Clay supply for Aguada ordinary vessels from Piedras Blancas (IV to XII centuries AC) at the Ambato Valley (Argentina)

BERTOLINO, SILVANA; LAGUENS, ANDRÉS; ZIMMERMANN, UDO; GASTALDI MARCOS R.

APPLIED CLAY SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 131 p. 158 - 174

0169-1317

The provenance of the raw materials used to produce ordinary ceramicvessel of the Aguada Culture (4th to 12th c. AC) from the Ambato Valley(Catamarca, Argentina) has been evaluated. Since there are no commercial claydeposits in the area, local clayish sources were selected as possiblecandidates. Samples were collected from Precambrian to Low Paleozoicmetapelites, clays from fault gouges derived from crystalline basement rocks,epiclastic rocks and Quaternary loessic sediments that filled the valley andcrop out close to the archaeological sites. The pottery sherds were found atPiedras Blancas highly hierarchical site. Mineralogical and geochemical studieswere conducted by XRD and FE-SEM-EDS on both the pot sherds and the possiblesource materials. The latter were also preliminary evaluated on basic physicaland technological properties; test specimens were heated at differenttemperatures (800, 900 and 1000 °C) to study their thermal behavior andtheir mineralogical and textural transformations. The physical properties ofthe metapelites, the clay gouges and the loessic sediments suggest that theyare suitable for ceramic production. The epiclastic rocks are mostly bentoniticand could have been used as additives to improve the plasticity and otherproperties of other clay materials. The mineralogy of the sherds is quitehomogeneous with no significant differences between technological classes E andD; most of them bear either phlogopite, hornblende and/or hypersthene and hightemperature phases (diopside, spinel, mullite and cristobalite) also found insome clays under natural conditions or after firing at 1000 °C. Commonlyused provenance geochemical ratios are relatively similar in all potterysamples and in the selected source rocks and comparable with typical UCC.Hence, according to those values, all samples are related to each other andindistinguishable except for one sample (B30) highly enriched in REE. Nearlyall raw materials and ceramics are either enriched in Cs, Bi, Sb or in any ofthese elements. The trend of using local materials for the pottery is suggestedby the mineralogy and the geochemistry.