U-PB GEOCHRONOLOGICAL EVIDENCE ABOUT ASSEMBLAGE AND DISMEMBERING CYCLE AT WESTERN OF PANGEA: TEZIUTLÁN MASSIF, PUEBLA, MÉXICO, AT EASTERN OAXAQUIA MICROCONTINENT

Teziutlán Massif consist of an assemblage of medium to high grade metamorphic and igneous rocks that crops out as isolated patches at eastern-central Mexico. Metamorphic rocks includes mylonitic gneisses in greenschist facies. Possible protoliths include granites, basalts, clastic(?) sedimentary rocks and rhyolites. The lack of geochronologic data and the apparently juxtaposition with the eastern of Oaxaquia microcontinent it does not allow assignment to Maya or Sierra Madre terranes in backbone of crystallized basement of México.

In this work, we present new U-Pb data of metasedimentary and igneous rocks of Teziutlán Massif and sedimentary cover. Paragneisses have zircon populations at ~926, ~1010, ~1100 and ~1200 Ma, consistent with a Grenville source. Mica schist shows zircons that range in age between ~296 and ~330 Ma. Interfingering the metasediments exist a mylonitic granitoid that have younger ages in ~323 Ma and peak in ~331 Ma; metasedimentary units age is constrained by a mylonitic granite intrusion dated at 323 Ma. Further to the south, not deformed syenitic rocks yield an U-Pb zircon age of ~168 Ma. These igneous and metamorphic are overlayed by sandstones with detrital populations at ~195 Ma and a common population at ~255 Ma, most probably derived from a Permo-Triassic arc.

Proterozoic ages for detrital zircons confirm that Paleozoic sedimentary units were deposited in basins with remarkable influence of Oaxaquia. Teziutlán area was intruded by magmatic rocks that record a possible Carboniferous approach between Laurentia and peri-Gondwana terranes. This approach results in the assembling of Pangea progressively until Permian. Middle Jurassic igneous rocks probably represent the first stages of magmatism during the opening of Gulf of México. These ages are distributed along central and southern México. Teziutlán area represent then, a critical piercing point for understanding assembly and breakup of Pangea.