Date File Created	Name of Creator
6/8/07	Trevor Nace
GeoRef Data	2007-035831
DN	GeoRef
TI	"Geology and complex collapse mechanisms of the 3.72 Ma HanneganCaldera, north Cascades, Washington, USA"
AU	"Tucker, David; Hildreth, Wes; Ullrich, Tom; Friedman, Richard"
AF	"Western Washington University, Geology Department, Bellingham, WA,United States (USA)"
AF	"U. S. Geological Survey, United States (USA); University of BritishColumbia, Canada (CAN)"
SP	"USGSOP, Non-USGS publications with USGS authors"
SO	"Geological Society of America Bulletin, vol.119, no.3-4, pp.329-342,Apr 2007"
RL	[U
RL	http://www.gsajournals.org/]
IS	0016-7606
CD	BUGMAF
DE	absolute age; andesites; Ar/Ar; ash flows; breccia; calderas; CascadeRange; Cenozoic; collapse structures; dacites; dates; dikes; diorites;erosion; eruptions; experimental studies; faults; geochemistry;geomorphology; glacial erosion; glaciated terrains; granites; HanneganCaldera; igneous rocks; ignimbrite; intrusions; lava;lithostratigraphy; major elements; megabreccia; Neogene;nesosilicates; orthosilicates; Pliocene; plutonic rocks; plutons;pyroclastics; quartz diorites; rhyolites; ring faults; silicates;snow; spectra; Tertiary; U/Pb; United States; volcanic centers;volcanic features; volcanic rocks; Washington; Whatcom CountyWashington; X-ray fluorescence spectra; zircon; zircon group
AB	"Contiguous ring faults of the 8 x 3.5 km Hannegan caldera enclose theHannegan volcanics in the Cascade arc of northern Washington. Thecaldera collapsed in two phases, which each erupted rhyoliticignimbrite (72.3%-75.2% SiO (sub 2) ). The first collapse phase,probably trap-door style, erupted the > or =900-m-thick ignimbriteof Hannegan Peak at 3.722+ or -0.020 Ma. This single cooling unit,generally welded, has an uppermost facies of nonwelded ignimbrite andfine ash. A short period of localized sedimentation followed. Eruptionof the ignimbrite of Ruth Mountain then led to a second trap-doorcollapse as the first-phase partial ring fault propagated to the southto completely enclose the caldera. Wall-rock breccias are intercalatedas lenses and megabreccia blocks in both ignimbrites. The minimumintracaldera volume is 55-60 km (super 3) . No base is exposed, norare outflow sheets preserved. Caldera collapse and glacial erosionhave removed precaldera volcanic rocks, which survive only asintracaldera breccias. Rhyolite dikes and pods, one of which yielded a(super 40) Ar/ (super 39) Ar age of 3.72+ or -0.34 Ma, intrude thering fault and caldera fill. Dacite-andesite domes, dikes, and lavaflows were emplaced subsequently; one lava flow gives a (super 40) Ar/(super 39) Ar age of 2.96+ or -0.20 Ma. The quartz diorite of Icy Peakand the granite of Nooksack Cirque (plutons with (super 206) Pb/(super 238) U zircon ages of 3.42+ or -0.10 Ma and 3.36+ or -0.20 Ma,respectively) intrude caldera fill and basement rocks on the southwestmargin of the caldera. Both plutons are now exceptionally well exposedon high, glacially sculpted peaks within the caldera, indicatingerosion of at least 1 km of intracaldera fill. Hannegan calderaanchors the northeast end of a linear NE-SW age-progressive migrationof magmatic focus from the Chilliwack batholith to the active MountBaker volcano."
