Mesozoic-Pleistocene fission-track ages on rocks of the Venezuelan Andes and their tectonic implications.
BP Kohn, R Shagam, PO Banks, LA Burkley
Geological Society of America Memoir (The Caribbean-South American plate boundary and regional tectonics), ed W. E. Bonini, R. B. Hargraves & R. Shagam | Published : 1984
A total of 45 fission-track ages are reported for 22 apatite, 21 zircon and 2 sphene concentrates from 23 rock samples. Apatite ages range from approx 1.4 to 24.0 m.y. and are interpreted as cooling ages due to uplift and erosion of cover rocks. Age vs elevation plots indicate a straight line slope of 0.8 km/m.y. uplift. This rapid rate of uplift is inferred to be due to updoming of isotherms. A new model for Tertiary Andean uplift, based on apatite ages, is presented in which initial uplift in the Oligocene-Miocene involved the leading margin, followed by uplift of the trailing edge in the late Miocene and of the central Andes in the Pliocene-Pleistocene. Zircon ages range approx 60-172 m.y..View full abstract