Gabbros

Boslough, M.B., and Ahrens, T.J. (1984), Particle Velocity Experiments in Anorthosite and Gabbro, in Shock Waves in Condensed Matter—1983, (edited by Asay J.R. et al.), Elsevier Science, New York, pp. 525-528. 

Figure 1.166. Distribution or initial Sr/ Sr (r, ) for the Cretaceous-Paleogene plutonic rocks. Open squares gabbros open circles granites. Numbers indicate the last two or three digits of r, values. Solid squares and solid circles imply the magnetite-series open squares and open circles the ilmenite-series. (Shibata and Ishihara, 1979).

Fig. 6.11. Calibration lines by using several CRM samples (S soil BHB-1, T Tibet soil GBW 8302, R river sediment CRM 320, Ga Gabbro MRG-1, A Andesite AGV-1, Gr Granodiorite GSP-1) and varying the sample weight (Zn 307.6 nm)...

In chernozems formed on serpentinite diluvium, Co content is in the range of 10-30 mg/kg, while in chestnut and chestnut vertic soils, Co concentrations vary from 3-15 and 15-45 mg/kg, respectively. Soils on basalt, andesite and gabbro contain 15-68 mg/kg total Cu. Total Mn in chernozems is in the range of 520-850 mg/kg. Chestnut soils have 42-106 mg/kg Zn content. Total Zn in saline alkali soils is in the range of 40-60 mg/kg Zn. Bioavailable Zn (ammonium acetate-extractable Zn) in chernozems, chestnut soils and saline alkali soils of the steppe zones varies from trace amounts to 3.8 mg/kg (1-8.3% of total Zn). In chernozems of Northern Bulgaria, total B is in the range of 25-53 mg/kg. Boron increases in saline soils and saline alkali soils. 

OTHER 5 GABBRO RELATED KOMATIITIC DEPOSITS SULFIDE DEPOSITS (N 0)... 

The Dumas Formation is uncomformably overlying the Archean Superior Province. It hosts metasediments and intercalated iron formations, as well as peridotite and gabbro bodies, which were identified and separated with the help of both Band ratio and Principal Component Analysis. 

The Expo Intrusive Suite is for the most part composed of mafic and ultramafic intrusions, shaped as tabular-shaped discordant bodies, so are referred as dykes. The Expo suite is economically important due to the presence of sulfide mineralization in the internal part of the intrusion. It is composed of gabbro norite, pyroxenite, peridotite, and dunite. 

Figure 3 displays a Band Ratio image (5/3, 7/3, 4/2), in which peridotite appears dark yellowish black colour. It is difficult to distinguish between gabbro and basalt, due to their similar reflectance properties. 

In general, the spectral band ratio technique is helpful to identify the peridotite, but basalt and gabbro are not uniformly separable over the entire region. 

Fig. 5. Comparison of Geological Map and PCA image showing distinction between gabbro, peridotite (Expo Intrusive Suite), metabasalt (Upper Beauparlant Formation).

As displayed in Figure 4, basalt, gabbro, and peridotite has distinctly different spectral signature and shows texture variations between different rock types. 

Fig. 6. Supervised Classification image with peridotite, gabbro, metabasalt, metasediments, are shown as Red, Green, Blue, and Yellow.

Remote sensing techniques have been successfully applied for the identification of rocks in Cape Smith fold belt region. Principal Component Analysis is very effective for the separation of gabbro, metabasalt and peridotite. Band Ratio was helpful for the preliminary identification of peridotite. Supervised Classification approach is taken to verify the results obtained by Principal Component Analysis and Band Ratio. It is also useful to remap the unknown regions once the results are verified. 

Table 1.3. Major-element composition (%) of the minerals used to calculate the composition of a gabbro with known modal abundances.

Table 5.4 Olivine major element compositions (in weight %). Samples occur in different types of rocks (1) = forsterite from a metamorphosed limestone (2) = hortonolite from an olivine gabbro (3) = fayalite from a pantelleritic obsidian (4) = fayalite from an Fe-gabbro (5) = forsterite from a cumulitic peridotite (6) = forsterite from a tectonitic peridotite. Samples (1) to (4) from Deer et al. (1983) sample (5) from Ottonello et al. (1979) sample (6) from Piccardo and Ottonello (1978). ...

Enstatite-bronzite (MgTel Si O, Gabbros Mg-iich ultramafic rocks serpentinites meteorites... 

Augite (Ca,Mg,Fe,Al)2(Si,Al)206 Basalts, andesites, tephrites, limburgites gabbros, dolerites, ultramafic rocks. Sometimes in granites... 

Biotite Gabbros, norites, diorites, granites, pegmatites Phyllites, chlorite-sericite schists, biotite facies of the regional metamorphism, gneisses ... 

Figure 11,21 Age spectra of hornblendes of a Paleozoic gabbro (367 Ma) intruded by a granitic body during the Cretaceous (114 Ma). Samples underwent permeation of " Ar from lower crustal portions and differential losses of radiogenic argon (32, 57, and 78% respectively), proportional to distance from contact (0.3, 1, and 2.5 km). Reprinted from T. M. Harrison and I. McDougall, Geochimica et Cosmochimica Acta, 44, 2005-2020, copyright 1980, with kind permission from Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington 0X5 1GB, UK.

Early and iniemnediate stages gabbro quarlz gabbm-tpnalJle (IholeitliC to transitional)... 

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