DETERMINATION OF TRACE ELEMENTS USING HAWAIIAN BEACH SANDS: CONSTRAINTS ON PROVENANCE

The objectives of this research are focused on two important geologic considerations and include the mineralogy and provenance of green, black and white sands. Current research was made possible through a grant from the TMCF* awarded to the author. Representative sand samples were collected from several key locations including the Big Island and Diamond Head Crater (Oahu) in Hawaii and grain size plus compositional investigations conducted by using available facilities at York College. Aside from color contrast, examined sand samples exhibited a characteristic anomaly in terms of specific minerals, bulk oxide, trace element distributions, and sedimentological parameters. Overall, Hawaiian sand composition can be summed up as having more than half biogenic grains with approximately equal amounts of basalt fragments, pyroclastic, and olivine. The total amount of magnetite in the sample is small. Hawaiian black sand is heterogeneous in composition and includes weathered basalts, Ca-feldspars, scattered ilmenite and magnetite. Olivine crystals dominated the green and black sands, whereas white sands largely lacked olivine and are almost entirely made from reworked marine shells, or calcium carbonate. Chemical analyses indicated a marked difference in Fe, Ti, Ca, Zr, Sr, Ni, and Cr with respect to green, black and white sands. Preliminary data indicated two different pathways for enrichment of particular trace-elements suite associated with green, black and white sand and final mineralogy was constrained by the distinctive geomorphic processes operating along the Hawaiian shoreline.

* Thurgood Marshall College Fund (TMCF) provided logistical and financial support to this project.