Abstract
Miocene basalts of eastern California provide a potentially useful tool for deciphering the Neogene to recent structural evolution of the White and Inyo Mountains (White/Inyos). The Tres Plumas Lava (TP) and the Deep Springs Valley (DSV) basalts are two separated ( nearly equal 26 km apart) mafic lavas that have been loosely correlated in other studies. DSV basalts are normal faulted and scattered across the valley with as much as 1300 ft of offset. A K/Ar date gives 10.8 Ma for the basalt and 10.9 Ma for a directly underlying tuff. No dates are available for the TPs or underlying tuff. Previous studies have suggested the lava in DSV was erupted within the White/Inyos, but no study has yet compared the two locations to test the TPs as the White/Inyos source. Field work, geochemical analysis, and thin section work have been conducted to test the correlation of the TP and DSV basalts. XRF and trace element analysis of samples from both locations display very similar alkaline to subalkaline chemistry, both enriched in LREEs. These magmas were erupted in an attenuated lithospheric tectonic setting. The distribution of outcrops in TP and DSV suggest an elongate paleo-channel. Field evidence suggests a complicated paleo-terrain as the basalts directly overly granitic material, sedimentary deposits, and ash flow tuffs. A potential dike has been located and sampled for petrographic and geochemical analysis in the Chocolate Mountain region of DSV. This dike provides evidence for an eruption source in DSV, contradicting claims from previous studies suggesting a White/Inyos source for the DSV lavas. More field work is planned to compare the two areas, locate the eruption vent(s), and determine the flow direction of these lavas. If the TP and DSV lavas are correlative, then the lava distribution can be used to constrain the timing and amount of White/Inyos uplift and answer longstanding questions about the influence of Basin and Range tectonics in the region.