Site: Alamagan (NWC)

Island: Alamagan Lithology: Volcanic high island ( Nunn et al. (2016) )

Lithology and Age: None ( Chorlton (2007) ) Macrostrat Geological Map Link

Near/In Geonames ID: 4041123 Wikidata ID: Q478663 Getty Thesaurus of Geographic Names ID: 1006220

Mindat Loc ID: None

In:

Northern Islands Province Wikidata ID: Q1608103

Alamagan Island Wikidata ID: Q478663

Mariana Islands Wikidata ID: Q153732

Volcanoes:

Alamagan: Andesite / Basaltic Andesite, Composite type, Stratovolcano.

Note that to see the 'Geology' layer (layer options in top right corner) you may have to zoom out.

Fabrics:

None (0)	Minor (1)	Few (2)	Common (3)	Frequent (4)	Major (5)	Very Dominant (6)
0%	0-5%	5-15%	15-30 %	30-50%	50-70%	70-100%

Name	Cal.	Quartz	Feldspar	Pyroxene	Amphibole	Opaques	Olivine	Biotite	Muscovite	Epidote	Garnet/ Spinel	Ig./Met. Rocks	Sed. Rocks	Grog	Lithics/ Region
tpr11	0	2	2	0	0	1	0	0	0	0	0	6	0	0	vitric, felsitic
Saipan dacitic-vitric	0	1	2	0	0	1	0	0	0	0	0	6	0	0	Marianas
tpr28	0	0	4	2	0	2	0	0	0	0	0	4	0	0	vitric, microlitic
Saipan andesitic	0	0	4	2	0	2	0	0	0	0	0	4	0	0	Marianas

Slides:

Slide	Fabric	Possible Origin	Cal.	Quartz	Feldspar	Pyroxene	Amphibole	Opaques	Olivine	Biotite	Muscovite	Epidote	Garnet/ Spinel	Ig./Met. Rocks	Sed. Rocks	Grog	Lithics
WD_2_7	tpr11 (Saipan dacitic-vitric)	Saipan	0	2	2	0	0	1	0	0	0	0	0	6	0	0	felsitic
WD_4_11	tpr28 (Saipan andesitic)	Saipan	0	0	4	2	0	2	0	0	0	0	0	4	0	0	vitric, microlitic

WD_2_7

AlamaganA1 — Sherd A1 from Alamagan (NWC) (Alamagan). Slide WD_2_7 from Dickinson Collection, Bishop Museum. x4 Magnification PPL (left) XPL (right). Scale bar: 0.5mm. High resolution image in VIMIPO (user: Guest pwd: Guest). Imaged by K. Hardy and M. Leclerc, ANU.

AlamaganA1 — Sherd A1 from Alamagan (NWC) (Alamagan). Slide WD_2_7 from Dickinson Collection, Bishop Museum. x4 Magnification PPL (left) XPL (right). Scale bar: 0.5mm. High resolution image in VIMIPO (user: Guest pwd: Guest). Imaged by K. Hardy and M. Leclerc, ANU.

Quartzose dacitic volcanic sand temper. Fine temper.

WD_4_11

AlamaganA_4 — Sherd A-4 from Alamagan (NWC) (Alamagan). Slide WD_4_11 from Dickinson Collection, Bishop Museum. x4 Magnification PPL (left) XPL (right). Scale bar: 0.5mm. High resolution image in VIMIPO (user: Guest pwd: Guest). Imaged by K. Hardy and M. Leclerc, ANU.

AlamaganA_4 — Sherd A-4 from Alamagan (NWC) (Alamagan). Slide WD_4_11 from Dickinson Collection, Bishop Museum. x4 Magnification PPL (left) XPL (right). Scale bar: 0.5mm. High resolution image in VIMIPO (user: Guest pwd: Guest). Imaged by K. Hardy and M. Leclerc, ANU.

Coarse temper. Quartz-free andesitic temper sands. Probably from Saipan as orthopyroxene present.

References:

323 Mariana, reports 1-15 for MTAT, 1998 (Dickinson, W.)