LA	English
NT	With GSA Data Repository Item 2007008
FE	"References: 44; illus. incl. sects., 3 tables, geol. sketch maps"
PY	2007
PT	Serial; Analytic
CP	United States (USA)
LL	"Latitude:N484900,N485400 Longitude:W1212800,W1214000"
CL	12 Stratigraphy; 03 Geochronology
CY	"GeoRef, Copyright 2007, American Geological Institute. Referenceincludes data from GeoScienceWorld, Alexandria, VA, United States |Reference includes data supplied by the Geological Society of America,Boulder, CO, USA, United States"
UD	200710
DO	10.1130/B25904.1
AN	2007-035831
JV	119
JI	4-Mar
JP	329-342
Sample Data	
Item	SiO2	TiO2	Al2O3	FeO	MnO	MgO	CaO	Na2O	K2O	P2O5	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu	Ba	Th	Nb	Y	Hf	Ta	U	Pb	Rb	Cs	Sr	Sc	Zr	Location_Name	Rock_Type	Rock_Class	Age	Max_age	Min_age	Age	Max_age	Min_age	Age	Max_age	Min_age	Age	Max_age	Min_age	Age	Max_age	Min_age	Age	Max_age	Min_age	Age	Max_age	Min_age	LatDD	LongDD	Loc_prec	material	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	ppm	ppm				Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	Ma	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	2	2	2	2	2	2	2	2	2	2	2				3	3	3	8	8	8	4	4	4	9	9	9	5	5	5	10	10	10	6	6	6	7	7			
Sample Name																																																																		
HC-47	54.72	1.16	17.98	7.16	0.15	4.58	9.17	3.36	1.45	0.27	13.93	29.12	3.66	16.1	4.05	1.35	4.25	0.7	4.4	0.9	2.45	0.36	2.25	0.36	370	2.12	5.27	23.38	3.16	0.35	0.79	3.64	40.8	1.01	522	29.6	123	Dike	Plutonic	Dike																			3.72	4.06	3.38	48.87918473	-121.5219691	0.0001	whole rock	Washington
HC-49	55.95	1.12	18.17	6.49	0.13	4.81	7.26	3.51	2.23	0.31	19.61	39.69	4.97	21.07	4.84	1.45	4.53	0.72	4.3	0.86	2.35	0.34	2.13	0.34	465	3.47	6.93	23.06	4.17	0.44	1.13	4.25	44.6	0.62	710	22.2	161	Dike	Plutonic	Dike																			3.72	4.06	3.38	48.8791507	-121.5263346	0.0001	whole rock	Washington
HC-65	59.19	1.16	18	6.12	0.1	2.84	7.19	3.79	1.29	0.33	20.9	40.79	4.89	20.47	4.85	1.47	4.62	0.74	4.4	0.91	2.36	0.35	2.2	0.34	617	3.45	7.83	23.65	3.98	0.52	1.24	6.78	21.6	1.47	619	18.3	153	Cassiope Dome	Volcanic	Andesite	3.4	4.9	1.9	2.4	8.5	0																48.87881713	-121.5283903	0.0001	whole rock	Washington
HC-18	59.36	0.84	17.44	5.59	0.1	4.13	6.65	3.5	2.18	0.21	17.84	35.88	4.29	17.76	4.1	1.2	3.75	0.59	3.56	0.73	1.97	0.3	1.9	0.3	503	4.69	6.19	19.47	4.06	0.45	1.69	11.56	39.4	0.38	552	16.3	151	Dike	Plutonic	Dike																			3.72	4.06	3.38	48.87857621	-121.5236237	0.0001	whole rock	Washington
HC-123	59.87	1.11	17.24	6.38	0.12	2.7	5.21	4.8	2.2	0.37	27.77	55.27	6.56	26.91	6.21	1.55	5.83	0.94	5.78	1.14	3.17	0.46	2.93	0.47	570	5.31	14.3	31.45	6.54	0.96	1.94	11.29	42.3	1.16	522	15.6	265	Icy Peak	Plutonic	Monzonite													2.96	3.12	2.8	2.2	3.8	0.8				48.8516209	-121.5332771	0.0001	whole rock	Washington
HC-48	59.91	0.92	17.68	5.49	0.11	3.43	5.82	4.12	2.26	0.26	18.52	36.31	4.46	18.71	4.36	1.27	4.06	0.65	3.88	0.81	2.16	0.32	1.99	0.32	522	3.75	6.78	21.51	4.05	0.47	1.36	6.54	44.4	0.57	609	16.5	156	Dike	Plutonic	Dike																			3.72	4.06	3.38	48.88024986	-121.5208465	0.0001	whole rock	Washington
HC-135	60.37	0.95	17.35	6.03	0.14	2.81	5.67	4.37	2.01	0.31																												Dike	Plutonic	Dike																			3.72	4.06	3.38	48.82582913	-121.5213592	0.0001	whole rock	Washington
HC-88	62.31	0.99	17.47	4.89	0.11	2.25	5.34	3.52	2.8	0.31	24.87	47.51	5.58	22.25	5.21	1.45	4.8	0.76	4.61	0.94	2.54	0.38	2.37	0.38	734	6.01	9.68	25.02	5.23	0.69	2.16	8.99	59.6	0.62	566	14.3	204	Chilliwack Pass. Short	Volcanic	Andesite							3.01	3.29	2.63	2.47	2.84	2.1										48.86483322	-121.4974393	0.0001	whole rock	Washington
