Leanne M. Mallory-Greenough

Provenance of temper in a New Kingdom Egyptian pottery sherd: Evidence from the petrology and mineralogy of basalt fragments

A New Kingdom spinning bowl from Karnak (Luxor) Egypt is similar in form to spinning bowls commonly found at other Egyptian sites and has a bulk chemical composition in the range for other Egyptian marl vessels. These data support a domestic origin. The matrix of the bowl contains unaltered, sand-sized, mafic rock fragments with volcanic, subophitic textures. Over 20% of the sand-sized grains consist of angular, unweathered rock fragments, and of these ∼20% are volcanic. Apparently they were added as temper. Electron microprobe analyses show that augite, plagioclase, and, where present, pigeonite, in nine of these have compositions typical of mafic igneous rocks. Geothermometry confirms crystallization at ∼1100°C. Pyroxene discrimination diagrams indicate geological sources ranging from within-plate alkali basalts to within-plate, continental tholeiites. Suitable sources for the temper are rare in Egypt. Both alkaline and tholeiitic, postorogenic (unaltered) late Cenozoic basalts occur in the Cairo area, making this the most likely but not the only possible source for the temper. The pottery may have also originated in Cairo because raw rock materials were moved upstream less commonly than down the Nile. A Cairo provenance for the Karnak artifact is consistent with the everyday movement of people and goods along the Nile between the ancient twin capitals of Memphis and Thebes. These results and the common occurrence of volcanic rocks as temper indicate that microbeam analytical techniques may help narrow the provenance of ancient pottery.

Incompatible element ratios in French Polynesia basalts: describing mantle component fingerprints

The chemical composition and origin of the isotopically identified end-member mantle components have been difficult to describe because their melted samples—oceanic basalts—are affected by many processes such as variable degrees of partial melting. Exploratory data analysis [multidimensional scaling (MDS)] applied to ∼200 basalts from French Polynesia reveals over 100 ratios of similarly incompatible elements (SIER) that are minimally affected by these processes. Ratios from elements with dissimilar incompatibility are identified as affected by melting percentages. When basalt samples are compared simultaneously using ∼100 SIER and MDS, they organise in the same way that they would with isotopes, according to mantle component type. Applying discriminant analysis to the most extreme French Polynesia samples representing each mantle component yields preliminary discrimination diagrams that improve the description of chemical variation in the mantle. As a test of their utility and reliability, they are used ...