Date File Created	Name of Creator																																																
7/3/06	Lang Farmer																																																
GeoRef Data	2006-020188																																																
DN	GeoRef																																																
TI	"Origin of rhyolite by crustal melting and the nature of parentalmagmas in the Oligocene Conejos Formation, San Juan Mountains,Colorado, USA"																																																
AU	"Parker, D F; Ghosh, A; Price, C W; Rinard, B D; Cullers, R L; Ren, M"																																																
SO	"Journal of Volcanology and Geothermal Research, vol.139, no.3-4,pp.185-210, 15 Jan 2005"																																																
RL	[U																																																
RL	http://www.sciencedirect.com/science/journal/03770273]																																																
DE	andesites; basalts; Cenozoic; chemical composition; Colorado; ConejosFormation; crust; Hinsdale Formation; igneous rocks; magmas; majorelements; metals; North America; Oligocene; Paleogene; partialmelting; rare earths; rhyolites; Rocky Mountains; San Juan Mountains;Summer Coon; Tertiary; trace elements; U. S. Rocky Mountains; UnitedStates; volcanic centers; volcanic features; volcanic rocks;volcanism; volcanoes																																																
AB	"Four closely spaced volcanoes (Summer Coon; Twin Mountains; Del Norte;Carnero Creek) form the east-central cluster of Conejos volcaniccenters. These Conejos rocks range from high-K basaltic andesite torhyolite, with andesite volumetrically the most abundant. Summer Coonand Twin Mountains are composite volcanoes. The Del Norte and CarneroCreek Volcanoes are deeply eroded dacite shields. Rhyolite (10% of ourConejos analyses but a much smaller percentage by volume) is onlyknown from Summer Coon and Twin Mountains Volcanoes, although high-SiO(sub 2) dacite occurs in the Del Norte Volcano. The younger HinsdaleFormation contains a related series ranging from transitional basaltto high-K andesite; we use Hinsdale Formation analyses to representConejos parental magmas. Conejos and Hinsdale magmas evolved throughAFC processes: Basalt, after interacting with lower crust, assimilatedlow K/Rb crust, similar in some ways to Taylor and McLennan (Taylor,S. R., and McLennan, S. M., 1985, The continental crust: itscomposition and evolution. Oxford, Blackwell Scientific) model uppercrust; main series basaltic andesite fractionated to high-K andesite;rhyolite was produced by melting of high K/Ba upper crustal rockssimilar to granite gneiss known from inclusions and basement outcrops.Some rhyolite may have been back-mixed into fractionating andesite anddacite. Field evidence for assimilation includes sanidinite-facies,partially melted, gneiss blocks up to 1 m in diameter. Temperatureestimates (1100-900 degrees C) from two-pyroxene equilibria areconsistent with this interpretation, as are the sparsely porphyriticnature of the most-evolved rhyolites and the absence of phenocrysticalkali feldspar. Our study supports the conclusions of previousworkers on AFC processes in similar, but generally more mafic, Conejosmagmas of the southeastern San Juan Mountains. Our results, however,emphasize the importance of crustal melting in the generation ofConejos Rhyolite. We further speculate that Conejos magmatism, and theSan Juan Volcanic Field (SJVF) in general, may represent an earlyphase of Rio Grande Rift magmatism, the orogenic geochemical signatureof the series having been generated through multi-level and extensiveassimilation of varied Precambrian orogenic and anorogenic rocks."																																																
