New Mexico Geological Society Annual Spring Meeting — Abstracts

The study of the magnetic properties of minerals and rocks and the geochronologic applications of these properties is a relatively new sub-discipline of geology. Whereas initial applications of paleomagnetism and magnetostratigraphy tended to focus solely on igneous rocks, especially lava flows, advances in technology now allow us to develop accurate geomagnetic polarity chronologies for a wide variety of sedimentary rock types. Examples of the application of paleomagnetic techniques for geochronologic purposes in New Mexico cover many rock types across the state. Individual lava flows in the Boot Heel and Mogollon silicic volcanic fields in southwestern New Mexico have been accurately dated using a combination of radioisotopic dating and paleomagnetic techniques.

Geomagnetic polarity chronologies have been developed for sedimentary strata ranging from the Upper Permian Quartermaster and Dewey Lake Formations near Carlsbad through Triassic strata in northern and eastern New Mexico and Upper Cretaceous-Paleocene strata in the San Juan Basin to Plio-Pleistocene Camp Rice and Palomas strata in southern New Mexico. Instrumentation is now refined enough to measure magnetic remanence in fine-grained magnetite in marine limestones, opening a whole new area of research. In addition, New Mexico is home to the locality where the Jaramillo polarity event was first documented. The Jaramillo event is a short-duration normal polarity event that occurred about 1 Ma, during the Matuyama reverse polarity chron and has proven useful for the correlation of very young strata.