Sample IVP

NavDat sample number 3668 · GRANODIORITE

Sample

Sample ID	IVP
Rock name	GRANODIORITE
Rock type	PLUTONIC
Composition	INTERMEDIATE
Material	IGNEOUS
Comment	medium grained, uniformly textured; conspicuous hornblende and biotite in about equal proportions; honey-brown euhedral sphene prominent; plagioclase is white; K-feldspar megacrysts are rare as opposed to in other parts of this pluton

Location

Latitude	45.5208
Longitude	-112.839
Location	easternmost of several blasted outcrops along mine road; Beaverhead County
State / province	Montana
Volcanic field	Pioneer Batholith

Age

Age (Ma)	Error	Min	Max	Geologic age	Dated by
69.5		67.5	71.5

Analyses

Whole rock

Item	Value	Std. dev.	Unit	Method
SIO2	65.7		WT%	RAPID_ROCK
AL2O3	16.2		WT%	RAPID_ROCK
FE2O3	2.8		WT%	RAPID_ROCK
FEO	2.1		WT%	RAPID_ROCK
MGO	1.5		WT%	RAPID_ROCK
CAO	4.5		WT%	RAPID_ROCK
NA2O	3		WT%	RAPID_ROCK
K2O	2.6		WT%	RAPID_ROCK
H2O_PLUS	0.8		WT%	RAPID_ROCK
H2O_MINUS	0.12		WT%	RAPID_ROCK
TIO2	0.42		WT%	RAPID_ROCK
P2O5	0.21		WT%	RAPID_ROCK
MNO	0.08		WT%	RAPID_ROCK
CO2	0.02		WT%	RAPID_ROCK
TOTAL	100		WT%	RAPID_ROCK

References

Zen, E-an; Marvin, R F; Mehnert, H H (1975) Preliminary petrographic, chemical, and age data on some intrusive andassociated contact metamorphic rocks, Pioneer Mountains, southwesternMontana. Geological Society of America Bulletin, vol.86, no.3, pp.367-370,1975 doi:10.1130/0016-7606(1975)86<367:PPCAAD>2.0.CO;2