Magnetic Polarity Stratigraphy, Age and Tectonic Setting of Fluvial Sediments in an Eastern Andean Foreland Basin, San Juan Province, Argentina

  1. P. A. Allen and
  2. P. Homewood
  1. Noye M. Johnson1,
  2. Teresa E. Jordan2,
  3. Patricia A. Johnsson1 and
  4. Charles W. Naeser3

Published Online: 5 MAY 2009

DOI: 10.1002/9781444303810.ch3

Foreland Basins

Foreland Basins

How to Cite

Johnson, N. M., Jordan, T. E., Johnsson, P. A. and Naeser, C. W. (2009) Magnetic Polarity Stratigraphy, Age and Tectonic Setting of Fluvial Sediments in an Eastern Andean Foreland Basin, San Juan Province, Argentina, in Foreland Basins (eds P. A. Allen and P. Homewood), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303810.ch3

Author Information

  1. 1

    Earth Sciences Department, Dartmouth College, Hanover, New Hampshire 03755, USA

  2. 2

    INSTOC, Cornell University, Ithaca, New York 14853, USA

  3. 3

    Branch of Isotope Geology, U.S. Geological Survey, Denver, Colorado 80225, USA

Publication History

  1. Published Online: 5 MAY 2009
  2. Published Print: 22 DEC 1986

ISBN Information

Print ISBN: 9780632017324

Online ISBN: 9781444303810

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Keywords:

  • magnetic polarity stratigraphy, age and tectonic setting of fluvial sediments in eastern Andean foreland basin, San Juan Province, Argentina;
  • lithostratigraphy and depositional environments;
  • Huachipampa Formation;
  • Quebrada del Jarillal Formation;
  • Rio Jachal Formation - conformable on Quebrada del Cura Formation;
  • Mogna Formation overlying Rio Jachal Formation;
  • siwalik molasse of Pakistan

Summary

A 5·4 km thick sequence of tectonically derived sediment has been dated by means of magnetic polarity stratigraphy and fission track methods. The sequence is located at Sierra de Huaco in the Precordillera of western Argentina. Sedimentation occurred over some 12 Myr from 14 to 2 Myr. Throughout this period the climate was arid as indicated by the dominance of alluvial fan and playa deposits. Sedimentation rates increased radically at about 9 Myr going from 0·17 to 0·92 mm yr−1, a five-fold change. At about this time sedimentary style also changes and by 8·6 Myr new detrital minerals appear in the sequence. We attribute these transitions to the initiation of uplift in the Central Precordillera, uplift activity which continues to the present day. Locally derived conglomerate first appears in the section at 4·8 Myr and subsequently this conglomerate facies becomes pervasive. These conglomerates suggest that the Sierra de Huaco structure itself was being formed and eroded perhaps as early as 4·8 Myr. The pediments and gravel straths flanking the Sierra de Huaco today are the modern extensions of this process.