Magnetic records from latest Triassic to earliest Jurassic red beds, Utah and Arizona, and from mid-Pleistocene lake beds, New Mexico

Paleomagnetic data obtained from the upper Triassic to lower Jurassic strata of the Moenave Formation, southern Utah and northern Arizona, were used to construct a composite magnetostratigraphy and further refine the position of the base of the Jurassic in the southwest U.S.A. The composite magnetostratigraphy provides a chronostratigraphic framework to tie Triassic-Jurassic sedimentation in the southwest U.S.A to marine strata in the United Kingdom, Turkey, and Italy, and to the Pangean rift history including extrusive igneous rocks, preserved in Morocco, and in the Newark Basin, northeast U.S.A. In addition, paleomagnetic data from the Moenave Formation were used to calculate a pole position for North America for the latest Triassic to earliest Jurassic time. A lesser amount of inclination error, flattening factor of 0.78, is record in Moenave Formation strata compared to observation from coeval Newark Basin strata. The new paleomagnetic pole position for North America, corrected for inclination error and 4° of clockwise Colorado Plateau rotation is located at 62.3° N, 68.0° E (A95 = 7.4°, N = 102). Pole positions from the southwest U.S.A. continue to indicate a westerly pole position for North America at the latest Triassic to earliest Jurassic time.;A mid-Pleistocene lake sedimentary record obtained from the Valles Caldera, northern New Mexico was investigated using rock magnetic and paleomagnetic techniques. Lake sediments span three glacial and two interglacial intervals, MIS 14--10. Both detrital and diagenetic phases are preserved in sediment throughout the core. Preservation of detrital phases indicates well mixed lake conditions were more common during interglacial intervals. Discrete intervals of diagenetic phases indicate anoxic conditions are more common in sediments deposited during glacial intervals. A series of anoxic intervals are identified in sediment deposited during MIS 12 that are closely related to interstadial events characterized by increased Cyperaceae and Juniper pollen counts and increased mean annual temperatures. Paleomagnetic data are mostly normal polarity consistent with Brunhes normal polarity chron. However, paleomagnetic data combined with relative paleointensity records support the presence of three geomagnetic field phenomena 14&agr;/Calabrian Ridge II at ∼536 ka, 11&agr; at ∼400 ka, and Levantine at ∼360--360 ka.