gas Geology, 24(1): 28-31. (in Chinese with English abstract).
Liu, W., and Zhu, X., 2005. Reservoir space evolution of volcanic rocks in the yingcheng formation of the Xujiaweizi fault depression, the Songliao Basin. Petroleum Geology & Experiment. 27(1): 44-49 (in Chinese with English abstract).
Liu, W., 2004. Reservoir characteristics of deep volcanic rocks and prediction of favorable areas in Xujiaweizi fault depression in Songliao basin. Oil & Gas Geology. 25(1): 115-119 (in Chinese with English abstract).
Luo, J., and Zhang, C., 2002. Characteristics and oil source for Mesozoic volcanic pools in Fenghuadian region. Oil & Gas Geology, 23(4): 357-360 (in Chinese with English abstract).
Qiu, J., Tao, K., and others, 1996. Volcanic rocks, Geological Publishing House. (in Chinese with English abstract).
Ren, Zuowei and Jin Chunshuang, 1999. Reservoir space feature of the volcanic rocks in the area of Well Wa-609 , Liaohe sag. Petroleum Exploration and Development, 26 (4): 54-56 (in Chinese with English abstract).
Shu Ping, Qu Yanming, Ding Rixin, et al., 2007. Research on lithology and facies of volcanic reservoirs in Qingshen gas field of north Songliao basin. Petroleum Geology and Development of Daqing, 26(6): 31-35 (in Chinese with English abstract).
Sruoga, P., and Rubinstein, N., 2007. Processes controlling porosity and permeability in volcanic reservoirs from the Austral and Neuque´n basins, Argentina. AAPG Bulletin, 91(1): 115–129
Tao, K., Yang, Z., Wang, L., and others, 1998. Oil reservoir geological model of basalt in Minqiao, Nofthern Jiangsu province.Earth Science-Journal of China University Geosciences, 23(3): 272- 276 (in Chinese with English abstract). 48 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Wang, P., and Feng, Z., 2008. Volcanic rocks in petroliferous basins, Science Press. (in Chinese with English abstract).
Wang, P., Ren, Y., and Shan, X.. 2002. The Cretaceous volcanic succession around the Songliao Basin, NE China: relationship between volcanism and sedimentation. Geological Journal,37(2): 1~19
Wang, Z., Zhao, C., and Liu, M., 1991. Volcanoc lithofacies and their petrophysical properties in Abei oilfield. Journal of the University of Petroleum, China, 15(3): 15-21 (in Chinese with English abstract).
Wu, Y., and Zhou, L., 2007. Formation and distribution features of large-medium oil and gas fields in main fault depressions in the Songliao basin. Petroleum Geology & Experment, 29(3): 231-237 (in Chinese with English abstract).
Wu, Z., Hou, X., and Li, W., 2007. Discussion on Mesozoic basin patterns and evolution in the eastern north China block. Geotectonica etMetallogenia, 31(4): 385-399 (in Chinese with English abstract).
Xiao, J., Kanaye Tourba, Wang, H., and others, 2004. Characteristics of igneous rocks and their favorable pool-forming conditions in Nanpu sag, Bohai Bay basin. Geological Science and Tecnology Information, 23(1): 52-56 (in Chinese with English abstract).
Xiao, S., 1999. Classification of igneous and its related reservoir in Bohai gulf basin. Special Oil and Gas Reservoirs, 6(4): 6-10 (in Chinese with English abstract).
Yang, S., Liu, W., Yu, S., and others, 2007. Pore Textures and its causes of Volcanic reservoir in Songliao Basin. Journal of Jinlin University (Earth Science Edition), 37(3): 506-512 (in Chinese with English abstract).
Yu, J., and Tang, T., 1988. Preliminary study on the Abei andersite reservoir in Erlian Basin. Petroleum Exploration and Development, 1:38-44 (in Chinese with English abstract).
Zhang, K., 2004. Characteristics and areal prediction of fractures in trachyte reservoir of Oulituzi- Huangshatuo. Special Oil and Gas Reservoirs, 11(2): 20-24 (in Chinese with English abstract).
Zhang, Y., Zhao, Y., Dong, S., and others, 2004. Tectonic evolution stages of the Early Cretaceous rift basins in Eastern China and adjacent areas and their geodynamic background. Earth Science Frontiers (China University of Geosciences, Beijing), 11(3): 123-133 (in Chinese with English abstract).
Zhao. H., Li, X., Chen, Z., and others, 2006. Petroloty and genesis of Mesozoic volcanic rocks in Tuo32 well block of Liaohe oilfield. Oil & Gas Geology, 27(4): 549-556 (in Chinese with English abstract).
Zhao, W, Zou, C., Feng, Z., and others, 2008. Geological features and evaluation techniques of deep- seated volcanic gas reservoirs, Songliao Basin. Petroleum Exploration and Development, 35(2): 129-142 (in Chinese with English abstract).
Zhou, L., Wu, Y., and Zhang, H., 2007. Zoned-distribution of oil and gas accumulation in fault depressions in the Songliao basin. Petroleum Geology & Experiment, 29(1): 7-12 (in Chinese with English abstract).
Zou, C., Zhao, W., Jia, C., and others, 2008. Formation and distribution of volcanic hydrocarbon reservoirs in sedimentary basins of China. Petroleum Exploration and Develoment, 35(3): 257-271 (in Chinese with English abstract).
49 50 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
The shale gas characteristics of Upper Ordovician Wufeng formation and Lower Silurian Longmaxi formation in Southwestern Sichuan Basin
Chao Wang, Wentao Li, Shufang Yu, Xianglin Chen, Tianxu Guo, and Kun Yuan
Oil & Gas Survey, China Geological Survey, Beijing 100083, China
Abstract
The geological conditions and shale gas-bearing capacity of Wufeng formation and Longmaxi formation in Suijiang-Yongshan region of Southwestern Sichuan are studied using drilling data of SY-1 and other wells. The shale gas geological conditions are systematically analyzed including petromineralogy, organic geochemistry and pore characteristics. The well SY-1 samples are organic-rich shale of Wufeng and Longmaxi formations which has a thickness of 108.2 m. The lithology consists mainly of black carbonaceous shale, siliceous rock, dark grey silty mudstone, etc. It is also characterized by high TOC content (average 2.75%), high thermal maturity degree (average 3.67%), high brittle mineral content (average 66.0%) and high porosity (average value is 1.53%). The highest total gas content from samples of the wells in this area is 4.5 m3/t, which indicates good gas-bearing capacity.. The favourable conditions mentioned above indicate that the research area is a good prospect for exploration of shale gas resources.
Keywords: Shale gas; Well SY-1; Wufeng and Longmaxi formations; Resources potential
1. Introduction
The Sichuan Basin and its surrounding areas are important exploration fields for shale gas in China. With increasing exploration efforts, China has made breakthroughs in the exploration of shale gas in Fuling, Changning, Weiyuan and other places in Sichuan Basin, which showed that the Wufeng and Longmaxi formations in Sichuan Basin has good prospects for shale gas (Zou et al., 2016). The discovery of shale gas in the Wufeng and Longmaxi formations in Northern Guizhou and Western Hubei confirmed that this structurally complex area outside the Sichuan Basin still has good potential for shale gas resource.(Zhai et al., 2017).
The Suijiang-Yongshan area is located in the southwestern margin of Sichuan Basin, and the exploration activity for shale gas was relatively low. The understanding of the geological conditions of shale gas in the area needs to be improved, and the potential of shale gas resources is still unclear. On the basis of well SY - 1 and other shale gas drilling results, and sample analysis data, this article analyzes the shale gas accumulation conditions and its hydrocarbon characteristics and evaluates the shale gas resource potential.
2. Regional geological features
The Suijiang-Yongshan area is located in the southwestern margin of Sichuan Basin. The area is mainly dominated by the north-northwest structural system with anticlinal and synclinal foldings. The southwest margin of Sichuan Basin was in the stage of passive continental marginal basin evolution in early Paleozoic. Organic-rich shale was deposited in the late Ordovician, which was controlled by the paleo-uplift. In the early stage of Wufeng and Longmaxi formations, the area showed a large transgression, accompanied by the subsidence and clastic materials deposition, and the sediments were deposited from shallow to deep environment from the southwest to the northeast.
51 Chao Wang, et.al., The shale gas characteristics of Upper Ordovician Wufeng formation and Lower Silurian Longmaxi formation in Southwestern Sichuan Basin
In the late early Silurian period, with the further strengthening of orogenic movement, the area gradually became shallower due to the impact of compression and uplift as well as basin sedimentation, and the deep-water shelf environment was gradually transformed into the shallow shelf and shore-shallow marine facies (Wang et al., 2018). Since Silurian, the tectonic evolution in the southwest margin of the Sichuan Basin has undergone Caledonian, Hercynian, Indo-chinese, Vanshanian and Himalayan tectonic movements, forming a series of tectonic dome, basin and arc structures. On the whole, the southwest margin of Sichuan Basin has undergone several tectonic stress fields and superimposed transformations. The tectonic style is complex, and it hasan important influence on the formation, adjustment and destruction of oil and gas deposits.
The Wufeng and Longmaxi formations in the southwestern margin of Sichuan Basin is in the transition zone between shallow and deep water shelves. The organic-rich shale is found in the lower strata of the Wufeng and Longmaxi formations (Figure 1), and the organic matter abundance gradually decreases from the bottom to the top. The thicknesses of the high-potential oil- and gas-bearing shale of well SY-1, well Xd1 and well Xd2 in this area are 108.2 m, 106 m and 162 m respectively whereas the thicknesses of the high potential petroleum bearing shale sections of Yanjin Niuzhai, Leibo Bajiao Beach, Yongshan Sutian and Yongshan Yunqiao at the edge of the basin are 38.7 m, 76 m, 67 m and 26.42 m respectively. Controlled by paleo-uplift and sedimentary facies, the high-quality shale constituting the petroleum bearing zone gradually thickened from southwest to northeast, and the thickness of organic-rich shale (TOC> 1%) is generally 26 ~ 162 m. 3. Shale characteristics
3.1 Petrographic features
Wufeng andLongmaxi formations in the southwestern margin of Sichuan Basin is located in the transition zone between shallow and deep shelves. The lithology consists mainly of black carbonaceous shale, siliceous rock, dark gray silty mudstone, etc.
Figure 1. Lithofacies paleo- geographic map of Suijiang- Yongshan area in southwestern Sichuan Basin (modified from Wang et al., 2018). 52 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 2. Mineral composition of shale in well SY-1.
3.2 Mineral composition
The mineral composition of 20 core samples from different depths in SY-1 well was determined by X-ray diffraction analysis. The minerals are mainly composed of quartz, plagioclase and carbonate, main minerals and clay matrix such as illite and chlorite (Figure 2). The total content of the main minerals is 46% ~ 82%, with an average of 63%, among which quartz (with an average content of 31%), plagioclase (with an average content of 5%) and calcite (18%) and dolomite (7%) predominate. The total content of clay minerals ranged from 16% to 52%, with an average of 34%, including illite, chlorite and illite/smectite mixed minerals (I/S), with an average content of 21.13%, 9.26% and 3.61%, respectively. Pyrite is less abundant, with an average content of 3%. The analysis and test results show that the main minerals in the shale in this area are relatively developed and their content is relatively high. Under the action of external forces, natural and induced fractures were developed , and such conditions are conducive to the reservoir fracturing in the later stage.
Compared with Fuling and Qijiang areas, the organic-rich shale of Wufeng and Longma formations in Suijiang-Yongshan has its own characteristics. High potential petroleum bearing shale section has higher calcium (25% ~ 33%), lower clay mineral t (20% ~ 25%), and moderate siliceous mineral (about 25% ~ 40%) contents.
3.3 Organic geochemical characteristics
3.3.1 Organic matter type
On the whole, the shale samples of the Wufeng and Longma formations in well SY-1 are mainly sapropelic with an average content of 96%, followed by vitrinite with an average content of 4%. Organic matter is mainly type I which reflects that the organic matter is mainly from marine facies deposition. Organic matter dominated sapropelic type is usually easy to generate micropores in the process of hydrocarbon generation, which has a good adsorption capacity and provides a large storage space for shale gas.
53 Chao Wang, et.al., The shale gas characteristics of Upper Ordovician Wufeng formation and Lower Silurian Longmaxi formation in Southwestern Sichuan Basin
3.3.2 Total organic carbon content
Total organic carbon content (TOC) is considered to be one of the key factors of hydrocarbon generation potential of shale. The TOC content of 25 samples from Wufeng and Longmaxi formations in well SY-1 is 0.96% ~ 5.36%; generally more than 2%, with an average of 2.75%. The thickness of organic-rich shale in well SY-1 is 108.2 m. The content of TOC gradually increases from the top to the bottom: it is a high-quality source rock.
From the shale section of Wufeng andLongmaxi formations in the area, the TOC in Yanjin niuzhai is 2.32% ~ 4.87%, with an average of 3.39%; the TOC in Yongshan yunqiao is 2.08% ~ 4.64%. However, the TOC of the Wufeng formation in Yongshan sutian is relatively low, with a content of 0.49% ~ 2.20%; whereas the TOC of the Longmaxi formation in the same area is 1.93% ~ 5.94%. According to the well sample analysis data, the TOC of organic-rich shale in Xd1 reached 9.86%, with an average of 3.78%; the TOC of shale in Xd2 reached 10.12%, with an average of 3.61%; The TOC of organic-rich shale in Yy1 well reached 9.80%, with an average of 3.57%.
The distribution of organic carbon content in shale has a good linear correlation with its thickness. Generally speaking, the organic matter content is high in areas with greater shale thickness.
3.3 3 Thermal evolution
The degree of thermal evolution is considered to be one of the key indicators for hydrocarbon generation by organic matters in source rocks. According to the analysis results, the maturity of 18 samples ranged from 3.19% to 4.12%, with an average of 3.67%. The maturity gradually increased with burial depth.
From the perspective of regional thermal evolution e, Ro of shale in well Xd1 is 2.62% ~ 2.80%, with an average of 2.71%. Ro of shale in Yy1 well is 2.76% ~ 2.88%, with an average of 2.83%. Ro of shale in Xd2 well is 2.66% ~ 2.87%, and the average is 2.79%. Ro of shale in Yongshan yunqiao section is 2.60% ~ 2.76%, and the average is 2.67%. Ro of shale in Yongshan sutian is 2.40% ~ 2.67%, and the average is 2.57%. Ro of shale in Yanjin niuzhai is 2.38% ~ 2.67%, and the average is 2.55%.
These data show that the regional thermal evolution is normal. The higher degree of thermal evolution in well SY-1 may be caused by local hot spots under the warming mechanism of Emeishan large igneous rock province in late Hercynian period.
3.4. Pore characteristics
A large number of fractures and pores are developed in shale, which are considered to be conducive for shale gas accumulation and storage. Compared with high-potential marine gas-bearing shale, the samples of well SY-1 are relatively dense with poor porosity, ranging from 0.47 to 8.01%. The porosity of most samples is in the range of 1%~3%, with an average of 1.84%.
The shale porosity of Yanjin niuzhai section is 1.98% ~ 10.43%, with an average of 4.72%. The porosity of shale in Yongshan yunqiao section is 0.71% ~ 11.36%, with an average of 4.77%. The porosity of shale samples in well Yy1 is 0.11% ~ 3.63%, with an average of 0.63%, and that in Xd2 well is 2.39% ~ 8.50%, with an average of 4.53%.
54 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
The pore diameter of shale samples was analyzed by low-temperature nitrogen adsorption experiment, and the specific surface area and total pore volume were calculated by BET and BJH models respectively. The test results showed that the specific surface area of the sample was 9.82 ~ 23.21 m2/g, with an average of 17.34 m2/g, the total pore volume was 0.0128 ~ 0.0275 ml/g, with an average of 0.0194 ml/g. The pore size was 4.80 ~ 6.55 nm, with an average of 5.33 nm.
TOC is positively correlated with pore volume and specific surface area (Figure 3), indicating that TOC content is one of the main influencing factors of pore structure characteristics. Under the influence of hydrocarbon-generation during thermal evolution, some organic matters were consumed to form pores and contraction cracks. These pores and contraction cracks formed microscopic pore network cracks, and increased pore volume and specific surface area. In addition, organic acids which were generated in the process of hydrocarbon generation have a dissolution effect on shale minerals forming pores and gas storage space.
Figure 3. Relationship of pore structure characteristics with TOC content.
4. Evaluation of shale gas resource potential
4.1 Gas-bearing characteristics
The shale gas content in well SY-1 is poor; ranging from 0.00 to -0.09 m³/t. The maximum value is from carbonaceous shale at 3552 meters depth. The maximum total gas content is 0.22 m³/t. In well SY-1, organic-rich shale was developed, but it was affected by the heating effect of Emeishan large igneous rock province in the Hercynian period. The local hot spots under the heating effect caused that shale to undergo high degree of thermal evolution. In addition, during the tectonic uplift in the Yanshan period and Himalayan period, the strata were fractured and the shale was subjected to overburden pressure, which led to the strong compaction of the shale. The pores and the cracks of large organic matter basically disappeared and the porosity decreased to 2% ~ 3% or less, accompanied with the release of shale gas.
However samples from some wells nearby show good gas-bearing characteristics. In well Xd2, core average porosity is 4.53%, and the total gas content is 2.53 ~ 8.97 m3 / t, with an average of 4.52 m3 / t. The thickness of the high-potential gas-bearing shale with total gas content higher than 2.0 m3/t is 32 m, and the thickness of the shale with total gas content between 1.0-2.0 m3/t is 71 m. Moreover, there is an obvious positive correlation between gas content and core porosity. The highest shale gas content in site analysis is 1.44 m3/t, and the highest total gas content is 2.41 m3 /t (Yang et al, 2019).
55 Chao Wang, et.al., The shale gas characteristics of Upper Ordovician Wufeng formation and Lower Silurian Longmaxi formation in Southwestern Sichuan Basin
4.2 Shale gas resource evaluation
Regionally, organic-rich shale bed of Suijiang-Yongshan area in southwestern Sichuan Basin is relatively thick and has a wide distribution.. With the characteristics of high content of organic carbon, slightly higher degree of thermal evolution, moderate porosity, favorable preservation conditions, shale gas resource potential in Suijiang-Yongshan is relatively high. Based on the comprehensive analysis of the distribution of favorable facies belts in Wufeng and Longmaxi formations, the thickness distribution of organic-rich shale, the degree of thermal evolution, the burial depth and the development of fractures, the area of Suijiang-Yongshan area with a total a of 852.04 km2 was preliminarily selected as favourable for shale gas.
Figure 4. Thickness contour map of organic-rich shale in Suijiang-Yongshan area.
Figure 5. TOC contour map of organic-rich shale in Suijiang-Yongshan area.
56 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 6. Ro contour map of organic-rich shale in Suijiang-Yongshan area.
The thickness of the organic-rich shale in this Suijiang-Yongshan area is 26 ~ 162m, the total organic carbon content is 2.99% ~ 3.78%, the thermal evolution degree 2.55% ~ 2.83% (Figures 4, 5, and 6), the total porosityabout 4.5%, and the gas content 2.41 ~ 4.52 m3/t. By using the probabilistic volume method, the shale gas resources of Wufengand Longmaxi formations in the Suijiang-Yongshan area is estimated to be 2346.53×108 m3, and the resource abundance is 2.75×108 m3/km2.
5. Conclusion
(1) The thickness of the organic-rich shale of Wufengand Longmaxi formations in well SY - 1 is 26 ~ 162m, the average total organic carbon content 2.99% ~ 3.78%, and the average thermal evolution degree 3.67%. The lithology consists mainly of black carbonaceous shale, siliceous rock and dark gray silty mudstone. Shale in SY-1 has a high content of main minerals with clay minerals in matrix, which provided the good reservoir conditions and reservoir transformation potential.
(2) The favorable shale gas area of Suijiang-Yongshan Wufeng -Longmaxi formation is 852.04km2, the shale gas resource amount is estimated to be 2346.53×10 m3, and the resource abundance is 2.75×108 m3/km2.
57 Chao Wang, et.al., The shale gas characteristics of Upper Ordovician Wufeng formation and Lower Silurian Longmaxi formation in Southwestern Sichuan Basin
References
Wang, Z., Yu, Q., Yang, P., et al., 2018. The main controlling factors of shale gas enrichment and exploration prospect areas in the Sichuan-Yunnan-Guizhou border areas, Southwestern China. Sedimentary Geology and Tethyan Geology, 38(3):1-15.
Yang, P., Wang, Z., Yu, Q., Liu, J., Xiong, G., He, J., and Yang, F., 2019. An resources potential analysis of Wufeng- Longmaxi formation shale gas in the southwestern margin of Sichuan Basin. Geology in China, 46(3): 601- 614 (in Chinese with English abstract).
Zhai, G., Bao, S., Pang, F., Ren, S., Chen, K., Wang, Y., Zhou, Z., and Wang, S., 2017. Peservoir-forming pattern of “four-storey” hydrocarbon accumulation in Anchang syncline of northern Guizhou Province. Geology in China, 2017, 44(1):1-12 (in Chinese with English abstract).
Zou, C., Dong, D., Wang, Y., Li, X., Huang, J., Wang, S., Guan, Q., Zhang, C., Wang, H., Liu, H., Bai, W., Liang, F., Lin, W., Zhao, Q., Liu, D., Yang, Z., Liang, P., Sun, S., and Qiu, Z., 2016. Shale gas in China: characteristics, challenges and prospects (II). Petroleum exploration and development, 43(2): 166-178.
58 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
New approaches for the identification of prospective gold mineralization localities in Chukchi and Magadan areas, Artic region by medium-scale geochemical prospecting.
A.G. Pilitsyn
Institute of Mineralogy, Geochemistry and Crystal Chemistry of Rare Elements, Moscow, Russia
Abstract
Geochemical mapping is one of the main tools to identify prospective mineralization areas. General geochemical mapping includes identification and delineation of the geochemical zones and districts, influenced by the ore-forming processes and local system of the ore mineralized districts. Geochemical mapping work would be able to determine the key epicenters of ore- forming processes up to the scales of the ore-mineralized clusters. Modern software programs are capable of processing large amount of geochemical data, facilitating the direct interpretation of the data using single and poly-elemental geochemical maps, covering large territories. Hence, spatial irregularities of the observed geochemical data that may be affected by the ore-forming processes could be deduced. To recognize the prospective gold mineralization localities in medium-scale geochemical prospecting works within the Chukchi and Magadan areas, Arctic region, a single general database was developed populated with the archive data from the relevant geochemical studies in the scales of 1:200,000 – 1:1,000,000. More than 100 local databases of 388,355 samples have been included into the general database. Comprehensive analysis of the geochemical maps using the multiplicative index of Au*As*Ag enabled the identification of the regional gold-mineralization processes, attributed to the Cretaceous magmatism. Gold- mineralized zones are delineated both within the volcanogenic and sedimentary complexes, and beyond. Medium-scale geochemical works are proven to be effective in poorly investigated or unknown territories for the identification of gold-mineralized zones.
Keywords: Geochemical mapping, Mineralization, Gold-mineralization process, Massif
1. Introduction
Geochemical survey is one of the main tools to locate prospective mineralization patterns. Ultra- low density geochemical survey enables identification of the regional-to-provincial geochemical patterns influenced by the ore-forming processes. In turn, one of the tasks of the low density geochemical survey is the delineation of the geochemincal pattern that may be controlled by the ore-forming processes in the regional scale of the ore-mineralized clusters.
Currently the ultra-low density geochemical survey is represented by the Geochemical Map of Russian Federation at the scale of 1: 2,500,000 and its contoured geochemical, structural and mineragenic derivatives. The low density geochemical survey also include similar maps at the scale of 1: 1,000,000. Thus the ultra-low density geochemical survey outcome comprises a large number of areal maps. These maps provide information on the resource potential for the observed areas, their geochemical specification as well as provincial and local geochemical patterns identification.. The maps are based on the tectonic demarcation scheme of the Russian Federation, where geological complexes are combined into units of regional, trans-regional and global scales in accordance with the geodynamic settings of the formations. In this regard on the structural and mineragenic demarcation scheme of the Russian Federation, the tectonic units are categorized in terms of their resource potential (Figure1). The maps are commonly attributed to the particular geodynamic settings, deduced from each tectonic block; therefore,
59 A.G. Pilitsyn, New approaches for the identification of prospective gold mineralization localities in Chukchi and Magadan areas, Artic region by medium-scale geochemical prospecting. these are not always applicable for the localization of the structures affected by the ore-forming processes, which frequently reveal the epigenetic rather than syngenetic derivation. Modern software programs are capable to process nearly limitless amount of geochemical data, enabling interpretations directly using the single- and poly-element geochemical maps covering large territories. Hence, geochemical patterns affected by the ore-forming processes could be reliably determined.
Databases
To recognize the prospective gold mineralization localities in medium-scale geochemical prospecting works within the Chukchi and Magadan areas (Arctic region), a generalization of the archive data from the relevant geochemical studies at scales of 1: 200,000 – 1:1,000,000 into the single database has been conducted. More than 100 local databases with a total of 388,355 samples have been included into the generalized database (Figure 2). The generalized database consists of the analyses results (predominantly Au-spectrochemical and semi-quantitative spectrochemical analyses) of the following elements: Au (100% of the analyses from the generalized database), Mn (100%), Cu (100%), Zn (100%), Pb (100%), Co (99%), Ni (99%), Sn (99%), Mo (98%), Be (97%), Cr (97%), As (97%), W (97%), V (96%), Bi (95%), Ag (94%), Ba (91%), Hg (88%), Ti (82%), Ga (80%), Sb (75%), Li (73%), Ge (73%).
Figure 1. Part of the structural and minerogenic demarcation scheme of Russian Federation at the scale of 1: 5,000,000
60 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 2. Dispersion trains sampling map at scale of 1:200,000 – 1:1,000,000 (Chukchi and Magadan areas, Arctic region). Interpretations
Within the studied area, the silver-gold adular-quartz and gold-low-sulfidation mineragenic types are widespread (Figure 3). The controlling geochemical parameters, obtained from the clastic dispersion trains, include associations of Au, Ag, As, Cu, Zn, Pb, Mo, Sn, Bi, and Hg for the silver-gold adular-quartz mineragenic type and Au, As, Sb, W (Hg, Cu, Ag) for the gold-low- sulfidation mineragenic type. An association of Au, Ag, and As plays a key role for the major part of the identified gold-mineralized localities. It is worth noting that an increase in the number of the components leads to an enhanced differentiation of the output layer: it is dependent more on the source of the data rather than the geochemical characteristics of the gold-mineralized localities.
Figure 4 shows the iso-concentration scheme of the multiplicative index of Au*As*Ag, constructed using of the ArcGis software in conjunction with the Spatial Analyst module by means of the Kriging method (width of the cell is 500 m x 500 m).
61 A.G. Pilitsyn, New approaches for the identification of prospective gold mineralization localities in Chukchi and Magadan areas, Artic region by medium-scale geochemical prospecting.
