The U–Pb and Hf isotope evidence of detrital zircons of the Ordovician Ollantaytambo Formation, southern Peru, and the Ordovician provenance and paleogeography of southern Peru …

Abstract:

The Ordovician Ollantaytambo Formation represents one of only two known occurrences of Lower Paleozoic volcanic rocks in southern Peru and northern Bolivia. Its lower part consists of mafic lapilli tuffs, shales and mature sandstones form the upper part. We present LA-ICP-MS U–Pb ages and Hf isotope data of detrital zircons from one of the upper member sandstones in order to determine both the duration of volcanism and the provenance of the mature detritus, and to use the data to further define the paleogeography of the Ordovician basin in the northern Central Andes. The detrital zircon ages of the Ollantaytambo Formation range from 2013 Ma to 445 Ma. They are grouped mainly between 1400 and 1100 Ma (35%), 1100 and 900 Ma (14%), 770 and 650 Ma (14%), and from 500 Ma to 440 Ma (30%). Within these groups the main peaks are at 1249 Ma, 1052 Ma, 741 Ma and 459 Ma. The older groups …

Año de publicación:

2011

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