1 / 12

Mineralogy of Siliceous Hot Springs Deposits:

Mineralogy of Siliceous Hot Springs Deposits:. Comparing Earth and Mars. Intern. Mentor. Vicki Mills. Prof. Jack Farmer. Opaline Silica Deposits. (> 90 % Silica ). (Ruff, 2008). Mini-TES Spectra.

edmund
Download Presentation

Mineralogy of Siliceous Hot Springs Deposits:

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mineralogy of Siliceous Hot Springs Deposits: Comparing Earth and Mars Intern Mentor VickiMills Prof. Jack Farmer

  2. Opaline SilicaDeposits (>90% Silica) (Ruff, 2008)

  3. Mini-TES Spectra (Ruff, S., J. Farmer, W. Calvin et al. 2007. Evidence for possible siliceous sinter at Home Plate in Gusev Crater Eos Transactions, American Geophysical Union, Fall Meeting Suppl, Abstract, P23A-1097)

  4. Transformational Sequence for Silica (SiO2) Polymorphs Quartz Opal-A (SiO2.n H2O) Opal-C/T Microcrystalline Amorphous Paracrystalline 2-theta peaks: 20-24° 2-theta peaks: 20.8° 2-theta curve: centered at 22° Decrease in porosity, permeability & structural H20 Preservation Potential Low High

  5. Opaline Silica (Opal-A) forms in Hot Spring Environments Study Locations: • Excelsior Geyser, Yellowstone National Park, Wyoming

  6. Orakei Korako, New Zealand • Steamboat Springs, Nevada

  7. X-Ray Powdered Diffraction (XRPD) Sample Preparation For JADE Analysis For Rock Jock Analysis • Sample Preparation • Mortar & Pestle • Sieved 150μm • Run Conditions • Siemens D-5000 • 40kV at 30mA • CuKα Radiation • Step size 0.03-0.05° • Sample Preparation • 3g sample + 0.33g ZnO • Crushed <20μm w/micronising mill • Run Conditions • Siemens D-5000 • 40kV at 30mA • CuKα Radiation • Step Size 0.0163

  8. JADE XRPD Results Opal-C/T Quartz Clay Profile Opal-A New Zealand New Zealand Opal-A Steamboat Yellowstone Amorphous Curve Centered at 22° 2θ

  9. Rock Jock Results 63.8 61.7 20.0 22.1 12.3 11.9

  10. Thin Section Analysis Finely laminated sinter Coniform Fabric

  11. Characterization of Thin Sections Microbial fossil assemblage <35°C (20X) 35-59°C (10X) Calothrix (thermophilic cyanobacterium; filaments are ~30μm in diameter) Phormidium (thermophilic cyanobacterium; filaments are ~5μm in diameter)

  12. Interpretations • Similarities between mini-TES spectra of high silica deposits at Home Plate and those of opaline siliceous sinter from hot springs on Earth, suggests a common origin. On earth, siliceous sinters have been shown to preserve a diverse fossil record of microbial life. • This interpretation is consistent with the geological setting of Home Plate, which has been interpreted to be an explosive volcanic feature. Two alternative hypotheses have been suggested: Thermal spring deposits, or fumerolic deposits. It is not possible to choose based on current evidence! • Other outstanding issues: On Earth, opaline sinters quickly transform to ordered phases, like quartz. However, it appears that even after billions of years on Mars, the high silica deposits at Home Plate have not undergone any significant digenetic transformation. Why?

More Related