Figure 3. Minerogenic types of the gold deposits of the Eastern part of Russian Federation. In the scheme, the multiplicative index of Au*As*Ag displays the contrast characteristics (Figure 4); at the same time a north-east trending zone extending for 1,500 km with a width of up to 100 km, could be recognized.
Figure 4. Map of concentrations of the multiplicative index of Au*As*Ag, applied to the Chukchi and Magadan areas, Arctic region. 62 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
The zone is covered by a broad dispersion halo of the Au*As*Ag index with the maximum concentrations within the Magadan area and narrow linear dispersion halo with local maximum within the Chukchi area. The observed differences mainly reflect the diversities of the Au*As*Ag index values in the databases, obtained for the Magadan and Chukchi areas. Furthermore, the local north-west trending subzones of 500 km long cutting the main zone in various parts, are similarly identified. The most prominent local subzones are shown on Figure 5.
Spatial dependence
Spatial correlation between the identified gold-mineralized zones and gold deposits clearly demonstrates their link. It is noteworthy that the largest gold deposits of Mayskoe and Kupol (Magadan and Chukchi areas) are attributed to the main north-east trending zone (Figure 6). This zone is subparallel to the extension of the volcanogenic and sedimentary complexes of the Okhotsk-Chukchi volcanic belt and spatially covers its frontal part both within the belt ( the Chukchi segment in the northern part) and just beyond the belt ( the Magadan segment in the southern part). In turn, the local north-west trending subzones are also mostly located within the Okhotsk-Chukchi volcanic belt; however, there are occasionally present mineralized zones similar to the north-west trending apophyses beyond the volcanogenic and sedimentary complexes. (Figure 6).
Figure 5. The gold-mineralized localities within the Chukchi and Magadan areas, Arctic region
63 A.G. Pilitsyn, New approaches for the identification of prospective gold mineralization localities in Chukchi and Magadan areas, Artic region by medium-scale geochemical prospecting.
Figure 6. Correlation between the indicated gold-mineralized zones with the large gold deposits in igneous and volcanogenic complexes.
Thus, these indicated gold-mineralized zones do not possess the direct link with the volcanogenic complexes and reflect the ore-forming process. However, within volcanogenic complexes the silver-gold adular-quartz type deposits are commonly present, whereas beyond these complexes the gold-low-sulfidation type deposits are observed. Hence the most part of the gold deposits is spatially attributed to the Cretaceous granitoid massifs which are widespread in the studied area.
Prospective localities from the medium-scale geochemical prospecting works
Part of the indicated gold-mineralized zones and subzones are located within areaswhere there are no available databases on the concentrations of Au, As and Ag. At the same time these might be indicated through the layering. For example, the north-west trending zone in the western part of the Chukchi area is postulated in the maps Q-58-VII, VIII (Figure 7); to the east in these maps the anomalies pass through the Peschanka and Vesennee gold deposits, and in the western part the zone passes through the Klen gold deposit.
64 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure7. Gold-mineralized zones within the Peschanka and Klen deposits (Chukchi area, Arctic region). Similarly, at the boundary of the Chukchi and Magadan areas, the maps Q-58-XXXI-XXXIV (Figure 8), show the north-east-trending gold-mineralized zone and local anomalies of the north- west-trending subzones; these have not been well investigated.
Figure 8. Gold-mineralized zones at the boundary of the Chukchi and Magadan areas (Arctic region).
65 A.G. Pilitsyn, New approaches for the identification of prospective gold mineralization localities in Chukchi and Magadan areas, Artic region by medium-scale geochemical prospecting.
Geophysical Aspects
The identified prospective gold-mineralized zones are well-correlated to the negative gravity anomalies (Figure 9) and granitoid magmatism. The main north-east-trending ore-forming zone is perfectly highlighted by the negative gravity anomaly, and for the most part of the local north- west-trending subzones, they pass through the gravity fields with the co-directed minimums. From here, the observed gravity minimums are related to the intense fracturing and decompaction of the rocks, resulting in the high penetrating qualities for emplacement of the magmatic rocks together with the gold-bearing fluid systems.
Figure 9. Gravity fields map with the indicated gold-mineralized zones and granitoid magmatism .
Summary
Comprehensive analysis of the geochemical map using of the Au*As*Ag multiplicative index, covering the Chukchi and Magadan areas (Arctic region), allowed the identification of the gold- mineralization processes attributed to the Cretaceous magmatism. The gold-mineralized zones are localized both within the volcanogenic and sedimentary complexes, and beyond. The future perspectives of the medium-scale geochemical prospecting works are to focus on the poorly investigated or unknown territories within the identified gold-mineralized zones.
66 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Investigation of acid mine drainage (AMD) with long-term release of arsenic (AS) at Kyaukpahto gold mine, Myanmar
Shinji Matsumoto1, Akihiro Hamanaka2, Thant Swe Win2, Hiroto Yamasaki2, Takashi Sasaoka2 and Hideki Shimada2
1Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Japan 2Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, Japan
E-mail: [email protected]
Abstract
In the Kyaukpahto gold mine, Kawlin Township, Sagaing, Myanmar, gold ore is mined in open-pit and waste rocks are disposed of at dumps near the mine. According to the environmental report by the mining company, no water pollution due to acid mine drainage (AMD) is currently detected at the surface-water monitoring points downstream from its wastewater treatment facility. However, AMD generation has been reported both in the open-pit area and near the waste rock dump where backfill material contains sulfide minerals. To assess the potential risk of contamination by AMD generation, geochemical and batch leaching tests were conducted on the rock samples from the mine area. The quality of the associated wastewater was analysed in this study. The results show that the wastewater in the open-pit and low-grade ore dump areas has low pH values of less than 3.0 and contain more than 1.0 mg/L of As, suggesting the generation of As-bearing AMD. On the other hand, AMD was not detected at the waste dump filled with a large volume of waste rocks, because acidic water is neutralized due to the >50.0 kg H2SO4/ton acid-neutralizing capacity of the waste rocks. Nevertheless, the results of standardized two-step batch leaching tests indicated the possibility of long-term release of As from the waste dump area. Therefore, to ensure the sustainable development of the resources in this mine, some AMD prevention measures need to be put in place to avoid long-term contamination of wastewater by As, regardless of whether or not AMD is detected at present.
Keywords: sulfide minerals, acid mine drainage, long-term release, arsenic, gold mines, Myanmar
1. Introduction
Myanmar is rich in natural resources such as gold, silver, and copper (Swe et al., 2017). The mining industry exploiting these resources is expected to be further expanded due to the mining legislation enacted in late 2015. (Connette et al., 2016). However, the environmental impacts of mining should be considered to enable sustainable resource development. Acid mine drainage (AMD), also known as acid rock drainage (ARD), results from the exposure of sulfides to water and oxygen during mine operation and causes environmental problems that have affected many countries with historic or current mining activities. Sulfates and heavy metals such as iron, copper, zinc, aluminum, and arsenic are also released and contaminate the mine water (Moodley et al., 2018). Acidic waters with heavy metals may, additionally, be generated in spoil heaps, waste rocks, and in mine adits, shafts, pit-walls, and pit-floors (Johnson and Hallberg, 2005). They also mentioned that the potential for long-term contamination due to AMD may continue for a long time after mine closure and tailing dams are decommissioned. Therefore, source control of AMD within mine operations plays an important role in the long-term prevention of AMD. As resource development in Myanmar only started within the last few decades, AMD can be prevented in mine operations by taking appropriate countermeasures. However, more information on AMD
67 Shinji Matsumoto, et. al., Investigation of acid mine drainage (AMD) with long-term release of arsenic (AS) at Kyaukpahto gold mine, Myanmar is needed for many mines so that appropriate countermeasures can be applied. In this study, geochemical and batch leaching tests were conducted on rock samples, and wastewater quality was analyzed for a mine area in Myanmar to evaluate its potential AMD contamination risk.
2. Materials and methods
The Kyaukpahto gold mine is located about 30 km east of the Kawlin Township and 250 km north of Mandalay, in the north of Myanmar (Swe et al., 2004). According to Swe et al. (2004), the reserves were estimated at approximately 6 million tons at an average grade of 2.11 ppm Au with a cut-off grade of 0.4 ppm based on the results of geological investigation in the 1990s. They also indicated that the main ore minerals associated with gold are pyrite, arsenopyrite, and chalcopyrite, etc. In this mine, the gold ore is exploited by open-pit mining, and waste rocks are disposed at waste dumps near the mine site. Figure 1 shows the location of the “open pit”, “low- grade ore dump”, and “waste dump”. An environmental report from the mining company states that no water pollution due to AMD is currently detected at the wastewater quality monitoring point outside the mining area after water treatment procedures. However, there are residential areas adjacent to the mining area, and so, the assessment of the potential contamination risk from AMD from the Kyaukpahto gold mine is required to protect the health of the residents and to enable the sustainable development of the gold.
Water samples for pH and electric conductivity (EC) measurements were collected from a total of 41 points in the areas A, B, C, D, E, and F (Figure 1). These areas are respectively located in the tailing pond, a waste dump, the mining town, the low-grade ore dump, the open pit, and downstream of the drainage from the mining area. The water samples were introduced into an Agilent 7500 Series Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) after adding 0.1% of HNO3. Waste rocks were sampled from three areas in the mine site, the open pit, the low-grade ore dump, and the largest waste dump as marked in Figure 1. These samples were named OP-1, OP-2, OP-3, LG-1, LG-2, LG-3, WD-1, WD-2, and WD-3. A paste pH, a net acid generation (NAG) test, acid-base accounting (ABA), and X-ray fluorescence (XRF) analysis were performed to characterize the geochemical characteristics of the waste rocks (Australian Mineral Industries Research Association (AMIRA) International, 2002). In the paste pH test, pulverized rock samples are dissolved with deionized water. The change in pH and EC are measured 12 h after dissolution and are reported as paste pH, respectively. For the NAG test, rock samples are subjected to forced oxidation through dissolution in H2O2. Their acid-producing potential is quantified on the basis of the change in pH after the dissolution process, which is reported as the NAG pH. The result for NAG pH test indicates the net acid and/or base left in the rock sample after acid production and consumption. The balance between the acid-producing capacity and potential for neutralization of a rock sample, its net acid-producing potential (NAPP), is calculated by subtracting its acid- neutralizing capacity (ANC) from its maximum potential acidity (MPA), which are obtained in an ABA test (Sobek et al., 1978). MPA is calculated based on total sulfur content, whereas ANC is calculated through titration with hydrochloric acid. These values are expressed in units of kg H2SO4/ton. In addition, the percentage of total sulfur, as a representative index of acid potential, was obtained through XRF analysis using a Rigaku RIX 3100 spectrometer. Rock samples were classified as Potentially Acid Forming (PAF) if the NAG pH ≤ 4.5 and the NAPP ≥ 0, and as Non-Acid Forming (NAF) if the NAG pH ≥ 4.5 and the NAPP ≤ 0 (Miller et al., 1997). Rocks not classifiable as PAF or NAF were classified as uncertain (UC).
68 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 1. Schematic view of Kyaukpahto gold mine: red letters indicate water-sampling areas; waste dump (WD), low-grade ore dump (LG), and open pit (OP) indicate waste rock sampling areas.
Standardized batch leaching tests were conducted to determine the potential for leaching metals from the waste rocks. A two steps sequential leaching procedure based on CEN prEN 12457-3 was adopted to investigate the dissolution behavior of metals under different liquid/solid (L/S) ratio and dissolution times (Schultz et al., 2002). In this method, the pulverized rock samples are dissolved at a rotation rate of 200 rpm under the condition L/S = 2 for 6 hours for the first step, and L/S = 8 for 18 hours for the second. The concentration of Fe and As in the water sample from batch leaching tests was measured by the Agilent 7500 Series ICP-MS after being filtered through 0.45 mm filters. The result was expressed as mg/kg, indicating the molecular weight of dissolved elements per unit weight of solid.
3. Results and Discussion
Table 1 summarizes the water quality results for surface water in the areas A, B, C, D, E, and F (Figure 1). The measured pH was less than 3.0, and the measured EC was more than 2.0 mS/cm for most samples in the areas D and E. Furthermore, high concentrations of Fe and As were detected in these areas. These values exceed the Myanmar National Environmental Quality Standards (Ministry of Environmental Conservation and Forestry, 2015), which for pH is 6–9, Fe < 2.0 mg/L, and As < 0.1 mg/L. Although both the pH and the Fe and As concentrations also exceed standard levels at several points in A, B, C, and F, the very low pH values and extremely high Fe and As concentrations in areas D and E make them the main AMD areas.
The geochemical properties of the waste rocks are summarized in Table 2. OP-1, OP-2, and OP-3 in the open pit area and LG-1, LG-2, and LG-3 in the low-grade ore dump area were classified as PAF. The paste pH for all samples except LG-2 and LG-3 ranged from 3.60 to 5.20, which exceeds the official standard for pH NAG pH ranged from 2.05 to 3.27, and NAPP showed positive values in the open-pit and low-grade ore dump areas. Thus, there is a potential risk of AMD in these areas. This is consistent with the findings from the water quality results that the major areas of AMD are D and E. 69 Shinji Matsumoto, et. al., Investigation of acid mine drainage (AMD) with long-term release of arsenic (AS) at Kyaukpahto gold mine, Myanmar
Table 1. Summary of water sample qualities from the Kyaukpahto gold mine area. EC (mS/ Fe As EC (mS/ Fe As Area No. pH Area No. pH cm) (mg/L) (mg/L) cm) (mg/L) (mg/L) A 1 5.00 1.46 3.6 0.04 D 21 2.57 6.50 298.7 0.16 A 2 4.87 1.48 1.8 0.13 D 22 2.50 6.00 538.8 1.52 A 3 6.48 1.43 1.9 0.08 D 23 1.54 12.60 5585.9 132.46 A 4 6.58 2.04 20.6 0.17 E 24 2.61 3.80 9519.2 373.43 B 5 7.67 1.67 99.4 0.38 E 25 7.23 0.93 359.4 10.66 B 6 7.44 1.56 31.0 0.42 E 26 6.76 3.70 521.6 9.78 B 7 7.92 1.64 40.7 0.38 E 27 2.59 2.70 170.5 1.59 B 8 8.00 0.73 0.6 0.01 E 28 7.24 2.20 232.6 3.73 B 9 8.18 1.31 12.7 0.04 E 29 2.68 2.70 113.7 0.71 B 10 5.18 1.28 12.4 0.08 E 30 2.85 3.90 79.0 0.29 C 11 8.64 0.64 0.6 0.01 E 31 2.66 2.70 87.5 0.34 C 12 8.25 0.59 1.1 0.01 E 32 2.53 4.00 171.1 0.50 C 13 8.20 0.67 1.8 0.01 F 33 7.63 0.49 2.0 0.03 C 14 8.35 0.05 0.5 0.00 F 34 7.62 0.44 1.4 0.04 C 15 8.59 2.70 55.3 0.38 F 35 7.6 0.39 1.3 0.03 C 16 8.19 1.09 3.7 0.11 F 36 7.94 0.38 0.7 0.02 C 17 8.31 0.85 1.5 0.03 F 37 7.73 0.42 11.1 0.02 C 18 8.41 0.53 2.6 0.10 F 38 7.19 0.66 2.4 0.49 C 19 8.89 0.64 3.4 0.08 F 39 7.98 0.59 0.4 0.01 C 20 8.77 0.92 2.5 0.03 F 40 8.30 0.31 0.3 0.00 ------F 41 8.41 0.36 0.1 0.00
Table 2. Geochemical characteristics of rock samples from the Kyaukpahto gold mine area. Paste Total S MPA (kg ANC (kg NAPP (kg Location Sample NAG pH Classification pH (%) H2SO4/ton) H2SO3/ton) H2SO3/ton) OP-1 3.90 1.82 55.69 2.03 53.66 2.40 PAF Open pit OP-2 5.20 2.59 79.25 2.99 76.26 2.05 PAF (Area E) OP-3 4.40 1.16 35.5 2.94 32.56 2.57 PAF Low grade LG-1 3.60 0.60 18.36 0.84 17.52 3.27 PAF ore dump LG-2 6.10 1.03 31.52 1.80 29.72 3.05 PAF (Area D) LG-3 7.00 1.69 51.71 0.60 51.11 2.33 PAF WD-1 8.10 2.04 62.42 51.50 10.92 5.54 UC Waste dump WD-2 8.70 0.71 21.73 55.56 -33.83 8.49 NAF (Area B) WD-3 7.80 3.52 107.71 2.04 105.67 2.03 PAF
On the other hand, WD-2 was classified as NAF, and WD-3 was classified as PAF. WD-1 was classified as UC due to its positive NAPP and NAG pH of more than 4.5. This suggests that acid produced at WD-3 is neutralized by WD-2, resulting in an absence of AMD in the area B, where the measured pH of the wastewater can be seen to range from 5.18 to 8.18 in Table 1. Although WD-3 was classified as PAF and its paste pH was 7.80, its NAG pH was 2.03, and its NAPP was 105.67 kg H2SO4/ton. NAG pH indicates acid potential after complete dissolution of the rock sample with H2O2, indicating that WD-3 poses a potential AMD contamination risk in the future, although there is currently no AMD in the area B.
70 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Table 3 lists the chemical components of the rock samples. OP-1, OP-2, OP-3, LG-2, and LG-3 in the areas E and D which showed a high concentration of As. This is consistent with the detection of a high As concentration in many of the surface water samples in the areas D and E (Table 1). The high concentrations of Fe, Cu, As, and S observed in the areas D and E can be attributed to the common occurrence of pyrite, arsenopyrite, and chalcopyrite in the waste rocks. Geological investigations of the rocks produced at the mine also indicate the presence of these minerals. Moreover, waste rocks in the area B showed higher concentrations of Mg and Ca than in other areas. This suggests the presence of carbonate minerals, which will have contributed to the acid neutralization capacity reported in Table 2 for rocks from this area.
Table 3. Chemical components of rock samples from the Kyaukpahto gold mine area. Al O Location Sample SiO (%) 2 3 FeO (%) MgO (%) CaO (%) S (%) Cu (%) As (ppm) 2 (%) OP-1 78.8 10.1 2.3 0.35 0.03 1.82 69 852 Open pit OP-2 74.0 9.5 4.6 0.43 0.01 2.59 8 23524 (Area E) OP-3 85.1 7.2 1.6 0.28 0.03 1.16 45 249 Low-grade LG-1 87.3 6.9 0.7 0.23 0.02 0.60 5 169 ore dump LG-2 84.8 7.5 1.5 0.44 0.05 1.03 205 426 (Area D) LG-3 83.8 6.3 2.4 0.49 0.07 1.69 201 826 WD-1 67.2 12.8 4.4 1.44 2.25 2.04 0 404 Waste dump WD-2 67.3 13.5 4.0 2.22 2.68 0.71 3 90 (Area B) WD-3 66.1 12.8 5.9 1.31 0.36 3.52 2 637
Table 4. Results of two-step sequential leaching tests based on CEN prEN 12457-3 (Schultz et al., 2002). Fe As Condition Sample Condition Sample Fe (-) As (-) (mh/kg) (mg/kg) 1st step (L/S=2) OP-1 64.0 0.04 (L/S=8)(L/S=2) OP-1 0.8 2.42 1st step (L/S=2) OP-2 13.5 52.21 (L/S=8)(L/S=2) OP-2 0.8 4.17 1st step (L/S=2) OP-3 72.3 0.65 (L/S=8)(L/S=2) OP-3 1.3 0.85 1st step (L/S=2) LG-1 12.3 0.23 (L/S=8)(L/S=2) LG-1 1.1 1.23 1st step (L/S=2) LG-2 24.5 0.19 (L/S=8)(L/S=2) LG-2 1.4 1.89 1st step (L/S=2) LG-3 61.8 0.28 (L/S=8)(L/S=2) LG-3 1.1 1.39 1st step (L/S=2) WD-1 1.1 0.21 (L/S=8)(L/S=2) WD-1 6.4 5.62 1st step (L/S=2) WD-2 1.2 0.12 (L/S=8)(L/S=2) WD-2 2.2 7.32 1st step (L/S=2) WD-3 157.7 0.25 (L/S=8)(L/S=2) WD-3 1.5 2.46 2nd step (L/S = 8) OP-1 48.6 0.09 2nd step (L/S = 8) OP-2 10.2 217.80 2nd step (L/S = 8) OP-3 96.1 0.55 2nd step (L/S = 8) LG-1 13.2 0.28 2nd step (L/S = 8) LG-2 33.1 0.36 2nd step (L/S = 8) LG-3 69.7 0.39 2nd step (L/S = 8) WD-1 7.2 1.17 2nd step (L/S = 8) WD-2 2.6 0.91 2nd step (L/S = 8) WD-3 244.3 0.60
71 Shinji Matsumoto, et. al., Investigation of acid mine drainage (AMD) with long-term release of arsenic (AS) at Kyaukpahto gold mine, Myanmar
Table 4 summarizes the concentrations of Fe and As in the solution at the first step and second step of the sequential leaching test based on CEN prEN 12457-3 (Schultz et al., 2002). The ratio of the concentration of Fe or As at the first step to that at the second step is also shown in Table 4 (Sakai et al., 1996). The greater a ratio value, the longer the time of dissolution of the elements. On the other hand, a smaller ratio value indicates that the elements dissolve into the solution as initial wash-off. The concentrations of Fe and As at the first step were found to be 12.3–72.3 mg/ kg and 0.23–52.21 mg/kg, respectively, for OP-2, OP-3, LG-1, and LG-3. These waste rocks lead to the high concentrations of Fe and As with AMD shown for the areas D and E in Table 1. The concentrations of Fe and As were less for WD-1 and WD-2 than for the other samples at the first step. However, the ratio of the concentration at the first step to that at the second step was more than 1.5 for Fe and more than 2.46 for As in the area B (WD samples), suggesting that dissolution of Fe and As occurs there over time. Although AMD with a high concentration of Fe and As was not observed in the area B at the present time, there is a potential for As-bearing AMD contamination in the future. This long-term threat should be considered despite the present non- detection of AMD if resource development is to be responsible and sustainable.
4. Conclusions
Geochemical tests and batch leaching tests on rock samples and quality analysis on wastewater were carried out on samples from the immediate vicinity of the Kyaukpahto gold mine in Myanmar to evaluate the potential contamination risk from AMD. It was found that, although the pH and As concentrations of surface water outside the mine area currently meet official standards for wastewater quality because AMD is treated before being discharged from the mine area, this is not so in the mine area itself. The pH and concentration of Fe and As exceed the standards at several points, and there is a major area of AMD near the open-pit mine and at a low-grade ore dump, where the pH is less than 3.0 and the concentrations of Fe and As are very high. In addition, the results of NAG and two-step sequential leaching tests indicate a potential As-bearing AMD contamination risk in the future in the waste dump area, though currently the quality of its wastewater indicates that there is no AMD there. In conclusion, to ensure the sustainable development of resources at this mine, long-term contamination of wastewater by As should be considered in AMD prevention measures regardless of the evidence for AMD at the present time.
Acknowledgments
The authors gratefully acknowledge the KIZUNA Program, Japan International Cooperation Agency (JICA) for financial support. We acknowledge the kind and strong support for this research from the Director General and Staff Members of the Department of Mines, Ministry of Natural Resources and Environmental Conservation, Myanmar and ETERNAL Mining Company Limited.
72 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
References
Australian Mineral Industries Research Association (AMIRA) International, 2002. ARD Test Handbook: Prediction & Kinetic Control of Acid Mine Drainage. AMIRA P387A. Reported by Ian Wark Research Institute and Environmental Geochemistry International Ltd. AMIRA International, Melbourne, 42p.
Connette, K.J.L.J., Connette, G., Bernd, A., Phyo, P., Aung, K.H., Tun, Y.L., Thein, Z.M., Horning, N., Leimgruber, P., and Songer, M., 2016. Assessment of Mining Extent and Expansion in Myanmar Based on Freely-Available Satellite Imagery. Remote Sens., 8(11), 912.
Johnson, D.B., and Hallberg, K.B., 2005. Acid Mine Drainage Remediation Options: A Review. Sci. Total Environ., 338(1-2), 3–14.
Miller, S., Robertson, A., and Donahue, T., 1997. Advances in Acid Drainage Prediction Using the Net Acid Generating (NAG) Test. Proc. of 4th International Conference on Acid Rock Drainage, May 31–June 6, 1997, Vancouver, Canada, 2, 533–547.
Ministry of Environmental Conservation and Forestry, 2015. National Environmental Quality (Emission) Guidelines (NEQG), the Republic of the Union of Myanmar, 70–71.
Moodley, I., Sheridan, C.M., Kappelmeyer, U., and Akcil, A., 2018. Environmentally Sustainable Acid Mine Drainage Remediation: Research Developments with a Focus on Waste/by-products. Miner. Eng., 126, 207–220.
Sakai, S., Mizutani, S., and Takatsuki, H., 1996. Leaching Tests for Waste Materials. Journal of the Japan Society of Waste Management Experts, 7(5), 383–393.
Schultz, E., Vaajasaari, K., Joutti, A., and Ahtiainen, J., 2002. Toxicity of Industrial Wastes and Waste Leaching Test Eluates Containing Organic Compounds. Ecotoxicol. Environ. Saf., 52(3), 248– 255.
Sobek, A.A., Schuller, W.A., Freeman, J.R., and Smith, R.M., 1978. Field and Laboratory Methods Applicable to Overburdens and Minesoils. Report EPA-600/2-78-054, US National Technical Information Service Report PB-280, 495.
Swe, Y.M., Lee, I., Htay, T., and Aung, M., 2004. Gold Mineralization at the Kyaukpahto Mine Area, Northern Myanmar. Resour. Geol., 54(2), 197–204.
Swe, Y.M., Aye, C.C., and Zaw, K., 2017. Gold Deposits of Myanmar. In: Barber A.J., Zaw K., and Crow M.J., Eds., Myanmar: Geology, Resources, and Tectonics, Geological Society, London, Memoirs, 48, 557–572.
73 74 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Potential contribution of geosciences to Mekong’s environmental problems founded on cooperation of the CCOP member countries
Toru Tamura
Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology
E-mail: [email protected]
Abstract
The Mekong River is one of the largest rivers and supports lives of tens of million people across the six CCOP Member Countries: China, Myanmar, Laos, Thailand, Cambodia, and Vietnam. While its river basin has remained relatively environmentally intact, this is now threatened by human-induced disturbances, such as the construction of the hydropower dams and river sand extraction, for economic development since the 1990s. These disturbances, possibly augmented with ongoing climate change, are thought to have decreased the river sediment discharge, which has caused coastal and river bank erosion downstream. Effective mitigation of the environmental risk requires appropriate assessment, but objective quantification of the impact of individual factors remains to be established; for example, some studies stress the influence of hydropower dams on the deterioration of coastal erosion, but in some areas, the rate of coastal erosion has been constant since before the construction of the first river dam. The sediment accumulation in the Mekong delta appears to vary over time on the centennial scale, which implies to understand the impact of land-use and climate changes on the river sediment discharge needs long term studies. One geoscientific contribution to this problem is the detailed characterization of the provenance of the Mekong River sediment. Analysis of the provenance of bedrocks and soils in the river basin and river sediment load may help quantify the relative contribution of each of the river basin segment to the total river sediment discharge, and this is critical information for assessing the environmental impact of human-activities and climate changes. All the six CCOP Member Countries are encouraged to participate in this project and exchange their ideas for the sustainable development of the Mekong River basin.
