Taiwan assists in Micronesian coral pyramid study

2015-03-18

A group of National Taiwan University researchers using high-precision radiometric dating techniques have assisted an international team redefine the chronology of coral pyramid tombs on the Micronesian island of Kosrae.

Employing cutting-edge uranium-thorium, or U-Th, techniques, the researchers placed the date for the three youngest structures at between 1311 and 1388, around 300 hundred years older than previously thought. This finding was a key plank in the team’s study published March 13 in the journal Science Advances.

Led by Shen Chuan-chou, a professor with NTU’s Department of Geosciences, the researchers identified the use of biotic materials as a unique trait of the royal tombs. “A total of 15 percent employ scleractinian corals in their construction,” Shen said. “This is in stark contrast to the abiotic resources used in most ancient burial structures.”

Coral building materials are a defining feature of Leluh, the lagoon-based capital of the fabled Micronesian empire of Kosrae. The crypts studied by Shen’s team employed a mixture of live and fossil corals, some dating from 4,000 to 6,000 years ago.

Standing about 4-6 meters tall, the Leluh pyramids are shaped like frustums with the pointy tops truncated. One aspect of the tombs eluding researchers for many years also came to light during the study.

“These mortuary structures served as a temporary resting place for the Kosraen kings,” Shen said. “After a maximum of three months, the bones would be exhumed and buried in the nearby reef, warranting the open-top structure of the Leluh pyramids.”

The NTU researchers joined the Western Australia Museum-led initiative three years ago, with the Ministry of Science and Technology and university providing grants to support the U-Th dating project.

Source: Taiwan Today (http://taiwantoday.tw/ct.asp?xItem=228369&CtNode=413)