T239 Archaeological Geology (Posters)

Wednesday, 7 November 2012
9:00 AM - 6:00 PM
Hall B

THE WALLS OF SAQSAYWAMAN

Paper number: T239-5
Program: Technical Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

This archeological complex Saqsaywaman is located on a steep hill overlooking the ancient Incan capitol of Cusco, Peru. The complex is 3,700 meters above sea level to the North - West of Cusco. Most of the complex was demolished by Spanish settlers, who used the Incan stone to rebuild Cusco into a Spanish colonial town. What remains of the Saqsaywaman complex are large limestone blocks along with some shales, plasters and limonites which were too large for the Spanish settlers to easily remove. Some of these blocks are over 125 tonnes. Chroniclers state, that the construction of Saqsaywaman was initiated by the ninth Inca, Pachacutec and was continued by his son Tupac Yupanqui Inca, between 1431 and 1508. The construction of Saqsaywaman is testament to the stonework engineering ability of its builder architects: Huallpa Rimachi Inca, the first and main Builder, followed by Maricachi Inca, Acahuanca Inca and Calla Cunchuy Inca. The remaining walls lean inward, which according to current theory allowed the Inca to create a more earthquake resistant structure, and are comprised of mortar-less joints so closely interlocked that even a single sheet of paper cannot fit between the blocks.

Phase analysis and Rietveld refinement was accomplished using data collected with a Rigaku Miniflex-II diffractometer. Both fresh and weathered samples were analyzed. Each sample was crushed with a sledge hammer and ground in an agate mortar and pestle. Rietveld analysis converged with a χ2 = 6.55. The analysis determined that the fresh rock consisted of 94.7 (5) % calcite, 2.9 (2) % quartz and 2.4 (4) % microcline. The lattice parameters of the trigonal (hexagonal setting) calcite a = b = 4.9881 (3) Å, c = 17.0492 (13) Å indicate that it is a solid-solution which could contain nearly 3 % magnesium ions.

The rocks associated with the weathering of the Saqsaywaman complex reveal a complex mixture of feldspars, chlorites and amphiboles. The exact composition is under current investigation.