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Figure 1.
(A) Evolution of the Yellowstone hotspot (YHS) track relative to the North American plate. Siletzia is restored to its relative position at ca. 42 Ma when the YHS was overridden by the accreted Siletzia terrane, now part of North America. Ancestral Cascades arc location at ca. 40 Ma is modified from Wells and McCaffrey (2013). Colored locations east of Siletzia correspond to progressive sites of crustal melting along the hotspot track since ca. 30 Ma, without removal of Basin and Range extension. Purple diamond and circle are locations of YHS with respect to N. America at 40.5 Ma from McCrory and Wilson (2013) in Pacific (PAC) and Atlantic (ATL) hotspot frames; red dots are projected YHS locations using plate motion of Matthews et al. (2016) and assuming a fixed YHS. Black and gray dotted lines are possible YHS tracks modified from Wells et al. (2014). NNR—northern Nevada rift; YSRP—Yellowstone–Snake River Plain. Calderas, felsic volcanic fields, and lava centers from Shervais and Hanan (2008), Benson et al. (2017), and Anders et al. (2019), with colors corresponding to color-code ages in panel B. Mafic fields in the Coast Range: T—Tillamook; Y—Yachats; G—Grays River. Felsic volcanic fields: LOVF—Lake Owyhee Volcanic Field; MVF—McDermitt Volcanic Field; HRCC—Field of the High Rock Caldera Complex; OP-BJ-TF—Owyhee Plateau–Bruneau Jarbidge–Twin Falls Volcanic Field. Individual calderas shown in irregular oval polygons: MR—Magic Reservoir; OH—Owyhee-Humboldt; BJ—Bruneau-Jarbidge caldera; TF—Twin Falls caldera; R—Rooster Comb caldera; CR—caldera at Castle Rock; DM—Dooley Mountain; JM—Juniper Mountain. Contemporaneous felsic centers shown as yellow boxes: SC—Silver City; LJ—Little Juniper Mountain; HH—Horsehead Mountain; JB—Jackass Butte; SW—Swamp Creek Rhyolite; TMC—Twenty Mile Creek Rhyolite; BB—Bald Butte; D—Drum Hill; HV—Hawks Valley–Lone Mountain; S—Sleeper Rhyolite; SR—Santa Rosa–Calico; IN—Inzenhood; IV—Ivanhoe; J—Jarbidge. The two stars represent alternative sites for the plume center at 17–16 Ma, the blue-star location supported by some workers (e.g., Glen and Ponce, 2002; Shervais and Hanan, 2008; Wolff and Ramos, 2013), and the red-star location supported by others (e.g., Camp and Ross, 2004; Pierce and Morgan, 2009; Benson et al., 2017). (B) Timeline of tectonomagmatic events along the YHS track.
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