PY	2005																																																
AN	2006-020188																																																
Sample Data																																																	
Item	SiO2	TiO2	Al2O3	FeO	MnO	MgO	CaO	Na2O	K2O	P2O5	Rb	Sr	Zr	Y	Ba	Ni	Nb	Th	La	Ce	Nd	Sm	Eu	Tb	Yb	Lu	Th	La	Ce	Nd	Sm	Eu	Tb	Yb	Lu	143Nd_144Nd	Total	Age	Max_age	Min_age	LatDD	LongDD	Loc_prec	Rock_Type	rock_class	Material	Unit	Volcanic_Field	State
Units	wt%	wt%	wt%	wt%	wt%	wt%	wt%	wt%	wt%	wt%	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm	ppm		wt%	Ma	Ma	Ma	dd	dd							
Method	1	1	1	1	1	1	1	1	1	1	2	2	2	2	2	2	2	2	2	2	2	2	2	2	2	2	3	3	3	3	3	3	3	3	3	4	5	6	6	6	7	7							
Sample Name																																																	
92606	49.53	1.96	16.86	9.58	0.15	6.46	9.01	4.22	1.54	0.69	20	985	203	24	539	117	7	1.6	25.3	52	24	5.38	1.67	0.7	2.16	0.32											99.3	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Basalt	Whole Rock	Los Mogotes	Eastern San Juan Volcanic Field	Colorado
92619	52.55	1.3	17.16	8.21	0.16	8.03	8.9	3	0.54	0.15	8	322	93	20	591	129	3	0.9	8.54	19	11	3.15	1.05	0.5	1.95	0.28											102.4	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Basaltic Andesite	Whole Rock	Los Mogotes	Eastern San Juan Volcanic Field	Colorado
94575	55.99	1.59	15.5	7.6	0.12	4.95	6.56	4.18	2.88	0.62	60	1000	213	16	1027		21	4.2	46.8	92	46	7.08	2.25	0.8	1.54	0.23											99.4	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Basaltic Andesite	Whole Rock	Hinsdale Fm.	Eastern San Juan Volcanic Field	Colorado
85911KSU	56.07	1.18	16.13	8.07	0.11	5.04	6.96	3.52	2.48	0.44	38	770	185	28	1010	69	7	3.8	30.8	63.4		6.39	1.7	0.73	2.2	0.34										0.512192	100.8	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Andesite	Whole Rock	Summer Coon volcano	Eastern San Juan Volcanic Field	Colorado
85911AL																											3.3	35.9	70	33	7.11	1.85	0.8	2.51	0.38			32.5	35	30	37.8333	-106.3333	0.5	volcanic	Andesite	Whole Rock	Summer Coon volcano	Eastern San Juan Volcanic Field	Colorado
87705	60.31	1.02	16.49	5.73	0.1	3.35	5.67	3.47	3.48	0.39	58	798	190	28	1223	33	8	4.2	36.4	71	33	6.78	1.74	0.7	2.4	0.36										0.512162	100.5	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Andesite	Whole Rock	Summer Coon volcano	Eastern San Juan Volcanic Field	Colorado
87703	62.21	0.87	15.98	5.23	0.09	3.09	5.05	3.83	3.27	0.39	54	819	200	20	1238	31	7	4.9	36.1	66.6		5.98	1.48	0.57	1.32	0.22											100.5	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Andesite	Whole Rock	Summer Coon volcano	Eastern San Juan Volcanic Field	Colorado
83408	65.72	0.65	15.56	3.69	0.06	2.87	3.51	3.67	3.96	0.32	64	647	182	19	1302	20	7	5.4	32.1	59.2		4.85	1.18	0.42	1.12	0.18											99.7	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Dacite	Whole Rock	Summer Coon volcano	Eastern San Juan Volcanic Field	Colorado
99901	67.96	0.51	15.91	2.52	0.08	5.04	2.64	1.49	3.76	0.1	105	307	453	41	1035	0	30	12.8	74.3	146	65.4	11.58	2.25	1.45	4.67	0.643											102.9	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Dacite	Whole Rock	Summer Coon volcano	Eastern San Juan Volcanic Field	Colorado
89703SC	73.79	0.36	15.31	0.48	0	0.47	0.23	4.35	4.84	0.16	90	482	305	20	1777		8	6.8	56.7	100	34	5.73	1.38	0.5	1.92	0.3										0.512159	102.8	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Rhyolite	Whole Rock	Summer Coon volcano	Eastern San Juan Volcanic Field	Colorado
