Investigators:	Hans G. Avé Lallemant
Consultant:	V.(Jinny) B. Sisson
Collaborators:	Anne Dowd & George E. Harlow, American Museum of Natural History; New York City Sorena S. Sorensen, Smithsonian, Washington, DC Hannes K. Brueckner,Queens College-CUNY, New York City Sidney Hemming, Lamont-Doherty Earth Observatory, Columbia University Karl Taube, University of California-Riverside
Graduate Student:	Ashley H. Francis
Funding Source:	National Science Foundation

The Motagua Valley, Guatemala: the Caribbean-North American plate boundary

Abstract

The Motagua fault zone in Guatemala is the western part of the Caribbean - North American plate-boundary zone (PBZ). At present this PBZ is a left-lateral strike-slip fault zone, but in the past (mid Cretaceous to Eocene) it was a subduction zone. In Guatemala this PBZ separates two very different terranes: the Maya block in the north and the ChortÀ܈ÑÀ܈†’ÄôˆÑˆ¥À܈ëÀÜÔø‡s block to the south. Along the fault zone several slices of serpentinite occur that enclose fragments of high pressure / low temperature (HP/LT) metamorphic rocks such as blueschists, eclogites, and jadeitites. The origin and the evolution of the jadeitites are the centerpiece of this study. The main approaches to understand the evolution of the jadeitites are geochemical and petrological. However, structural analysis and geochronological studies are performed as well so as to put the jadeitites and other HP/LT metamorphic rocks into a plate-tectonic framework.

Recently, we found jade in this region that is similar to that used in antiquity particularily by Olmecs, the people who created the first complex culture in pre-Columbian Mesoamerica (Seitz et al., 2001). Other jade from the region is also linked to Mayan and Aztec cultures. This find was the rediscovery an ancient source for wealth. (I could say more but I was trying to keep this short)

Also, there are now some publications related to this research that could be referenced:

Publications:

Sisson, V. B., Harlow, G. E., Avé Lallemant, H. G, Hemming, S., Sorensen, S.S., 2003, Two belts of jadeitite and other high-pressure rocks in serpentinites, Motagua Fault Zone, Guatemala, Geological Society of America Abstracts, 35, 4, 75

Sisson, V.B., Harlow, G.E., Sorensen, S.S., Bruekner, H.K., Sahm, E., and Avé Lallemant, H.G., 2003, Lawsonite Eclogite and other high-pressure assemblages in the southern Motagua Fault zone, Guatemala: Implications for Chortis Collision and Subduction Zones, Geological Society of America Abstracts, 35, 7, 639

Harlow, G.E., Sisson, V. B., Avé Lallemant, H.G., Sorensen, S. S., 2003, High-pressure, metasomatic rocks along the Motagua Fault Zone, Guatemala, Ofioliti, 28 (2), 115-120.

Harlow, G.E., Hemming, S.R., Avé Lallemant, H.G., Sisson, V.B., Sorensen, S.S., 2004, Two HP-LT serpentinite-matrix mélange belts, Motagua fault zone, Guatemala: A record of Aptian and Maastrichtian collisions, Geology, 32, 17-20.

http://www.agiweb.org/geotimes/aug02/NN_jade.html

Seitz, R., Harlow, G. E., Sisson, V. B., and Taube, K. E., 2001, Formative jades and expanded jade sources in Guatemala. Antiquity, v. 75, no. 290, 687-688

Sisson, V.B., 2002, Re-Discovery of Olmec blue jade, Houston Geological Society Bulletin, 45, 2, 23-25.

Sisson, V. B., Harlow, G.E., Hemming, S., Sorensen, S.S., Avé Lallemant, H.G, 2002, Jadeitite and eclogite occurrences along the Motagua Suture Zone, Guatemala, International Mineralogist Association abstracts.