P., 2016, Geologic map of the Rio Rico and Nogales 7.5' quadrangles, Santa Cruz County, Arizona: U. Geological Survey Scientific Investigations Map 3354, 32 p. E., 2016, Preservation of ancient impact ages on the R chondrite parent body: Ar age of hornblende-bearing R chondrite LAP 04840: Meteoritics and Planetary Science, 51(9), 1678-1684, doi:10.1111/maps.12692. Samples are loaded into special holders and placed into infrared (IR) or ultraviolet laser chambers (UVLC) such that argon isotopes can be released from single grains and whole-rock samples by incremental heating and fusion or by spatially controlled ablation when mineral separation is impossible or in cases when we wish to analyze mineral inclusions, overgrowths, or preserve textural relationships. Facilities include workshop space with a disk mill, multiple rock saws, jaw crusher, and a sample storage room. The versatility of the Ar method permits determining the timing of processes and events such as igneous intrusions and extrusions, ore mineralization and hydrothermal fluid circulation, metamorphic cooling and exhumation, mineral formation and recrystallization, and shallow crustal faulting. Scientists are dependent on the geochronologist for data and interpretations to determine these parameters. The Ar method is used to date terrestrial, lunar, and meteoritic rocks and minerals ranging in age from approximately 10,000 years to the age of the solar system (~4.56 billion years).
The Ar isotopic dating method has evolved into the most commonly applied geochronological method, and can be applied to many geological problems that require precise and accurate time and temperature control. E., 2017, Weak bedrock allows north-south elongation of channels in semi-arid landscapes: Earth and Planetary Science Letters, 478, p. E., Nunez, L., and Renne, P., Archaeology and Context of Hugub, an Important New Late Acheulean Locality in Ethiopia's Northern Rift: Paleo Anthropology, 2016, p. pamphlet, 2 sheets, scale ,000, https://doi.org/10.3133/sim3354. We also have a chemical workspace for heavy liquid separation and Frantz magnetic separation. M., and Johnson, K., 2017, Field evidence for the control of grain size and sediment supply on steady-state bedrock river channel slopes in a tectonically active setting: Earth Surface Processes and Landforms, 42(14), p. The sample preparation facilities include a series of microscopes to allow the inspection of mineral separates, sample picking, and loading of the irradiation packets.