85913SC	74.7	0.18	14.38	0.14	0.03	0.39	1	4.5	4.61	0.07	88	290	180	23	1531		14	9.3	35.9	70	33	7.11	1.85	0.8	2.51	0.38											99.9	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Rhyolite	Whole Rock	Summer Coon volcano	Eastern San Juan Volcanic Field	Colorado
87712DN	61.59	0.87	15.98	5.7	0.11	3.31	5.52	3.37	3.16	0.4	51	762	180	24	1185	33	4	4.4	37.5	72	33	5.36	1.65	0.6	2.44	0.37											101.8	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Andesite	Whole Rock	Del Norte volcano	Eastern San Juan Volcanic Field	Colorado
92902	55.8	1.47	16.61	8.16	0.15	3.63	7.46	3.48	2.61	0.63	49	839	211	30	1117	40		3	35.7	72	36	6.47	2.1	0.8	2.66	0.39											101.8	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Basaltic Andesite	Whole Rock	Twin Mountain volcano	Eastern San Juan Volcanic Field	Colorado
92806TM	73.76	0.5	14.27	0.61	0.08	0.3	1.07	4.06	5.22	0.12	102	210	159	34	1487			6.3	51.6	95	39	5.86	1.34	0.8	3.4	0.51											101.6	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Rhyolite	Whole Rock	Twin Mountain volcano	Eastern San Juan Volcanic Field	Colorado
94555CC	55.43	1.02	16.37	8.82	0.15	4.97	7.55	3.21	2.07	0.4	31	814	137	28	827	66		2.9	27.4	64	30	6.55	1.67	0.8	2.9	0.37											98.1	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Basaltic Andesite	Whole Rock	Carnero Creek-Biedell Creek Volcano	Eastern San Juan Volcanic Field	Colorado
94556CC	55.63	1.11	14.99	9.39	0.13	5.3	7.48	2.8	2.66	0.52	46	759	177	28	1102	85		3.3	35.7	81	35	7.45	2.03	0.9	2.8	0.38											100.2	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Basaltic Andesite	Whole Rock	Carnero Creek-Biedell Creek Volcano	Eastern San Juan Volcanic Field	Colorado
94716CC	60.99	0.9	16.19	5.78	0.09	2.89	5.27	3.96	3.48	0.46	62	878	199	21	1672	35		4.8	43.5	92	40	6.89	2.03	0.8	2.02	0.28											102.1	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Andesite	Whole Rock	Carnero Creek-Biedell Creek Volcano	Eastern San Juan Volcanic Field	Colorado
94705CC	63.92	0.71	15.93	4.6	0.07	2.26	4.26	4.13	3.83	0.3	68	915	260	22	1600	35		6.7	50.1	99	39	6.42	1.67	0.8	1.97	0.26											102.4	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Andesite	Whole Rock	Carnero Creek-Biedell Creek Volcano	Eastern San Juan Volcanic Field	Colorado
94724CC	65.96	0.71	15.45	4.21	0.07	1.9	3.82	3.79	3.74	0.35	78	655	203	25	1306	23		6.8	48.9	104	42	7.19	1.71	0.7	2.45	0.33											100.2	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Dacite	Whole Rock	Carnero Creek-Biedell Creek Volcano	Eastern San Juan Volcanic Field	Colorado
94715CC	67.91	0.4	16.05	3.11	0.05	1.34	2.91	3.98	3.92	0.31	86	628	254	22	1529	5		6.5	47.9	97	38	6.12	1.62	0.7	2.25	0.32											101.1	32.5	35	30	37.8333	-106.3333	0.5	volcanic	Dacite	Whole Rock	Carnero Creek-Biedell Creek Volcano	Eastern San Juan Volcanic Field	Colorado
Method Data																																																	
1	XRF	146																																															
2	INAA	466																																															
3	INAA	384																																															
4	MC_ICP_MS	472																																															
5	XRF	384																																															
6	REG_COR	384																																															
7	REG	2006-020188																																															

Fractionation Data																																																	
Method Number		4
Item		Nd146_Nd144
Value		0.7219