3D Mineral mapping of Queensland - Version 2 ASTER and related geoscience products

The digital 3-dimenional (3D) mineral mapping suite of Queensland comprises ~20 “standardized” products at the spectral resolution of the ASTER (Advanced Space-borne Thermal Emission and Reflection Radiometer) sensor and generated from publicly-available satellite, airborne, field and drill core spectral data spanning the visible near infrared (VNIR; 0.4 to 1.0 µm), shortwave infrared (SWIR; 1.0 to 2.5 µm) and thermal infrared (TIR; 7.5 to 12.0 µm) wavelength regions, including:
1. Satellite ASTER maps at both 30 m and 90 m pixel resolution with complete coverage of the state of Queensland, i.e. 1.853 million km²;
2. Airborne HyMap maps at ~5 m pixel resolution with a coverage of ~25,000 km2 from areas across north Queensland;
3. Field point samples (~300) from the National Geochemical Survey of Australia (NGSA) collected from a depth of 0-10 cm of flood overbank sediments;
4. Drill-core profiles (~20) of the National Virtual Core Library (NVCL) selected from the area around the Georgetown seismic line (07GA-IG2).
Key to the processing of the remote sensing data-sets (ASTER and HyMap) was the implementation of unmixing methods to remove the effects dry and green vegetation. This unmixing was not applied to the Australian ASTER geoscience maps released in 2012 (called here Version 1 or V1) resulting in extensive areas with little/no mineral information because of the need to apply masks. The vegetation unmixing methods used in the Version 2 (V2) processing of the ASTER and HyMap imagery has resulted in very few areas without coherent mineral information.
The resultant V2 “mineral group” products were designed to measure mineral information potentially useful for mapping: (i) primary rock composition; (ii) superimposed alteration effects; and (iii) regolith cover. These V2 products may assist in mapping soil properties and groundwater conditions. However their relatively low spectral resolution (based on ASTER’s 14 VNIR-SWIR-TIR bands) means that they do not provide the high level of mineralogical detail available from hyperspectral systems (>100 spectral bands), like HyMap and the HyLogger. Nevertheless, the relatively low spectral resolution of ASTER means that all other sensor data can be spectrally resampled to that resolution. Furthermore, the ASTER global data archive, which now spans entire Earth’s land surface <80degrees latitude, means that it can be used as global base-map for integrating all other spectral data.

昆士兰州数字三维（3D）矿物制图套件包含约20种“标准化”产品，其光谱分辨率与ASTER（先进星载热发射和反射辐射计）传感器一致，由覆盖可见近红外（VNIR；0.4至1.0微米）、短波红外（SWIR；1.0至2.5微米）和热红外（TIR；7.5至12.0微米）波长区域的公开可用卫星、机载、野外和岩心光谱数据生成，包括：
1. 卫星ASTER地图，分辨率分别为30米和90米，覆盖昆士兰州全境（即185.3万平方公里）；
2. 机载HyMap地图，分辨率约5米，覆盖昆士兰州北部区域约25,000平方公里；
3. 澳大利亚国家地球化学调查（NGSA）的野外点样本（约300个），采集自泛滥平原沉积物0-10厘米深度；
4. 国家虚拟岩心库（NVCL）的岩心剖面（约20个），选自乔治敦地震测线（07GA-IG2）周边区域。

处理遥感数据集（ASTER和HyMap）的关键在于应用解混方法以消除干旱和绿色植被的影响。这种解混方法未应用于2012年发布的澳大利亚ASTER地学地图（本文称为版本1或V1），由于需要施加掩膜，导致大片区域几乎没有或完全没有矿物信息。在ASTER和HyMap影像的版本2（V2）处理中使用的植被解混方法，使得几乎没有区域缺乏连贯的矿物信息。

最终的V2“矿物组”产品旨在测量可能用于制图的矿物信息，包括：（i）原生岩石成分；（ii）叠加的蚀变效应；（iii）风化层覆盖。这些V2产品可能有助于绘制土壤属性和地下水状况图。然而，其相对较低的光谱分辨率（基于ASTER的14个VNIR-SWIR-TIR波段）意味着它们无法提供像HyMap和HyLogger等高光谱系统（>100个光谱波段）所能提供的高水平矿物学细节。尽管如此，ASTER相对较低的光谱分辨率意味着所有其他传感器数据都可以在光谱上重采样至该分辨率。此外，ASTER全球数据档案库目前覆盖纬度<80度的整个地球陆地表面，这意味着它可以作为整合所有其他光谱数据的全球底图。