Keywords: catchment disturbance; coastal erosion; Mekong River; riverbank erosion; sediment provenance
1. Introduction
The Mekong River is one of the largest rivers in the world. Its catchment covers six countries, China, Myanmar, Laos, Thailand, Cambodia, and Vietnam, supporting total population of c.80 million. In contrast to the huge environmental disturbances in many of developed countries since the industrial revolution, the Mekong River basin has remained relatively intact, but started to be altered much with the rapid economic growth after 1990s. The construction of main stream and tributary dams for irrigation and hydropower generation (Figure 1) has regulated the river- water flow and caused siltation in dam basins, which then dramatically decreased the downstream supply of nutrients and sediments (Kummu et al., 2010; Piman and Shrestha, 2017). The decline in the sediment discharge in the Mekong River is also considered to have been caused by fluvial sand extraction (Brunier et al., 2014) and climate changes (Darby et al., 2016), which have led to the erosion of the riverbank and deltaic coast (Figure 2; Anthony et al., 2015; Li et al., 2017). Appropriate management of river sediments based on an accurate prediction under changing climatic conditions is an important societal challenge for the catchment countries, where many of the people still live in poverty.
75 Toru Tamura, Potential contribution of geosciences to Mekong’s environmental problems founded on cooperation of the CCOP member countries
This paper proposes a geoscience project that contributes to solving the sediment problem of the Mekong River. The project invites active participation of the CCOP Member Countries to exchange ideas and share the information and data on the issue.
Figure 1. A map of the Mekong River basin showing the locations of mainstream and tributary dams (after http://mekongriver.info/hydropower).
2. Motivation
The long-term evolution of the fluvial and deltaic landform provides geological evidence that the sediment supply from the Mekong River has temporally fluctuated significantly even before the human-induced disturbances over the last several decades. For example, the rapid natural levee aggradation in southern Cambodia (Tamura et al., 2009), the remarkable coastal mud sedimentation and resultant build-up of the Camau Peninsula (Nguyen et al., 2000), and the accelerated coastal progradation (Ta et al., 2002) all imply more sediment supply to the lower reaches of the Mekong River in the last 1000–2000 years. Studies on Chinese rivers (Wang et al., 2011) and the Red River (Tanabe et al., 2006) link land-use changes in their catchments to changes in the fluvial sediment discharge. Similar impacts of the longer-term land-use changes are also inferred from the consistent coastal erosion of the Mekong delta since 1970s (Figure 2), before the commissioning of the first river dam (Li et al., 2017). However over much of the Mekong River basin, details of the past land-use changes are largely unclear.
The 4,600 km stretch of the Mekong River, from Tibet to South China Sea, is unlikely to respond consistently to external force, such as climate changes. The precipitation increase/decrease in response to the ongoing global warming is predicted to be variable within the Mekong River basin (Beilfuss and Triet, 2014). Therefore, the relative contribution of the tributaries to the sediment flux of the Mekong River is considered as critical information for sediment management, but is not well constrained so far due to the insufficient monitoring network (Piman and Shrestha, 2017).
76 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 2. A) Disappearance of a village after severe coastal erosion in the central Mekong delta, Vietnam. B) Riverbank erosion of the Mekong River near Kampong Cham, Cambodia.
3. Project outlines
To constrain the contribution of tributaries to the Mekong River’s sediment discharge, comprehensive geochemical mapping throughout the basin and provenance analysis is recommended. The outline of the geology in the Mekong River basin is characterized by Paleozoic sedimentary rocks in the upper reaches, Mesozoic sedimentary rocks with patchy igneous rocks in the middle reach, and Quaternary sediments in the lower reach (Figure 3; Gupta, 2009). Sediments discharged from individual tributaries are therefore expected to show their own characteristic geochemical composition that reflects the source geology.
This project aims to sample and analyze suspended and bedload sediments of the mainstream and tributaries (Figures 4A and 4B) to map the geochemical properties from the upstream to downstream. The total sediment flux in the lower reach is defined as the sum of the sediment discharge from tributaries to the main stream and deposition/erosion in the main stream (Figure 5). Assuming the temporal consistency of the geochemical composition of tributary sediments, its comparison with that of the modern and ancient sediments in the lower reach (e.g., in the Mekong delta) can be used for constraining the relative contribution of individual tributary to the total sediment flux both in the present and past centuries and millennia.
It is fundamental to characterize the fluvial sedimentation processes and sample sediments in the Mekong River in the six countries in both the rainy and dry seasons, and thus the participation of specialists from all of the six Mekong River catchment countries is the key to the success of this project. Geological Surveys and other geoscience organizations in China, Myanmar, Thailand, Laos, Cambodia, and Vietnam are encouraged to participate into the project and exchange their ideas.
77 Toru Tamura, Potential contribution of geosciences to Mekong’s environmental problems founded on cooperation of the CCOP member countries
Figure 3. Generalized geology of the Mekong River basin (Gupta, 2009).
Figure 4. A) Suspended silt and clay sediments in the rainy season river water (September 2018). B) Sand dunes exposed in the dry season (February 2019). Both photos were taken near Kampong Cham, Cambodia.
78 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 5. Schematic illustration of the sediment flux of the lower reach of the Mekong River, totalF . Fn and D represent the sediment flux of the nth tributary and sediment stored in the mainstream, respectively.
4. Summary
The fluvial sediment decline in the Mekong River basin is an urgent international issue that relates to the sustainable development/future of the southern China and Indochina countries, and requires comprehensive assessment from geological perspectives. The proposed project is planned to be carried out as an initiative of the CCOP, to which all the six catchment countries are members.
79 Toru Tamura, Potential contribution of geosciences to Mekong’s environmental problems founded on cooperation of the CCOP member countries
References
Anthony, E. J., Brunier, G., Besset, M., Goichot, M., Dussouillez, P., and Nguyen, V. L., 2015. Linking rapid erosion of the Mekong River delta to human activities. Scientific reports, 5, 14745.
Beilfuss, R., and Tran, T., 2014. Climate Change and Hydropower in the Mekong River Basin: A Synthesis of Research. Mekong River Commission - GIZ Cooperation Programme, 89 p.
Brunier, G., Anthony, E. J., Goichot, M., Provansal, M., and Dussouillez, P., 2014. Recent morphological changes in the Mekong and Bassac river channels, Mekong delta: The marked impact of river-bed mining and implications for delta destabilisation. Geomorphology, 224, 177-191.
Darby, S. E., Hackney, C. R., Leyland, J., Kummu, M., Lauri, H., Parsons, D. R., and Aalto, R., 2016. Fluvial sediment supply to a mega-delta reduced by shifting tropical-cyclone activity. Nature, 539(7628), 276.
Gupta, A., 2009. Geology and landforms of the Mekong Basin. In The Mekong (pp. 29-51). Academic Press.
Kummu, M., Lu, X.X., Wang, J. J., and Varis, O., 2010. Basin-wide sediment trapping efficiency of emerging reservoirs along the Mekong. Geomorphology, 119(3-4), 181-197.
Li, X., Liu, J. P., Saito, Y., and Nguyen, V. L., 2017. Recent evolution of the Mekong Delta and the impacts of dams. Earth-Science Reviews, 175, 1-17.
Nguyen, V.L., Ta, T.K.O., and Tateishi, M., 2000. Late Holocene depositional environments and coastal evolution of the Mekong River Delta, southern Vietnam: Journal of Asian Earth Sciences, v. 18, p. 427–439, doi:10.1016/S1367-9120(99)00076-0.
Piman, T., and Shrestha, M., 2017. Case Study on Sediment in the Mekong River Basin: Current State and Future Trends. Stockholm Environment Institute Project Report 2017-03, 45 p.
Ta, T.K.O., Nguyen, V.L., Tateishi, M., Kobayashi, I., and Saito, Y., 2002. Holocene delta evolution and sediment discharge of the Mekong River, southern Vietnam: Quaternary Science Reviews, v. 21, p. 1807–1819, doi:10.1016/S0277-3791(02)00007-0.
Tamura, T., Saito, Y., Sieng, S., Ben, B., Kong, M., Sim, I., Choup, S., and Akiba, F., 2009. Initiation of the Mekong River delta at 8 ka: Evidence from the sedimentary succession in the Cambodian lowland: Quaternary Science Reviews, v. 28, p. 327–344, doi:10.1016/j.quascirev. 2008.10.010.
Tanabe, S., Saito, Y., Vu, Q. L., Hanebuth, T. J., Ngo, Q. L., and Kitamura, A., 2006. Holocene evolution of the Song Hong (Red River) delta system, northern Vietnam. Sedimentary Geology, 187(1-2), 29-61.
Wang, H., Saito, Y., Zhang, Y., Bi, N., Sun, X., and Yang, Z., 2011. Recent changes of sediment flux to the western Pacific Ocean from major rivers in East and Southeast Asia. Earth-Science Reviews, 108(1-2), 80-100.
80 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Purification of zeolite from Mae Moe power plants coal fly ash by microwave synthesis from improvement of sulfate removal from wastewater
Khamngoen Kiattipong
Electricity Generation Authority of Thailand. Lampang, 52220, Thailand, Tel: 66 (0)54 254041, Fax: 66 (0)54 254037
Abstract
Synthetic zeolites have been synthesized from fly ash by hydrothermal activation with NaOH using the microwave process. Microwave is one of the most effective and short methods that cause water dipole rotation resulting in a rapid heating process. However, the activated ash (the residues) has been found to exhibit a lower cation exchange capacity. Therefore, the composition of fly ash from the Mae Moh coal mine in northern Thailand includes SiO2, Al2O3, Fe2O3 and high levels of CaO (>25%) and inhibits the conversion to zeolite. In this study we investigate the purification of microwave zeolite synthesis of Mae Moh coal fly ash with alkali basis to improve its sulfate adsorption.
Keywords: Zeolite, Fly ash, Microwave synthesis, Mae Moh basin, Sulfate removal
1. Introduction
Coal remains one of the key energy sources for developing countries around the world with C. 40% of global electricity derived from coal combustion energy (Wang, et al., 2014). One important and valuable byproduct of coal combustion is coal fly ash which typically contains high volumes of Al and Si. These elements may be converted to zeolite by reactions with alkaline metal ions (such as Na+, K+, etc.) via hydrothermal synthesis (Ngamcharussrivichai, et al., 2008). Zeolite coal fly ash synthesis via the microwave process is one of the most effective methods of synthesis (Inada, et al., 2005) causing water dipole rotation and resulting in a rapid process and rapid heating. The ultrasonic method induces the crystallization process which controls crystal growth in a saturated mixture where the concentration of soluble silicate species in the mixture directly influences crystal growth rate (Ozdemir & Piskin, 2019). Therefore, ultrasonic-assisted microwave hydrothermal synthesis could increase crystal growth of zeolite and decrease the length of time for the process. Often termed a molecular sieve, zeolite is a material with equal pore size along its structure and high adsorption properties and capable of changing alkaline ions to capture anions. In this study, we investigate the potential for synthesising zeolite with sulfate adsorption from mine wastewater from the Mae Moh coal mine in Lampang province, north Thailand.
2. Experimental procedure
2.1 Materials
Coal fly ash was supplied from Mae Moh power plantand prepared by calcined at 800°C for two hours. The calcined fly ash was then sieved through 60 mesh (250 µm) and divided into two parts. The first part was washed with HCl solution (7%v/v, Grade AR, Merck) at the liquid/solid ratio of 1g/25ml and stirred for one hour, and then filtered and washed with DI water. Finally, the washed fly ash (WFA) was dried at 105°C (Ozdemir & Piskin, 2019). The second part of fly ash was only calcined without washing with HCl (FA).
81 Khamngoen Kiattipong, Purification of zeolite from Mae Moe power plants coal fly ash by microwave synthesis from improvement of sulfate removal from wastewater
2.2 Synthesis
Zeolite was synthesized via ultrasonic-assisted microwave hydrothermal (Querol, et al., 1997) (Ozdemir & Piskin, 2019). A 5 g of fly ash was placed in 5.0 M NaOH solution (20 ml, Grade AR, Merck) and sonicated in an ultrasonic bath (Branson 2510) for 60 minutes. Then, slurry mixture of fly ash was treated by microwave (CEM MARS6, 2.45 GHz.) heating process with 255 °C for 30 min. The mixture was then filtered, washed with DI water, and dried at 105 °C for 24 h.
2.3 Characterization
Zeolite’s structure and composition were investigated by x-ray diffraction (XRD, Bruker D2PHASER) and wavelength dispersive x-ray fluorescence (WDXRF, Bruker Tiger S8).
2.4 Sulfate adsorption
Synthetic fly ash zeolite was placed in Na2SO4 solution (2,000 ppm, Grade AR, Merck). The mixture was stirred for 24 h. and the remaining SO42- analyzed using ultraviolet-visible absorption spectroscopy (UV-vis) following the method EPA375.4.
3. Results and discussion
3.1 Characterization
Table 1 shows the chemical composition of untreated fly ash and the treated fly ash. The composition of Mae Moh fly ash is dominated by Si, Al, Ca, Fe and other metal oxides. In the synthesis condition, SiO2 and Fe2O3 composition increased in the sample washed with HCl solution. Conversly,the CaO content dramatically decreased from 24.46% to 7.58% along with aluminum as noted in the ratio of SiO2/Al2O3 in Table 1. The composition of synthetic fly ash zeolite shows Si increasing with time in the ultrasonic bath compared with synthesis zeolite from raw fly ash. In this aging process, aluminosilicate in the fly ash dissolved into the alkaline mixture, is reassembled and nucleates to increase crystal growth of zeolite (Bukharia, et al., 2015). The iron content in fly ash is an impurity but may also adsorb the energy in microwave filed and increase synthesis rate (Cui, et al., 2012).
Table 1 Chemical composition of fly ash and its production (wt%).
Zeolite’s synthesis condition Washed with NaOH 5 M 225 NaOH 5 M 225 Raw Calcined NaOH 5 M 225 Compositions HCl calcined °C (calcined, °C (calcined, fly ash fly ash °C (from raw fly ash sonicated, and sonicated without fly ash) washed) washed)
SiO2 36.77 35.11 43.81 27.35 32.93 31.65
Al2O3 20.15 19.40 20.69 15.73 20.19 15.60
Fe2O3 12.22 12.56 20.20 11.63 19.90 12.02
Na2O 1.90 1.88 2.30 13.79 21.16 9.35 CaO 24.46 24.10 7.58 24.19 7.80 27.04
SO3 3.64 3.43 0.13 1.76 0.13 1.04
SiO2/Al2O3 1.82 1.81 2.12 1.743 1.63 2.03
82 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 1 shows an X-ray diffractogram of fly ash zeolite washed and synthesised at 5M NaOH and 225°C. Comparing with the raw fly ash (top line) and the unwashed zeolite (middle line)
(Na2O·Al2O3·1.68SiO2·1.73H2O, JCPSD 00-031-1270), it is shown that the peak was low intensity. The unwashed zeolite also forms aluminum tobermorite (AlCa5H11O23Si5), caused by the effect of CaO and Fe2O3 content (Murayama, et al., 2002) competing with sodium ion to occupy the active sites in the chemical zeolite synthesizing process (Thuadaij & Nuntiya, 2012). In the condition of washed fly ash, it was found that synthetic zeolite was zeolite X confirming structure with JCPSD 00-028-1036 peak that it was Na14Al12Si13O51·6H2O (Sodium Aluminum Silicate Hydrate).
Figure 1. XRD pattern of (top) raw fly ash, (middle) 5M 255°C unwashed and (bottom) 5M 255°C washed;
Q:quartz, F:Fe2O3, Ca:CaSO4, Z:zeolite, C-A-S: aluminum tobermorite, Z-X: zeolite X.
3.2 Sulfate adsorption
The results of sulfate adsorption (Table 2) show that the raw fly ash was negativedue to the amount of sulfate in its original composition. When calcined, fly ash sulfate composition was decreased at high temperature rising to to 3.92 mg/g by adsorption from the with synthetic zeolite derived from the raw fly ash. In the condition of impure zeolite (unwashed, calcined and sonicated) adsorbed sulfate is similar to that of zeolite-X because calcium in this composition can also adsorb sulfate anion due to the Na ion in the zeolite structure, via π-electronic interaction. (Ngamcharussrivichai, et al., 2008)
Table 2 Sulfate adsorption 2 Materials SO4 -Adsorption (mg/g adsorbed) Raw Fly Ash -58.48 5M 225°C (raw fly ash) 3.92 Calcined fly ash 20.15 Washed calcined fly ash 28.70 5M 225°C calcined, washed, sonicated 59.53 5M 225°C calcined and sonicated 60.25
83 Khamngoen Kiattipong, Purification of zeolite from Mae Moe power plants coal fly ash by microwave synthesis from improvement of sulfate removal from wastewater
4. Conclusion
In this study, Mae Moh coal fly ash was successfully synthesized to zeolite-X14 (Na Al12Si13
O51·6H2O) via ultrasonic-assist microwave hydrothermal synthesis. We demonstrate that the nw zeolite can adsorb sulfate (59.53 mg/g) under the synthesis condition of a 5M NaOH and a 225°C reaction temperature. When CaO was eliminated from raw material, zeolite’s XRD peaks were sharp and grew more zeolite.
Acknowledgement
We would like to thank Electricity Generating Authority of Thailand (EGAT) for materials, laboratory, and fund. I would like to thank to Police Forensic Science Center 10 for experimental instruments.
References
Bukharia, S. S., Behinab, J., Kazemiana, H., and Rohania, S., 2015. Conversion of coal fly ash to zeolite utilizing microwave and ultrasound energies: A review. Fuel. Volume 140, pp. 250-266.
Cui, H. . M., Ke, L. F., Li, F., and Kang, T., 2012. Microwave-Assisted Zeolite Hydrothermal Synthesis from Coal Fly Ash and its Application. Applied Mechanics and Materials, Volume 178-181, pp. 380-384.
Inada, M. et al., 2005. Microwave-assisted zeolite synthesis from coal fly ash in hydrothermal process. Fuel, pp. 1482-1486.
Murayama, N., Yamamoto, H., and Shibata, J., 2002. Zeolite synthesis from coal fly ash by hydrothermal reaction using various alikali sources. Journal fo chemical technology and biotechnology, pp. 280-286.
Ngamcharussrivichai, C., Chatratananon, C., Nuntang, S., and Prasassarakich, P., 2008. Adsorptive removal of thiophene and benzotiophene over zeolite from Mae Moh coal fly ash. Fuel,V olume 87, pp. 2347-2351.
Ozdemir, O. D., and Piskin, S., 2019. A Novel Synthesis Method of Zeolite X From Coal Fly Ash: Alkaline Fusion Followed by Ultrasonic-Assisted Synthesis Method. Waste and Biomass Valorization, 10(1), p. 143–154.
Querol, X. et al., 1997. A Fast Method for Recycling Fly Ash: Microwave-Assisted Zeolite Synthesis. Environmental Science & Technology, pp. 2527-2533.
Thuadaij, P., and Nuntiya, A., 2012. Effect of the SiO2/Al2O3 ratio on the synthesis of Na-x zeolite from Mae Moh fly ash. ScienceAsia, Volume 38, pp. 295-300.
Wang, S., Zhang, C., and Chen, J., 2014. Utilization of Coal Fly Ash for the Production of Glass-ceramics With Unique Performances: A Brief Review. Journal of Materials Science & Technology, 30(12), pp. 1208-1212.
84 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Studying the pH effect for sulfate removal in water by using Electrocoagulation Method
Jaturong Kongwutthivech
Laboratory Section, Geology Department, Mae Moh Mine Planning and Administration Division, Electricity Generation Authority of Thailand. Lampang, 52220, Thailand. Tel: 66 (0)54 254041, Fax: 66 (0)54 254037
E-mail: [email protected]
Abstract
Mae Moh lignite coal mine in northern Thailand is required to implement environmental quality controls including on air pollution, sound and wastewater from mine drainage. Monitoring on mine waters had been carried out between 2016 and 2018. Recently sulfate ions concentrations have been found to be higher than the average levels usually in the second quarter (April) each year. Electrocoagulation is a growing technology for waste water treatment because of its low operating cost and high efficiency in sulphate removal. Using the UV-Vis Spectroscopy technique for sulfate ion detection, this paper focuses on a study aimed at identifying the optimum conditions of pH and electrode type (Fe and Al) that are most appropriate for remove sulfate in batch electrocoagulation processes. Our results show that the Fe electrode has a high efficiency of 91.63% at pH 5; however, for economic reason, pH 6 is also suitable with an efficiency of 88.44% in 70 minutes. The Al electrode has an efficiency of 40.87% at pH 6.
Keywords: pH, Sulfate removal, electrocoagulation method
1. Introduction
Mae Moh Mine, operated by the Electricity Generating Authority of Thailand (EGAT) is the largest lignite coal mine in Thailand and provides fuel to power stations for electricity generation). Environmental impact of mine waste is of concern and the mine is required to follow environmental regulations of the Pollution Control Department (PCD). In particular mine drainage has many varieties of pollutant parameters including pH value, particles, chemical compositions, heavy metals and sulfate that depended on the location of mine (Johnson, 2005; Papirio et al., 2013). Therefore, Mae Moh Mine usually monitors the water quality of mine drainage using several techniques to control all of the parameters before releasing the drainage to the environment. During 2016 and 2018, the monitoring found that the Total Dissolved Solids (TDS) parameters, a measure of the dissolved combined content of all and organic substances present in a liquid had increased in the second quarter (April) of these years. In addition, Mae Moh mine is located in the old volcanic terrain which has a sulfur-rich ore such as pyrite (FeS). Sulfide in pyrite can be changed to the form of sulfate by two major processes, which are reactions to the changing of climate and self-oxidation. After that, sulfate was dissolved and contaminated in the drainage. Sulfide in pyrite will react in response to changing of climate and self-oxidation into the form of sulfate which is then available to be dissolved and become a contaminant in the drainage system.
There are several modern technologies and methods to treat pollutants, for example, membrane filtration (Kurniawan et al., 2006; and Schoeman and Steyn, 2001), biodegradation andion exchange (Dann et al., 2009; Haghsheno et al., 2009; and Martin et al., 2009). These methods are not very effective with sulfate ions due to their high solubility and stability in aqueous solution. The main approach for sulphate removal is electrocoagulation (insert reference) because it can generate cations Fe2+ and Al3+ which will adsorb anion as sulfate by using a precipitation reaction
85 Jaturong Kongwutthivech, Studying the pH effect for sulfate removal in water by using Electrocoagulation Method with hydroxide species. The electrocoagulation method has the advantages of being robust, easy to automate and low energy requirements (Drouiche et al., 2007; Murugananthan et al, 2004; and Pulkka et al, 2014). This work aims to study the effect of pH in electrocoagulation technique in terms of decreasing the amount of sulfate and TDS parameter at the laboratory scale.
2. Material and Methods
2.1 Chemical
Anhydrous sodium sulfate and barium chloride (AR grade) were purchased from Merck and deionized water (Millipore Milli-Q system, resistivity: 18.2 MΩ at 25°C) was used to prepare all solutions. Hydrochloric acid and sodium hydroxide (AR grade) were used to adjust the pH of the solutions, and supplied by RCI Labscan. All of chemicals were used without further purification.
2.2 Standard Sulfate solution
Anhydrous Na2SO4 1.48xx g. was dissolved in deionized water 200 mL and volume adjusted in 1 L volumetric flasks.
2.3 Experimental Setup.and Methodology
The experimental approach was as follows:
1 L of standard sulfaλte solution was decanted into a beaker and two plates of Fe electrodes by using stand were clamp in place in the beaker. The direction between cathode and anode were adjusted to 5 cm and deep 20 cm from the top of the beaker as shown in Figure 1. and then both were connect to a 24 V power supply and plugged in to commence the experiment. Each experiment varied the pH condition was optimized by using conc. HCl and NaOH solution and repeated for a range of pH values including 3, 4, 5, 6, 7, 8 and 9.30 mL of sample solutions were collected using a dropper every 10 min from 0 to 80 min. All of samples were tested with pH test (universal indicator paper) and sulfate determination. After that, we setup the experiment with the optimum pH condition and changed the Fe electrode to an Al electrode.
2.4 Sulfate Determination by using UV-Visible spectroscopy (λmax = 420 nm)
To carry out sulphate determinations by the UV spectroscopy we filtered 2.00 ml of sample solutions using a syringe filter and injected this into an Erlenmeyer flask. We then prepared a quality control standard (QCS 20 ppm) and pipetted 2 ml of the standard sulfate stock solution (1000 ppm) put into the Erlenmeyer flask with pipetted 5 ml of conditioning reagent and finally adjusted the volume to 100 mL with deionized water. After that, BaCl2 was added into the flask and stirred for 5 min. Finally, the resulting sample solution was taken into the cuvette and analyzed.
86 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 1. Experimental equipment includes Electrodes, 1 L beaker, 24 V power supply and ampmeter. 3. Results and Discussion
3.1 the effect of pH condition by using Fe electrode
Once the experiment commenced, the colorless solution discoloured into a brownish solution within 80 min as the anode corroded and generated Fe2+ ions which were oxidized to Fe3+ ion. Meanwhile, the cathode produced hydrogen gas bubbles and hydroxide ions due to the water 2+ reduction reaction. As a result Fe and OH- ion combined to form ferrous hydroxide (Fe(OH)2) which could be used to removed sulfate ions from sample solutions by agglomeration. In this process ferrous hydroxide would be changed to ferric hydroxide.
Figure 2 summarises the results of SO4 removal at varying pH values over time. We note that the percentage of sulfate removal dramatically increases between 0 to 40 min and that the percentage then remains constant after 70 min in the acid condition. This can be explained by the Fe2+ ion rapidly dissolving to form the stable Fe2+ free ion which can easily combine with the sulfate ion due to their complementary electrostatic force. Therefore, the Fe(OH)2 sediment is highly effective in removing sulfate ions until the contained amount of sulfate and the surrounding sample solution was equaled. In contrast, the percentage of sulfate removal only slightly increased from 0 to 60 min and thereafter constant at 70 min in its basic condition. This is explained by the fact that as the Fe2+ free ion was precipitated to form ferrous hydroxide sediment any excess hydroxide ion produced by the reaction would prevent the sulfate ion agglomerating within Fe(OH)2 sediment. The efficiency for sulfate removal was dramatically decreased in basic condition. By varying the pH value the performance of sulfate removal changed and was very high effective at pH 3, 5 and 6 which removed sulfate at 80%, 91.63% and 88.44%, respectively. Higher acid values inhibit the formation of excess OH- ion instead of sulfate ions. In summary, in this experiment we found that the optimum pH condition is 6 because pH 6 use the less chemical reagent for adjusted the sample solution due to the chemical qualities of Mae Moh Mine drainage.
