Sample TAD-4

NavDat sample number 12131 · ANDESITE

Sample

Sample ID	TAD-4
Rock name	ANDESITE
Rock type	VOLCANIC
Composition	INTERMEDIATE
Material	IGNEOUS
Comment	Dark gray to black, locally speckled, moderatley finely porphyritic with olivine and plagioclase phenocrysts set in intergranular to hyalo-ophitic groundmass

Location

Latitude	40.76
Longitude	-120.817
State / province	California
Volcanic field	Walker Lane

Age

Age (Ma)	Error	Min	Max	Geologic age	Dated by
6.9		6.3	7.5

Analyses

Whole rock

Item	Value	Std. dev.	Unit	Method
SIO2	57.3		WT%	UNKNOWN
TIO2	0.9		WT%	UNKNOWN
AL2O3	17.46		WT%	UNKNOWN
FEOT	6.86		WT%	UNKNOWN
MNO	0.12		WT%	UNKNOWN
MGO	4.3		WT%	UNKNOWN
CAO	7.21		WT%	UNKNOWN
NA2O	3.61		WT%	UNKNOWN
K2O	1.57		WT%	UNKNOWN
P2O5	0.32		WT%	UNKNOWN

References

Grose, Thomas L T; McKee, Edwin H (1986) Potassium-argon ages of late Miocene to late Quaternary volcanic rocks in the Susanville-Eagle Lake area, Lassen County, California. Isochron/West, vol.45, pp.5-11, Apr 1986