Stratigraphy and geochemistry of volcanic rocks in the Lava Mountains, California; implications for the Miocene development of the Garlock Fault
Smith, Eugene I; Sanchez, Alexander; Keenan, Deborah L; Monastero, Francis C (2002) Stratigraphy and geochemistry of volcanic rocks in the Lava Mountains, California; implications for the Miocene development of the Garlock Fault. Memoir - Geological Society of America, vol.195, pp.151-160, 2002
| Authors | Smith, Eugene I; Sanchez, Alexander; Keenan, Deborah L; Monastero, Francis C |
|---|---|
| Year | 2002 |
| Title | Stratigraphy and geochemistry of volcanic rocks in the Lava Mountains, California; implications for the Miocene development of the Garlock Fault |
| Source | Memoir - Geological Society of America, vol.195, pp.151-160, 2002 |
| Book editors | Glazner, Allen F; Walker, J Douglas; Bartley, John M |
| Publisher | Geological Society of America GSA, Boulder, CO, United States USA |
| ISBN | 813711959 |
| ISSN | 0072-1069 |
| GeoRef | 2003-005547 |
| Keywords | Almond Mountain; basalts; California; Cenozoic; displacements; Dove Spring Formation; El Paso Mountains; faults; Garlock Fault; geochemistry; igneous rocks; lateral faults; Lava Mountains; left-lateral faults; metals; Miocene; Neogene; rare earths; slip rates; Summit Range; Teagle Wash; Tertiary; trace elements; United States; volcanic rocks; volcanism |
Abstract
Volcanism in the Lava Mountains occurred between 11.7 and 5.8 Ma and was contemporaneous with sinistral motion on the Garlock fault. Volcanic rocks, equivalent in age and chemistry to those in the Lava Mountains, crop out 40 km to the southwest in the El Paso Mountains across the Garlock fault. Three chemical groups of volcanic rocks erupted in the Lava Mountains over a period of 5 m.y. These are 1 andesite of Summit Diggings, Almond Mountain volcanic section, and Lava Mountains Andesite, 2 basalt of Teagle Wash, and 3 tuffs in the northeastern Lava Mountains and dacite in the Summit Range. Volcanic rocks of each group have distinctive chemical signatures useful for correlation of units across the Garlock fault. Our work demonstrated that tuffs in the Almond Mountain volcanic section may be equivalent to a tuff in member 5 of the Miocene Dove Spring Formation, El Paso Mountains. The basalt of Teagle Wash probably correlates with basalt flows in member 4, and tuffs in the northeast Lava Mountains may be equivalent to tuff of member 2. Correlation of these units across the Garlock fault implies that the Lava Mountains were situated south of the El Paso Mountains between 10.3 and 11.6 Ma and that 32-40 km of offset occurred on the Garlock fault in approximately 10.4 m.y., resulting in a displacement rate of 3.1 to 3.8 mm/yr. Projecting this rate to the total offset of 64 km on the Garlock suggests that left-lateral slip began at ca. 16.4 Ma.