Big Science Questions

Crevasse Canyon Formation BSQ

• What drives the laterally extensive sand layers in the Crevasse Canyon Formation? [Brian Hampton]
  • Sea-level changes?
  • Orogenic pulses – if so, from which orogenic causes; from the west or from the south?
  • Both?
  • What is the time interval between transgressions?
  • How far does regression extend between transgressions – are the intervening layers terrestrial delta plain or shoreline coastal deposits?
  • How do these change along the Cretaceous Seaway in Crevasse Canyon equivalents? Do the major transgressions correlate?
  • Could Milankovich Cycles have any correlation to or influence on the transgressions? [ALan Reynolds]
  • Can disparate paleoclimatic studies along the Cretaceous Seaway provide sufficient fidelity to add to a regional correlation analysis
  • What are the key tools and disciplines to get at these questions
    • Sedimentology, detrital zircon analysis
    • Paleobotany
    • Palynology
    • Micropaleontology
    • Geochemistry, stable isotope analysis
    • Celestial dynamics
    • Geophysics, tectonics
    • Paleoclimatology

Need to brainstorm about how some tools can inform or are informed by data from other tools. Brainstorming before and during sample collection, mapping, and analysis might stimulate collecting data for possible answers not seen before the discussion. [Nancy McMillan]

The Great Siderite Mystery

• The Great Siderite Mystery – why are siderites (iron carbonates) ubiquitous in the Crevasse Canyon Formation at the Field Station, a formation dominated by sands and shales? [Jennifer Thines]
  • Is the siderite formation related to Cretaceous diagenesis or are they related to Cenozoic magmatism (see Igneous Epoch BSQ below)? When were the calcite veins emplaced in the
    more massive siderite lenses?
  • Are different siderite textures caused by the type of rock (e.g. sandstone vs. shale) in which they are found, or do siderites form preferentially in certain types of rocks?
  • What are the siderite-forming processes and are they indicative of the environment (marine / non-marine) of the surrounding rock? Do the siderites provide information about the geochemistry of the rock pore fluids?
  • Are the cone-in-cone limestones found in close proximity to siderite deposits as a rule or by coincidence? How did the cone-in-cone limestones form?
• The Quaternary fill in Alamocita Creek, which is made up of eroded Crevasse Canyon rocks undergoes a dramatic color change from distinctively red at its headwaters at Third Mesa Ranch, to light yellow/brown about 5 miles north of Third Mesa Ranch.
  • Is this color change attributable to a significant orogenic source change at the south end of the Criswell Ranch area? [A-Lan Reynolds, Brian Hampton]

Paleoecology of Terrestrial Landscape during the Coniacian-Santonian in Southern Laramidia BSQ

• What was the vegetation and ecosystem structure of terrestrial landscapes in southern Laramidia during the Coniacian-Santonian?
  Context [Dori Contreras]: The Coniacian-Santonian is a key interval because: (1) terrestrial landscapes are relatively poorly understood for this time interval, largely due to the lack of fossiliferous terrestrial exposures relative to other times of the Cretaceous and to the extent of marine deposits. (2) immediately follows the Cretaceous Thermal Maximum, which is thought to have driven migration of tropical taxa into higher latitude (including angiosperms); (3) Captures the key
  time slice where angiosperm ecological expansion in southern parts of Laramidia (Dori’s hypothesis – by Campanian they are dominant in many areas of the south, but not north)
  • Angiosperm Terrestrial Revolution: What plants made up the landscape, what were the differential roles of major plant taxonomic groups across the landscape, and what was
    the general structure of the vegetation? What were the abundance and diversity patterns of angiosperms (flowering plants) in different habits?
  • What were terrestrial temperature, seasonality, and precipitation, as estimated from plant ecophysiological traits?
  • What were patterns of plant-insect interactions and ecosystem structure? Quantified from trace fossils of insects on leaves and in wood.

Regional Setting in the Igneous Epochs of New Mexico BSQ

• Where does the Field Station fall in the igneous epochs (phases) of New Mexico?
  Context [Nancy McMillan]: The Reynolds Field Station is literally surrounded by major igneous deposits and volcanic lineaments related to subduction of the Farallon Plate and the opening of the Rio Grande Rift:
  • Massive volcanic necks less than 10 million years old rise 5 miles east of the Field Station.
  • The massive Jemez volcanic field 20 miles to the north and northwest of the Field Station erupted from 14 to 1.2 million years ago.
  • Certain volcanic flows in the Malpais area less than 20 miles to the north erupted as recently as human time frames.
  • Large volcanic fields to the south and west erupted from 34 to 24 million years ago.

We have not yet identified volcanic rocks originating on Field Station land, although it seems likely some will be found, given the great volume of igneous deposits nearby.

• Are igneous deposits present at the Field Station and adjacent BLM lands? If so, what is their age? Which epoch of tectonic plate subduction will those igneous deposits represent?