87 Jaturong Kongwutthivech, Studying the pH effect for sulfate removal in water by using Electrocoagulation Method
Figure 2. The trending of percentage of sulfate removal versus reaction time depended on several pH by using Fe electrode. pH was varied from 3 to 9. 3.2 Comparison of sulfate removal between Fe and Al electrodes
Figure 3 shows the percentage of sulfate removed by using an Fe electrode up to 80 min. significantly increased up to 88.44%. Meanwhile, the percentage of the sulfate removal by using Al electrode was only increased up to 40.87% over 80 min. This can be explained by hard-soft acid base theory; the Fe sediment is formed by Fe2+ (soft acid) and OH- ions which attract the sulfate (soft base) ions. This reaction to form Fe(OH)3 sediment formation is rapid with a rising rate of sulfate removal as described above. In contrast, the Al3+ (hard acid) ion is not attracted to combine with sulfate (soft base) ions. Instead Al(OH)3 could be formed [Al(OH)4 ] specie which act as a Lewis acid to gain the OH- ion in the sample solution. Therefore, the Al(OH)3 sediment was slowly precipitated. The Fe electrode therefore at pH6 conditions more highly effective for the sulfate removal than the Al electrode.
4. Conclusions
From the experiment, we conclude that pH condition affects the efficiency for sulfate removal when using the electrocoagulation method. The ideal pH condition is 6 using Fe electrodes. This condition is as same as the Mae Moh mine drainage and facilitates a high percentage of sulfate removal potentially up to 88.44%. The percentage of sulfate removal by using Al electrode is significantly less efficient at 40.87%.
88 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 3 Comparison of sulfate removal between Fe and Al electrodes References
Dann, A., Cooper, R., and Bowman, J., 2009. Investigation and optimization of a passively operated compost-based system for remediation of acidic, highly iron- and sulfate-rich industrial waste water, Water research, 43, 2302-16.
Drouiche, N., Ghaffour, N., Lounici, H., and Mameri, M., 2007. Electrocoagulation of chemical mechanical polishing wastewater, Desalination, 214(1), 31-37.
Haghsheno, R., Mohebbi, A., Hashemipour, H., and Sarrafi, A., 2009. Study of kinetic and fixed bed operation of removal of sulfate anions from an industrial wastewater by an anion exchange resin, Journal of Hazardous Materials, 166(2), 961-966.
Johnson, D., 2005. Acid Mine Drainage Remediation Options: A Review. The Science of the total environment, 338, 3-14.
Kurniawan, T.A., Chan, G.Y.S., Lo, W.-H., Babel, S., 2006. Physico–chemical treatment techniques for wastewater laden with heavy metals, Chemical Engineering Journal, 118(1), 83-98.
Martins, M., Faleiro, M.L., Barros, R.J., Veríssimo, A.R., Barreiros, M.A., Costa, M.C., 2009. Characterization and activity studies of highly heavy metal resistant sulphate-reducing bacteria to be used in acid mine drainage decontamination, Journal of Hazardous Materials, 166(2), 706-713.
Murugananthan, M., Raju, G.B., Prabhakar, S., 2004. Removal of sulfide, sulfate and sulfite ions by electro coagulation, Journal of Hazardous Materials, 109(1), 37-44.
Papirio, S., Villa-Gomez, D.K., Esposito, G., Pirozzi, F., Lens, P.N.L., 2013. Acid Mine Drainage Treatment in Fluidized-Bed Bioreactors by Sulfate-Reducing Bacteria: A Critical Review, Critical Reviews in Environmental Science and Technology, 43(23), 2545-2580.
Pulkka, S., Martikainen, M., Bhatnagar, A., Sillanpää, M., 2014. Electrochemical methods for the removal of anionic contaminants from water – A review, Separation and Purification Technology, 132, 252–271.
Schoeman, J.J., Steyn, A., 2001. Investigation into alternative water treatment technologies for the treatment of underground mine water discharged by Grootvlei Proprietary Mines Ltd into the Blesbokspruit in South Africa, Desalination, 133(1), 13-30.
89 90 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Arsenic and Cadmium: under the DMR Hazardous Elements Project
Apsorn Sardsud1 and Jitisak Premmanee2
1Division of Mineral Resources Analysis and Identification, Department of Mineral Resources. 2An ex-official of the Department of Mineral Resources, contact: [email protected]
E-mail: [email protected]
Abstract
The Department of Mineral Resources (DMR) for Thailand has been collecting stream sediments, soil and water samples, and analyzing for hazardous elements under a national project since 2007. The data are an important geochemical baseline dataset of the country and up to 2015, covers 10 provinces including 5,438 stream sediments, 1,414 soils and 4,959 water samples. Arsenic and cadmium are among those elements that are of interest because of their dissimilarity of dispersion behaviors. Cadmium disperses physically from sources by stream sediments and soil whereas Arsenic disperses not only physically but also chemically through the water due to its dissolution ability.
Averages of the DMR’s arsenic and cadmium assays are comparable with WHO/FAO standards which refer to maximum permissible limit (MPL) while there are significant differences with Thai MPL. For example, DMR’s cadmium in soil/sediments average at 0.4 ppm while WHO/ FAO limits to 1-3 ppm but the Thai MPL are at 37 ppm for residential/agriculture and 810 ppm for other purposes areas. Low arsenic in soil/sediment (3.9 ppm for residential/agriculture land and 27 ppm for other purposes areas) was tabulated in Thai regulation while DMR’s average at 12-15 ppm and WHO/FAO guideline at 20-100 ppm. It is presumed therefore that the arsenic and cadmium tabulated in Thai regulation may not be applicable figures for comparison in environmental studies. The DMR’s averages are the actual figures and therefore, should be used to inform national guideline values. We propose thatthe applicable levels of MPL should be about 5-10 times of the averages, i.e. arsenic at 50-100 ppm and cadmium at 2-5 ppm in soil and sediments. Finally, to create a reliable and referenceable baseline dataset on the hazardous elements, DMR is planning to collect stream sediments, soil and water in other remaining provinces of the entire country and to disseminate the information to public regularly.
Keywords: Arsenic, cadmium, maximum permissible limit, geochemical database, baseline data.
1. Introduction
Since 2007 the Division of Mineral Analysis and Identification within the Department of Mineral Resources (DMR), Thailand has been collecting stream sediments, soil and water samples, and analyzing these for hazardous elements under a project named ‘Risk Areas Delineation from Natural Toxic Elements Project’ or normally called ‘Hazardous Elements Project’. The project is focussed on on metals in the natural environment, especially those toxic elements, such as arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), lead (Pb), and others. The project plan?strategy is to cover an entire province or a several provinces within a field season or budget year, and hopefully to delineate any areas of elevated content of the key toxic elements.
Up to 2015, the project has covered 10 provinces (Ratchaburi, Chiangrai, Chiangmai, Lamphun, Lampang, Phrae, Uthaithani, Suphanburi, Pitsanulok and Petchabun) around 97,000 square kilometers or 20% of the country (Figure 1) mainly in the north, central and upper south of
91 Apsorn Sardsud and Jitisak Premmanee, Arsenic and Cadmium: under the DMR Hazardous Elements Project
Thailand. In total 11,811samples were analysed using standard sampling/analytical protocols comprising 5,438 stream sediments, 1,414 soils and 4,959 water samples, (Table 1). These data form an important geochemical baseline dataset for the country in this paper we document this dataset as reference materials to underpin future environmental studies.
Arsenic and Cadmium Table 1. Samples under the DMR Hazardous Elements Project during 2007 to 2015. Year Province Stream sediments Soil Surface water TOTAL 2007 Ratchaburi 503 410 426 1,339 2008 Chiang Rai 697 367 697 1,761 2009 Chiang Mai 782 146 752 1,680 2010 Lamphun 390 59 306 755 2010 Lampang 620 103 542 1,265 2011 Phrae* 328 329 231 888 2012 Uthai Thani 369 362 731 2013 Suphan Buri 439 428 867 2014 Pitsanulok 679 636 1,315 2015 Petchabun 631 579 1,210 TOTAL 5,438 1,414 4,959 11,811 Note: * Parts of data available. Data sources list in the References.
Figure 1. Samples under the DMR Hazardous Elements Project during 2007 to 2015.
Arsenic and cadmium are among those elements and are of key interest due to their dissimilarity of dispersion behaviors in the natural environment. Cadmium is typically dispersed physically from its source by stream sediments and soilIllustrated for example by the elevated cadmium levels in the Mae Tao catchment, Amphoe Mae Sod and Changwat Tak. Here cadmium from upstream zinc deposits is eroded by fluvial processes and carried in stream sediments, t downstream to soils in the local paddy fields, and ultimately is transferreds to the rice grains growing on the 92 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand soil (Premmanee and Kanchanasthit, 2005). In contrast, arsenic disperses not only physically but also chemically through water due to its dissolution ability. Arsenic is readily dissolved from the common primary sulfide mineral arsenopyrite (FeAsS) when exposed to water and air. For example, at A. Banrai C. Uthai Thani, arsenic regularly disperses in surface/ground water which effectively helps to locate the arsenic sources (Premmanee, 2019).
Distribution
For the purposes of this study a simple classification (Table 2), is assigned to the assays for presentation (Figures 2 and 3). Province names of the highest assays class (Class 1) are listed in Table 3. However, it is important to note e that these locations do not refer to any specific areas of arsenic and cadmium contamination, nor to any risk of exposure, they are simply mean anomalous points. At this stage the data are preliminary; more detailed study and systematic surveys are required over these anomalous points to verify the assay results.
Statistics and Comparisons
Table 2. Assays classification for plots. Arsenic Cadmium Class Range (sediment, soil) Range (water) Range (sediment, soil) Range (water) 1 > 200 (9, 5) > 100 (9) > 6 (10, 2) > 10 (3) 2 100–200 (39, 13) 50–100 (19) 3–6 (80, 12) 5–10 (6) 3 50–100 (120, 31) 25-50 (85) 1–3 (359, 148) 3-5 (12) 4 < 50 (5270, 1365) <25 (4846) < 1 (3989, 1252) <3 (4938) Note: Range refers to interval of assays. Units for sediments and soil are ppm, for water is ppb. Figures in blankets refer to number of samples of corresponding materials.
Table 3. List of provinces where portrayed the highest class (Class 1) of the assays. Elements Materials Povinces Arsenic Stream sediments Ratchaburi, Suphanburi, Lampang, Lamphun, Chiang Mai Soil Ratchaburi, Phrae, Lamphun, Chiang Rai Surface water Ratchaburi, Suphanburi, Uthai Thani Cadmium Stream sediments Suphanburi, Uthai Thani, Lamphun, Phrae Soil Ratchaburi, Phrae Surface water Uthai Thani, Chiang Mai
The statistical analysis of the results for the 10 provinces is shown in Table 4. It appears that the arsenic assays in general have better statistics than the cadmium. More than 50% of arsenic assays exceed the minimum detection limit (DL). The arithmetic means are comparableto the median values, i.e. 11.9 vs 11 ppm, 14.6 vs 11 ppm and 0.0042 vs 0.004 ppm for stream sediment, soil and water respectively. Whereas, cadmium analyses show significant numbers of samples below the DL, i.e., 79% of stream sediment, 66 % of soil and 99% of water. Cadmium contents in stream sediment, soil and water average at 0.36, 0.42 and 0.0015 ppm respectively.
93 Apsorn Sardsud and Jitisak Premmanee, Arsenic and Cadmium: under the DMR Hazardous Elements Project
Figure 2. Distribution of arsenic in (A) stream sediments, (B) surface water and (C) soil.
94 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 3. Distribution of cadmium in (A) stream sediments, (B) surface water and (C) soil.
95 Apsorn Sardsud and Jitisak Premmanee, Arsenic and Cadmium: under the DMR Hazardous Elements Project
In Figure 4 we compare the above findings with other references, includingthe guideline values (GV) of Ministry of Environment Finland, the standards or maximum permissible limit (MPL) of the Pollution Control Department (PCD) Ministry of Natural Resources and Environment Thailand, abundance in Earth’s crust, the British Geological Survey (BGS) mean values and others. We note thatthe averages of the DMR’s assays of arsenic and cadmium correlate well with other reference datasets and that by comparison, we note that the MPL figures of the national guidelines are not comparable and there is some disconformity among those figures.
Table 4. Statistics of arsenic and cadmium content in stream sediments, soil and surface water samples. Arsenic Cadmium Statistics Sediments Soil Water Sediments Soil Water (ppm) (ppm) (ppb) (ppm) (ppm) (ppb) Number of samples 5,438 1,414 4,959 5,438 1,414 5,959 Maximum <5 <5 2 <0.3 <0.3 <3 Minimum 945 374 422 10.6 7.5 29 Average* 11.9 14.6 4.2 0.36 0.42 1.5** Median (or P50) 11 11 4 0.7 0.6 - Standard deviation 30.1 24.8 15.7 1.2 0.8 - Detection limit (DL) 5 5 2 0.3 0.3 3 Number of
Arsenic and cadmium in sediments and soil of the DMR’s averages vary at the same level as the other references, 6.5-14.6 ppm arsenic and 0.4-0.8 ppm cadmium. MEF limits the GVs at 50 ppm arsenic and 10 ppm cadmium. But, the PCD’s MPLs are tabulated at 3.9/27 ppm arsenic and 37/810 ppm cadmium for residential and agriculture / other land areas. Therefore the arsenic values seem too low while cadmium too high. The PCD’s MPLs of arsenic values range at the same level as the averages or even lower, hence, the figures may not practical as MPLs. The MPLs should be set at a value much higher than the averages unless some other important factors are involved. The MEF’s GVs positioned at 5 and 10-20 times for arsenic and cadmium above the averages, i.e. 50 vs 10 ppm arsenic and 10 vs 0.5-0.8 ppm cadmium.
Similarly, DMR’s averages in surface water fall at the same levels with other references, i.e., 4 vs 10 ppb arsenic and 1.5 vs 1 ppb cadmium. These figures are many times less than those MPLs specified by WHO/FAO (10-100 ppb arsenic and 3-10 ppb cadmium) and PCD (10-50 ppb arsenic and 10-25 ppb cadmium). However, it seems that some of these MPLs set at too high levels comparing to the DMR’s averages, for example 1.5 vs 25 ppb cadmium tabulated by PCD.
96 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Notes: This illustration has simplified some numbers for presentation. Sources/explanation are given below: Ppm - part per million or milligram/kg; ppb – part per billion or microgram/liter. MEF (2007): guideline values, Ministry of the Environment Finland (2007) in Toth and others (2016). PCD - resident and PCD-others: maximum permissible limits by PCD (2019a and 2019b); PCD-resident refers to residential and agricultural land areas and PCD-other refers to land areas other than resident and agriculture uses. Soil/sediments-DMR: averaged assays under the DMR hazardous element project (this paper). Soil/sediment-Smed: means quoted by Smedley and Kinniburgh (2002). Soil/Sediment-BGS: mean values by BGS (2000). Earth’s crust: average quoted by Wikipedia (2019). WHO - cons: guideline for drinking water by WHO (2011) and WHO (2019). FAO - agri: maximum concentration in irrigation water by Ayers and Westcot (1985) under FAO webpage. PCD - cons and PCD-natural: maximum permissible limits by PCD (2019a and 2019b); PCD-cons refers to consumable/bottled water and PCD-natural refers to surface and ground water. Water - DMR: averaged assays under the DMR hazardous element project (this paper). Water - Smed: mean quoted by Smedley and Kinniburgh (2002). Water - WHO: average quoted by WHO (2011).
Figure 4 Comparison of DMR averages with other references and guideline values and/or maximum limits.
At this point, some MPL figures for arsenic and cadmium of the Thai regulation may be difficult to use for comparison in environmental studies because they are too high or too low compared to the actual figures. The DMR’s averages are the actual figures and therefore, should be the basis for regulation. It is proposed that MPLs should be set around 5-10 times of the actual figures or the DMR’s averages, i.e., 50-100 ppm arsenic and 2-5 ppm cadmium in soil and sediments; 50- 100 ppb arsenic and 5-10 ppb cadmium in surface water.
97 Apsorn Sardsud and Jitisak Premmanee, Arsenic and Cadmium: under the DMR Hazardous Elements Project
Conclusions
The DMR Hazardous Elements project is a good project for environmental studies. The data have formed a province-wide and then countrywide, geochemical database which is provides a reliable and referenceable baseline dataset for hazardous elements to inform environmental studies and guidelines. DMR is planning to collect stream sediments, soil and water in the remaining provinces to complete national coverage and also to disseminate the information to the public regularly.
The paper proposes on a basis of a large spatial dataset that the practical MPL should be set at 5-10 times of the DMR’s averages for comparison in environmental studies. The health impacts related to these natural hazardous elements need further study, commencing from the MPL values into the food chain and into the human body. We note that there is a high arsenic content in surface water which potentially has more impact on people than in stream sediments/soil while high cadmium content in stream sediments/soil has greater more impact than in surface water.
Acknowledgement
The authors would like to thank DMR officials who provided reports of the DMR Hazardous Elements Project. We also thank everyone involved in this project from the beginning; including many retired and resigned ones who made the data available and CCOP who gave us opportunity to present this paper. References
Ayers and Westcot, 1985. Water quality for agriculture. FAO Irrigation and Drainage Paper, accessed at http://www.fao.org/3/T0234E/T0234E06.htm, on Oct. 5, 2019.
BGS, 2000. Map layer: Cadmium (Cd) in stream sediments and soil. Geochemical Baseline Survey of the Environment (G-BASE), accessed at https://www.bgs.ac.uk/gbase/maps/sediment/ cadmium. html, on Sep. 30, 2019.
DMR, 2007. Risk Areas from Natural Hazardous Elements. Ratchaburi Province, Risk Areas Delineation from Natural Toxic Elements Project, Department of Mineral Resources – Bangkok: Department of Mineral Resources, Ministry of Natural Resources and Environment, 194p.
______, 2008. Risk Areas from Natural Hazardous Elements, Chiang Rai Province. Risk Areas Delineation from Natural Toxic Elements Project, Department of Mineral Resources – Bangkok: Department of Mineral Resources, Ministry of Natural Resources and Environment, 312p.
______, 2009. Risk Areas from Natural Hazardous Elements, Chiang Mai Province. Risk Areas Delineation from Natural Toxic Elements Project, Department of Mineral Resources – Bangkok: Department of Mineral Resources, Ministry of Natural Resources and Environment, 270p.
______, 2010a. Risk Areas from Natural Hazardous Elements, Lampang Province. Risk Areas Delineation from Natural Toxic Elements Project, Department of Mineral Resources – Bangkok: Department of Mineral Resources, Ministry of Natural Resources and Environment, 124p.
______, 2010b., Risk Areas from Natural Hazardous Elements, Lamphun Province. Risk Areas Delineation from Natural Toxic Elements Project, Department of Mineral Resources – Bangkok: Department of Mineral Resources, Ministry of Natural Resources and Environment, 112p.
______, 2011. Risk Areas from Natural Hazardous Elements, Phrae Province. Risk Areas Delineation from Natural Toxic Elements Project, Department of Mineral Resources – Bangkok: Department of Mineral Resources, Ministry of Natural Resources and Environment, 120p. 98 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
______, 2012. Risk Areas from Natural Hazardous Elements, Uthai Thani Province. Risk Areas Delineation from Natural Toxic Elements Project, Department of Mineral Resources – Bangkok: Department of Mineral Resources, Ministry of Natural Resources and Environment, 202 Pages.
______, 2013. Risk Areas from Natural Hazardous Elements, Suphanburi Province. Risk Areas Delineation from Natural Toxic Elements Project, Department of Mineral Resources – Bangkok: Department of Mineral Resources, Ministry of Natural Resources and Environment, 174p.
______, 2014. Risk Areas from Natural Hazardous Elements, Phitsanulok Province. Risk Areas Delineation from Natural Toxic Elements Project, Department of Mineral Resources – Bangkok: Department of Mineral Resources, Ministry of Natural Resources and Environment, 223p.
______, 2015. Risk Areas from Natural Hazardous Elements, Phetchabun Province. Risk Areas Delineation from Natural Toxic Elements Project, Department of Mineral Resources – Bangkok: Department of Mineral Resources, Ministry of Natural Resources and Environment, 208p.
PCD, 2019a: Soil standard or maximum acceptable/allowable concentration, Pollution Control Department, Ministry of Natural Resources and Environment, accessed at http://www.pcd.go.th/info_serv/ reg_std _soil.html on Oct. 1, 2019.
______, 2019b. Water Standard or maximum acceptable/allowable concentration. Pollution Control Department, Ministry of Natural Resources and Environment, accessed at http://www.pcd.go.th/ info_ serv/ reg_ std_water.html on Oct. 1, 2019.
Premmanee, J., and Kanchanasthit, S., 2005. Mae Tao cadmium: natural or human activities. Department of Mineral Resources Meeting of 2005, 17-18 September 2005, Bangkok, p. 247-249 (in Thai).
Premmanee, J., 2019. Study on possible sources of arsenic distribution in Uthai Thani province. Department of Mineral Resources, Bangkok, 79p, (in Thai).
Smedley, P.L., and Kinniburgh, D.G., 2002, A review of the source, behavior and distribution of arsenic in natural water. Applied Geochemistry 17 (2002), p. 517-568.
Toth, G., Hermann, T., Da Silva, M.R., and Montanarella, L., 2016. Heavy metals in agricultural soil of the European Union with implications for food safety, Environment International 88 (2016), page 299-309, accessed at https://www.sciencedirect.com/science/article/pii/ S0160412015301203 , on Oct. 1, 2019.
WHO, 2011. Cadmium in drinking-water background document for development of WHO guidelines for drinking-water quality, access at https://www.who.int/water_sanitation_health/ dwq/chemicals/ cadmium.pdf on July 30, 2019.
WHO, 2019. Arsenic fact sheet. accessed at https://www.who.int/news-room/fact-sheets/detail/arsenic, on July 30, 2019.
Wikipedia, 2019. Abundance of elements in Earth’s crust, accessed at https://en.wikipedia.org/wiki/ Abundance_of_elements_in_Earth%27s_crust, on June 12, 2019.
99 100 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Managed aquifer recharge to ensure sustainable groundwater availability and quality under ongoing climate change and rapid economic development in Vietnam (Viet MAR)
Nguyen Thi Ha1,*, Jaana Jarva3, Kristiina Nuottimäki3, Pham Thanh Long2, Dang Tran Trung1, Hoang Van Duy1, Nguyen Thi Hong1, and Nguyen Kim Hung1
1Center for Water Resources Warning and Forecast (CEWAFO), Hanoi, Vietnam; 2Sub-Institute of Hydrometeorology and Climate Change (SIHYMECC), Ho Chi Minh City, Vietnam; 3Geological Survey of Finland (GTK), Espoo, Finland.
*E-mail: [email protected]
Abstract
Viet MAR is a co-operation project financed by the Ministry for Foreign Affairs of Finland between CEWAFO, SIHYMECC and GTK. It aims to secure the future management of fresh water resources in Vietnam with sustainable and environmentally friendly solutions, such as Managed Aquifer Recharge (MAR). The project involves capacity building and knowledge transfer to local experts and stakeholders in the geological and technical requirements for feasible MAR solutions and to implement a full-scale MAR. It targets to raise awareness and improve understanding of the MAR approach as a sustainable water management option relevant to the Vietnamese hydrogeological and climatic conditions.
The project case study is located at the Phuong Mai peninsula, in Quy Nhon in the Binh Dinh province in South Central Coast region of Vietnam where the estimated water demand is forecast to double by 2040. The area is located in the tropics with two distinct seasons: a dry season from January to August and a rainy season from September to December. During the long dry season, local inhabitants have encountered a lack of freshwater in the area accentuated by an increasing water demand from industry and tourism. In the context of climate change, it is forecast that dry seasons will be further prolonged and more extreme rain events may occur during the rainy seasons. Thus, the purpose of the Viet MAR project is to study whether the implementation of MAR could inform future water demand for the Phuong Mai peninsula, especially during the long dry season.
An investigation and evaluation of the freshwater resource indicates that the hydrogeology of the area is favourable for MAR. The preliminary results of water sample analyses indicate that the groundwater quality met almost all national criteria set for the potable groundwater. The total volume of aquifer reservoirs is estimated to be high and can most likely be exploited in a sustainable manner.
The preliminary studies suggest that a number of feasible solutions may be conducted to increase groundwater volume via artificial methods. These include: 1) the construction of an infiltration basin to increase and control the aquifer recharge. Both rainwater and surface water are sufficient to be used as raw water; and 2) to build up water storage facilities or dykes for the rainwater and aquifer discharge points in order to prevent freshwater runoffs to the Thi Nai lagoon and the sea. The studies of the Phuong Mai peninsula aquifer will continue by numerical modelling under different climate change scenarios to assess the long-term quantity and quality of groundwater. Other MAR methods, related technical solutions, socio-economic analyses and their impact on groundwater quality and quantity will also be assessed. In addition,
Keywords: Phuong Mai peninsula; infiltration basin; groundwater, water quality; Managed Aquifer Recharge (MAR); climate change. 101 Nguyen Thi Ha, et. al., Managed aquifer recharge to ensure sustainable groundwater availability and quality under ongoing climate change and rapid economic development in Vietnam (Viet MAR)
1. Introduction
The need to mitigate the risks associated with water resources in Vietnam is been highlighted in the Vietnamese National Strategy on Climate Change (2011) noting that concrete actions to ensure availability and good quality of groundwater resource are urgently needed in Vietnam. In addition to adverse climate change impacts, groundwater resources are at risk specifically on coastal areas in Vietnam, due to the expected intensification of groundwater consumption and changes in land use and economic patterns in the next decades.
One solution is to implement Managed Aquifer Recharge (MAR) as an option to increase groundwater quantity and quality in aquifers facing overexploitation, climate change impacts or vulnerability to pollution in a cost-effective and environmentally friendly manner. In brief, MAR represents a set of hydrogeological methods that contribute to boosting the amount of water that naturally enters a groundwater reservoir by recharge using artificial means. An effective MAR application requires a thorough understanding of various geological fields including hydrogeology, sedimentology, geochemistry and geophysics. It also needs background information and knowledge of environmental and meteorological aspects. In addition, the successful implementation of MAR requires detailed analysis of its potential environmental risks and socio- economic impacts.
In order to assess if and how MAR can be used to safeguard groundwater use under changing climatic and socio-economic conditions in Vietnam, a project “Managed aquifer recharge to ensure sustainable groundwater availability and quality under ongoing climate change and fast economic development in Vietnam (Viet MAR)” commenced in 2018.
The case study area of the Viet MAR project is located at the Phuong Mai peninsula, in Quy Nhon in the Binh Dinh province in South Central Coast region of Vietnam (Figure 1). The area is located in tropics, having two distinct seasons: a dry season from January to August and a rainy season from September to December with a total annual average rainfall of 1,970 mm during the period of 1990 to 2016. During the long dry seasons, local inhabitants have encountered lack of fresh water in the area exacerbated by a rising water demand for industry and tourism. In the context of climate change, it is forecasted that dry seasons will become further prolonged and more frequent extreme rain events may occur during the rainy seasons. Thus, the purpose of the Viet MAR project is to study whether the implementation of MAR could respond to future water demand for the Phuong Mai peninsula, especially during the long dry season.
