Correlación entre los grupos cámbricos Nikizanga y Caucete en la Sierra de Pie de Palo. Implicaciones paleogeográficas

CASQUET, C.; BALDO, E.G.; RAMACCIOTTI, C.

Congreso; XX Congreso Geológico Argentino; 2017

The Sierra de Pie de Palo in the Andean foreland consists mainly of a Mesoproterozoic basement, an Ediacaran metasedimentary cover, and Cambrian metasediments (Nikizanga and Caucete groups). These Cambrian groups are key units to understand the role of the Pie de Palo block in the SW Gondwana margin. We show here U-Pb SHRIMP detrital zircon ages from the Nikizanga Group, along with a reinterpretation of detrital zircon ages from the Caucete Group, and Sr-isotope composition of marbles. One quartzite from the Nikizanga Group has zircons with ages between 506 and 2753 Ma with a main peak at ca. 530 Ma and minor groups at ca. 680, 1040 and 2040 Ma. A reinterpretation of ages from previous contributions from the Caucete Group yielded the youngest zircons at ca. 520 Ma. Sr-isotope composition of marbles from both groups suggests a sedimentation between ca. 480 and ca. 510 Ma. A deposition at this age, sourced with zircons of ca. 530-520 Ma is consistent with a Gondwana provenance. Thus, the Cambrian zircons were eroded from the Pampean orogen.