[1] Between June 2003 and September 2005, 20 broadband, three-component seismometers were deployed along the MacKenzie-Liard Highway in Canada’s Northwest Territories as part of the joint Lithoprobe-IRIS Canada Northwest Experiment (CANOE). These stations traverse a paleo-Proterozoic suture and subduction zone that has been previously documented to mantle depths using seismic reflection profili...

The Cuatro Ciénegas Basin (CCB) is a rare oasis in the Chihuahuan Desert in the state of Coahuila, Mexico. It has a biological endemism similar to that of the Galapagos Islands, and its spring-fed ecosystems have very low nutrient content (nitrogen or phosphorous) and are dominated by diverse microbialites. Thus, it has proven to be a distinctive opportunity for the field of astrobiology, as th...

We agree with Glikson [1] that the identification of Precambrian impact deposits is an important and largely unresolved problem, and thank him for providing us with an opportunity to further discuss our mineralogical and geochemical results [2] on the enigmatic spherule layers in the Barberton Mountain Land of South Africa. We note, however, that unfortunately Glikson has not been able to name ...

The sudden appearance of fossils that marks the so-called 'Cambrian explosion' has intrigued and exercised biologists since Darwin's time. In On the Origin of Species, Darwin made it clear that he believed that ancestral forms 'lived long before' their first fossil representatives. While he considered such an invisible record necessary to explain the level of complexity already seen in the foss...

Microbialites are the most abundant macrofossils of the Precambrian. Decline in microbialite abundance and diversity during the terminal Proterozoic and early Phanerozoic has historically been attributed to the concurrent radiation of complex metazoans. Similarly, the apparent resurgence of microbialites in the wake of Paleozoic and Mesozoic mass extinctions is frequently linked to drastic decl...

[1] Reliable global crustal field anomaly maps produced from magnetic measurements of the CHAMP satellite mission now allow for quantitative geological studies of crustal structure and composition. We have developed a GIS based forward modeling technique to model these anomaly maps. On the basis of the geologic and tectonic maps of the world, laboratory susceptibility values of the occurring ro...

Ab&r&-Quartz crystals from calcite veins of unknown age in Precambrian metasedimentary rocks at Geiaus No. 6 and Aukam farms in South-West Africa contain both primary and secondary inclusions filled with one or a variable combination of: organic liquid, moderately saline aqueous liquid, dark-colored solid, and vapor. Analysis of these materials by microscopy and by gas chromatography and maas s...