Mineral Assemblages Mapping Of Porphyry Copper Deposits Based On Normalized Multispectral Remote Sensing Data In The Dulong Ore Concentrating Area

ASTER data is a preferred data source for large-area alteration minerals mapping due to its wide coverage,large archive data,high signal-to-noise ratio,easy acquisition,high spatial resolution,and high spectral resolution.In addition,clay minerals can be apparently discriminated by its six SWIR band data.However,the OLI data has five spectral bands in the VNIR spectral range,with increasing in spectral coverage and improving in the spectral resolution and signal-to-noise ratio,which significantly improves the ability to identify Fe³⁺minerals within VNIR spectral interval.On the basis of pseudo-invariant feature method,the four scenes ASTER data are seamlessly mosaiced by radiometric normalization method in the Dulong ore concentrating area.The analysis of the typical mineral USGS and field sampling spectral curves in the area is combined with the OLI data.On that condition,MTMF method is used to extract the alteration minerals?combination?information of the surface at the same scale.Besides,the multi-spectral remote sensing alteration zoning of each ore deposit in the Dulong ore concentrating area is divided and the characteristics of the alteration zone are summarized.Above all,the main conclusions are as following:?1?The results show that the image of the four scenes in the Dulong ore concentrating area has a good effect of radiometric normalization.It effectively eliminates the influence of seasonal ground radiation changes,solar lighting conditions,atmospheric scattering,absorption,and cloud cover changes.It also provides reliable basic images for the extraction of large-area alteration minerals?combination?information at the same radiation level.?2?The remote sensing surface alteration zones are consistent with the field survey results.The multispectral remote sensing surface alteration zones of various deposits in the Dulong ore concentrating area meet the zoning characteristics from the interior to the exterior are:?1?muscovite+kaolinite/montmorillonite;?2?kaolinite/montmorillonite;?3?chlorite+epidote.There is a good spatial relationship between the alteration belts in each deposit,which correspond to the porphyry copper deposits:?1?the phyllic+the argillic zone;?2?the argillic zone;?3?the prophylitic zone respectively.?3?In the southern part of the Dulong ore concentrating area,roughly 8km and10km away from the Dibaonamugang deposit,remote sensing surface alteration zones from the interior to the exterior are are:?1?muscovite+kaolinite/montmorillonite;?2?kaolinite/montmorillonite;?3?Fe³⁺minerals;?4?chlorite+epidote,which has a good spatial relationship between the alteration zones.It corresponds to the porphyry copper deposits:?1?the phyllic+the argillic zone;?2?the argillic zone;?3?th prophylitic zone respectively,which has similar alteration zone characteristics with other deposits in the region.So the suggestion is that it may emerge as a key exploration area for next step.