In the Phuong Mai peninsula, Quaternary sand aquifer (qh) covers almost the whole peninsula, with thickness from 10 to 60 meters (average thickness 30-40 m). Over 60 km2 of the aquifer is exposed to the surface. Below Quaternary aquifer is a bed rock layer (Figure 2).
2. Methodology
2.1. Field survey methods
Spring flow measurement
There are a number of natural springs on the foothill of the peninsula that discharge to the lagoon. The amount of water discharge from aquifer to springs was measured by using a Thomson weir (Figure 3).
102 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 1. The location of the Phuong Mai peninsula case study area. Measurements of the volume of an artificial pond
In order to evaluate the possibility of using an artificial pond located in the peninsula as a surface water reservoir for MAR was calculated volume of the pond was calculated by making several profiles with water depth measurements (Figure 4). Besides the water depth analysis, water quality measurements (temperature, pH, EC and DO) were made and bottom sediment samples were collected for further study.
Water sampling
Water was sampled and analyzed from a number of observation wells, one private well, a spring and the artificial pond. The analyzed parameters included major elements, heavy metals, some organic compounds and coliform bacteria. The locations of the sampling points are shown in Figure 5.
2.2. The estimation of the static reserve of an aquifer Static groundwater reserve of an aquifer (or aquifer volume) is the amount of water that is existing and is drainable and is calculated with following formula [1]: V = A * h * ŋ [1]
In which: V (m3): total volume of an aquifer A (m2): the area of an aquifer h (m): the saturated thickness of an aquifer ŋ: specific yield
103 Nguyen Thi Ha, et. al., Managed aquifer recharge to ensure sustainable groundwater availability and quality under ongoing climate change and rapid economic development in Vietnam (Viet MAR)
A.
B.
Figure 2. Hydrogeological map (a) and Cross section (b) of the Phuong Mai peninsula. Figure (a) shows the area of the Quaternary aquifer (qh) and location of the observation wells. In addition, the estimated boundary of saline intrusion is shown with red line. In figure (b), the Quaternary sand aquifer (qh) is shown in blue brown color indicates clay lenses, green color shows the underlain bedrock. Groundwater level is shown with blue dash line. 104 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Figure 3. Measuring spring discharge with Thomson weir.
Figure 4. The pond profiles and depth measurement points
Figure 5. The location of the water sampling points in the Phuong Mai peninsula. 105 Nguyen Thi Ha, et. al., Managed aquifer recharge to ensure sustainable groundwater availability and quality under ongoing climate change and rapid economic development in Vietnam (Viet MAR)
2.3 The estimation of groundwater recharge
Groundwater recharge from precipitation is calculated with two different methods: the empirical method and the water-table fluctuation (WTF) method.
Evaluation of groundwater recharge with empirical method
The composition of the Holocene aquifer is mainly coarse-grained to medium sand. Based on empirical studies carried out in Vietnam, infiltration from rainfall of the total annual rainfall to aquifer during the rainy season is about 15% and during the dry season about 9%.
Evaluation of groundwater recharge with water-table fluctuation (WTF) method
Based on the groundwater level monitoring data, the groundwater recharge is calculated with water-table fluctuation method that takes into account effective porosity and hydraulic conductivity of the unsaturated zone and can be used to calculate the vertical seepage of rainwater through an unsaturated zone. The method was used to estimate the total volume of infiltration of annual rainfall. Based on monitoring data with the principle if there was no precipitation in dry or rainy season, groundwater level would continuously decline. The change in the peak of the rise and low point of the extrapolated antecedent recession curve at the time of the peak (∆H+∆Z) can be calculated, the volume of annual groundwater recharge (W) from rainfall to aquifer can be determined as shown in formula [2] and Figure 6.
W=µ((∆H+∆Z))/∆t [2]
Figure 6. The graph of the water-table fluctuation method showing how the change in groundwater level maximum and minimum affects groundwater recharge (Healy and Cook, 2002).
In which: µ: specific yield N, O: highest water level value each year M = P: lowest water level value Δt: period between the highest and lowest water level ∆H: change in values from the lowest water level of the previous year to the highest water level of the following year (m) ∆Z: difference between the bottom of the decline and low point of the extrapolated antecedent recession curve (dashed line M-Q) at the time of the peak (m)
From annual groundwater recharge (W) determined with formula [2], total volume of ground water recharge (Q) can be calculated with formula [3].
Q = A*W [3] In which: W: annual ground water recharge (m/day) Q: total volume of groundwater recharge (m3/day) A: the area of aquifer (m2)
106 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
3. Results and Discussion
3.1. Groundwater resources
Groundwater reserves The static reserve of the aquifer are calculated with formula [1]. Based on data from borehole logs and the results of the pumping tests, aquifer can be divided into different thickness units from which static water reserves can be calculated. In the Phuong Mai peninsula, the estimations of the aquifer thickness are based on limited number of observation well log data and the specific yield used in calculations is based on the results of pumping tests conducted in well BD17. Using these data the preliminary estimations of the static reserve of the aquifer (Table 1)
Table 1. Preliminary estimations of static reserve of the aquifer Average specific Thickness # Area (km2) yield Static reserves (m3) (average) (m) (Giang, 2018) 1 0 – 10 (5) 5.37 0.11 2,953,000 2 10 – 20 (15) 6.05 0.11 9,982,500 3 20 – 30 (25) 8.22 0.11 22,605,000 4 30 – 40 (35) 15.32 0.11 58,982,000 5 40 – 50 (45) 13.61 0.11 67,369,500 6 50 – 60 (55) 14.22 0.11 86,031,000 Total 62.79 247,923,500
According to the field survey results, the total groundwater discharge rate equals the total spring flow to the sea. Based on the Thomson weir measurements, the discharge flow from the springs is 35,488 m3/day. The informed exploitation rate of the springs is 4,989 m3/day. If we assume that the discharge and exploitation rate of springs is equal to total aquifer recharge, then the total recharge would be approximately 40,477 m3/day.
On the other hand, based on simple calculation that only takes into account the annual rainfall and infiltration rate, the total aquifer recharge would be 50,576 3m /day.
The recharge rate of the aquifer from precipitation has been calculated using the water-table fluctuation method for each observation wells separately.
Figure 7. Groundwater level at monitoring wells BD2 and BD26.
107 Nguyen Thi Ha, et. al., Managed aquifer recharge to ensure sustainable groundwater availability and quality under ongoing climate change and rapid economic development in Vietnam (Viet MAR)
Table 2. Result of aquifer recharge rate Well H + Z 2t µ W (mm/day) BD2 7.38 214 0.11 3.79 BD17 6 123 0.11 5.37 BD26 3.27 365 0.11 0.99 Average 3.38
Based on the water-table fluctuation method, the total recharge of the aquifer is 212,230 3m /day.
The permitted rate of groundwater exploitation was estimated based on the calculated groundwater recharge rates. According to the Vietnamese regulations, groundwater exploitation rate can be 50% of the static aquifer reserve in 10,000 days (about 27 years). In summary, based on previous annual aquifer recharge calculations the exploitation rate can be about 52,000 m3/day (water balance), 62,000 m3/day (empirical) or 220,000 m3/day (water-table fluctuation). However, in this calculation, the sustainability of the exploitation rate compared to groundwater recharge and the negative impacts of saline intrusion or changes in groundwater dependent ecosystems are not considered.
Groundwater quality
According to the analysis results of water samples taken in November 2018, (Table 3) the majority of the analyzed elements and compounds met the limit values set in the national technical regulations on groundwater quality in Vietnam. However, in some sampling points and wells, the iron and manganese content and nickel and cadmium concentrations were higher than the national limit value.
3.2. Surface water resources
According to the field survey’s results (Figure 8), surface area of the artificial pond is 0.39 2km , with maximum water depth of 3.2 m and average water depth of 2.1m. The volume of the lake is thus about 800,000 m3.
Figure 8. The profile BT5-BP3 and E1-E0 within the artificial pond showing their estimated water depth. The location of the profiles is shown in figure 4.
108 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Table 3. Analysis results of water quality. The concentrations that exceed the Technical regulations on groundwater quality (QCVN 09-MT:BTNMT) are marked with red. Point Total concentration, non-filtered samples (mg/l) National limit value Fe3+ Fe2+ Al Mn National limit value 5 (total Fe) 5 (total Fe) 0.5 Spring 7.2 0.16 0.55 BD18 0.73 0.41 0.00112 0.02 BD17 0.69 0.4 0.00582 0.0446 BD26 3.64 3.24 0.0236 0.0708 BD2 0.66 0.39 <0.001 1.89 BD9 0.06 0.00224 Private well <0.001 0.00393 Pond 0.0176 0.0141 Dissolved concentration, filtered samples (µg/l) Element As Cd Cr6+ Cu Hg Mn Pb Zn Ni Al CN- National limit 50 5 50 1000 1 500 10 3000 20 200 10 value BD26 0.27 0.51 2.55 3.77 0.03 126 0.77 0.56 10.6 <1 0.02 BD18 0.25 0.52 9.78 4.05 0.03 6.47 0.82 1.53 2.25 11.9 0.01 BD9 0.24 0.53 2.55 20.2 0.02 9.51 0.84 18.2 52.4 40.6 0.025 BD17 0.28 18.4 0.15 12.2 0.02 46.2 9.85 19.1 35.7 30.3 0.01 BD2 0.28 0.51 <0.1 3.82 0.02 2210 0.82 31.3 19 1.71 0.01 Spring 0.15 0.38 <0.1 <1 0.02 443 0.75 2.89 2.25 <1 0.01 Private Well 0.19 0.42 0.15 <1 0.03 3.08 0.79 5.12 2.14 <1 Pond 0.21 0.69 1.35 <1 0.02 35.1 0.75 3.94 2.3 20.9 0.01
4. Conclusion
According to Decision No. 514/2019/QĐ-TTg approved by the Prime Minister of Vietnam (May 08, 2019), the estimated water demand for the Nhon Hoi economic zone that is located in the Phuong Mai peninsula is forecast to be 72,000 m3/day by 2030 increasing to 120,000 m3/day in 2040. Under the current conditions (rainfall, evaporation), and comparing the water demand to groundwater recharge rates calculated with different methods, the water shortage is estimated to be 11,000-31,000 m3/day by 2030 and 60,000-80,000 m3/day by 2040. Thus, as the current natural groundwater recharge does not meet the water demand in the area then our research indicates that measures for sustainable water management are urgently required. Based on laboratory analysis, water quality in general meets the technical regulations on groundwater quality, except for Fe, Mn, Ni and Cd in some sampling points. More detailed studies on water quality are still needed and a regular monitoring is proposed to create a time series dataset. The origin of elements exceeding the limit values should also be investigated.
The project also notes that from preliminary studies at least two feasible solutions may be used to increase groundwater volume via artificial methods. Firstly, the construction of an infiltration basin to increase and control the aquifer recharge and utilising both rain water and surface water as sources of raw water, Secondly, we could consider construction of water storage facilities or dikes to capture rain water and aquifer discharge points in order to prevent fresh water runoff into the Thi Nai lagoon and the sea. 109 Nguyen Thi Ha, et. al., Managed aquifer recharge to ensure sustainable groundwater availability and quality under ongoing climate change and rapid economic development in Vietnam (Viet MAR)
The studies of the Phuong Mai peninsula aquifer will continue by numerical modeling using different climate change scenarios to assess the long term quantity and quality of groundwater. Different MAR methods, related technical solutions, socio-economic analyses and their impact on groundwater quality and quantity will be further assessed.
References
Anderson, M.P., Woessner, W.W., and Hunt, R.J., 2015. Applied Groundwater Modeling. 2nd ed., Academic Press.
Đặng Hữu Ơn. 2003. Tính toán Địa chất thủy văn. (Hydrological calculation). Hanoi. Decision No. 514/2019/QĐ-TTg approved by the Prime Minister, published on 8 May 2019 about water demand allocation for the Nhon Hoi economic zone.
Đoàn Văn Cánh, 2015. Nghiên cứu đề xuất các tiêu chí phân vùng khai thác bền vững, bảo vệ tài nguyên nước dưới đất vùng đồng bằng Bắc Bộ và đồng bằng Nam Bộ. (Study and proposed criteria for the zoning of sustainable exploitation and protection of groundwater resources in the northern and southern delta).
Report of the project KC08.06/11-15. Department of the Science and Technology.
Fetter, C.W., 2001. Applied hydrogeology. 4th ed., Prentice Hall.
Healy, R.W., and Cook, P.G., 2002. Using groundwater levels to estimate recharge, Hydrogeology Journal, 10, 91-109.
Nguyễn Văn Giang, 2018. Đề án bảo vệ nước dưới đất các đô thị lớn giai đoạn 1, đô thị Quy Nhơn. (Scheme of underground water protection in big cities, phase 1, Quy Nhon city). Center for Water Quality and Protection.
Vietnamese National Strategy on Climate Change. 2011.
110 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Potential Hazard from the M8.7 Sunda Strait Megathrust Earthquake: a Deterministic Approach
Amalfi Omang, Akhmad Solikhin*, Athanasius Cipta and Supartoyo
Centre for Volcanology and Geological Hazard Mitigation (CVGHM), Geological Agency, Ministry of Energy and Mineral Resources, Indonesia.
*Corresponding author / presenter E-mail: [email protected]
Abstract
The Sunda Strait Megathrust (SSM) segment, part of the Sunda Megathrust, stores potential earthquakes with a maximum magnitude of M8.7. A deterministic seismic hazard modelling is undertaken in order to analyse the earthquake hazard originating from SSM, as well as studying the contribution of local geological conditions to earthquake ground motion in the area around the Sunda Strait. Based on modelling, when an M8.7 earthquake from SSM occurs, the shock will be felt widely and maximum ground motion will strike the southwestern region of Banten and West Java. Surface geological conditions can significantly amplify earthquake ground motion, where its amplification value is also depend on its distance to the source and basin geometry. In locations that are relatively close to earthquake sources and the soil condition is softer, the acceleration value is higher in the 0.2 to 0.3 second periods. At locations that relatively far from the source of the earthquake and standing on a deep basin, a higher acceleration occurs in periods greater than 0.5 second.
Key words: Megathrust, Sunda Strait, Vs30, deterministic earthquake hazard analysis, OpenQuake, amplification.
1. Introduction
The most seismically active regions on earth occur in the subduction zone or convergence zone between the Earth’s tectonic plates, where one plate moves under another plate, is the most seismically active region. The contact surface between the subducting plate and the overriding plate to a certain depth (~ 50 km) is known as a megathrust or a large dimension of reverse fault. The western region of Indonesia includes the Sunda Megathrust system, which is the convergence zone between the Indo-Australian Plate and the Eurasian Plate. The Sunda Megathrust extends along 5,500 km from the Andaman Sea to the south, curved around the western and southern sides of Sumatra, Java, Bali, and Nusa Tenggara to northwest Australia. Irsyam et al. (2017) divides the Sunda Megathrust zone in the Indonesian region into 10 segments, and one of them is the Sunda Strait Segment. The Sunda Strait Megathrust segment (Figure 1), hereinafter referred to as SSM, is located in the transition zone between two different subduction modes, namely oblique Sumatran Subduction and frontal Java Subduction (Huchon & Le Pichon, 1984; Deplus, 1987).
111 Amalfi Omang, et. al., Potential Hazard from the M8.7 Sunda Strait Megathrust Earthquake: a Deterministic Approach
Figure 1. Map of the study area covering the southern tip of Sumatra Island, the Sunda Strait area, and the western part of Java Island, also shows the distribution of the average velocity of shear waves on the 30 m topmost soil (Vs30). The pink striped box indicates the Sunda Strait Megathrust (SSM) zone.
Many large earthquakes are generated from megathrust movement, which can be destructive and sometimes trigger tsunamis that lead to increasing damage levels. The 2004 Sumatra earthquake was the classic example of interplate earthquake triggering tsunami that devastated north Sumatra and other countries facing the Indian Ocean. This earthquake was produce by the Aceh-Andaman segment of the Sunda Megathrust. The SSM segment also has the potential to generate large earthquakes threatening the Sunda Strait region, the western part of Java and the southern tip of Sumatra Island (Figure 1). The SSM segment is inferred to be the source of two destructive earthquakes that affected the Jakarta area, occurring on January 5, 1699 (Nguyen et al., 2015) and January 9, 1852 (Soloviev & Go, 1974). Geodetic study by Hanifa et al. (2014) interpreted that the subduction zone in south of Ujung Kulon - Pelabuhan Ratu is currently building pressure and could potentially trigger an earthquake with a magnitude of about Mw 8.7 when released at once. Earthquake mitigation efforts initiated by figuring the potential seismic source out, as well as understanding its hazard and risk. The urban planner subsequently plays a role to incorporate hazard and risk parameters to implement a risk-based planning. Thereafter, civil engineers work with government to ensure every structure is built with concern to seismic risk. This paper presents deterministic earthquake modelling techniques with SSM as its source, analyses the hazard, and discusses the contribution of local geological factors to the ground motion in the study area (southern Sumatra, the Sunda Strait, and western Java).
112 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand
Implication of Local Geology to Earthquake Ground Motion
Local geological conditions can greatly influence the characteristics of seismic waves, which in turn can magnify ground motion and increase the potential for seismic hazards. Local geological conditions are simply divided into two categories: surface geological conditions represented by the value of the average shear-wave velocity on rocks to a depth of 30 m, is called Vs30 (Figure 1), and the total thickness of sediments above the bedrock or also called the depth of basins (Figure 2). Surface geological conditions greatly affect high-frequency seismic waves (short periods) while the depth of the basin greatly influences low-frequency seismic waves (long periods).
Seismic waves during an earthquake can be amplified when they propagate through unconsolidated surface sediments (soil, weathered rock, alluvium), collectively called regolith. Therefore, the regolith aspect must be included in the estimation of ground motion in earthquake hazard analysis (Robinson et al., 2006). The theory of elastic wave propagation explains that the amplitude of ground motion on the surface is influenced by the density and velocity of shear waves from the media near the surface (i.e. Aki & Richards, 1980). As soil density depends on depth, accordingly seismic wave amplification is determined from shear wave velocity near the surface or represented by the value Vs30.
There are various methods in determining Vs30, both by geophysical and geotechnical measurements as well as by an empirical approach such as those conducted by Matsuoka et al. (2006), Wald & Allen (2007), and Allen & Wald (2008). Both Wald & Allen (2007) and Allen & Wald (2008) use slope-topography as a proxy for Vs30 estimation. On the other hand, the geomorphological approach to estimating Vs30 by Matsuoka et al. (2006) based on geological information (rock type and age, as well as depth of sediment) and topography (altitude and slope). The geological and topographic information is processed to produce geomorphological classes, which will be used as a proxy for empirical calculations of Vs30. Our Vs30 map (Figure 1) generated using the method of Matsuoka et al. (2006). Based on Vs30 map, our study area is dominated by soil class E (soft soil; Vs30 ≤ 180 m/s) and class D (stiff soil; 180 m/s Amplification caused by the accumulation of sediment above the bedrock is called basin resonance. Paleo-topography of the bedrock causes the total thickness of sediment accumulated above the bedrock to be very different from one location to another. Sediment thickness or depth of the basin acts as a filter that will pass on and amplify seismic waves with a certain frequency. Based on map of basin depths that generated from Vs30 conversion, soil thickness in study area are vary from 11 m to 650 m (Figure 2). Shallow basins (less than 50 m deep) are generally located in hilly and mountainous areas, while basins with depths of more than 450 m are located in the flat terrain formed by young sedimentary rocks. Deeper basins will amplify longer seismic waves, which in turn greatly affects the buildings on these locations. On the other hand, certain basin geometries can trap seismic waves, therefore the duration of ground motion in the basin is much longer (Cipta et al., 2018). Amplification and duration of ground motion can exacerbate the impact on buildings on the surface. 113 Amalfi Omang, et. al., Potential Hazard from the M8.7 Sunda Strait Megathrust Earthquake: a Deterministic Approach Figure 2. The map of total sediment thickness (basin depth) in the study area, which is represented by the depth when the S-wave propagation velocity of the rocks reaches 1000 m/s (Z1.0). Deterministic Seismic Hazard Modelling Deterministic seismic hazard modelling was carried out to estimate earthquake ground motion in an area covering the provinces of Banten, DKI Jakarta, West Java, most of Lampung, and a small portion of Bengkulu and South Sumatra. OpenQuake Engine, an open-source software developed by the Global Earthquake Model (GEM) Foundation, is used to model the seismic hazards. This software is available in public repository www.github.com/gem, where the software code development takes place. Earthquake param used in this modelling refer to the 2017 Indonesian Earthquake Source and Hazard Map (Irsyam et al., 2017) and Slab2 (Hayes et al., 2018). In this modelling, the epicentre of the SSM earthquake is at coordinates 105.079° E and 6.292° S, at a depth of 50 km, with a magnitude of M8.7. Geometry from SSM earthquake source (SSM) based on Slab2 (Hayes et al., 2018) combined with data from Irsyam et al. (2017). The value of Vs30 that was estimated by using the method of Matsuoka et al. (2006) was selected for regolith input on our earthquake modelling due to its higher accuracy compared to the slope-topography approach (Cipta et al., 2016). Calculation of earthquake ground motion uses three attenuation equations for megathrust, namely: Abrahamson et al. (2016), Zhao et al. (2006), and Atkinson & Boore (2003). Seismic hazard originating from SSM was modelled on bedrock and surface soil resulting in peak ground acceleration (PGA) value or ground motion experienced by soil particles. Besides PGA, modelling also produces spectral acceleration values in periods of 0.2 seconds (SA0.2), 0.5 seconds (SA0.5) and one second (SA1.0). Put simply, the acceleration spectra of SA0.2, SA0.5 and SA1.0 illustrate the acceleration of earthquake ground motion that may mainly affected by two-, five- and ten-storey buildings, respectively. 114 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Result and Discussion The intensity of earthquake ground motion in an area depends on the param of the earthquake source and the location where the ground motion is measured, as well as the distance between the source and the observation site. Seismic hazard modelling on bedrock only take into account homogeneous local geological condition or use a fixed value of Vs30 (in Class B). Therefore, since param of the source and the observation location are fixed, the intensity of ground motion is only affected by the distance from the source to the observation site. Modelling on bedrock (Figure 3) shows that the highest ground motion are in the area nearest earthquake source or in the southwest of the Sunda Strait. Whereas for areas located farther from earthquake source to the northeast, the intensity of ground motion decreases with increasing distance. The concentric colour pattern with the centre in the SSM segment shows clearly that distance is the only factor affecting the decay of the acceleration value (Figure 3). The highest PGA value (0.65 g) will be suffered in the Ujung Kulon area (Figure 3A) and then decreases with increasing distance. Likewise, the spectral acceleration of SA0.2, SA0.5 and SA1.0, the farther away from the source, the smaller the ground motion that might be received. The maximum ground motion for SA0.2, SA0.5 and SA1.0 are 1.41 g, 0.92 g and 0.52 g, respectively (Figs. 3B-D). Modelling on surface soil takes into account the heterogeneity of local geological conditions into the calculation of ground motion, which in this paper are represented by earthquake acceleration. Figure 4 shows a map of the results of earthquake modelling on surface soil. In general, distance (from source to site) remain plays an important role in the pattern of PGA distribution as shown by concentric lines with the centre at earthquake sources. Modelling results show that when an earthquake in accordance with the model scenario occurs, the southwest region of Banten and West Java will suffer ground motion (PGA) up to 0.74 g or potentially be shaken with intensity of up to IX MMI (Modified Mercalli Intensity). Earthquake ground motion also potentially to be felt in the Central Java region, but with a lower intensity ( Figure 3. The results of seismic hazard modelling on bedrock from SSM earthquake, showing the map of PGA (A), as well as the spectral acceleration of SA0.2 (B), SA0.5 (C) and SA1.0 (D). 115 Amalfi Omang, et. al., Potential Hazard from the M8.7 Sunda Strait Megathrust Earthquake: a Deterministic Approach To quantify the contribution of local geological conditions to earthquake ground motion, we compared the acceleration of seismic waves in surface soil to the acceleration in bedrock. The ratio of the acceleration or contribution of local geology is often referred to as the amplification factor or amplification only. The modelling result in Figure 4A shows the contribution of local geology in amplifying earthquake ground motion. The maximum PGA on soil in the nearest area to the source is 0.74 g (compared to 0.65 g in bedrock) or 0.09 g larger (an increase of almost 14%) when compared to PGA in bedrock. Significant difference between the ground motion in Bukit Barisan area (hills) and Kotaagung City (sedimentary basin) in Lampung Province, showing the effect of local geological conditions. At almost the same distance from earthquake source, PGA amplification in Bukit Barisan is about 3% while in Kota Agung is 9%. Similarly, the east coast of Lampung, which was composed by swamp deposits, is potentially affected by an 8% PGA amplification (Figure 4A). It can be simply concluded that areas with lower Vs30, e.g. areas with Vs30 less than 180 m/s in Figure 1, have larger ground motion and amplification factors (Figure 5) when compared to modelling results in bedrock. Models SA0.2, SA0.5 and SA1.0 on surface soil generate maximum acceleration of 1.75 g, 1.83 g and 1.36 g, respectively. The maximum acceleration are not only generated in the nearest area to the source, such as the west coast of Lampung and the south coast of Banten, but also in relatively distal areas, such as Kota Agung, the northern and northeastern parts of G. Rajabasa in Lampung, Labuan in west coast of Banten, and the north coast of Banten. All areas with the potential to receive severe shaking are geologically composed by alluvium. Several areas such as in Kota Agung and in the north coast of Banten and West Java are tectonic basins filled with thick sediment deposits. Those area, despite the distance is more than 200 km from earthquake source, remain receive very strong ground motion especially at SA1.0 (Figure 4D). Figure 4. The results of seismic hazard modelling on soil from SSM earthquake, showing the map of PGA (A), as well as the spectral acceleration of SA0.2 (B), SA0.5 (C) and SA1.0 (D). The table shows the relationship between peak ground acceleration (PGA) value with ground motion intensity (in MMI), perceived shaking and potential damage. 