Subcritical Phase Separation and Occurrence of Deep-Seated Brines at the NW Caldera Vent Field, Brothers Volcano: Evidence from Fluid Inclusions in Hydrothermal Precipitates

Table 2

Statistical parameter for individual samples, host minerals, and lithologies in the microthermometric study. Note: two inclusions with extraordinary low (-14.0°C and -15.0°C) as well as two inclusions with higher than that of pure water (+1.8°C and +3.3°C) are excluded. The exclusion of the two highly saline inclusions results in two inclusion less for the sum of than mentioned in the text above.

Sample/lithology/host mineral	(number of observations)				(wt.% NaCl)					(°C)
					Mean	SD	Min	Max	Median	Mean	SD	Min	Max	Median
Chimneys	216	214	195	181	3.2	1.2	0.2	8.5	3.4	260	44	135	344	268
061-17S	26	24	15	13	3.6	1.3	0.8	8.5	3.6	205	51	149	295	182
061-1S	35	34	34	31	3.6	0.9	0.2	5.2	3.8	246	37	135	335	243
064-10S	34	34	34	31	1.8	1.6	0.2	5.3	0.8	289	32	251	344	269
067-14R	15	15	16	13	3.6	0.6	2.1	5.0	3.4	301	15	277	344	302
081-1S	37	36	34	32	3.6	0.4	3.0	4.4	3.6	246	33	185	303	234
1038-13-R8	39	39	35	35	3.7	1.0	3.3	7.9	3.4	295	4	288	306	296
1039-14-CH2	21	21	19	18	3.6	0.3	3.3	4.4	3.4	226	42	144	298	225
1041-31-CH1	10	10	8	8	3.3	0.5	2.3	3.9	3.4	214	36	169	270	222
Anhydrite (all chimneys)	123	122	117	110	3.1	1.3	0.2	7.9	3.4	279	35	170	344	292
Barite (all chimneys)	93	92	78	71	3.6	0.9	0.2	8.5	3.6	231	42	135	335	234
Stockwork	195	195	134	127	2.9	1.3	0.1	8.9	2.6	242	42	155	345	246
064-9R	44	44	25	25	2.9	0.9	1.5	4.1	3.0	284	44	184	345	290
085-6R	61	61	42	41	1.9	0.5	0.1	3.9	1.8	241	27	155	295	251
085-8R	33	33	29	25	3.3	1.5	0.9	8.9	3.3	208	28	168	265	198
1039-17-R1	57	57	38	36	3.6	1.4	0.1	8.0	3.4	226	40	155	318	241
Anhydrite (all stockwork)	40	40	26	26	2.4	0.7	1.5	4.1	2.3	257	39	184	331	248
Barite (all stockwork)	155	155	109	101	3.0	1.4	0.1	8.9	3.1	238	42	155	345	245
Propylitic	17	17	17	17	3.5	1.1	1.1	5.0	3.6	329	9	306	346	329
081-6R	17	17	17	17	3.5	1.1	1.1	5.0	3.6	329	9	306	346	329
Quartz (all propylitic)	17	17	17	17	3.5	1.1	1.1	5.0	3.6	329	9	306	346	329
All	429	425	346	325	3.1	1.3	0.1	8.9	3.4	257	47	135	346	255
Barite (all samples)	249	246	186	172	3.2	1.3	0.1	8.9	3.4	235	42	135	345	239
Anhydrite (all samples)	163	162	143	136	2.9	1.2	0.2	7.9	3.3	275	37	169	344	289
Quartz (all samples)	17	17	17	17	3.5	1.1	1.1	5.0	3.6	329	9	306	346	329