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141.
142.
Glen S. Mattioli Pamela E. Jansma Lorna Jaramillo Alan L. Smith 《Bulletin of Volcanology》1996,58(5):401-410
A desktop image processing and photogrammetric method was developed for digitizing black-and-white aerial photographs. The
technique was applied to airborne optical images of Mt. Pelée, Martinique, a historically active volcano in the tropical Lesser
Antilles island arc, to evaluate its utility for rapid geologic mapping and hazard assessment in vegetated areas. The digital
approach provides several advantages over traditional air-photo interpretation by allowing for change detection in time-series
images, morphologic characterization, development of digital elevation models from stereopairs, and geo-referencing with other
digital data sets. A digital mosaic of Mt. Pelée was created from air photos acquired in 1951, which covered the region affected
by the 1902 eruption. Severe mismatches occurred along edges of adjacent photographs prior to correction, which precluded
quantitative morphologic analysis of the volcanic edifice. Geometric corrections and histogram equalization of digitized air
photos allowed creation of a continuous mosaic. Comparison of the mosaic and a map based on differences in gray scale and
texture to a volcanostratigraphic map revealed that not only the various deposits produced during the 1902 event were easily
differentiated, but that older eruptive products were identified, suggesting that this approach may be used for rapid hazard
evaluation of historically active tropical volcanoes.
Received: 22 January 1996 / Accepted: 26 July 1996 相似文献
143.
Victor B. Maglambayan Sj Montes Katherine Hipol Maireen Mamitag Rikki Pamela Pineda Raymond Rodolfo Noel Oliveros Antonio Sy 《Resource Geology》2005,55(3):145-154
Abstract. Three calcareous sedimentary rock-hosted Carlin type-like gold prospects were mapped in a mineral production sharing agreement area of Philex Gold Philippines Inc. in Taganaan municipality, Surigao del Norte province in Mindanao island in the Philippines. They occur along a 20–25 km long trend of known epigenetic gold and porphyry copper deposits that lie close to several splays of the Philippine Fault Zone. The gold district forms part of the Late Cretaceous Eastern Mindanao Range that hosts early Paleogene and late Pliocene to Quaternary intrusive rocks.
Gold is invisible in the jasperoid outcrops in Lascogon, Napo, and Danao prospects. The jasperoids occur in lenses of marls belonging to the Taganaan Marl Member that is associated to a turbiditic member of the Middle Miocene Mabuhay Formation. The marl lenses include gently dipping interbedded silty limestones and calcareous shales. The "invisible gold" mineralization in silicified calcareous rocks resembles Carlin-type deposits. Based on the mapped igneous and sedimentary rocks, a possible heat source for the gold mineralization is either or both of the two main phases of intrusion, Mabuhay An-desite or Alipao Andesite Porphyry. Forty-eight rock samples, fifteen stream sediment samples, and one soil sample were critical in delineating the general features of the potential Carlin-type prospects. The gold grades of jasperoids in the three prospects range from trace amounts to 20 g/t Au. Regional studies of gold and porphyry copper mineralization in the Surigao del Norte mineral district are important in delineating ore targets for drilling in the three prospects. 相似文献
Gold is invisible in the jasperoid outcrops in Lascogon, Napo, and Danao prospects. The jasperoids occur in lenses of marls belonging to the Taganaan Marl Member that is associated to a turbiditic member of the Middle Miocene Mabuhay Formation. The marl lenses include gently dipping interbedded silty limestones and calcareous shales. The "invisible gold" mineralization in silicified calcareous rocks resembles Carlin-type deposits. Based on the mapped igneous and sedimentary rocks, a possible heat source for the gold mineralization is either or both of the two main phases of intrusion, Mabuhay An-desite or Alipao Andesite Porphyry. Forty-eight rock samples, fifteen stream sediment samples, and one soil sample were critical in delineating the general features of the potential Carlin-type prospects. The gold grades of jasperoids in the three prospects range from trace amounts to 20 g/t Au. Regional studies of gold and porphyry copper mineralization in the Surigao del Norte mineral district are important in delineating ore targets for drilling in the three prospects. 相似文献
144.
145.
146.
Pamela Murphy 《岩石学报》2000,16(4)
Using Raman spectroscopy to improve our understanding of geological fluidsMurphy andRoberts.1995.Geochim.Cosmochim.Acta,59:4809~4824
Murphy andRoberts.1997.ChemicalGeology,135:1~20
Murphy,Stevens andL aGrange.2000.Geochim.Cosmochim.Acta,64:479~494
Sam son andWalker.2000.CanadianMineralogist,38:35~43… 相似文献
147.
Marie Grace Pamela G. Faylona Claire E. Lazareth Anne‐Marie Smah Sandrine Caquineau Hugues Boucher Wilfredo P. Ronquillo 《Geoarchaeology》2011,26(6):888-901
Tridacnidae shells, a valuable archive of past environments, are common in the Balobok Rockshelter archaeological site on Sanga‐Sanga Island in the south Philippines. This site was occupied during the mid‐Holocene (ca. 5000–8800 14C yr B.P.), a period of Neolithic cultural expansion in the Philippines. This paper focuses on the preservation of two shell specimens, Hippopus hippopus and Tridacna maxima, unearthed from two mid‐Holocene layers within the rockshelter. The shells' mineralogy and microstructure (prismatic and crossed‐lamellar) were studied using micro‐Fourier transform infrared spectroscopy and scanning electron microscopy to determine if the samples were suitable as paleoenvironmental records. Both shells are still aragonitic but aragonite crystals of both microstructure types are partly dissolved. This dissolution, characteristic of meteoric water alteration, precludes their utility in paleoenvironmental geochemical studies. Nevertheless, these shells are abundant in archaeological sites in the region and may be better preserved in other depositional contexts; more studies on Philippine Tridacnidae shell diagenesis are needed. © 2011 Wiley Periodicals, Inc. 相似文献