Fundamental Minerals

Sialic Minerals

Feldspars

Feldspathoids

Quartz

Femic Minerals

Spodumene

Accessory Minerals

Rare Accessory

Alteration Products

Microstructures

Rocks

Jacupiranga complex

Olivine hornblendite

The Adamello batholith, generated, during the Oligocene, in an arc-related continental margin setting, is the largest Tertiary intrusive complex along the Pedriadriatic lineament, and is located in the Eastern Southern Alps.
The Adamello batholith is exposed over an area of about 700km² at the intersection of the Periadriatic Lineament with the Giudicarie Line and consists of multiple intrusive units (up-to 98 % tonalites and granodiorites and minor ultramafic and gabbroic rocks) ranging in age from about 42 Ma to about 29 Ma. Mafic and ultramafic bodies are found locally, especially in the southernmost Re di Castello unit. The mafic bodies are mainly concentrated at the border of this unit and best exposed in the Val Fredda and Cornone di Blumone areas.

Fig.1: Geologic map of the Adamello batholith.

Monte Mattoni

The Val Fredda Complex consists of granodiorites, tonalites and quartz-diorites intruded by several mafic sheets of metre to decametre thickness. Two types of mafic sheet have been recognized in the Val Fredda Complex, specifically in the Mt. Cadino and Mt. Mattoni sequences.
The Mt. Cadino mafic rocks range from hornblende gabbros to quartz-diorites, mostly with equigranular textures. The Mt. Mattoni mafic rocks consist of hornblende-phyric, pyroxene-bearing gabbros (hereafter amph-gabbros) with subordinate hornblendite blocks or bands. Subhorizontal layering is locally recognizable and is defined by an irregular succession of different types of amphibole gabbro, in places associated with hornblendite. The chilling of the mafic intrusions against the host tonalite suggests that the mafic sheets of both Mt. Cadino and Mt. Mattoni were emplaced into the pre-existing Val Fredda tonalite.

The Mt. Mattoni mafic to ultramafic rocks are interpreted as deep-seated cumulates crystallized from a hydrous melt with a basalt or picro-basalt composition that were disrupted by new injections of mafic magma and then transported to the emplacement level. The trace element signature of the parental melt of the Mt. Mattoni mafic intrusive rocks has been attributed to partial melting of spinel-facies subcontinental mantle metasomatized by slab-derived fluids.

Hornblendites:
The hornblendites from Mt. Mattoni consist of large (upto 1cm) zoned amphibole grains (80 vol. %). Amphibole cores are dark brown, grading to brownish-green and light green towards the outermost rim. The brown amphibole cores are frequently characterized by exsolution of Ti-oxide phases and inclusions of olivine, spinel and clinopyroxene. The abundance of inclusions decreases from the brown cores to the brownish-green rims. The external outer, light green, amphibole rim is commonly inclusion free.
Two types of olivine grains are included within the brown amphibole domains: (1) large isolated olivine grains (up to 500mm) with irregular boundaries, containing iso-oriented micro-exsolution of Fe-oxide phases; (2) small olivine grains with rounded or elliptical shapes and lobate boundaries.
These small olivine grains areusually grouped inclusters with the same optical orientation, suggesting that they were part of a pre-existing larger grain.

Fig.2: Simplified sketch map showing the location of the major mafic and ultramafic intrusive rocks (black areas) in the southern part of the Re di Castello unit (modified after Ulmer et al.,1983).

bibliography

• Tiepolo, M., Tribuzio, R., Ji, W. Q., Wu, F. Y., & Lustrino, M. (2014). Alpine Tethys closure as revealed by amphibole-rich mafic and ultramafic rocks from the Adamello and the Bergell intrusions (Central Alps). Journal of the Geological Society, 171(6), 793-799.
• Tiepolo, M., Tribuzio, R., & Langone, A. (2011). High-Mg andesite petrogenesis by amphibole crystallization and ultramafic crust assimilation: evidence from Adamello hornblendites (Central Alps, Italy). Journal of Petrology, 52(5), 1011-1045.

Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 1x (Field of view = 9mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 1x (Field of view = 9mm)/td>
Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 1x (Field of view = 9mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>
Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 1x (Field of view = 9mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 1x (Field of view = 9mm)/td>
Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 1x (Field of view = 9mm)/td>
Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 1x (Field of view = 9mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>
Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 1x (Field of view = 9mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 1x (Field of view = 9mm)/td>
Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 1x (Field of view = 9mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 1x (Field of view = 9mm)/td>
Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 2x (Field of view = 7mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals); Note how abundance of inclusions decreases from the brown cores to the green rims. Hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 2x (Field of view = 7mm)/td>
Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 2x (Field of view = 7mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>
Zoned hornblende crystal rich in inclusions of olivine (colorless, rounded crystals); Note how abundance of inclusions decreases from the brown cores to the green rims. Hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 2x (Field of view = 7mm)/td>	Hornblende crystal rich in inclusions of olivine (rounded crystals with high interference colors); Note how abundance of inclusions decreases from the cores to the rims. Hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 2x (Field of view = 7mm)/td>
Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 2x (Field of view = 7mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>
Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 2x (Field of view = 7mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>
Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 2x (Field of view = 7mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 2x (Field of view = 7mm)/td>
Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 2x (Field of view = 7mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 2x (Field of view = 7mm)/td>
Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 10x (Field of view = 2mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 10x (Field of view = 2mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 10x (Field of view = 2mm)/td>
Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 10x (Field of view = 2mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 10x (Field of view = 2mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 10x (Field of view = 2mm)/td>
Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 10x (Field of view = 2mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 10x (Field of view = 2mm)/td>	Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 10x (Field of view = 2mm)/td>
Zoned hornblende crystals rich in inclusions of olivine (colorless, rounded crystals) in a hornblendite from Monte Mattoni, Adamello, Italy. PPL image, 10x (Field of view = 2mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 10x (Field of view = 2mm)/td>	Hornblende crystals rich in inclusions of olivine (rounded crystals with high interference colors) in a hornblendite from Monte Mattoni, Adamello, Italy. XPL image, 10x (Field of view = 2mm)/td>