Provenance of Cretaceous through Eocene strata of the Four Corners region: Insights from detrital zircons in the San Juan Basin, New Mexico and Colorado

Cretaceous through Eocene strata of the Four Corners region provide an excellent record of changes in sediment provenance from Sevier thin-skinned thrusting through the formation of Laramide block uplifts and intra-foreland basins. During the ca. 125–50 Ma timespan, the San Juan Basin was flanked by the Sevier thrust belt to the west, the Mogollon highlands rift shoulder to the southwest, and was influenced by (ca. 75–50 Ma) Laramide tectonism, ultimately preserving a >6000 ft (>2000 m) sequence of continental, marginal-marine, and offshore marine sediments. In order to decipher the influences of these tectonic features on sediment delivery to the area, we evaluated 3228 U-Pb laser analyses from 32 detrital-zircon samples from across the entire San Juan Basin, of which 1520 analyses from 16 samples are newly reported herein. The detrital-zircon results indicate four stratigraphic intervals with internally consistent age peaks: (1) Lower Cretaceous Burro Canyon Formation, (2) Turonian (93.9–89.8 Ma) Gallup Sandstone through Campanian (83.6–72.1 Ma) Lewis Shale, (3) Campanian Pictured Cliffs Sandstone through Campanian Fruitland Formation, and (4) Campanian Kirtland Sandstone through Lower Eocene (56.0–47.8 Ma) San Jose Formation. Statistical analysis of the detrital-zircon results, in conjunction with paleocurrent data, reveals three distinct changes in sediment provenance. The first transition, between the Burro Canyon Formation and the Gallup Sandstone, reflects a change from predominantly reworked sediment from the Sevier thrust front, including uplifted Paleozoic sediments and Mesozoic eolian sandstones, to a mixed signature indicating both Sevier and Mogollon derivation. Deposition of the Pictured Cliffs Sandstone at ca. 75 Ma marks the beginning of the second transition and is indicated by the spate of near-depositional-age zircons, likely derived from the Laramide porphyry copper province of southern Arizona and southwestern New Mexico. Paleoflow indicators suggest the third change in provenance was complete by 65 Ma as recorded by the deposition of the Paleocene Ojo Alamo Sandstone. However, our new U-Pb detrital-zircon results indicate this transition initiated ∼8 m.y. earlier during deposition of the Campanian Kirtland Formation beginning ca. 73 Ma. This final change in provenance is interpreted to reflect the unroofing of surrounding Laramide basement blocks and a switch to local derivation. At this time, sediment entering the San Juan Basin was largely being generated from the nearby San Juan Mountains to the north-northwest, including uplift associated with early phases of Colorado mineral belt magmatism. Thus, the detrital-zircon spectra in the San Juan Basin document the transition from initial reworking of the Paleozoic and Mesozoic cratonal blanket to unroofing of distant basement-cored uplifts and Laramide plutonic rocks, then to more local Laramide uplifts.National Science Foundation (NSF grant EAR-1649254

Collection on Alabama authors and publishers, W.0043

Abstract: Correspondence, newspaper articles, publishers' catalogs, and ephemera compiled by Patrick Cather, most of which pertains to his professional work as a partner in Cather and Brown Books, as well as a smaller set of correspondence written by other Alabama figures, including archivist Peter Brannon.Scope and Content Note: This collection consists of correspondence, newspaper articles, publication announcements, book catalogs, and ephemera relating to Alabama authors, publishers, and publications. The collection is contained in two phase boxes. The first box includes materials that Patrick Cather created and collected. While the collection contains materials written by multiple authors, the bulk of the material consists of Cather's professional and personal correspondence. Most of this correspondence is dated between 1980 and 1994 and includes orders placed to Cather and Brown Books and correspondence related to Cather's personal collection of Alabama books and pamphlets. Notable correspondents include author Kathryn Tucker Windham and historians Frank L. Owsley, Leah Rawls Atkins, and Wayne Flynt.In addition to Cather's correspondence, the collection contains a smaller set of correspondence written by other Alabama figures, including letters received by archivist Peter Brannon between 1907 and 1948 and individual letters written by authors including Carl Carmer, Clarence Cason, and F. Scott Fitzgerald. The letters written by Carl Cramer and F. Scott Fitzgerald are photocopies, but other letters included in the collection are originals.The second phase box contains publication announcements, book catalogs, and newspaper clippings relating to Alabama authors and publishers. Although most of the material in this group dates between 1920 and 1988, the bulk are dated from 1980 to 1988. In addition to announcements released by small local publishers, University of Alabama Press materials are also included.Biographical/Historical Note: A book dealer and collector, James Patrick Cather was born on May 12, 1947, in Birmingham, Alabama. In addition to his professional work as a partner in Cather and Brown Books, a rare book firm that specializes in locating books published in Alabama, Cather also developed an extensive personal collection of books and pamphlets written by Alabama authors.Source: Alabama Authors Databas