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Crater Morphologies in Monogenetic Volcanic Fields of Western New Mexico

Crater Morphologies in Monogenetic Volcanic Fields of Western New Mexico. R. A. De Hon 2011 GSA Annual Meeting. Rebranded. THE SIGNIFICANCE OF MAARS ON EARTH AND MARS R. A. De Hon 2011 GSA ANNUAL MEETING. THIS PRESENTATION.

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Crater Morphologies in Monogenetic Volcanic Fields of Western New Mexico

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  1. Crater Morphologies in Monogenetic Volcanic Fields of Western New Mexico R. A. De Hon 2011 GSA Annual Meeting

  2. Rebranded THE SIGNIFICANCE OF MAARS ON EARTH AND MARS R. A. De Hon 2011 GSA ANNUAL MEETING

  3. THIS PRESENTATION • As original title states… Morphology of landforms in three monogenic volcanic fields in western New Mexico • Specifically, the morphology of… Maar craters Tuff cones Cinder cones • Located in …New Mexico: Red Hill-Quemado Volcanic Field Bandera Volcanic Field Mt. Taylor-Mesa Chivato Volcanic Field

  4. With special attention to MAAR craters • Maar craters are formed when magma encounters groundwater. The resultant steam explosion excavates a bowl-shaped pit surrounded by a tuff ring that resembles a meteorite crater. • The term maar comes from a Franconian dialect for lake derived from the Latin “mare” (sea). • In the type locality—the Efiel Region of Germany— the craters extend below the water table and are occupied by lakes. • Maar craters range in size from a few hundred meters to several kilometers in diameter. • Their eruptive history consists of repeated venting over a period of weeks or months.

  5. CREDITS – Previous workers • Jayne C. Aubele • Larry S. Crumpler • A. W. Laughlin • P. W. Lipman • C. Maxwell • And many others

  6. WHY do we care? • Early ejecta in maar craters contain accidentals from underlying strata. • Occasionally the ejectaincudes mantle xenoliths. • Maare on Mars may be unique sites to obtain deep crustal samples. Mantle xenolith Kilbourne Hole, NM

  7. ULTIMATE OBJECTIVES • Volcanic morphometry with attention to explosive craters and transitional forms • Early ejecta as sampling of subjacent rock materials • Magma, vapor, country rock interactions and final crater morphology • Application to Mars volcanic craters and possibility of maar craters as crustal sampling sites

  8. This talk

  9. Mesa Chivato Bandera (Malpias) MAAR CRATERS in Northeast New Mexico Red Hill

  10. N 100 km

  11. CHAIN OF CRATERS BANDERA FIELD Maar

  12. ZUNI SALT LAKE 1 km

  13. CERRO AMERICO 1 km

  14. EXAMPLE: Cinder Cone—Cerro Americo Basal Diameter 1 237 meters Crater Diameter 269 Cone Height 118 Crater Depth 41

  15. 1 km BANDERA CRATER

  16. EXAMPLE: TUFF RING—Bandera crater Basal Diameter 1156 Crater Diameter 556 Rim Height 128 Crater Depth 156

  17. HEUCO CRATER 1km

  18. EXAMPLE: Maar—hueco Basal Diameter 1150 meters Crater Diameter 718 Rim Height 75 Crater Depth 98

  19. Scoria mound

  20. CD Curve is best fit to Red Hill and Mesa Chivato data Cd

  21. Depth vs. Height Tuff Rings

  22. Base surge and Air Fall— Reworked shallow sublacent material Vent Opening Breccia— Most of the subcrater xenoliths are found here.

  23. VOLCANIC CENTRAL VENT VARIATIONS PRISTINE Constituents of the eruption changes as eruption progresses… Lava Scoraceous cinders Epiclastic tuff Early xenolith-rich breccia Cinder cone Variation in size is chiefly due to the duration of eruptions and volume of material ejected. Tuff Ring Maar 1 km All profiles to same scale.

  24. VENT MORPHOLOGYa function of • Composition of magma and volatile content of magma • Depth of magma and groundwater interaction • Volatiles in country rock • Connate water • Groundwater • Ground ice • Continuing activity • Pyroclastic • Lava • Resistance of country rock • Slumping during eruptive phase • Degradation following eruption

  25. Highly eroded -or- Blew its top?

  26. Crater-in-crater

  27. Rimless depression

  28. RED HILL MAAR with internal cinder cones

  29. Cone filling maar

  30. VOLCANIC CENTRAL VENT VARIATIONS Renewed activity Pristine Degraded Explosion crater? Cinder cone Scoria Mound Cone filling maar Tuff RingBreached crater Cone-in-maar Maar Rimless depression 1 km All profiles to same scale.

  31. So, the point is… • Earliest maar ejecta provide a sampling of substrate materials. • Those materials may be preserved in a variety for subsequent structures. • Some day, in future exploration of Mars, maare will be important sites to visit and sample.

  32. THANK YOU Mars Volcanic field

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