116 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Figure 5. Amplification factors for PGA (A), SA0.2 (B), SA0.5 (C), and SA1.0 (D). Amplification factor is defined as the ratio between acceleration in surface soil and acceleration in bedrock. The amplification factor map (Figure 5) shows more clearly the contribution of local geological conditions to earthquake ground motion on surface soil. Vs30 value that represents the physical properties of rocks near the surface has a significant effect on the spectral acceleration SA0.2, so it is not surprising that the amplification pattern in SA0.2 (Figure 5B) resembles the Vs30 pattern in Figure 1. Meanwhile, since SA1.0 is strongly affected by bedrock depth or basin geometry, the SA1.0 amplification pattern (Figure 5C) resemble the bedrock depth pattern in Figure 2. Furthermore, we look in more detail at the seven locations, namely Ujungkulon, Bandar Lampung, Sukabumi, Jakarta, Bandung, Pangandaran and Cirebon (locations in Figure 2). On bedrock, the spectra model reaches its peak at SA0.2 - SA0.3, and afterwards decays rapidly at higher periods (Figure 6). When the surface geological conditions (represented by Vs30) and basin geometry (represented by Z1.0) are taken into account, the spectral model changes very drastically. Only in Ujungkulon and Bandar Lampung the pattern of the spectra model on the surface soil resembles the spectra model in the bedrock, although of course the acceleration in the soil is higher than the acceleration in the bedrock. A similar pattern of spectra models in Bandar Lampung City is very likely due to homogeneous Vs30 (Figure 1) and thin Z1.0 (Figure 2). In that case, seismic waves in the short period (0.2 - 0.3 s) were highly amplified while the long period seismic waves slightly amplified due to the absence of thick sediment deposits. Meanwhile in Ujung Kulon, the acceleration in the short period (0.2 - 0.3 seconds) is very high due to the short distance between the site and the source so that only short waves reach this location while long period waves have not yet formed. The curve of the acceleration spectra model on soil in Bandung reaches its peak at SA0.2 then decays slowly at a longer period. This indicates that both Vs30 and Z1.0 have a significant impact. Very interesting results are shown on the curve of the acceleration spectra in Sukabumi, Jakarta, Pangandaran and Cirebon Cities. The spectral acceleration curves in these cities reach its peak in 117 Amalfi Omang, et. al., Potential Hazard from the M8.7 Sunda Strait Megathrust Earthquake: a Deterministic Approach the 0.5-second period and afterwards the curves tend to be flat. The high acceleration value at a period of longer than 0.5 seconds in areas relatively distant to earthquake source indicates the high impact of Z1.0. In other words, it indicates how thick the sediment accumulated under the cities. Thick sediments that accumulate beneath these cities amplify seismic waves in a longer period. Therefore, even though the location of these cities towards the SSM is farther than Bandung (except Sukabumi), it is potentially receive a stronger ground motion at SA0.7 or more. Figure 6. Spectral acceleration curves for seven cities (Ujung Kulon, Bandar Lampung, Sukabumi, Jakarta, Bandung, Pangandaran and Cirebon) based on modelling on bedrock (solid line) and soil (dot line). Conclusion Ground motion due to an SSM earthquake with magnitude M8.7 scenario will have large maximum values, i.e. in PGA, SA0.2, SA0.5, and SA1.0 are respectively 0.65 g, 1.41 g, 0, 92 g, and 0.52 g for modelling on bedrock, and 0.74 g, 1.75 g, 1.83 g and 1.36 g for modelling on soil. If an earthquake event occurs according to the scenario, consequently the southwest region of Banten and West Java has the potential to experience ground motions with intensity up to IX MMI. The quake may also be felt extensively even to the Central Java region with an intensity less than V MMI. Local geological conditions contribute significantly to amplifying earthquake ground motion with various amplification factors that depending on the distance to earthquake source (SSM) and the values of Vs30 and Z1.0. The spectra acceleration model on bedrock reaches its peak at SA0.2 - SA0.3, and afterwards decays rapidly at higher periods. In SSM earthquake scenario, the spectral model changes very drastically when the surface geological conditions and basin geometry are taken into account to the modelling. At locations near SSM, seismic acceleration with a period of 0.2 - 0.3 seconds is very high due to the dominance of the short-period waves at this location and the long period waves have not formed. We interpret that in areas relatively close to earthquake source, two- to three–storey buildings will receive stronger shaking. In some locations, which are relatively far from the source of the earthquake and stand on very thick sediments, high seismic acceleration values take place in periods above 0.5 seconds, which shows high impact of basin depth in amplifying long period waves. Thus, in locations that are relatively far from the source of the earthquake, five- or more storey buildings can experience stronger shaking. 118 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand References Abrahamson, N., Gregor, N., and Addo, K., 2016. BC Hydro Ground Motion Prediction Equations for Subduction Earthquakes, Earthquake Spectra 2016 32:1, 23-44. DOI: 10.1193/051712EQS188MR, Aki, K., and Richards, P.G., 1980. Quantitative Seismology, Theory and Methods. Volume I: 557 pp. Allen, T.I., and Wald, D.J., 2008. Short Note: On the Use of High-Resolution Topographic Data as a Proxy for Seismic Site Conditions (VS30). BSSA 99(2A), 935-943. DOI: 10.1785/0120080255 Atkinson, G.M., and Boore, D.M., 2003. Empirical ground-motion relationships for subduction-zone earthquakes and their application to Cascadia and other regions, Bulletin of Seismological Society of America, Vol. 93, pp. 1703-1729. Cipta, A., Cummins, P., Irsyam, M. and dan Hidayati, S., 2018. Basin resonance and seismic hazard in Jakarta, Indonesia, Geosciences, 8(4). Deplus, C., 1987. Comportement mécanique de la lithosphere océanique: Cas d'une subduction complexe. Ph.D. thesis, Université de Paris Sud, Orsay. Hanifa, N.R., Sagiya, T., Kimata, F., Efendi, J., Abidin, H.Z., and Meilano, I., 2014. Interplate coupling model off the southwestern coast of Java, Indonesia, based on continuous GPS data in 2008–2010. Earth and Planetary Science Letters, 401, 159–171. DOI: 10.1016/j.epsl.2014.06.010 Hayes, G.P., Moore, G.L., Portner, D.E., Hearne, M., Flamme, H., Furtney, M, and Smoczyk, G.M., 2018. Slab2, a Comprehensive Subduction Zone Geometry Model. Science. DOI: 10.1126/science. aat4723 Huchon, P., and Le Pichon, X., 1984. Sunda Strait and Central Sumatra Fault, Geology1, 2, 668-672. Irsyam, M., Widyantoro, S., Natawidjaja, D.H., Meilano, I., Rudyanto, A., Hidayati, S., Triyoso, W., Hanifa, N.H., Djarwadi, D., Faizal, L., and Sunarjito, 2017. Peta Sumber dan Bahaya Gempa Indonesia Tahun 2017. Pusat Penelitian dan Pengembangan Perumahan dan Permukiman. Badan Penelitian dan Pengembangan Kementerian Pekerjaan Umum dan Perumahan Rakyat. Matsuoka, M., Wakamatsu, K., Fujimoto, K., and Midorikawa, S., 2006. Average shear-wave velocity mapping using Japan engineering geomorphologic classification map. Journal of Structural Mechanics and Earthquake Engineering, JSCE, 23, 57–68. Nguyen, N., Griffin, J., Cipta, A., and Cummins, P.R., 2015. Indonesia’s Historical Earthquakes: Modelled examples for improving the national hazard map. Record 2015/23. Geoscience Australia, Canberra. DOI: 10.11636/Record. 2015.023. Robinson, D., Dhu T., and Schneider, J., 2006. Practical Probabilistic Seismic Risk Analysis: A Demonstration of Capability. Seismological Research Letters, Vol. 77, No. 4, pp. 453-459. Soloviev, S.L., and Go, Ch.N., 1974. A Catalogue of Tsunamis on the Western Shore of the Pacific Ocean. Moscow, “Nauka” Publishing House, 308h. Terjemahan dalam bahasa Inggris oleh Canada Institute for Scientific and Technical Information, National Research Council, Ottawa, Canada KIA OS2. Wald, D.J., and Allen, T.I., 2007. Topographic Slope as a Proxy for Seismic Site-Conditions (VS30) and AmplificationAround the Globe. USGS Open-File Report 2007-1357. Zhao, J.X., Zhang, J., Asano, J., Ohno, Y., Oouchi, T., Takahashi, T., Ogawa, H., Irikura, K., Thio, H.K., Somerville, P.G., Fukushima, Y., and Fukushima, Y., 2006. Attenuation relations of strong ground motion in Japan using site classification based on predominant period, Bulletin of the Seismological Society of America, Vol. 96, pp. 898-913. 119 120 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand The Study of Temperature Effect on Q-seam of Mae Moh Mine’s Coal Pyrolysis Nucharin Whangdeeniran1, Chatchawan Chaichana2, and Suparin Chaiklangmuang3 1Laboratory Section, Mae Moh Mine Planning and Administration Division, Electricity Generation Authority of Thailand. Lampang, Thailand, E-mail: [email protected] 1Graduate School, Chiang Mai University, Chiang Mai, Thailand; 2Energy Technology for Environment Research Centre (ETE), Chiang Mai University, Chiang Mai, Thailand, E-mail: [email protected] 3Department of Industrial Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand, E-mail: [email protected] Abstract Pyrolysis is an important key to all coal utilization processes such as combustion, gasification and liquefaction. Effect of coal pyrolysis from Mae Moh mine, Lampang, Thailand for producing charcoal was investigated in this work. The pyrolysis of Q-seam coal was studied under the temperature of 400, 500, 600, and 700°C with the heating rate of 10, 20, and 30°C/min. From the proximate, ultimate, and gross calorific value analyses of charcoal, it was observed that the suitable condition for producing charcoal is at 700°C with 20°C/min heating rate. Keywords: coal, pyrolysis, temperature, heating rate 1. Introduction Mae Moh Mine in northern Thailand is the largest open-pit lignite mine in Southeast Asia. The mine produces and supplies lignite to Mae Moh power plants to generate electricity - which can supply 50% of the electricity to the northern area, 30% to the central area, and 20% to the northeast area of Thailand. The fuel consumption is approximately 16 million tons per year, to meet the requirements of 2400 MW power plants (Teparut and Sthiannopkao, 2011). Mae Moh coal is low-grade lignite, containing relatively high percentages of ash and sulfur contents (Pintana and Tippayawong, 2013). Because of the variety of Mae Moh coal layer, it is difficult to maintain the qualification of coal according to the requirement of the power plants. The lignite qualification determines by proximate analysis, ultimate analysis, gross calorific value, and calcium content in ash composition. Pyrolysis has been defined as the decomposition of organic substances by heat. The thermal decomposition is also the substance descriptive of the transformation into another substance or into other substances through the severance of chemical linkages under the influence of heat (Hackh and Grant, 1973) In other words, pyrolysis is the fundamental principle underlying carbonization and proximate analysis. In the pyrolysis stage, volatiles are driven off and the properties of the formed char change significantly when compared to the original coal (Odeh et al., 2017). The changes in the char structure were traced by establishing the relationship between char formation process indices and coal/char properties. This work intends to study the effect of temperature on pyrolysis process of Mae Moh coal for producing charcoal which can be applied as more stable and higher quality fuel. 121 Nucharin Whangdeeniran1, et. al, The Study of Temperature Effect on Q-seam of Mae Moh Mine’s Coal Pyrolysis 2. Materials and methods 2.1 Materials Q-seam coal was evaluated in this study: brown coal obtained from Mae Moh mine, Thailand. The sample coal prepared according to ASTM D2013 (ASTM D2013/D 2013M Standard Practice for Preparing Coal Samples for Analysis). 2.2 Pyrolysis experiments The pyrolysis experiments were performed in the lab-scale according to ASTM D3175 (ASTM D3175 Standard Test Method for Volatile Matter in the Analysis Sample of Coal and Coke). D3175 using the instrument in the Laboratory Section, EGAT Lampang, Thailand. Muffle Furnace – Cabolite Model Gero was heated, the investigated temperatures were: 400, 500, 600, and 700 °C. At the heating rate: 10, 20, and 30 °C/min. The weighed coal samples (2 g) were contained in a ceramic crucible with a cap (limit amount of oxygen) and put in the furnace at atmospheric condition. Figure 1. Muffle Furnace and ceramic crucible with cap in this study. 2.3 Proximate and ultimate analyses The proximate analyses of raw material and char were conducted according to the following standard test method: ASTM D7582 (ASTM D7582 Standard Test Methods for Proximate Analysis of Coal and Coke by Macro Thermogravimetric Analysis) (moisture, volatile matter, ash, and fixed carbon). The ultimate analyses of raw material and char were carried out according to the following standard test methods: ASTM D5373 (ASTM D5373 Standard Test Methods for Determination of Carbon, Hydrogen, and Nitrogen in Analysis Samples of Coal and Carbon in Analysis Samples of Coal and Coke) (carbon, hydrogen, and nitrogen), ASTM D4239 (ASTM D4239 Standard Test Method for Sulfur in the Analysis Sample of Coal and Coke Using High- Temperature Tube Furnace Combustion) (sulfur). Finally, the high heating values (HHV) of raw material and solid products of pyrolysis were determined by a bomb calorimeter according to the ASTM D5865 (ASTM D5865 Standard Test Method for Gross Calorific Value of Coal and Coke) standard test method. All analyses were performed in the Laboratory Section, EGAT Lampang, Thailand. 3. Results and Discussion In the study of temperature effect on Q-seam coal from Mae Moh mine. The factors studied were pyrolysis temperature and heating rate. The basic characteristics of raw material in this study such as proximate analysis, ultimate analysis, and energy content are presented in Table 1. Q-seam coal has higher moisture and ash content (19.19 and 27.10 wt% air-dried), and low calorific value (14.98 MJ/kg air-dried) compared to lignite. When including the volatile matter content (30.48 wt% air-dried) then it is better categorized as a medium volatile coal. 122 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Table 1. Basic characteristics of Q-seam coal. wt (% air dried) wt (%/daf) H/C Coal CV (MJ/kg) IM Ash VM FC CHNOS ratio Q-seam 19.19 27.10 30.48 23.24 14.98 66.43 5.33 2.28 19.12 6.82 0.96 IM Inherent moisture, VM Volatile matter, FC Fixed carbon, CV Calorific value, daf – dry ash-free basis 3.1 Effect of temperature on characteristics of char during pyrolysis Table 2 shows the results after the coal pyrolysis at temperatures 400, 500, 600, and 700°C using the heating rate at 10°C/min. The characteristics of charcoal including IM, Ash, FC, C, and S were slightly increased when the temperature was increased. In contrast, calorific value (CV) was non-significantly changed. During pyrolysis, chemical bonds in the structure of coal molecules are broken (Odeh et al., 2017) and volatiles are driven off such as CO2, CH4, H2, and H2O. In accordance with the result of volatile matter (VM), H, and O contents were decreased and H/C ratio dramatically decreased as pyrolysis temperature was increased. The H/C ratio indicates that the structure of charcoal was rearranged and hydrocarbon compounds are converted to fixed carbon (FC) in its structure (Nelson et al., 1987). By 700°C, the charcoal characteristics become highly ordered resulting in an increase in carbon content. Table 2. Characteristics of charcoal from Q-seam coal at temperature 400, 500, 600, and 700°C. CHAR wt (% air dried) CV wt (% daf) H/C (°C) IM Ash VM FC (MJ/kg) CHNOS ratio 400 2.58 33.95 31.50 31.97 16.23 66.59 4.22 2.38 20.28 6.52 0.76 500 2.67 36.76 28.29 32.29 15.94 68.99 3.51 2.69 18.19 6.62 0.61 600 2.23 40.95 22.97 33.87 15.56 73.36 3.02 3.03 13.85 6.72 0.48 700 2.84 43.38 19.45 34.33 15.59 77.24 2.20 2.72 11.02 6.83 0.34 IM Inherent moisture, VM Volatile matter, FC Fixed carbon, CV Calorific value, daf – dry ash-free basis 3.2 Effect of heating rate on characteristics of char during pyrolysis In the heating rate experiment ranging from 10, 20, and 30°C/min with pyrolysis temperature at 700°C, the characteristics of charcoal on Q-seam included significantly decreased amounts of VM, H, N, and O during the high operating condition of the heating rate as showed in Table 3. Decreasing of H, N, and O can explained by heterocyclic chains in the charcoal molecules. During the pyrolysis, the contents of hydrogen, nitrogen, and oxygen in heterocyclic linkage are broken into H2O, CO, CH4, and H2 (Fuchs and Sandhoff, 1942). Inherent moisture (IM) and VM parameters are easily evaporated so these factors have a major effect on the H/C ratio. Moreover, hydrocarbon chains in the coal structure were destroyed due to thermal decomposition reaction. Although the H/C ratio of the heating rate at 20 and 30°C/min condition are similar to each other, the condition using the heating rate at 20°C/min has been assessed as it shows the highest carbon content. 123 Nucharin Whangdeeniran1, et. al, The Study of Temperature Effect on Q-seam of Mae Moh Mine’s Coal Pyrolysis Table 3. Characteristics of charcoal from Q-seam coal at heating rate 10, 20, and 30°C/min. CHAR wt (% air dried) CV wt (% daf) H/C (°C/ (MJ/kg) ratio min) IM Ash VM FC CHNOS 10 2.84 43.38 19.45 34.33 15.59 77.24 2.20 2.72 11.02 6.83 0.34 20 1.55 45.69 17.41 35.36 15.45 80.97 1.55 2.19 8.27 7.01 0.22 30 1.81 45.62 16.20 36.38 15.43 80.79 1.46 2.02 8.78 6.95 0.21 IM Inherent moisture, VM Volatile matter, FC Fixed carbon, CV Calorific value, daf – dry ash-free basis 4. Conclusions In conclusion, this work has successfully studied the temperature effect on Q-seam of Mae Moh Mine coal during pyrolysis. Two key factors of the study were the temperature and heating rate. The temperature affects chemical compositions and its structure. The optimum temperature and heating rate were found to be 700°C and 20°C/min, that gives H/C ratios of 0.34 and 0.22 respectively. From this pyrolysis, we conclude that these conditions can produce charcoal which can be utilised as more stable and higher quality fuel than the original coal. References Fuchs W., Sandhoff A.G., 1942. Theory of Coal Pyrolysis. Industrial and Engineering Chemistry, Vol. 34 No. 5, The Pennsylvania State College, pp. 567-571. Hackh I. W. D., and Grant J., 1973. Chemical Dictionary, 2nd ed., pp 770. Nelson P.F., Smith I.W., and Tyler R.J., 1987. Pyrolysis of Coal at High Temperatures. North Ryde: CSIRO Division of Fossil Fuels, 142-147. Odeh A.O., Ogbeide S.E., and Okieimen C.O., 2017. Coal pyrolysis: Comparative evaluation of the technical performance of two Southern Hemisphere demineralized bituminous coals. Thermal Science and Engineering Progress, Vol. 3, 1-9. Pintana P., and Tippayawong N., 2013. Nonisothermal Thermogravimetric Analysis of Thai Lignite with High CaO Content. The Scientific World Journal. Pages?? Teparut C., and Sthiannopkao S., 2011. Mae Moh Lignite Mine and Environmental Management. Geosystem Engineering, 14, 85-94. 124 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Study on Possible Sources of Elevated Arsenic Level in Water, Amphoe Ban Rai, Changwat Uthai Thani Apsorn Sardsud1, Onuma Khamphleang1 and Jitisak Premmanee2 1Division of Mineral Resources Analysis and Identification, Department of Mineral Resources. 2An ex-official of the Department of Mineral Resources, contact: [email protected] E-mail: [email protected] Abstract This study is a cooperation between the Division of Mineral Resources Analysis and Identification, Department of Mineral Resources, Thailand and the Uthai Thani Provincial Public Health Office to verify the reported elevated arsenic level at Tambon Nong Chok / Nong Bom Kluai, Amphoe Ban Rai, Changwat Uthai Thani because elevated arsenic level may pose a health risk to local residents. Geochemical techniques were employed through collecting water and stream/lake sediments samples and analyzing them for arsenic in the target and adjacent areas. A total of 371 water samples were collected. Arsenic analysis results of 281 surface water samples range from <2–2,713 ppb with anaverage of 97 ppb whereas results of 90 groundwater samples range from <2–505 ppb with an average of 47 ppb. Integrated spatial studies for these water analysis results with geography, water flow pattern and arsenopyrite mineralization guide were carried out to outline 2 tiers of risk areas. Tier 1 arsenic ≥300 ppb in 2 areas at south of Ban Thap Fai Mai and Wat Nong Mai Tai, Tambon Nong Chok and Tier 2 arsenic ≥100 ppb, encompasses 14 villages in Tambon Nong Chok / Nong Bom Kluai, Changwat Uthai Thani; Tambon Wang Khan, Changwat Suphanburi; and Tambon Suk Duean Ha Changwat Chainat. In addition, a total of 88 stream/lake sediments samples were compiled. Analysis results range from <5–167 ppm with an average of 31 ppm. A group of high analysis values (75-167 ppm) occurred closed to the expired tin-tungsten mining area in Ban Nong Yai Ngoen, Tambon Wang Khan. Other high As (≥50 ppm) are found within the Tier 2 area. These findings indicated that water sampling is a more practical approach than sediment sampling to outline the arsenic risk areas and potentially to identify the point sources. Four possible arsenic sources were identified: (1) Khao Koktungkung, (2) west of Ban Phu Takhian (3) Wat Nong Mai Tai and (4) west of Ban Nong Mai Kaen where altered granite with quartz veins and disseminated arsenic rich sulfide minerals were found at an under- construction water reservoir site. Keywords: arsenic, water contamination, 1. Introduction This project was initiated by the Uthai Thani Provincial Public Health Office (UTPHO). The Office has actively followed up on the reported elevated arsenic level in surface water since 2011. Elevated arsenic level in water was known before for many years in the areas. The Division of Mineral Resources and Identification, Department of Mineral Resources (DMR), Ministry of Natural Resources and Environment has filed the first available records in 2006. Later, some records were available from a cooperative project between DMR and the Department of Disease Control, Ministry of Health, in 2009. Also, the DMR Hazardous Element Project has sampled surface water and sediments in this area during 2012 and 2013. Nevertheless, most of the records do not cover the entire area but rather on repeated work focused on the known problematic sites. The data under the DMR Hazardous Element Project systematically covered parts of the area in Suphan Buri and Uthai Thani but Chainat provinces. 125 Apsorn Sardsud, et. al., Study on Possible Sources of Elevated Arsenic Level in Water, Amphoe Ban Rai, Changwat Uthai Thani The Division of Mineral Resources and Identification, DMR has launched this project in early 2019 to systematically document the elevated arsenic levels with the objective of trying to identify the possible sources. Geochemical prospecting techniques were employed by collecting water and stream/lake sediments covering the target and adjacent area and analyzing them for arsenic. Study Area Initial study area covered 5 villages (Ban1 Thap Fai Mai, Mai Phongan, Nong Mai Kaen, Kean Phet Phailin and Nong Mai Tai) of Tambon1 Nong Chok and a village (B. Lanka) of Tambon Nong Bom Kluai, Amphoe1 Banrai, Changwat1 Uthai Thani (Figure 1). However, after further compilation of previous data, the study area has been enlarged to include adjacent areas of T. Nong Chok/Nong Bom Kluai/Thap Luang, A. Banrai, C. Uthai Thani, of T. Wang Khan/Nong Krathum, A. Dan Chang/Doem Bang Nang Buat, C.Suphanburi, of T. Suk Duan Ha/Kabok Tia, A. Noen Kham C. Chainat. The entire study covered an area of about 16x20 km2 or 320 km2. Figure 1 shows that the area,is made up of broad and gentle slopes with higher ground forming an axis in the middle, like the turtle back. The axis orients almost north-south and divides the surface water flow to the east and west directions. To the east, water flows to the southeast direction and drains into the Tha Chin River, C. Chainat. In the western part, water drains into Krasiao stream, then to the Krasiao reservoir, Dan Chang, Suphan Buri. Khao2 Phu Klang and Urkhwai areas exhibit karst topography in the north and mainly consist of limestone of Ordovician Period. A group of hills, K. Koktungkung, Puchi and Pong Ngam present in the south underlain by meta-sediments, limestone and granite of Silurian/Devonian, Ordovician and Triassic Periods respectively. Contacts of these meta-sediments and limestone with granite have hosted tin- tungsten deposits. A few secondary elluvial and alluvial mines were in operation around 1987 at K. Koktungkung and at B. Thap Fai Mai. Jariyawat (1996) reported that the mineralization in 1-10 cm quartz veins oriented N45°W and N60°E are found in granitic rock. Interestingly, those hills in the south have formed natural geographic boundary of 7 sub-districts (Nong Chok, Nong Bom Kluai, Wang Khan, Nongmakhamong, Nongkrathum, Suk Duan Ha and Kabok Tia), 4 districts (Banrai, Dan Chang, Dermbangnangbuat and Noen Kham) and 3 provinces (Uthai thani, Suphanburi and Chainat). 1 Ban, Tambol, Amphoe and Changwat are local administrative names and refer to village, sub-district, district and province respectively. In this report may abbreviate to B., T., A. and C. respectively. 2 Khao refer to mountain or hill, in this report may abbreviate to K. 126 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Figure 1 Study areas under the DMR Hazardous Elements Project during 2007 to 2015 Previous Data and Additional Sampling Figure 2 shows locations of sample points in previous and current studies. The water and sediments sample (Figure 2A) results from previous studies detailed in Premmanee (2019a) were compiled from many sources, such as DMR’s reports, UTPHO, the DMR’s Hazardous Elements Project (Uthai Thani and Suphanburi provinces) and others. The total number of 211 samples consist of 32 stream sediments, 139 surface water and 50 groundwater. Figure 2b shows the additional samples collected in April 2019. The new sample set aimed to to infill sampling gaps, achieve higher sampling density and to verify some analysis results in the problematic areas. Additional samples consist of 56 stream/lake sediments, 142 surface water, 40 groundwater, totaling 238 samples. Note that these samples were collected, prepared and analyzed according to protocols in the Standard Method for Examination of Water and Waste Water (https://www.standardmethods.org/, on Sept. 26, 2019) for water samples and the Hazardous Waste Test Methods /SW-846 (https://www.epa.gov/hw-sw846, on Sept. 26, 2019) for solid samples. These analysis results were combined into a single set, total of 459 samples (Table 1). Arsenic contents in surface water, groundwater and sediments average about 97 ppb4, 47 ppb and 31 ppm3 respectively. These averages are about 20, 10 and 2 times higher than the average background As content in surface water (4 ppb) and stream sediments (12-15 ppm) under the DMR Hazardous Element Project (Premmanee, 2019b). 4Ppb – part per billion or microgram per liter (µg/l) and ppm – part per million or milligram per liter (mg/l) 127 Apsorn Sardsud, et. al., Study on Possible Sources of Elevated Arsenic Level in Water, Amphoe Ban Rai, Changwat Uthai Thani Figure 2 Distribution of arsenic in (A) stream sediments, (B) surface water and (C) soil. 128 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Note that the World Health Organization (WHO) has suggested arsenic content in drinking water at 10 ppb (https://www.who.int/en/ news-room/fact-sheets/detail/arsenic, on Sept. 26, 2019) while the Pollution Control Department (PCD) of Thailand has set the standard arsenic values (refer to maximum permissible limit or MPL) in water at 10-50 ppb and agricultural soil at 3.9 ppm. (http://www.Pcd.go.th/info_serv/reg_std_water.html and http://www.pcd.go.th/info_serv/reg_ std_soil01.html, on Sept. 26, 2019). Besides water and sediments, UTPHO has collected urine samples from local residents periodically every other year, since 2011 (Table 2). The samples were from 5 villages of T. Nong Chok and a village of T. Nong Bom Kluai, 288 (55%) out of 520 samples are above acceptable levels. Table 1. Statistics of arsenic assays in surface water, groundwater and sediments. Surface water Groundwater Combined water Sediments Assay statistics (ppb) (ppb) (ppb) (ppm) Number of samples 281 90 371 88 Minimum <2 <2 <2 <5 Maximum 2713 447 2713 167 Average* 97.0 46.8 85.9 31.1 Standard deviation* 167.2 83.1 153.8 30.7 Detection limit (DL) 2 2 2 5 Number of Table 2 Arsenic levels in local resident. Testing year T. Nong Chok T. Nong Bom Kluai Combined Total samples 202 - 202 2011 Anomaly (%) 73 (36%) - 73 (36%) Total samples 86 - 86 2013 Anomaly (%) 49 (57%) - 49 (57%) Total samples 101 - 101 2015 Anomaly (%) 86 (85%) - 86 (85%) Total samples 96 76 171 2017 Anomaly (%) 38 (40%) 42 (56%) 80 (47%) TOTAL 520 sample with 288 (55%) anomalous values Arsenic Distribution Figure 3 shows arsenic distribution in surface water (3A), groundwater (3B) and sediments (3C). Elevated arsenic in surface water, groundwater and sediments are scattered around the prospective tin-tungsten areas of K. Koktungkung and more prominent to the north, especially at abandoned tin mining pits, south of B. Thap Fai Mai. The furthest point to the north with high arsenic values are along water channels north of B. Mai Pho Ngam and Phu Takhian. 