The Tibetan plateau is a product of the most dramatic tectonic event of recent geological history: the collision of the Indian sub-continent with Eurasia. In spite of the topographic and tectonic implications of the plateau, the mechanisms for its uplift remain controversial. The controversy is in large part a result of poorly constrained uplift history. Types of evidence that have been adduced for the uplift history include paleoecological date, cooling histories of plutonic and igneous rocks, and geomorphic interpretations. Some lines of evidence indicate relatively gradual uplift since the mid-Tertiary, while others support rapid acceleration of uplift during the latest Cenozoic, with the greatest portion during the Quaternary.
Actually, its bacteria and elephants and monkeys and humans, oh my! Geochronology (the determination of a rock's age) has a wide variety of applications; one of which is placing absolute age constraints on evolution. The New Mexico Geochronology Research Laboratory mainly focuses on projects in New Mexico and the Southwestern USA. However, in a role that fulfills its broader commitment to the scientific community, projects are undertaken from throughout the world. Recent collaborations with geologists, archeologists, and biologists have lead to exciting advances in our understanding of
Mammal evolution in South America, including a refinement of when North American and South American critters began walking the present land bridge between the continents,
When humans arrived in Java, Indonesia, and
Confirmation that bacteria have lived in salt crystals found near the WIPP site in New Mexico for more than 200 million years
Publication and/or submission of these findings are being recognized in internationally acclaimed journals such as the Proceedings of the National Academy of Sciences, Nature, Science, and Geology.
Dr. Matthew Heizler (geochronologist) has just been awarded a three year grant from the NSF tectonics division to study the "Great Unconformity" exposed in western North America. An unconformity is a span of time for which no rock record is represented because it has been eroded away or because sediment was never deposited. The Great Unconformity was coined by John Wesley Powell during his epic run of the Colorado River through the Grand Canyon, AZ in 1876. Here he noticed that deformed ancient metamorphic rocks were covered by much younger undeformed sedimentary rocks. New Mexico has some of the best exposures of the contact between these very old Precambrian rocks (1.7 billion years) and younger sediments (300 million years) of anywhere in North America.
Two Bureau of Geology scientists, in collaboration with scientists at the United State Geological Survey, have discovered similarities between ground water systems that formed ore deposits 10 million years ago and modern ground water in the Rio Grande Rift. They reported their work in an invited presentation at the 2000 Annual Meeting of the Geological Society of America.
Dr. Virgil Lueth, mineralogist/ economic geologist, and Lisa Peters, senior lab associate at the New Mexico Geochronological Research Lab, have been studying the mineral jarosite in ore deposits from Chihuahua, Mexico, to Albuquerque.
The Laramide orogeny was a mountain building event that affected the US western interior during the Late Cretaceous to Paleogene (approximately 90–45 million years ago). Many of the iconic mountains and major oil and gas producing intermontane basins of the Rocky Mountains and Colorado Plateau, such as the Wind River range in Wyoming and the San Juan Basin here in New Mexico, formed during this time as Earth’s crust was compressed. The Laramide orogeny remains a major point of controversy, as it is difficult to explain how tectonism proceeded so far into the North American plate.
Currently seeking a graduate student to work on minor mid-Cenozoic igneous occurrences in eastern New Mexico, which form a patchy discontinuous belt representing the most distal periphery of Cordilleran magmatism emplaced approximately 50-200 km east of the closest major alkaline magmatic centers. They have received little attention and present excellent opportunities for exciting fieldwork, novel research, and impactful student mentorship. Initial reconnaissance of these igneous rocks is building towards holistic studies addressing basic aspects of these occurrences through mapping, petrography, geochemistry, and geochronology. This work will lead to bigger questions on the relationship between these peripheral intrusions and more major alkaline magmatic centers, exhumation and heat flow histories recorded in these rocks, and significance for tectonics of paleo-plate dynamics of the SW US Cordilleran margin!
New Mexico is home to many hundreds of volcanoes that erupted during the last several million years. However, the exact timing of these eruptions has proven difficult to determine by many previous studies. An ongoing NSF-funded project, led by NM Bureau of Geology researcher Matthew Zimmerer, examines the timing of eruptions during the last 500,000 years in order to understand the patterns of volcanism in space and time. This information provides the foundation for an assessment of volcanic hazards in New Mexico.
A new dating method, being developed at the NMBG&MR, uses our state-of-the-art geochronology laboratory, funded by NSF and NM Tech, to determine the age of detrital sanidine (tiny volcanic minerals) from sediments.
Directly dating the timing of deformation remains a challenging task. An ongoing collaboration seeks to establish U-Pb dating of titanite grains involved in ductile deformation as a promising new deformation chronometer by applying this technique to Laramide-age shear zones in Joshua Tree National Park.
Pre-Cordilleran rocks of western North America are predominantly composed of inboard, more stratigraphically coherent assemblages and more outboard assemblages with tectonostratigraphic histories obscured by extensive deformation, magmatism, and metamorphism. Inboard assemblages generally represent autochthonous deposits of the western Laurentian continental margin that formed in response to the breakup of the Rodinian supercontinent whereas outboard packages define a tectonic collage representing westward continental growth since mid-Paleozoic time . Detrital zircon U-Pb geochronology of metasedimentary strata across western North America has revealed varied sedimentary sources from both within and without the Laurentian craton that shift through time and space.
