47 D9. Energy Geology and Environmental Geoscience (Posters)

Sunday, 19 March 2023
8:00 AM - 12:00 PM
Grand Ballroom A–D

APPLICATIONS OF ELECTRICAL RESISTIVITY AT THE POZUELO ARCHAEOLOGY SITE, CHINCHA VALLEY, PERU

Paper number: 47-5
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

In June 2022, a multidisciplinary team of archaeologists, geologists, geophysicists and geotechnical engineers spent 10 days investigating the environmental context of a low-relief, human-constructed four-mound complex south of Chincha, Peru using Electromagnetic Resonance Tomography (ERT) and stratigraphic analysis. Each mound has a relief of 3-5 meters above the surrounding cultivated plain, and is arranged in a roughly N-S orientation. Previous archaeological excavations at the site date the earliest occupation to 900 BCE, with construction and occupation associated with the Paracas Culture. While the site is located in the Peruvian coastal desert, the earlier work found evidence of wetland sediments and vegetation. The focus of the current investigation was to provide a paleo-environmental context for occupation and mound construction, and to develop an understanding of the spatial relationships between the mound structure and the surrounding and underlying alluvial plain.

A total of ten ERT lines, with a total length of approximately 600 m, were collected using an ABEM Terrameter LS2 with four cables. Stratigraphic analyses of archaeological excavation data, including a four-meter deep unit in the adjacent alluvial plain and a nearly 5-meter deep unit in the mound, served as ground truth. Surveys utilized the full capacity of the system’s 81 data points. Pin spacing varied between 0.5 and 5 m, depending on the purpose of the survey and length of the survey line. Five lines were located on the southern-most mound (Mound D) to link the excavation and underlying stratigraphic information to the geophysical data. Five additional lines were acquired on the third mound to the north (Mound B) to examine subsurface mound architecture and help establish the regional subsurface stratigraphy.

Stratigraphic analyses suggest basal sediments are fine-grained, water-lain deposits overlain by a thick clay layer, overtopped by aeolian sands, with approximately a meter of mound fill at the top. Deposits underlying the mound showed evidence of liquefaction, likely the result of strong seismic shaking.

This paper will present results from the joint ERT surveys and stratigraphic analyses, and the project’s effort to provide a geological and environmental context for the archaeology of the site.

Geological Society of America Abstracts with Programs. Vol. 55, No. 2

doi: 10.1130/abs/2023SE-385836

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