40Ar/39Ar laser probe dating of detrital white micas from Cretaceous sedimentary rocks of the Eastern Alps: Evidence for Variscan high-pressure metamorphism and implications for Alpine orogeny: Reply
The detritus of Cretaceous synorogenic sandstones of the northern margin of the Austroalpine microplate contains evidence for a high-pressure metamorphic basement and obducted oceanic crust exposed in early Alpine time. 40 Ar/ 39 Ar laser-probe data of detrital white micas give excellent plateau ages in a narrow range from 320 to 360 Ma. White micas cover the whole range from muscovites up to phengites (3.04 to 3.48 Si per formula unit). Heavy mineral spectra contain chrome spinel, glaucophane, chloritoid, epidote, and garnet, as well as zircon, tourmaline, and rutile. Glaucophane, chloritoid, and phengite correlate in their abundance. These minerals also correlate positively with the stabl…
Time Markers for the Evolution and Exhumation History of a Late Palaeozoic Paired Metamorphic Belt in North-Central Chile (34°-35°30'S)
A multi-method geochronological approach is applied to unravel the dynamics of a paired metamorphic belt in the Coastal Cordillera of central Chile. This is represented by high-pressure - low-temperature rocks of an accretionary prism (Western Series), and a low-pressure- high-temperature overprint in the retro-wedge with less deformed metagreywackes (Eastern Series) intruded by magmas of the coeval arc. A pervasive transposition foliation formed in metagreywackes and interlayered oceanic crust of the Western Series during basal accretion near metamorphic peak conditions (∼350-400°C, 7-11 kbar) at 292-319 Ma (