129 Apsorn Sardsud, et. al., Study on Possible Sources of Elevated Arsenic Level in Water, Amphoe Ban Rai, Changwat Uthai Thani Figure 3 Distribution of cadmium in (A) stream sediments, (B) surface water and (C) soil. 130 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand The highest arsenic value (2,713 ppb) in surface water was collected from a small water channel, south of B. Thap Fai Mai. Four other high values (>1,000 ppb) were detected at the tin mining pits in this area. The sixth high value (1,170 ppb) was from Wat Nong Mai Tai, B. Nong Mai Tai, about 3.5 km east of the Thap Fai Mai’s tin pits. Interestingly, a group of high arsenic values (100-499 ppb) in surface water from different drainage catchments depicted at B. Mai Pho Ngam and further north to the one of B. Thap Fai Mai. These show that arsenic sources may not only originated from the tin and tungsten mining/prospective areas of K. Koktungkung but from other not-yet-known sources northeast of B. Mai Pho Ngam as well. High arsenic results in groundwater display a similar pattern to surface water, except at B. Phu Takhian (Figures 3A and 3B) where mixes of very low and high arsenic values (≤50 to ≥100 ppb) were detected. The highest value (505 ppb) was found in a 30 m water well here, but all surface water yielded <50 ppb. In addition, the downstream value of surface water gradually increase for about 5 km, i.e., 10, 22, 59, 72, 135 and 128 ppb, from the village. These findings lead to draw an illustration (Figure 4) showing a possible transport mechanism of arsenic in the water of this area. It is estimated that arsenic may mobilize as far as 10 km. High arsenic (≥75 ppm) in sediments is distributed in 2 areas, east/northeast of K. Koktungkung and around B. Mai Pho Ngam and Phutakien. Medium-high arsenic value (25-74 ppm) were recorded from tin pits at B. Thap Fai Mai. These results do not show the same pattern with water results. It seems that arsenic in sediments disperses irregularly around the sources. However, due to the sampling carried out during the dry season, very limited number of stream sediments were collected, but the majority was lake/pond sediment which are not representative of transported materials. Sediments may not be the practical sample media to be used in this case. Risk Areas and Possible Point Sources Many spatial factors (such as topography, drainage system, arsenic mineralization style, geological environment and others) can help to outline the risk areas and to identify arsenic sources. As mentioned, the water analysis will limit the risk areas comparing to sediments. Many authorities recommend MPL in consumable water at 10-50 ppb. The practical threshold arsenic value in surface water should be higher than that recommended by MPL in order to separate the risk areas. In this study, arsenic averages 97 ppb in surface water and 47 ppb in groundwater. Therefore, surface water arsenic at 100 ppb may be selected asv the practical threshold value. The Tier 1 (_>300 ppb) and Tier 2 (_>100 ppb) lines were manually drawn following drainage system and catchment areas. Figure 5 shows the results of the 2 tiers of risk areas as follow. Tier 1: arsenic ≥ 300 ppb in surface water, encompass 2 areas: (1) south of B. Thap Fai Mai where there are many abandoned tin mining pits and (2) Wat Nong Mai Tai, B. Nong Mai Tai; both at T. Nong Chok A. Banrai C. Uthai Thani, covering approximately 4 square km or 2,500 rai. Tier 2: arsenic ≥ 100 ppb in surface water, encompass 14 villages of B. Putakien, Mai Pho Ngam, Kok Sa-at, Nong Mai Kaen, Thap Fai Mai, Kaen Phet Phailin, Nong Mai Tai, Tambon Nong Chok; B. Lanka, Tambon Nong Bom Kluai, Amphoe Banrai, Changwat Uthai Thani; B. Nong Yai Ngoen, Bungyang, WangThong, Wang Khan, Phunglouang, Tambon Wang Khan, Amphoe Dan Chang, Changwat Suphanburi; and B. Huaisong, Tambon Suk Duan Ha, Amphoe Noen Kham, Changwat Chainat; covering approximately 65 square km or 40,000 rai. 131 Apsorn Sardsud, et. al., Study on Possible Sources of Elevated Arsenic Level in Water, Amphoe Ban Rai, Changwat Uthai Thani Note that the 100 ppb line is opened at T.Wankan due to insufficient data available for the area. Point sources of arsenic would be picked from distribution pattern of arsenic in water and sediment, topography, arsenic mineralization, geological environment and others, depending largely on personnel experiences. Initial field work at the tin-tungsten prospective area of K. Koktungkung found no evidence of primary sulfide minerals such as pyrite or arsenopyrite; only a blanket of some iron oxides residual on the surface was found. Still, K. Koktungkung remains the most likely important point source of arsenic. The area is at a higher ground than the surrounding, may radially distribute arsenic into water channels of 10 villages: Thap Fai Mai, Lanka, Huai Song, Bueng Yang, Wang Thong, Wang Khan, Phueng Luang, Nong Yai Ngoen, Nong Mai Tai and Kaen Phet Phailin. Thus, arsenic-rich sulfide minerals may be present in the primary tin-tungsten mineralization. However, on the other side of the water divide, west of B. Nong Mai Tai, Nong Mai Kaen, arsenic from K. Koktungkung cannot mobilize across the divide, unless another source is present. High arsenic values at B. Mai Pho Ngam and Phu Takhian are also located in a different catchment from K. Koktungkung; so, the areas may potentially have another unknown arsenic source indicated by the very high arsenic in water at Wat Nong Mai Tai. (Tier 1 area) Figure 4. Possible transport mechanism of arsenic at Ban Phu Takhian, Ban Rai, Uthai Thani. In summary, there are four possible point sources: (1) K. Koktungkung, (2) west of B. Phu Takhian and Mai Pho Ngam, (3) Wat Nong Mai Tai, B. Nong Mai Tai, and (4) west of B. Nong Mai Kaen. Fieldwork carried out at an under-construction water reservoir site in B. Nong Mai Kaen in July 2019, has found outcrops of altered granite with thin (<5cm) quartz veins and arsenic-rich sulfide minerals (Figure 5). Rock chip samples of mixed altered granite with weathered sulfides minerals and altered granite gave 4,890 and 25 ppm arsenic respectively. This evidence may confirm the arsenic source. However two water samples at this reservoir site gave only 20 and 23 ppb arsenic which are in the normal range. 132 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand A. Overview image of Ban Nong Mai Kaean water reservoir showing altered granite outcrop and pocket of weathered sulfides. B. Quartz veins in altered granite with disseminated sulfide minerals. C. Altered granite D. Mixed weathered arsenic rich sulfides and altered granite Figure 5. Nong Mai Kaen water reservoir showing quartz veins in altered granite with disseminated arsenic rich sulfide minerals. Conclusions and Remarks 1. Geochemical prospecting techniques are effective to outline the arsenic risk areas and to identify the sources. It also demonstrates that elevated arsenic may not only be associated with known tin-tungsten mining area but other yet unknown sources as well. In this study, water samples are shown to be more effective than sediments: However, both sampling media should be used. It is estimated that arsenic may mobilize for 10 km from the source. 2. The 100 ppb threshold arsenic value in surface water, a simple and rational figure, has separated the risk area in this study, but may not be in other area. However, the figure may be used for a quick evaluation in addition to the MPL standard (10-50 ppb for drinking and consumable water). 3. Local residents in the risk and nearby areas should be well aware of this elevated arsenic in surface water. Large water supply system should consider bringing water from outside the risk area with acceptable arsenic level. Rainwater is the best alternative for drinking water. 4. Related government authorities such as UTPHO, DMR, Local Administrative Offices, etc. should continue their efforts to deal with the elevated arsenic problem in the area, A few research type questions remain un-answered, such as (i) low arsenic content in water at the reservoir where some rich arsenic sulfide minerals has been identified; (ii) distribution pattern or behavior of arsenic in surface and groundwater at B. Phu Takhian; and (iii) dispersion distance of arsenic from source into water system and surrounded area. 133 Apsorn Sardsud, et. al., Study on Possible Sources of Elevated Arsenic Level in Water, Amphoe Ban Rai, Changwat Uthai Thani Acknowledgement The authors gratefully thank the Department of Mineral Resources who provided funding and gave us opportunity to study this project. We would like to thank the Uthai Thani Public Health Office personnel, especially to Ms. Sukanya Pataisophon who provided all information related to this study as well as helped us in the field, to all health care personnel at Ban Mai Pho Ngam Health Promoting Hospital, T.Nong Chok, A.Banrai, C.Uthai Thani who helped collecting samples. Also, we like to express our sincere to T. Nong Chok, Khun Sangop, who assisted us in the field. Last, we like to give special thanks to the officials in the Division of Mineral Resources Analysis and Identification, DMR who helped to collect all samples, preparation and analysis. They also helped to review and compile the data for this project. Thank to K. Thawatchai Cheulaowanich and K.Nikhon Chaiwongsen who gave us valuable comments and discussion. References Jariyawat, P., 1996. Tin Deposit in Central Thailand, in Economic Geology Division Meeting Year 1996, Department of Mineral Resources, Bangkok, 132-143 (in Thai). Premmanee, J., 2019a. Study on Possible Sources of Arsenic Distribution in Uthai Thani Province, Department of Mineral Resources, Bangkok, 79 p. (in Thai). Premmanee, J., 2019b. Arsenic and Cadmium: Under the DMR Hazardous Elements Project, in Geothai 2562, The Berkley Hotel Pratunam, Bangkok, 16-17 September 2019, 3-5. 134 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand How to disseminate geological knowledge: an attempt in the Miné-Akiyoshidai Karst Plateau Geopark Koji Wakita1, Takanori Nakagawa1, Hokuto Obara2 and Tristan Gray2 1Akiyoshidai Academic Centre of the Yamaguchi University, Japan 2Geopark Promotion Department, Miné City, Japan E-mail: [email protected] Abstract The Miné-Akiyoshidai Karst Plateau Geopark, Yamaguchi Prefecture, western Japan, is mainly composed of a Permian accretionary complex, overlain by Triassic sediments and intruded by Cretaceous granites. This karst plateau is quite unique compared with other ones in the world which typically formed on continental shelves, whereas the limestone of the Miné-Akiyoshi area represents original coral reefs on an ancient submarine volcano located in the ancient ocean called Panthalassa. As the volcanic island was formed, the coral reefs began to develop on its top. Located near oceanic ridges, the volcanic island migrated together with its the oceanic plate while the coral reefs were covering the island. After a long journey, the volcano and reef arrived at the convergent margin, onto which they were accreted. Such geological concepts are not easy to understand by local people who have little knowledge of geology but potentially very important for their daily life. This story is one of the various tools we have prepared including movies, comedy, and picture-story shows, in order to help them to understand this geoscience and how it impacts upon their lives. We also provide dissemination lectures, which are effective in enhancing their understanding for the geological history of the area nurturing a love for and pride in their hometown, which may help to stop the decline in population and contribute to the sustainable development of the area. Keywords: dissemination, sustainable development, karst, Geopark, Japan 1. Geological Background The geology of the Japanese islands reflects formation along a convergent margin setting throughout the Phanerozoic time (Wakita et al., 2018). The Japanese archipelago is thus mainly composed of ancient accretionary complexes of various ages including three major accretionary complexes of Permian, Jurassic and Cretaceous-Paleogene ages (Figure 1). All the accretionary complexes are mainly composed of a rock association of turbidite, siliceous mudstone, chert, limestone and basalt usually described as “Ocean Plate Stratigraphy (OPS)”, typical of ancient accretionary complexes around the world. Ocean Plate Stratigraphy comprises a set of oceanic rocks and formations, which were formed as oceanic island basalt, atoll carbonate, pelagic siliceous ooze, hemipelagic sediments, and trench–fill turbidite (Figure 1). The Miné-Akiyoshidai Karst Plateau Geopark is characterised by a limestone body located in the central part of Yamaguchi Prefecture, western Japan (Figure 2). The limestone, termed the Akiyoshi Limestone, was a major target of geological research in the 19th and 20th centuries. It is mainly composed of pure, white limestone including various fossils ranging in age from late Early Carboniferous to late Guadalupian (Nakazawa and Ueno, 2009). It is divided into four facies: skeletal - oolitic grainstone; muddy limestone; muddy limestone - skeletal grainstone; and reefal limestone (Sano et al., 2006). The limestone is underlain by basalt, which erupted to form an “off-ridge seamount” during the Carboniferous time. The palaeomagnetic data revealed 135 Koji Wakita, et. al., How to disseminate geological knowledge: an attempt in the Miné-Akiyoshidai Karst Plateau Geopark that the seamount on which Akiyoshi Limestone was built up was formed in the low latitudes of the Panthalassan ocean” (Fujiwara, 1967). It includes various shallow marine fossils such as fusulinids, corals, brachiopods, crinoids and calcareous algae. This Akiyoshi Limestone is underlain by basalt and is associated with bedded chert and turbidite sequences (Figure 3). The rock association includes limestone, basalt, chert, and turbidite and is recognised as an ancient Permian accretionary complex which is widely distributed across the region with the Akiyoshi Limestone, a massive white to light grey limestone, located in the central part. The Tsunemori Formation lies in the western part of this area (Wakita, 2009). The Ōda Formation is distributed on the southeast of the Akiyoshi Limestone area, while the northwest area is underlain by the Beppu Formation (Figure 3). The Ōda and Beppu units are composed in ascending order, mainly of pelagic chert, hemipelagic siliceous mudstone, alternations of sandstone and mudstone, massive sandstone and conglomerate, and chert breccia. The main purpose of this paper is to propose a dissemination model for the Miné-Akiyoshidai Karst Plateau Geopark. First, we introduce the geological miracles recorded in the geological entities of the geopark. Then we will introduce our recent activities to disseminate the geological miracles to the local people, especially the younger generation. Figure 1. Ocean Plate Stratigraphy of three major accretionary complexes in Japan (Wakita, 2012, 2019). Figure 2. The left map shows the location of the Akiyoshi Limestone (cyan color). The red box in the right map indicates the location of the left map. 136 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Figure 3. Geological map of the Akiyoshi Limestone and the other OPS components in the Permian accretionary complex of the Akiyoshi Belt (after Wakita, 2019). 2. Five geological miracles in the Miné Akiyoshidai Karst Plateau Geopark In order to disseminate the geological history to the public, we have divided it into the five geological miracles of the Miné Akiyoshidai Karst Plateau Geopark. These are, Miracle 1, the survival of atoll carbonate for ca. 90 million years, Miracle 2, the accretion of atoll carbonate within the Permian accretionary wedge, Miracle 3 is the recovery from the mass extinction in the Permian - Triassic boundary, Miracle 4, the reaction between the Cretaceous magma and the Permian limestone to form copper ore, and Miracle 5 the development of limestone caves and the karst plateau scenery. 2.1. Miracle 1: Survival of atoll carbonate for ca. 90 million years The Akiyoshi Limestone was a long-lived atoll that survived for about 90 million years from early Carboniferous (ca. 350Ma) to middle Permian (ca. 260Ma) times (Figures 4 and 5). The atoll was formed on the top of a seamount which was erupted onto an oceanic plate in the Late Devonian period. This extended period of atoll growth contrasts with modern settings for example, where the top of a seamount we see today at Hawaii only submerged below sea level within the last 30 million years, or in the case of Funafuseyama Limestone in the Jurassic accretionary complex of the Mino Belt, central Japan, the atoll survived only ca. 20 million years. However, evidence of longevity and that the Akiyoshi Limestone atoll growth kept pace with the settling of the oceanic plate may be due to the seamount migrating with continental drift into tropical areas where biological productivity was high. 137 Koji Wakita, et. al., How to disseminate geological knowledge: an attempt in the Miné-Akiyoshidai Karst Plateau Geopark 2.2. Miracle 2: Accretion of atoll carbonate within Permian accretionary wedge There are many seamounts on the floor of the Pacific Ocean. However, along a convergent plate margin most of them are consumed at the trench and transported into the mantle by the process of “tectonic erosion”. The Daiichi Kashima Seamount, is a modern example which has only recently arrived at the Japan Trench. To explain the long term survival of the Akiyoshi Limestone, either large amount of detrital sediments were supplied from the hinterland into the trench, or a subduction ceased and migrated to a separate younger slab (Figure 6). The former explanation is favoured by evidence that when the Akiyoshi Atoll arrived at the ancient trench, the presence of detrital zircons of middle Permian age in the surrounding trench sediments indicate large volumes of detrital grains were derived from the nearby active volcanic arc. Figure 4. Time distribution of the sedimentary and biotic events in the Akiyoshi Limestone (Sano et al., 2004). Figure 5. (A) Age of the seamounts and oceanic plate that formed Permian Akiyoshi Limestone estimated from the geological data of the Akiyoshi Limestone (after Wakita, 2019), (B) Time-series graph showing the second-order sea-level curve estimated from the empirical age-depth equation of the subsidence proposed by Parsons and Sclater (1977), and (C) Second-order sea-level change from Ross and Ross (1987). 138 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Figure 6. Tectonic model of the collision and accretion of buoyant oceanic plateau, in order to preserve limestone and basalt detached from volcanic seamount. 2.3. Miracle 3: Recovery from the mass extinction at the Permian – Triassic boundary The Akiyoshi seamount arrived at Japan in late Permian time, coincident with a tragic event was taking place on the Earth, i.e., the “End-Permian Mass Extinction”. More than 90% of species living on the Earth were wiped out and disappeared forever. We can imagine the world of death that spread over the Earth at that time. In early Triassic time, some of the species which survived from the mass extinction gradually began to evolve and diversify. In middle to late Triassic time, huge forests developed on some parts of the Earth including the Miné-Akiyoshidai area. Coal is obtained from the Triassic formations, which unconformably lies above the Akiyoshi Limestone. The coal beds include various kinds of insect fossils, such as dragonfly, cockroach, bee, locust, beetle, and Pleocoptera. The third miracle is thus the dramatic change from a world of death to huge forests rich in biodiversity. 2.4. Miracle 4: Reaction between Cretaceous magma and Permian Limestone forming copper The fourth miracle of this geopark is the development of a copper mine which was very important in the early history of Japan. The limestone provided by Miracle 1 and 2 was intruded by felsic magma in late Cretaceous time. This magma was formed by the formation of hot plumes of molten rock circulating within the mantle and which caused intense igneous activity all over the world at that time. The reaction between limestone and magma resulted in the formation of various skarn minerals, including copper ore. The copper ore has been mined since the 7th century, and used to construct the Great Buddha of Tōdaiji Temple, which was a symbol of national governance in the Nara period. 2.5. Miracle 5: Formation of limestone caves in the Akiyoshi Limestone Miracle 5 is the formation of more than 400 caves are recognised in the Akiyoshi Limestone. The caves have formed at various levels corresponding to the changes of groundwater systems in response to the Japanese archipelago gradually uplifted on the subducting oceanic plate. 139 Koji Wakita, et. al., How to disseminate geological knowledge: an attempt in the Miné-Akiyoshidai Karst Plateau Geopark Three major caves are used for the geo-tourism and sightseeing. The Akiyoshi-dō cave is the largest and most attractive and is the second largest in Japan. Here there are beautiful stalactites of various ornamentation and sizes (Figure 7). Not only are strange cave dwellers such as creatures without eyes and several types of bats to be found here but the groundwater system is complex and divided into two major underground river systems: one flows eastward and the other moves westward and combined are registered as an Ramsar Convention wetland. Groundwater springs are found along the contact between the limestone body and surrounding rocks. These provide an important water resource for the local society and so the blessings of nature provide the fifth miracle, beautiful caves and clean, delicious water. Figure 7. The entrance to Akiyoshi-dō Cave (left picture), and stalactites of the cave (right picture). 3. Methods to disseminate the geological knowledge to local people Given this amazing landscape and fascinating geological history a key role for geologists is to inform the local people of the uniqueness and wonder of their geological heritage. Limestone is one of the most common sedimentary rocks in the world. However, most of them were formed on the continental shelf along the inactive continental margin. On the other hand, the Akiyoshi Limestone was originally a coral reef on an oceanic island. Showing their difference on the simple figures (Figure 8), we allow local people to handle actual specimens of the two types of limestone, continental limestone and oceanic island limestone. Various activities such as guided tours and study courses are conducted by geopark staff and local volunteers called geoguides in order to disseminate the geological knowledge to the public (Figures 9 and 10). Some junior high school students also attempt to explain the knowledge of the geopark to foreign visitors in English in order to establish Akiyoshi as a new Global Geopark Network in future (Figure 10). Figure 8. Two types of the places where limestones are formed: on the continental margin and on the seamount. 140 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand A B C D Figure 9. A&B: activities for youth education, C&D: activities for senior education. The Miné-Akiyoshidai Karst Plateau Geopark is located in the Miné City. Like many cities across Japan and in developed countries around the world. the city suffers from a declining and aging population. It is hoped that the geopark may be a breakthrough concept to support “Sustainable Development” as one of the major goals of the UNESCO Global Geopark and we are aiming to be nominated as a UNESCO Global Geopark within a few years. The goals of our geopark are to work with the other global geoparks to tackle global issues and to revitalise the local economy through the activity and to build a rich and happy society in the Miné City. 5. Conclusions The Miné-Akiyoshidai Karst Plateau Geopark is rich in geological heritage. However, most of the geological features are not fully understood, and their utilisation and maintenance are not sufficient. We wish to build a better future for the region by means of geopark activities, through which we will disseminate geological knowledge in various ways to the public, especially young boys and girls, who are responsible for the sustainable future of the region. 141 Koji Wakita, et. al., How to disseminate geological knowledge: an attempt in the Miné-Akiyoshidai Karst Plateau Geopark Figure 10. Several activities of dissemination of basic geological knowledge and its application by young students and geoguides. 142 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand References Fujiwara, 1967. Paleomagnetism of upper Carboniferous rocks in Akiyoshi province, SW Honshu, Japan. Journal of the Faculty of Science, Hokkaido University, Series 4, 13, 395-399. Nakazawa, T. and Ueno, K., 2009. Carboniferous-Permian long-term sea-level change inferred from Panthalassan oceanic atoll stratigraphy. Palaeoworld, 18, 162-168. Parsons, B., and Sclater, J.G., 1977. An analysis of the variation of the ocean floor bathymetry and heat flow with age. Journal of Geophysical Research, 82, 803-827. Ross, C.A., and Ross, J.R.P., 1987. Late Paleozoic Sea Levels and Depositional Sequences, Cushman Foundation for Foraminiferal Research, Special Publication, 24, 137-149. Sano, H., Fujii, S., and Matsuura, F., 2006. Response of Carboniferous-Permian mid-oceanic seamount-capping buildup to global cooling and sea-level change: Akiyoshi, Japan. Palaeogeography, Palaeoclimatology, Palaeoecology, 213, 187-206. Wakita, K, 2009. Tectonic setting required for the preservation of sedimentary melange in Palaeozoic and Mesozoic accretionary complexes of southwest Japan. Gondwana Research, 74, 90-100. Wakita, K., Nazagawa, T., Sakata, M., Tanaka, N., and Oyama, N., 2018. Phanerozoic accretionary history of Japan and the western Pacific margin. Geological Magazine, doi: 10.1017/S0016756818000742. 143 144 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Geological Survey of Japan international training course for CCOP Member Countries, Follow-up training and collaborative research with General Department of mineral Resources in Cambodia Hidetoshi Hara1, Tsuyoshi Ito1, Sitha Kong2, Pagna Lim2, and GSJ International Coordination Group1 1Geological Survey of Japan, AIST, Japan 2Department of Mineral–Geology, General Department of Mineral Resources, Ministry of Mines and Energy, Cambodia E-mail: [email protected] Abstract The Geological Survey of Japan (GSJ) has held the “GSJ International Training Course on Practical Geological Survey Techniques” for young geologists of CCOP Member Countries since 2018. In this paper we introduced a summary of the training courses, an example of which is the follow-up training in Cambodia, and the research collaboration with the General Department of Mineral Resources (GDMR). Keywords: GSJ International Training Course, Geology, Pailin Crystalline Complex, Cambodia 1. Introduction The “GSJ International Training Course on Practical Geological Survey Techniques” has been held annually for young geologists of CCOP Member Countries since 2018. To date trainees from 11 countries have received three weeks of training in geological techniques. The training course includes various lectures including geology, petrology, geochronology, geophysics, remote sensing, urban geology, and geohazards. One of the main purposes of the lectures is to gain an understanding of the geological process associated with a plate convergence zone that is relevant to the Asian continent which comprises a collage of Gondwana-derived continental blocks assembled by continental collision and oceanic plate subduction (Metcalfe, 2013). Our lectures, presented in the laboratory but also in the field, focused on the accretionary complex as an example of geological phenomena along the plate convergence zone. However, the geological interest is different from one country to another depending on their geological and tectonic setting therefore support for follow-up training was tailored to each country so that, trainees gained further deeper understanding on how to study the geology of their countries. 2. Geological survey and follow-up training in Cambodia In March 2019 GSJ had an opportunity to conduct a geological survey, which included follow-up training, in western Cambodia in cooperation with the General Department of Mineral Resources (GDMR). In western Cambodia, the occurrence of the lower Permian radiolarian chert and basalt are reported and they are interpreted as the southeastern extension of the Sa Kaeo Suture Zone in southeastern Thailand, associated with a back-arc basin formed by the Paleo-Tethys subduction (Udchachon et al., 2018; Hara et al., 2018). Thus, the back-arc basin is a key geological setting in western Cambodia. Adjacent to chert and basalt, the Pailin Crystalline Complex is composed of mainly amphibolite, including granodiorite, diorite, gneiss, schist, quartzite and basic dike (Udchachon et al., 2018). During the follow-up training, GSJ provided advice to the staff of GDMR on how to observe the outcrops in detail and describe the rocks associated with the back- arc basin (Figure 1). 