1,721,013 research outputs found
VNIR spectral identification of Mars surface analogues: some problems related to basalt spectroscopy.
No full textDetermination of metamorphic grade in siliceous muscovite-bearing rocks in Madagascar using reflectance spectroscopy.
No full textVisible short-wave infrared laboratory reflectance spectra of quartzites and micaschists from the Precambrian basement of central-western Madagascar are dominated by the muscovite spectrum. The spectra were measured from rock samples collected along an E-W traverse across a metamorphic sequence recording progressively higher metamorphic grades. The wavelength of the AI-OH band around 2200 nm decreased westward and was inversely correlated with AI(VI) content of muscovite in rocks showing the same nonlimiting assemblage. This shift is correlated also with an increase of band intensity, which is attributed to the progressive increase of metamorphic grade. All of these variations in rock spectral properties can be detected by the high spectral resolution MIVIS and AVIRIS sensors, as well as by the lower resolution TM sensor
Mount Etna field and laboratory spectroscopy (300-2500 nm): implications for Mars exploration.
No full textAnalogues for Mercury' surface composition: examples from anorthosite kindred and basaltic rock suites.
No full textPrime considerazioni riassuntive sull'area appenninica dal F. Secchia al T. Nure
No full textCNR, P.F.GEODINAMICA-Sottoprogetto Neotettonic
influence of mineral interactions and texture on Mars Earth analogues spectra: preliminary results
No full textTurbidite Systems and Depositional Sequences in the Inner Eocene Basin of the South Central Pyrenees
No full textSpectral analysis and classification of metamorphic rocks from laboratory reflectance and transmittance spectra in the 0.4-2.5 nm and 2.5-25 nm intervals: a tool for hyperspectral data interpretation.
No full textLaboratory reflectance ( 0.4- 2.5 mum) spectra of 41 samples of metamorphic rocks from the Precambrian basement of Madagascar were analysed on the basis of absorption band position and shape, and classified on the basis of recurrent associations of absorption bands. Petrographic analyses allowed us to interpret the absorption features in compositional terms. Spectral and petrographic classes coincided when the principal mineralogy was also spectrally dominant (e.g. in carbonate rocks). When the principal mineralogy did not produce diagnostic spectral features (e.g. in siliceous rocks in the visible-short wave infrared region), the classification was based on spectrally dominant secondary phases. The reflectance spectra were measured on both freshly cut and exposed surfaces of the samples. Apart from a few cases of spectral features obliteration due to kaolinization, or overall albedo change related to texture variation, the two sets of spectra did not significantly differ. The responses of airborne MIVIS and AVIRIS hyperspectral sensors were simulated from spectra representative of the spectral classes, showing that significant identification and classification of well exposed metamorphic rocks are potentially possible using remote instruments providing high quality spectra. Although at present there are no plans for a spaceborne instrument of this quality, TM simulations and band composite images showed that a preliminary gross discrimination of the rocks belonging to the different classes was however possible
Sedimentary record of falling stages of Pleistocene glacio-eustatic cycles in shelf setting (Crotone Basin, south Italy)
No full textA thick Pleistocene shelf and nearshore cyclical succession was deposited in the S. Mauro sub-basin of the Crotone basin (southern Italy). The regressive units of the cycles are mostly represented by coastal siliciclastic and bioclastic prograding wedges showing a clinoform geometry. These are separated by blanket-like deposits of high lateral persistence recording major transgressive episodes. The aim of this paper is (1) to describe facies patterns and depositional setting of two prograding wedges, particularly focussing on their polycyclic internal architecture, (2) to analyze these units within a sequence-stratigraphic framework, and (3) to speculate on the possible origin of the small-scale cyclicity. The two wedges analyzed in this paper consist of a number of shingles. Individual shingles consist of two physically connected units: (1) a relatively thin package of sigmoid clinoforms, grading into (2) a volumetrically dominant package of oblique-tangential clinoforms with toplap terminations. The shingles are bounded by seaward-dipping surfaces with sigmoid clinoform geometry, which are ravinement surfaces updip, passing into conformable flooding surfaces downdip. The wedges are thus organized into high-frequency, small-scale sequences, each comprising transgressive, highstand and falling-stage systems tracts. As a whole, individual prograding wedges are interpreted as forced-regressive units, as the shoreline was subject to an overall shift basinwards and downwards along a low-angle trajectory, in spite of the repeated minor relative sea-level rises. Tectonic subsidence, and particularly the syndepositional growth of gentle synclines, are thought to have been the key factors allowing the preservation of these forced-regressive units. Progradation of the wedges took place in a high-energy wave climate characterized by high frequency of storms and very efficient alongshore redistribution of sediments. Recurrent, storm-driven, offshore currents led to intense reworking of sediments on the topset platform and gravity spreading on the foreset slope of the prograding wedges. Well-oxygenated conditions over the shelf due to intensified storm activity during glacial periods may have enhanced the rate of production of skeletal, foramol-type carbonates. It can reasonably be assumed that progradation took place from a line source and that the sand bodies are to be regarded as coastal prograding bodies. In spite of active syndepositional tectonics, the cycles can be correlated to Pleistocene high-amplitude sea-level oscillations. The older of the two wedges can be correlated, through bio-magnetostratigraphy, to the major climatic transition which occurred from the marine oxygen-isotope stage 25 to 24-22 (Rio et al., 1996). The younger probably developed during the sea-level fall that ended with substage 18.2, as suggested by sequence- and bio-stratigraphic data. The prograding wedges are thus interpreted to record long-lived sea-level falls of fourth-order cycles.
Due to the particular depositional setting, we are inclined to exclude authigenic mechanisms in the origin of small-scale cyclicity. Although the concomitance and interaction of different controlling factors may be taken into account, it is tempting to ascribe this cyclicity to minor eustatic changes punctuating long-lived, erratic falling stages, possibly accompanied by climate-driven fluctuations of sediment supply. Shelf-perched and shelf-edge prograding units consisting of foramol-type carbonates are apparently a common falling-stage to lowstand depositional feature in the Mediterranean area during the Late Pliocene and Pleistocene
Carta Neotettonica d'Italia. Revisione dei Fogli 72 (Fiorenzuola d'Arda), 73 (Parma), 83 (Rapallo) (p.p.), 84 (Pontremoli) (p.p.), 85 (Castelnovo ne' Monti) (p.p.), 86 (Modena) (p.p.), 96 (Massa) (p.p.)
No full textCNR, P.F.GEODINAMICA - Sottoprogetto Neotettonic
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