NEW EVIDENCE OF CLOCKWISE VERTICAL AXIS ROTATIONS SOUTH OF THE ARICA ELBOW (ARGENTINE PUNA)

The Central Andes show a pronounced bend at 18 degrees S. This bend is called the Arica elbow. The existence of counterclockwise vertical ax is rotations north of the Arica elbow and clockwise rotations to the s outh has been determined from palaeomagnetic data. Various authors hav e proposed different mechanisms to explain this, but whether rotations are local or regional and whether the Arica elbow is a primary or sec ondary feature of the Central Andes remains controversial. In order to contribute to the palaeomagnetic data available for the Argentine Pun a, 102 oriented cores were obtained from Cenozoic rocks cropping out i n the Bajo de las Siete Curvas area of the southern Argentine Puna. Di fferent demagnetization techniques were applied. Pretectonic remanent magnetizations were isolated, and indicate the existence of a clockwis e vertical axis rotation of approximately 7 degrees-18 degrees. Taking into account the presence of a major thrust fault to the west of the studied area, this rotation could be considered to be of local charact er, induced by a Miocene-Pliocene compression. (C) 1998 Elsevier Scien ce B.V. All rights reserved.