145 Hidetoshi Hara, et. al., Geological Survey of Japan international training course for CCOP Member Countries, Follow-up training and collaborative research with General Department of mineral Resources in Cambodia 3. Collaborative research in western Cambodia As a result of the collaborative research between GSJ and GDMR, new geological evidence relating to the development of the back-arc basin has been revealed. One of the noteworthy outcomes is the discovery of new species of lower Permian radiolarians in the chert (Ito et al., in press). In addition, we studied the amphibolite in the Pailin Crystalline Complex to investigate and understand their petrogenesis and geological significance. Our study, based on petrological observation and geochemical analysis, suggests that the amphibolite in the complex was originated from the basalt related to the back-arc basin. The anorthosite and plagiogranite intruded into the amphibolite are dated as early Permian by zircon U–Pb dating. We propose that the Pailin Crystalline Complex was originally an oceanic crust of the back-arc basin associated with the Sa Kaeo Suture Zone, and its back-arc spreading occurred in early Permian time. 4. Conclusions Our research collaboration with GDMR following the GSJ international training is an example of successful human resource development. It brought about a significant research result of a discovery of new species of lower Permian radiolarians. It also helped GDMR to open a new way for geological research in Cambodia. Figure 1. An outcrop of the Pailin Crystalline Complex. References Hara, H., Tokiwa, T., Kurihara, T., Charoentitirat, T., Ngamnithiporn, A., Visetnat, K., Tominaga, K., Kamata, Y., and Ueno, K., 2018. Permian–Triassic back-arc basin development in response to Paleo-Tethys subduction, Sa Kaeo–Chanthaburi area in Southeastern Thailand. Gondwana Research, 64, 50–66. Ito, T., Hara, H., Kong, S., Lim, P., in press. New materials of Cisuralian (early Permian) radiolarians from western Cambodia: Paleobiogeographic implications in the Paleotethys. Paleoworld, https:// doi.org/10.1016/j.palwor.2019.08.001. Metcalfe, I., 2013. Gondwana dispersion and Asian accretion: Tectonic and palaeogeographic evolution of eastern Tethys. Journal of Asian Earth Sciences, 66, 1–33. Udchachon, M., Thassanapak, H., and Burrett, C., 2018. Early Permian radiolarians from the extension of the Sa Kaeo Suture in Cambodia – tectonic implications. Geological Magazine, 155, 1449–1464. 146 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Constructing a comprehensive geoscience database in East and Southeast Asia: CCOP Geoinformation Sharing Infrastructure for East and Southeast Asia (GSi) Project Shinji Takarada, Joel Bandibas and Toshihiro Uchida Geological Survey of Japan, AIST, Japan E-mail: [email protected] Abstract The CCOP Geoinformation Sharing Infrastructure for East and Southeast Asia (GSi) project is one of the most important activities currently implemented by CCOP. The main objective of the project is to develop a web-based information system for the sharing of geoscience data among the countries in East and Southeast Asia. More than 740 maps from 11 countries (Cambodia, Indonesia, Japan, Korea, Lao PDR, Malaysia, Myanmar, Papua New Guinea, Philippines, Thailand and Vietnam) are currently available on the GSi system. More than 15 customized WebGIS portal sites are currently set up using the information system. The spatial data can also be downloaded and viewed using mainstream GIS software and WMS clients. The mobile version of GSi system is also available. The GSi information system can be accessed at https://ccop-geoinfo.org/main. Keywords: CCOP, geoinformation, WMS, share, database, GSi, WebGIS, mobile 1. Introduction Many geoscience maps and related data have been published by the countries of East and Southeast Asia. However, most of these data are not widely used because of the lack of information technology infrastructure to make them highly accessible to those who need them. To address the problem, the CCOP Geoinformation Sharing Infrastructure (GSi) Project was launched in 2015. The scope of the GSi project is to (1) compile various geoscientific information in the CCOP member countries and construct a web-based database using international standards and GIS (Figure 1; Bandibas and Takarada, 2019), (2) promote high-quality digitization of geoscience data in the CCOP member countries and (3) establish a geoinformation sharing system in Asia. The project aims to share a wide array of geoscientific information on the GSi system such as geology, geohazards, geophysics, mineral resources, geo-environment, groundwater, topography and remote sensing data to the world (Figure 2). The duration of the project is from 2015 to 2020. The first version of the GSi system was officially opened to the public during the 3rd CCOP GSi International Workshop in Langkawi, Malaysia on September 18-20, 2018 (Figure 3). 2. Major goals of the GSi project The major goals of the GSi project are subdivided into four target areas: (1) geoinformation sharing, (2) delivery of geoscience knowledge to society, (3) international standardization, and (4) capacity building. Geoinformation sharing aims to enhance the collaboration and communication among the CCOP member countries, to establish the comprehensive database in East and Southeast Asia, to create a data archive, to promote digitization, and to provide data analysis tools on the web. Delivery of geoscience knowledge to society aims to make geoscience information relevant and useful for society, to increase user accessibility, to provide the information on hazard mitigation and geo-environment, to make geoscience data freely available and understandable to users, and to provide visualization tools and data for outreach programs. 147 Shinji Takarada, et. al., Constructing a comprehensive geoscience database in East and Southeast Asia: CCOP Geoinformation Sharing Infrastructure for East and Southeast Asia (GSi) Project Figure 1. The main portal site of the GSi System (https://ccop-gsi.org/main/). Figure 2. The concept of the CCOP Geoinformation Sharing Infrastructure Project. 3. GSi main and portal sites The GSi main portal site (Figure 1) provides web-based functions for spatial data rendering and analysis using WMS and WPS, respectively. It can also be used to download data in several formats (KML, PNG and PDF). The system follows the standard model of the Spatial Data Infrastructure (SDI). The system also provides the interface for the creation of a customized WebGIS portal for spatial data viewing and processing. Currently more than 15 portal sites which include member country’s sites, CCOP Groundwater, ASEAN Mineral Resources, and OneGeology covering East Asia are generated (Figs. 4 and 5). 148 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Figure 3. Work plan of the CCOP Geoinformation Sharing Infrastructure Project. Figure 4. The portal site of GSJ, Japan (https://ccop-gsi.org/gsi/gsj_webgis/). More than 740 maps are saved on the GSi system (15 Sep. 2019). The maps include the following: 1:50k-1:10M geological maps, 1:200k-1:1M seamless geological maps, 1:10k-1:50k geological map of volcanoes, 1:10k-1:50k hazard zoning maps (earthquake, liquefaction, tsunami, volcano, flood and landslide), 1:1M seismotectonic map, 1:50k coastal erosion map, 1:250k Quaternary geology map, 1:1M geochemical map, 1:1M magnetic anomaly map, 1:750k-1:1M groundwater map, 1:50k hot spring distribution map, 1:250k-1:1M mineral resources map, ASTER satellite data, 1:100k road map, and 1:50k city map. The maps can also be viewed using GIS software and other Web Mapping Service clients (Figure 6). Mobile version of GSi system is also available (Figure 7). 149 Shinji Takarada, et. al., Constructing a comprehensive geoscience database in East and Southeast Asia: CCOP Geoinformation Sharing Infrastructure for East and Southeast Asia (GSi) Project Figure 5. OneGeology Portal covering East Asia (https://ccop-gsi.org/gsi/onegeologyasia/). Figure 6. 1:200k Seamless Geological Map of Japan WMS displayed using QGIS software. Figure 7. The mobile version of COOP GSi main site (https://ccop-gsi.org/gsi-mobile). 150 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Currently, the GSi project has four cloud servers: the CCOP GSi, GSJ Geoinfo, Geological Agency of Indonesia, and the MGB servers. The GSi system will also host and provide data for some applications and data analysis tools. Several mobile applications related to seismic and geological hazard mapping, field data capture and spatial data analysis are being developed. In addition, collaboration with other projects such as OneGeology, ASEAN Mineral Resources Projects, and those implemented by CCOP such as Groundwater, CCS-M, and KIGAM Unconventional Oil & Gas Resources Project is ongoing. Data publicly available in the country’s portals are listed below (Figures 8-18). Cambodia (Figure 8) Malaysia (Figure 12) • 1:750,000 Mineral Resources Map • 1:1M Geological Map of Peninsular Malaysia • 1:750,000 Geological Map (Fault & Lithology) • 1:200,000 Quadrangle Geological Map (14 • 1:1M Geological Map of Sabah (Fault & Sheets) Lithology) • 1:1M Fault Map • 1:1M Geological Map of Sarawak (Fault & Indonesia (Figure 9) Lithology) • 1:1M Geological Map of Indonesia • Mineral Resources of Malaysia • 1:100,000 Geological Map of Sumatra Myanmar (Figure 13) • 1:100,000 Geological Map of Lesser Sunda • 1:1M Seismic Hazard Map Islands • 1:1M Structure Map (2008) • 1:100,000 Geological Map of Java Papua New Guinea (Figure 14) • 1:1M Metallic Mineral Occurrence Map • Structure Map • 1:1M Non-Metallic Mineral Occurrence Map • PNG Rock Chip Samples (Co, Cu, Au, Ni, Ag, • Groundwater Map Zn) Japan (Figure 4) • Soil Samples (Co, Cu, Au Ni, Ag, Zn) • 1:10M Asia Geological Maps • Stream Samples (Co, Cu, Au, Ni, Ag, Zn) • 1:2M – 1:200K Geological Maps of Japan • Mineral Occurrences • 1:200K Geological Maps of Japan Philippines (Figures 15, 16) • 1:50K Geological Maps of Japan • 1:1M Limestone • 1:10M Asia Hazards Information • 1:1M Metallic Mineral Distribution • 1:1M Geochemical Map of Japan • 1:1M Mineral Potential • 1:2M Volcanoes of Japan, 3rd Edition • 1:1M Mineral Reservation • 1:10K – 1:50K Geological Maps of Volcanoes • 1:1M Non-Metallic Mineral Distribution in Japan • 1:10K Flood Susceptibility Korea (Figure 10) • 1:10K Landslide Susceptibility • KIGAM Earthquake Map • Ground Subsidence (Western Bohol) • 1:250K KIGAM Geological Map (Boundary, • 1:1M Geological Map Fault & Lithology) • 1:1M Groundwater Availability Map • KIGAM Isotope Rock Samples • Distribution of Volcanoes • KIGAM Lineament Map • Liquefaction Hazard Map • KIGAM Submarine Geological Map • Multi-scale Active Faults Map • KIGAM Geochemical Map • Tsunami Prone Areas • KIGAM Geophysical Map • Pinatubo Volcano Lahar Hazard Map Lao PDR (Figure 11) • Ballistic Projections Map • 1:1M Geological Map • Base Surge Hazard Map • 1:1M Mineral Occurrence Map • Danger Zone Areas of Volcanoes • 1:200K Geological Map of Northern Laos • Lahar Hazard Map • 1:50K Geophysical Raster (Luang Prabang) • Lava Flow Hazard Map Vietnam (Figure 18) • Pyroclastic Flow, Density current and Surge • 1:1M Geological Map Hazard Map • 1:1M Mineral Occurrence Map • 1:1M Groundwater Map 151 Shinji Takarada, et. al., Constructing a comprehensive geoscience database in East and Southeast Asia: CCOP Geoinformation Sharing Infrastructure for East and Southeast Asia (GSi) Project Thailand (Figure 17) • Geological Map (1M, 250K & 50K) • 1:50K Mineral Resources • Active Crust and Geohazard (Active Fault, • Topographic Maps (Highway, Hydrology, Gridded Landslide Hazard, Potential Sinkhole, GDEM, City, Province, Railway) Shoreline Erosion, Hot Spring Distribution) • 1:1M Nation-wide Airborne Geophysical • 1:1M Harmonized Geology of Indo-China Survey mainland Figure 8. The portal of DGMR, Cambodia, https:// Figure 9. The portal of Geological Agency, ccop-gsi.org/gsi/cambodia/. Indonesia, https://ccop-gsi.org/gsi/idn/. Figure 10. The portal of KIGAM, Korea, https:// Figure 11. The portal of DGM, Lao PDR, ccop-gsi.org/gsi/kigam1000/. https://ccop-gsi.org/gsi/Lao/. Figure 12. The portal of JMG, Malaysia, Figure 13. The portal of DGSE, Myanmar, https://ccop-gsi.org/gsi/mys_ccopgsi_portal/. https://ccop-gsi.org/gsi/myanmar/. 152 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Figure 14. The portal of MRA, Papua New Guinea, Figure 15. The portal of MGB, the Philippines, https://ccop-gsi.org/gsi/pngwebgisportal/. https://ccop-gsi.org/gsi/phl_mgb/. Figure 16. The portal of PHIVOLCS, the Philippines, Figure 17. The portal of DMR, Thailand, https://ccop-gsi.org/gsi/phivolcs/. https://ccop-gsi.org/gsi/thailand/. Figure 18. The portal of GDGMV, Vietnam, https://ccop-gsi.org/gsi/vietnam/. 4. CCOP GSi international workshops The GSi project was initiated by the CCOP member countries in 2015. The kick-off meeting was held on September 1-2, 2015 in Bangkok, Thailand and the 1st CCOP GSi International Workshop was held in Solo, Indonesia on September 20-22, 2016. The project plan, data policy and future strategies were discussed and subsequently the GSi system was introduced during the 52nd Annual Session in Bangkok, Thailand on October 31 - November 3, 2016. The 2nd International Workshop was held at Luang Prabang, Lao PDR on December 5-7, 2017. This was co-funded by the Ministry of Energy and Mines (MEM), Lao PDR. Twenty-two (22) participants from the CCOP member countries (Cambodia, Japan, Republic of Korea, Lao PDR, Malaysia, Myanmar, Papua New Guinea, Philippines, Thailand and Vietnam) and CCOP TS attended the workshop. The future activities and strategy of the project were discussed. A training course on mobile applications and field data capturing system was also conducted. 153 Shinji Takarada, et. al., Constructing a comprehensive geoscience database in East and Southeast Asia: CCOP Geoinformation Sharing Infrastructure for East and Southeast Asia (GSi) Project Figure 19. The 3rd CCOP GSi International Workshop at Langkawi, Malaysia. The 3rd International Workshop was held in Langkawi, Malaysia on September 18-20, 2018 (Figure 19). This was co-funded by the Department of Mineral and Geoscience (JMG), Malaysia. Forty-three (43) participants from the CCOP member countries (Cambodia, Indonesia, Japan, Republic of Korea, Lao PDR, Malaysia, Myanmar, Papua New Guinea, Philippines, Thailand and Vietnam) including CCOP TS attended the workshop. The GSi main portal and customized portal sites (Figures 8-18) were officially opened to the public on the first day of the workshop. Scheduling the important activities in the next two years, including, specific goals, mobile system, GSi country portals, development team, hazard information system, natural resource information system, and collaboration with other major spatial information-related projects were discussed. The 4th International Workshop was held in Siem Reap, Cambodia on October 1-3, 2019. The Ministry of Mines and Energy (MME) of Cambodia hosted the activity. 5. Conclusions The GSi project has successfully developed a comprehensive Asian geoscience database and infrastructure in collaboration with the CCOP member countries. The project aims to promote (1) geoinformation sharing, (2) delivery of geoscience knowledge to society, (3) international standardization, and (4) capacity building. The website of the GSi system was officially opened to the public on September 18, 2018. More than 740 data in 15 WebGIS portal sites from 11 countries are currently available on the CCOP GSi system. Overcoming each country’s regulatory restrictions for sharing geoscience information online is one of the most important challenges in the implementation of this project. Many countries allow data download, but some intend to share their data just for web page viewing. This is the reason why the information system provides options for the data owners to decide who can view, edit and download GIS data they entered to the web-based spatial database. Another challenge is the training of the participants on how to use the information system. Sharing data using the GSi 154 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand system requires knowledge about GIS, WMS formulation and structured query language (SQL), which most participants are not knowledgeable. We addressed this issue by conducting regular trainings on how to use the system, spatial data processing and WMS formulation. References Bandibas, J.C. and Takarada, S. (2019) Geoinformation Sharing System for East and Southeast Asia using SDI, OGC Web Services and FOSS. International Journal of Geosciences 10, p. 209-224. 155 156 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Formulating Web Processing Service (WPS) and Web Map Service (WMS) for the Processing and Sharing of ASTER Satellite Data Using the GSi Information System Joel Bandibas and Shinji Takarada Geological Survey of Japan, AIST, Tsukuba, Japan E-mail: [email protected] Abstract The GSi information system provides a wide range of geospatial information for a wide variety of research undertakings in the fields of social, biological and physical sciences. Including remote sensing data among the information available in the system has multiple applications and is important for environmental change monitoring, rapid mapping for areas affected by natural disasters and the management and sustainable use of natural resources. This paper focuses on the development of an innovative method of formulating Web Processing Service (WPS) and Web Map Service (WMS) for the processing and sharing of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data using the GSi system. The web-based user interface for the formulation of important satellite image processing operations including linear stretching and false-colour composite formulation is developed and packaged as a separate module in the GSi system. This interface provides users access to the WPS that will carry out satellite image processing on the GSi server. Furthermore, the module can also be used to generate satellite data map layer as a WMS. Using GSi’s ASTER module, many satellite map layers are now available in the GSi system. The data are mainly used for land-use change monitoring and vegetation cover mapping. The ASTER data is provided by MADAS (METI AIST Data Archive System) athttps:// gbank.gsj.jp/madas/map/ and the GSi main portal can be accessed at https://ccop-gsi.org/main/. Keywords: Reservoir compartmentalization, Reservoir connectivity, Carbonate rocks, Sequent stratigraphy, Ngimbang Formation, North East Java. 1. Introduction Making geoscience information readily available and accessible is very important for a wide range of activities to protect the environment and mitigate the effects of natural disasters. Developing a web-based spatial information system, using Free and Open Source Software (FOSS) and international standards, provides a cost effective and efficient platform to provide relevant information for these kinds of studies (e.g. Bandibas and Takarada, 2019; INSPIRE, 2019; OneGeology, 2019). The CCOP Geoinformation Sharing Infrastructure for East and Southeast Asia (GSi) project was implemented to develop a web-based spatial information system for sharing geoscience information among the countries in East and Southeast Asia. It follows the Spatial Data Infrastructure model (Stefanakis and Prastacos, 2008) and uses the Open Geospatial Consortium (OGC) Web Processing Service (WPS) and Web Map Service (WMS) as shown in Figure 1. The GSi information system was officially launched in Langkawi, Malaysia in 2018. More than 690 maps are currently stored in the GSi database and more than 15 GSi generated Web-GIS portals use the data for geospatial information processing and sharing. Figure 2 shows the GSi main portal at https://ccop-gsi.org/main/. Remote sensing data are very useful for environmental change monitoring and rapid mapping of areas affected by natural disasters. The information can also be used to quantify some important environmental parameters such as biomass and soil moisture content and the extent of the area 157 Joel Bandibas and Shinji Takarada, Formulating Web Processing Service (WPS) and Web Map Service (WMS) for the Processing and Sharing of ASTER Satellite Data Using the GSi Information System destroyed by forest fire. Incorporating remote sensing data with other geospatial information can also aid landslide susceptibility mapping (Kawabata and Bandibas, 2009). Including remote sensing data among the information available in the GSi database will therefore make the information system more useful to a broader range of research applications. This paper presents an innovative method of incorporating Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) into the GSi database. The procedure on ASTER data upload, separation of individual satellite bands and the computation of their frequency distribution and false color composite formulation will be explained. The formulation of the Web Processing Service (WPS) and Web Map Service (WMS) to process satellite data and render satellite images on the GSi system will also be presented. Figure 1. Major components of GSi following the SDI Model. Figure 2. The main page of the GSi information system. 158 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand 2. ASTER Satellite Data The ASTER data used by the GSi system are obtained from the publicly accessible METI AIST Satellite Data Archive System (MADAS) at https://gbank.gsj.jp/madas/. An ASTER scene data, which covers a 60km by 60km area, obtained from the site is in GeoTIFF format compressed as TAR file. Each TAR file can contain the ASTER bands as shown in Table 1, satellite scene metadata and a generated DEMZ data. Table 1. The ASTER Bands (Wikipedia, 2019). 3. Web Processing Service (WPS) for ASTER Data Processing The WPS provides a standard interface that simplifies the task of making simple or complex geospatial processing using HTTP. It provides robust, interoperable, and versatile protocols for process execution of web services (OGC, 2019a). Data processing is executed by sending WPS request to the server where PHP scripts and other software are executed to perform the task. The following are the WPS formulated to provide GSi users the tools to upload, process, view and integrate ASTER satellite data to the GSi system. 3.1 ASTER Data Upload and Registration A WPS is formulated to upload the ASTER data in TAR format to the GSi server, to unpack or decompress the file and parse through the scene metadata to determine the satellite extent, projection and other important information. Figure 3 shows the form to register the satellite image after uploading the data to the GSi server. It contains important information like the satellite data acquisition date, extent and the available satellite bands. Once the data are registered, it will be available for satellite image processing and display using the GSi system. 159 Joel Bandibas and Shinji Takarada, Formulating Web Processing Service (WPS) and Web Map Service (WMS) for the Processing and Sharing of ASTER Satellite Data Using the GSi Information System 3.2 Determining ASTER Bands Pixel Values Frequency Distribution Displaying satellite images for visual interpretation requires information about the satellite bands pixel values frequency distribution. The information is needed to recalculate the band’s pixels values so that the satellite image, either as a single band or color composite, will be displayed with good contrast. A WPS is formulated to read a satellite band and generate the frequency distribution and display the corresponding histogram on screen. Choosing a satellite band on the list will trigger the implementation of the WPS. Figure 4 shows the form to generate the chosen ASTER band’s pixel value frequency distribution and display the corresponding image histogram as shown in Figure 5. This will help the user determine the values of the image stretching parameters. Satellite image can be viewed to check if the contrast is good for satellite image visual interpretation. Figure 6 shows the difference between un-stretched and stretched satellite image. Stretched satellite image can improve contrast and reveal more information for visual interpretation. Figure 3. The GSi ASTER data registration form. Figure 4. The interface to formulate ASTER data WMS. 160 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Figure 5. Satellite image histogram. Figure 6. ASTER band VNIR3N displayed as A) unstretched and B) stretched satellite image. 3.3 Formulating Satellite Image Color Composite Satellite color composite images are the result of the combination of three satellite bands, each of which is assigned the colors red, green and blue and provide additional information about the area under investigation. ASTER color composite generally uses the visible to near infrared bands. A WPS is formulated to enable the user to generate color composite images of the chosen ASTER satellite image. Figure 7 shows the user interface to use the service. A user can choose any band to be assigned with red, green and blue color. The WPS in determining the band frequency distribution and stretching parameters can also be executed using the interface. Figure 8 shows the color composite satellite image covering Aso volcano, generated using the WPS. 161 Joel Bandibas and Shinji Takarada, Formulating Web Processing Service (WPS) and Web Map Service (WMS) for the Processing and Sharing of ASTER Satellite Data Using the GSi Information System Figure 7. The interface of the WPS to formulate ASTER satellite color composite image. Figure 8. ASTER color composite covering Aso volcano, Kyushu, Japan. 4. Formulating Web Map Service (WMS) to Integrate ASTER Satellite data to GSi WMS provides a simple Hypertext Transfer Protocol (HTTP) interface for requesting geo- registered map images from one or more distributed databases (OGC, 2019b). Figure 9 shows the main components of WMS. Integrating satellite data into the GSi display system requires the formulation of WMS of the satellite data. A WPS is formulated to automatically generate WMS of ASTER single band or color composite image. Figure 7 shows the form to prepare the satellite image for WMS formulation. Submitting the form will execute the WPS to generate WMS of chosen satellite image. This will also show the satellite image WMS metadata form as shown in Figure 10. Submitting this form will register the WMS of the satellite image to the GSi system. The satellite WMS layer will also be included in GSi’s list of available maps. Figure 11 shows the registered WMS of the ASTER color composite image covering Aso volcano, displayed on the main page of the GSi portal. Users can use the layer to overlay with other maps to derive more information about the area of interest. 162 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand Figure 9. Web Map Service. Figure 10. The WMS metadata form to register ASTER satellite data to the GSi system. 5. Discussion The GSi information system is presently sharing a huge volume of geoscience information from the countries in East and Southeast Asia. Making ASTER satellite images available in the system increases its utility for important research undertakings like environmental change monitoring and the mitigation of the effects of natural disasters. The ASTER satellite data module has been successfully formulated and integrated into the GSi system. It provides users easy access to the web services formulated to process, view and integrate ASTER satellite data to the GSi system. Figure 12 shows the list of registered ASTER satellite data in GSi. Users can choose any satellite scene on the list and process and view the data. Users can also choose any satellite scene in the MADAS site and upload the data to the GSi server. The uploaded satellite data will be automatically included in the list of registered ASTER data in GSi. The list of satellite data registered in the GSi system is steadily increasing since the integration of the ASTER module in 2018. This makes the GSi information system an important web-based platform to study the environment using remote sensing data. 163 Joel Bandibas and Shinji Takarada, Formulating Web Processing Service (WPS) and Web Map Service (WMS) for the Processing and Sharing of ASTER Satellite Data Using the GSi Information System Figure 11. ASTER satellite color composite covering Aso volcano, registered as a WMS in GSi. Figure 12. The list of ASTER satellite images registered in the GSi system. 164 Thematic Session “Geosciences for Sustainable Development” 55th CCOP Annual Session, 5-6 November 2019, Chiang Mai, Thailand 6. Conclusion The ASTER satellite data module is successfully integrated into the GSi system. The module provides user friendly interface to easily access the WPS and WMS formulated to upload, process and view satellite images using the GSi system. This enhances GSi as a powerfuland useful web- based system to the study the environment using remote sensing data. References Bandibas, J. and Takarada, S., 2019. Geoinformation sharing system for East and Southeast Asia using SDI, OGC Web services and FOSS. International Journal of Geosciences, 10, 209-224. INSPIRE, 2019. https://inspire-reference.jrc.ec.europa.eu/vocabularies/scope/webgis (Accessed 10 September 2019). OGC, 2019a. http://www.opengeospatial.org/standards/wps (Accessed 10 September 2019). OGC, 2019b. http://www.opengeospatial.org/standards (Accessed 10 September 2019). OneGeology, 2019. http://www.onegeology.org/ (Accessed 10 September 2019). Stefanakis, E., and Prastacos, P., 2008. Development of an open source-based spatial data infrastructure. Applied GIS, 4(4), 1-26. Kawabata D., and Bandibas, J., 2009. Landslide susceptibility mapping using geological data, a DEM from ASTER images and an Artificial Neural Network (ANN). Geomorphology, 113, 97-109. Wikipedia, 2019. https://en.wikipedia.org/wiki/Advanced_Spaceborne_Thermal_Emission_and_ Reflection_Radiometer (Accessed 10 September 2019). 165