A Rising Force: New Study on Ancient Mantle Plumes

TECTONICS

What are the origin and evolution of plumes as they rise through the mantle? Has the number of plumes varied with time? What is their connection to uplift, rifting, and continental break up? How are large volumes of magma transported thousands of kilometers from the plume center?

by Kara LeBeau, GSA Staff Writer
Boulder - Feb 4, 2002
The subject of mantle plumes -- bodies of hot buoyant material that rise through Earth's mantle -- has become increasingly popular as scientists explore new links between mantle plumes and other Earth processes.

The best way to answer many of these questions is to examine the entire record of mantle plumes. Much has been written about young mantle plumes, but those between 250 and 4000 million years old must also be considered in order to have a complete picture of what mantle plumes are and how they function.

Richard E. Ernst and Kenneth L. Buchan from the Geological Survey of Canada have addressed this need by editing a new book, Mantle Plumes: Their Identification Through Time, published by the Geological Society of America as Special Paper 352 (November 2001).

he editors and authors hope this work will stimulate further research in identifying and finding mantle plumes -- particularly those more than 250 million years old. The book evolved from research presented at a Geological Society of America symposium.

"Our book provides a road map for the identification of plumes in the older record," Ernst said. "Given the importance of mantle plumes in the geological evolution of Earth and also Venus and Mars, we need to provide geoscientists with a more varied and better constrained repertoire of techniques for identifying and characterizing mantle plumes in the geological record."

The process of plate tectonics -- which is so important on Earth -- is apparently absent from Mars and Venus.

"This means that on Venus and Mars we can study the nature and effect of plumes in an environment where complications due to continental breakup, drift, and collision are absent," Ernst explained.

Chapters provide new information and fresh insight into the nature of mantle plumes including: how to identify ancient plumes and distinguish their magmatic products; research on Mesozoic and Cenozoic plumes that can be applied to identifying and understanding plumes throughout time; examination of plumes on Mars and Venus and implications for understanding plumes on Earth; how to find the centers of magma plumes; a global compilation of rifts associated with plumes; a compilation of mafic magmatic events throughout geologic time; and a set of criteria to discern plume-related events.

TECTONICS

Researchers Investigate Mysteries Of The African Rift

University Park - Dec 17, 2001
The formation and evolution of the African Rift Valley are shaded in mystery, but geoscientists at Penn State are mapping the history of the Rift through space and time by analyzing the chemistry of ancient lava from Lake Turkana, northern Kenya.

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