Isao Takashima

Thermoluminescence dating of calcite shells in the pectinidae family

Abstract Previously we investigated the thermoluminescence (TL) of a calcite shell, Pectinidae Pecten (Notovola) albicans (Schroter) (abbreviated to albicans), and we found that TL dating was possible for fossil calcite shells of albicans from 5 × 10 5 years ago to the present. In the present work, we investigate the TL emission spectra and the first glow-growth of 5 other species in the Pectinidae family, and it is found that the TL characteristics of these species are the same as those of the albicans. This means that the application of TL dating can be extended to these species. Furthermore, we tried to date fossil calcite shells older than 5 × 10 5 years ago, and we found that the upper limit for TL dating of fossil calcite shells is about 6 × 10 5 years.

Chapter 22 Remote sensing and GIS studies of alteration and predictive mineral exploration in the Central Volcanic Arc, Myanmar

The objective of this study is to identify alteration associated with ore deposits for predictive mineral exploration in the Central Volcanic Arc Belt (CVAB) ofMyanmar (Figs 22.1 & 22.2). Modern techniques such as remote sensing (RS) and geographical information systems (GIS) were used to delineate structural lineaments and the hydrothermal alteration of the ore deposits. Landsat TM imagery and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) are now used more routinely for mineral exploration and shortwave infrared (SWIR) channels can be applied to detect associated altered mineral assemblages. Landsat and ASTER data are also applied to map iron oxides, structure and alteration minerals, and predict zones of mineralization potential as well as recognize different lithologies. This method is applicable to other mineralized areas in Myanmar where the potential is currently unknown. The Department of Geological Survey and Mineral Exploration (DGSE), Ministry of Natural Resources and Environmental Conservation, Myanmar is carrying out geological mapping and mineral prospecting in remote areas of Myanmar where it is not possible to cover large areas in a short period of time. Geological mapping and mineral exploration are required in mountainous terrains in the remote border regions of Myanmar. The use of modern techniques such as RS and GIS for geological survey is necessary in order to complete geological mapping of the whole country. Analysing and processing satellite imagery provide fast and effective methods for achieving this goal. Exploration geologists are engaged not only in the search for new mineral deposits, but also in the reassessment of existing deposits in order to identify the extent of ore bodies and mineralized zones. In its broadest sense, hydrothermal activity is responsible for chemical alteration of minerals over large areas of metallic ore deposits. In the early stages of exploration programmes, the detection of hydrothermal systems and alteration footprints provides a useful indication in the search for ore deposits. The identification of areas prospective for gold and copper mineralization within the CVAB will stimulate foreign investment in the country, resulting in job creation for metal mining and downstream industries. This will contribute to economic development and improve the living standards of the local people in impoverished rural areas. Landsat TM imagery has also been used routinely for mineral exploration as the associated altered mineral assemblages are detectable from the two SWIR channels (Podwysocki et al. 1984; Sabins 1997; Abdelsalam et al. 2000). New spaceborne multispectral and hyperspectral remote sensing instruments have been launched over the past decade, and have provided higher spectral resolution data that can be used for mineral exploration. In addition, the availability of laboratory-measured spectral data for rocks and minerals complements remote spectral measurements, and allows geologists to identify unique lithologies (e.g. JPL, USGS and ASU spectral libraries). These recent developments have enabled remote sensing technology to become an increasingly important tool for mineral exploration, particularly in remote areas with little or no access or areas that lack detailed topographic or geological base maps. ASTER is a multispectral imager that was launched on board NASA’s Terra spacecraft in December 1999. ASTER covers the visible, near-infrared (VNIR), SWIR and thermal infrared (TIR) spectral regions, with 14 channels yielding high spatial, spectral and radiometric resolution (Yamaguchi et al. 1998; Abrams & Hook 2001). The spatial resolution varies with wavelength; each ASTER image covers an area of 60 × 60 km. The ASTER channels are more spectrally contiguous than other multispectral sensors such as the Landsat 5 Thematic Mapper and the Landsat 7 Enhanced Thematic Mapper, especially in shortwave and thermal infrared wavelength ranges. The ASTER sensor can therefore achieve a higher degree of accuracy in the spectral identification of rocks and minerals (Crosta & Filho 2003). Previous studies indicate that ASTER data compare favourably with other similar sensors for lithological mapping (Zhang & Pazner 2007). Also, the ASTER sensor was the first spaceborne instrument with a high-resolution multispectral TIR subsystem, capable of differentiation between surface minerals based on spectral emissivity variations. Because of the low cost, large area of coverage and availability of ASTER data, it is an ideal tool for application in mineral exploration for mapping lithological and mineralogical units on the surface.The objective of this study is to identify alteration associated with ore deposits for predictive mineral exploration in the Central Volcanic Arc Belt (CVAB) of Myanmar (Figs 22.1 & 22.2). Modern techniques such as remote sensing (RS) and geographical information systems (GIS) were used to delineate structural lineaments and the hydrothermal alteration of the ore deposits. Landsat TM imagery and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) are now used more routinely for mineral exploration and shortwave infrared (SWIR) channels can be applied to detect associated altered mineral assemblages. Landsat and ASTER data are also applied to map iron oxides, structure and alteration minerals, and predict zones of mineralization potential as well as recognize different lithologies. This method is applicable to other mineralized areas in Myanmar where the potential is currently unknown. Fig. 22.1. Map showing regional tectonic setting of Central Volcanic Arc Belt (CVAB), Myanmar. Fig. 22.2. Map showing detailed mineral occurrences in the Monywa and Kawlin–Wuntho areas along the CVAB, Myanmar. The Department of Geological Survey and Mineral Exploration (DGSE), Ministry of Natural Resources and Environmental Conservation, Myanmar is carrying out geological mapping and mineral prospecting in remote areas of Myanmar where it is not possible to cover large areas in a short period of time. Geological mapping and mineral exploration are required in mountainous terrains in the remote border regions of Myanmar. The use of modern techniques such as RS and GIS for geological survey is necessary in order to complete geological mapping of the whole country. Analysing and processing satellite imagery provide fast and effective methods for achieving this goal. Exploration geologists are engaged not only in the search for new mineral deposits, but also in the reassessment of existing deposits in order to identify the extent of ore bodies and mineralized zones. In its broadest sense, hydrothermal activity …