Magnetic-polarity stratigraphy of the Miocene type Tesuque Formation, Santa Fe Group, in the Española Valley, New Mexico

Abstract

Research Article| December 01, 1981 Magnetic-polarity stratigraphy of the Miocene type Tesuque Formation, Santa Fe Group, in the Española Valley, New Mexico STEVEN BARGHOORN STEVEN BARGHOORN 1Department of Vertebrate Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024 Search for other works by this author on: GSW Google Scholar Author and Article Information STEVEN BARGHOORN 1Department of Vertebrate Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1981) 92 (12): 1027–1041. https://doi.org/10.1130/0016-7606(1981)92<1027:MSOTMT>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation STEVEN BARGHOORN; Magnetic-polarity stratigraphy of the Miocene type Tesuque Formation, Santa Fe Group, in the Española Valley, New Mexico. GSA Bulletin 1981;; 92 (12): 1027–1041. doi: https://doi.org/10.1130/0016-7606(1981)92<1027:MSOTMT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Several of the type sections of the Tesuque Formation, lower Santa Fe Group, exposed near Española, New Mexico, have yielded a composite magnetic-polarity stratigraphy in which the 230-m, fine-grained, tuffaceous middle (Skull Ridge) member is characterized by a long zone of uninterrupted reversed polarity; approximately 300 m of the coarser-grained, upper (Pojoaque) member is characterized by rocks predominantly of normal polarity. Results from AF demagnetization in fields up to 300 oe and from the acquisition and removal of IRM indicate that the more stable magnetic remanence in these rocks is probably borne by detrital magnetite and therefore can be taken as a record of the geomagnetic field at or near the time of deposition. The stratigraphic utility of the results is confirmed by replication in geographically separate, lithostratigraphically equivalent sections in different fault blocks. Within the constraints of a middle to late Miocene age long acknowledged for this part of the Santa Fe Group, this composite polarity stratigraphy appears best to correlate with the standard Tertiary polarity time scale as follows: fossiliferous Nambé Member, early Epoch 16; Skull Ridge Member, late Epoch 16 to early Epoch 15; Pojoaque Member, mid Epoch 15 to as young as early Epoch 12. The results indicate an age for at least part of the Pojoaque Member significantly older (by about 1.5 to 3.5 m.y.) than fission-track ages recently reported for ash beds in its type section. They are, however, more consistent with age assignments of these sediments based on placement of their contained mammalian faunas in the North American Land Mammal Age chronology. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.