HC-115	65.05	0.86	16.4	4.51	0.12	1.55	3	5.42	2.86	0.24	26.85	53.41	6.31	25.65	5.94	1.61	5.53	0.93	5.72	1.21	3.42	0.52	3.28	0.52	639	6.44	10.53	32.62	6.36	0.73	2.3	9.22	65	1.49	321	14.8	250	Dike	Plutonic	Dike																			3.72	4.06	3.38	48.88378897	-121.5023276	0.0001	whole rock	Washington
HC-17	67.06	0.7	16.69	3.23	0.09	1.15	2.67	5.26	2.93	0.21	27.21	50.35	6	23.37	5.1	1.38	4.62	0.76	4.61	0.95	2.66	0.42	2.67	0.42	754	6.88	11.95	25.5	6.33	0.88	2.53	9.74	62.3	1.21	343	8.4	253	Dike	Plutonic	Dike																			3.72	4.06	3.38	48.86946109	-121.528392	0.0001	whole rock	Washington
HC-124	67.87	0.6	15.59	3.47	0.06	1.31	2.86	4.23	3.85	0.16	26.28	50.25	5.61	21.51	4.76	0.98	4.29	0.73	4.47	0.91	2.68	0.4	2.63	0.42	646	11.05	11.29	25.98	6.66	0.95	3.5	9.26	97.3	1.83	305	8.3	242	Nooksack Cirque	Plutonic	Monzonite													3.164	3.238	3.09	3.15	3.245	3.055				48.84847685	-121.5336416	0.0001	whole rock	Washington
HC-140	67.99	0.64	16.11	3.61	0.07	0.87	2.16	6	2.38	0.17	25.64	48.4	5.44	21.33	4.64	1.24	4.28	0.72	4.6	0.96	2.82	0.43	2.83	0.43	2.83	0.46	713	6.66	13.26	26.89	6.62	0.94	2.84	11.36	48.6	1.21	276	Ruth Mountain	Volcanic	Rhyodacite																				5.3	1.8	48.85682824	-121.5395325	0.0001	whole rock	Washington
HC-98	68.67	0.61	15.97	2.89	0.09	0.93	2.27	5.37	3.03	0.16	27.84	52.62	6.04	23.37	5.22	1.31	4.77	0.81	5.01	1.04	2.93	0.45	2.91	0.46	769	7.57	12.76	28.18	6.89	0.93	2.86	13.26	65.5	1.01	276	8.7	275	Precaldera volcanic rocks	Volcanic	Andesite																			3.72	4.06	3.38	48.86791662	-121.52721	0.0001	whole rock	Washington
HC-46	72.1	0.29	16.37	1.31	0.02	0.11	1.22	8.39	0.11	0.09																												Ruth Mountain	Volcanic	Ignimbrite																				5.3	1.8	48.87219027	-121.5307666	0.0001	whole rock	Washington
HC-31	73	0.29	14.73	1.8	0.06	0.33	0.87	5.1	3.75	0.06	24.37	43.87	4.66	16.85	3.34	0.67	2.78	0.48	3.13	0.68	2.13	0.35	2.46	0.41	835	9.2	13.57	19.27	6.75	1.09	3.63	10.94	81.7	1.05	108	4.1	264	Dike	Plutonic	Dike																			3.72	4.06	3.38	48.90474927	-121.5161661	0.0001	whole rock	Washington
HC-57	74.34	0.19	14.18	1.27	0.05	0.04	0.74	5.17	3.98	0.03																												Hannegan Peak	Volcanic	Ignimbrite																			3.722	3.742	3.702	48.89582777	-121.494191	0.0001	whole rock	Washington
MB-380	75.2	0.17	13.55	1.17	0.07	0.26	0.67	4.53	3.89	0.09																												Hannegan Peak	Volcanic	Ignimbrite	3.722	3.742	3.702	3.811	3.853	3.769																48.89022981	-121.5344671	0.0001	whole rock	Washington
HC-113	75.51	0.16	13.99	0.93	0.04	0.26	0.61	4.65	3.82	0.03	26.33	43.98	4.47	15.18	2.91	0.51	2.42	0.42	2.6	0.55	1.66	0.27	1.9	0.31	823	10.71	11.74	16.4	4.35	1.13	3.69	13.8	82.2	1.05	84	2.2	143	Hells Gorge	Volcanic	Rhyolite													3.95	4.25	3.65	3.72	4.06	3.38				48.89303195	-121.5005508	0.0001	whole rock	Washington
MB-485	79.2	0.15	11.66	0.96	0.05	0.19	0.4	3.76	3.15	0.04																												Hannegan Peak	Volcanic	Ignimbrite																			3.722	3.742	3.702	48.88026295	-121.5288934	0.0001	whole rock	Washington
Method Data																																																																		
1	XRF	299																																																																
2	ICPMS	299																																																																
3	AR-AR:Plateau Age: PLAG	60																																																																
4	AR-AR: Plateau Age: WR	60																																																																
5	AR-AR: Plateau Age: BIO	60																																																																
6	REG_COR:UNK	60																																																																
7	TABLE	2																																																																
8	AR-AR:Isochron Age: PLAG	60																																																																
9	AR-AR: Isochron Age: WR	60
10	AR-AR: Isochron Age: BIO	60