4.6.1. Tripcevich source sampling work

In the course of Upper Colca 2003 survey work geological samples of unmodified obsidian were collected from a variety of natural contexts throughout the Upper Colca study area as well as elsewhere in the Colca valley. In order to best characterize the elemental variability within a chemical type, Shackley (1998: 100-101) recommends collecting samples from throughout the primary and secondary deposition area in sufficiently high numbers to recognize sub-source variability and reduce the chances of mischaracterization.

Figure 4-24. Bivariate plot showing Dysprosium against Manganese for Tripcevich 2005 samples.

Figure 4-25. Map showing locations of Colca valley obsidian source samples analyzed by MURR in 2005.

On Figure 4-24 only samples NT0005, NT0008, and NT0015 fall within the Chivay ellipse giving the impression that there is chemical variability at the Chivay source. Bivariate plots across other elements, however, show that all of the samples fall squarely within the Chivay ellipse.

MURR ID	Result	Region	Description	Quality	Date	Elev	Longitude	Latitude
CQP001	Chivay	Colca	Condorquiña source near Pulpera	Poor	2002	4160	-71.41795	-15.55677
CQP002	Chivay	Colca	Condorquiña source near Pulpera	Poor	2002	4155	-71.41793	-15.55675
CQP003	Chivay	Colca	Condorquiña source near Pulpera	Poor	2002	4160	-71.41795	-15.55677
NT0001	Chivay	Colca	East of Cerro Hornillo	Med	2002	4972	-71.51366	-15.63657
NT0002	Chivay	Colca	Maymeja SE rim along trail departing area at 140°	Good	2003	5003	-71.54049	-15.65356
NT0003	Chivay	Colca	Quarry pit Q02-2, A03-219	Good	2003	4916	-71.53554	-15.64233
NT0004	Chivay	Colca	Chivay	Good	2003	4911	-71.53577	-15.64257
NT0005	Chivay	Colca	Chivay, A03-570. Cortex battered, poss. from glaciers.	Good	2003	4722	-71.55058	-15.64167
NT0006	Chivay	Colca	Chivay, northern Maymeja	Med	2003	4900	-71.53812	-15.63772
NT0007	Chivay	Colca	Chivay, northern Maymeja	Med	2003	4902	-71.53794	-15.63770
NT0008	Chivay	Colca	On western shoulder of Ancachita with ash sample	Med	2001	4622	-71.55493	-15.64239
NT0009	Chivay	Colca		Good	2002	4798	-71.54423	-15.64587
NT0010	Chivay	Colca	Quarry pit Q02-2, A03-219	Good	2003	4915	-71.53556	-15.64247
NT0011	Chivay	Colca		Good	2003	4685	-71.55794	-15.65837
NT0012	Chivay	Colca		Good	2003	4885	-71.53793	-15.64292
NT0013	Uyo Uyo	Colca	W. side of Cerro Caracachi	Poor	2003	4450	-71.67602	-15.61547
NT0014	Uyo Uyo	Colca	East slope of Cerro Masita	Poor	2003	4372	-71.68787	-15.60532
NT0015	Chivay	Ayaviri	Artifact from Yana Salla, Llalli	Good	2001	4200	-70.87933	-14.94699
NT0016	Alca-3	Cotahuasi	Near small rock shelter by top of landslide	Good	2001	4288	-72.73238	-15.11981
NT0017	Alca-1	Cotahuasi	From across valley near old canal	Med	2001	4203	-72.71776	-15.12254
NT0018	Alca-1	Cotahuasi	From across valley near old canal	Med	2001	4202	-72.71776	-15.12254
NT0019	Alca-3	Cotahuasi		Good	2001	4329	-72.73268	-15.11858
NT0020	Alca-1	Cotahuasi	Above Ayawasi	Med	2001	3760	-72.73644	-15.14140

Table 4-5. Peruvian obsidian source samples submitted to MURR by Tripcevich in 2002 and 2005. Coordinate datum is WGS84.

Three samples were provided from the low-quality Condorquiña source in the Pulpera area that were collected in 2002 in order to evaluate the chemical variability within the Chivay source. While the quality was poor, this characterization demonstrates further association between that the Chivay obsidian chemical type and the Pliocene Barroso lava flows evident in the Colca valley. One artifactual sample that turned out to be Chivay was from the town of Llalli close to Ayaviri, in Puno.

Additional samples were submitted from the Alca source collected during fieldwork in 2001 from an exposure described by Justin Jennings (Pers comm. 2001) to the west and south of Cerro Aycano. Kurt Rademaker and colleagues (2004) have since encountered much larger obsidian exposures to the east of this area, on moraines located on the northern slopes of Nevado Firura at approximately 4700 masl.