Spatio-temporal forecasting of future volcanism at Harrat Khaybar, Saudi Arabia

Table 2 Age determinations for volcanic rocks from Harrat Khaybar, western Saudi Arabia. Map# refers to circled numbers on Fig. 4

Map#	Sample	Latitude (N)	Longitude (E)	Formation /Feature	Rock Type	Age (Ma)	(±2 s) (Ma)	N	%⁴⁹Ar	MSWD
1	HK-3	25°50′25.9”	39°57′10.7”	Abyad	alkali basalt	0.349	0.006	22/31	87	1.34
2	HK-32	25°46′28.7”	40°01′16.0”	Abyad	alkali basalt	0.130	0.005	22/31	76	1.28
3	HK-28	25°39′37.3”	39°45′14.4”	Abyad	alkali basalt	0.351	0.007	22/31	85	0.80
4	HK-27	25°37′33.4”	39°37′31.7”	Mukrash	alkali basalt	0.364	0.011	28/31	97	0.61
5	HK-26	25°36′58.3”	39°32′07.1”	Mukrash	alkali basalt	1.430	0.010	19/31	74	2.52
6	HK-5	25°40′04.6”	39°58′08.7”	Mukrash	comendite	1.700	0.030	17/35	71	> 100
7	HK-20	25°45′40.9”	39°17′43.4”	Jarad	alkali basalt	1.700	0.010	16/31	71	0.65
8	HK-6	25°21′04.4”	39°31′29.0”	Jarad	alkali basalt	1.530	0.010	12/31	50	1.41
9	K18	25°35′24.2”	39°56′20.9”	Jabal Sulajal Hayurah	basalt lava	0.158	0.013	40/40	100	0.60
10	K21H	25°35′55.6”	39°56′20.6”	Halat Kharshaal Hayyirah	trachyte pyroclast	0.436	0.001	30/40	75	1.51
11	K25A	25°39′52.6”	39°55′45.4”	Jabal Bayda	rhyolite pyroclast	0.136	0.002	31/40	87	1.03
12	K36B	25°39′50.1”	39°57′41.8”	Jabal Abyad	rhyolite pyroclast	0.053	0.017	39/40	97	1.88
13	K55B	25°37′44.6”	39°57′46.9”	middle steep dome	trachyte pyroclast	0.465	0.002	29/40	71	1.60
14	K57A	25°38′02.9”	39°59′31.8”	flat western coulee	trachyte dome	0.958	0.003	22/40	52	1.80
15	K60D	25°38′03.5”	39°56′36.9”	large old trachyte crater	trachyte pyroclast	0.486	0.002	32/40	79	1.85
16	K61B	25°38′11.7”	39°57′06.0”	low scoria/tephra cone	basalt bomb	0.454	0.002	14/40	58	0.80

Ages calculated using sanidine monitor FCs (28.201 Ma, Kuiper et al., 2008) and the total decay constant l = 5.530 × 10⁻¹⁰/yr. N is the number of heating steps (defining plateau/total); MSWD is an F-statistic that compares the variance within step ages with the variance about the plateau age

ISSN: 2191-5040