Leader(s): Daniel Koning, Jeremy Rugenstein, Siânin Spaur, Garrett Williamson

Description: Española and its namesake basin, located ~40 km north of Santa Fe, lie at the heart of northern New Mexico, a geographic region dominated by deep-rooted Puebloan and Hispanic culture and beautiful scenery. Additionally, the Española Basin offers the most extensive exposure of the clastic sediment filling the Rio Grande rift, here mapped as the Tesuque and Chamita Formations of the Santa Fe Group. These exposures have also yielded a trove of mammalian fossils, and these fossils and abundant tephra layers provide age control for sed/strat studies. This field trip uses these exposures to summarize recent and on-going sed/strat, paleoclimatic, paleontologic, and structural studies in the Española Basin. In the morning, we will visit exposures east of Española that illustrate key stratigraphic units (lithosomes) comprising the basin fill. We discuss how the sedimentologic characteristics and spatial distribution of two lithosomes, representing piedmont and basin-floor paleo-environments, are controlled by autogenic and extrinsic drivers, such as paleoclimate and tectonics. We also show how tephra layers and detailed sampling of carbonates have resulted in a detailed paleoclimate reconstruction using stable isotopes. In the afternoon, we inspect these same lithosomes in the younger Chamita Formation, compare them to outcrops seen earlier in the day, and discuss paleoclimatic studies in the Chamita Formation stratotype. Exposures of intra-basinal faults and the Embudo fault system will spur discussion of the tectonic evolution of the Española Basin and the transfer fault linking it with the San Luis Basin to the north, in addition to how this evolution affected Miocene sedimentation.

Considerations: At a given stop, the trip participants will walk about 0.5-2.0 miles on trails and badland topography. The badland topography involves navigating steep slopes and jumping across narrow gullies that may be 1 to 2 m deep. Total mileage of walking for the trip is about 4 miles. The weather will be warm (maximum temperatures of low 90s to middle 90s is possible), so participants should bring a hat, sunscreen, and appropriate clothing. The total driving time is ~4 hours, including 1.5 hours each way between Albuquerque and Espanola. A restroom stop will be available at the lunch site at noon. Lunch and water will be available.

Sign up

Leader(s): Darryl Reano, Wai Allen, Ranalda Tsosie, Leiaka Welcome

Description: This one-day field trip will explore Indigenous perspectives of geology and mineral resources in New Mexico. The first three stops will be to the Petroglyph National Monument on the west side of Albuquerque where we will discuss how geology was used to communicate between different Indigenous communities in the region. The fourth stop will be to eat lunch at the Indian Pueblo Kitchen at the Indian Pueblo Cultural Center. The fifth stop will be at Acoma Pueblo, the oldest continually inhabited community within the United States, where we will see Mesozoic through Cretaceous strata and discuss paleogeographic changes happening on the Colorado Plateau during that time.

Considerations: This is a moderately accessible field trip. Our visit to the Petroglyph National Monument has multiple areas that can be accessed to improve its suitability for diverse participants. Some Indigenous communities will not want to view petroglyphs. There are two trails at Piedras Marcadas Canyon: “Petroglyph Viewing Trail” and “North Rim Trail-no viewable petroglyphs." Another way that we have prepared to be more inclusive is by developing virtual field experiences that can be viewed online for people that may not be able to hike the trails. Stop 1: There are pit toilets available. The visitor center is wheelchair accessible. No food is available. There is an information center that does have items for purchase. Stop 2/3: 2.5 miles max trail length; No water, no restrooms. Stop 4: There are restrooms in the building. The restaurant is wheelchair accessible. Stop 5: There are restrooms and water refill stations available in the Sky City Cultural Center and Haak’u Museum that we will be able to use. A van will transport visitors to the top of the mesa as part of the tour. The total time we will spend walking at this stop is 2 hours. We will ride a van to the top of the mesa where Acoma is located and there is an opportunity to climb down the mesa afterward. This stop is mostly wheelchair accessible, although it is natural terrain (mostly rocky sandstone with some loose sand) and is not paved. Virtual field experiences are available only for stops 1-3.

Sign up

Leader(s): Daniel Koning, Matthew Heizler, Sean Connell

Volunteer(s): Charles (Jack) Oviatt

Description: The two largest rivers of the American Southwest, the Rio Grande and the Colorado, both experienced noteworthy downstream-orientated integration in the Neogene. This field trip focuses on an important component of the Rio Grande's history: its integration through the Socorro Basin in central New Mexico. We argue that for much of 9.5-7.0 Ma, this playa-lake served as the terminus for the axial river of the rift (the ancestral Rio Grande). This trip focuses on two general localities whose outcrops exhibit the stratigraphy and paleo-depositional environments of Lake Socorro, a major alluvial fan that served as its southern sill, and the earliest deposits of the eventual through-going river. Key to constraining this evolution is 40Ar/39Ar dating of interbedded basalts, tephra, and detrital sanidines of sand bodies. Detrital sanidine data also provide essential provenance information and confirm the Rio Grande carried sand from northern New Mexico through the study area by 7 Ma. This field trip showcases playa lake lithofacies and related depositional environments of a terminal playa-lake, and the utility of detrital sanidine dating in a volcanically active rift environment. After comparing the nature and timing of this integration with that of the lower Colorado River, we discuss the relative roles of paleoclimate, local tectonics, and regional uplift of the Rio Grande headwaters in driving early Rio Grande integration.

Considerations: The drive to and from Albuquerque to Socorro is 1.5 hours (each way). In the Socorro area, there will be an additional driving time of about 1.5 hours. This field trip involves one 2 mile, 3 hour long hike in addition to two short hikes from the vehicles. The short hikes are each less than 0.5 miles long. Hiking will involve going up and down steep slopes, climbing over a sloping 3 m-tall dry fall, and navigating badland topography. The weather will likely be hot (likely as warm as mid 90s Fahrenheit) and participants need to come prepared with hats, sunglasses, sunscreen, and appropriate clothing. Those who are not used to hiking in these temperatures will be at higher risk for serious heat-related ailments (e.g., heat exhaustion and sunstroke). Participants should be prepared to urinate and defecate "behind the bush", as there will be no restrooms available except for a gas-station stop in mid-afternoon. Water and lunch will be provided.

Sign up