The Anatomy of the Blue Dragon: Changes in Lava Flow Morphology and Physical Properties Observed in an Open Channel Lava Flow as a Planetary Analogue SSERVI Seminar Series NASA Museum Alliance and NASA Solar System Ambassadors 12 Sep 2017 Alexander Sehlke, NPP fellow NASA Ames Research Center, CA Lava flows on the Moon Hurwitz et al. (2013) The Moon Venus Lava flows on Mars Flood lavas observed by MRO NASA Gusev rocks solidified from lava, taken by Jaeger et al, 2010 MER Spirit (2009) Lava flows on Mars Flood lavas in the ancient plains of Mars (Daedalia Planum). Image taken by Mars Express 20 km Images: ESA JPL/NASA Lava flows on Mars Olympus Mons, a shield volcano (Hawaii). Largest volcano in the solar system JPL/NASA LPI Lava flow features on Mercury Image: NASA Lava flows on Mercury Features observed on the Northern Volcanic Plains Head et al. (2011) Brown University Lava flows (?) on Vesta (asteroid) Surface of Vesta resemble lava flow morphologies. Vesta was assumed to have had a magma ocean in its early history. Large impact structure ? ? ? ? ? Lava flows on Io (Jupiter) Only other planetary body where we currently observe volcanism. More volcanic activity than on Earth. Top: Mosaic from images acquired by NASA’s Galileo spacecraft. USGS Right: Amirani lava flow, with 23 new individual lava flows over the course of 173 days. JPL/NASA Lava flows on Mercury Features observed on the Northern Volcanic Plains Head et al. (2011) Brown University Hypothesis: q Morphology of lava flows corresponds to specific values in physical properties of the lava (crystallinity, vesicularity, density, and temperature à viscosity). Ø Exploration: Use morphology to infer these properties Peterson & Tilling, 1980 Morphological transition from pahoehoe to `a`a lavas Video 01a: Pahoehoe at Puuoo, Hawaii (overview) https://youtu.be/9EfjzrqmuMU Pahoehoe lava at PuuOo, Kilauea volcano (Hawaii), 2012 Morphological transition from pahoehoe to `a`a lavas Video 01b: Pahoehoe at Puuoo, Hawaii (sampling) https://youtu.be/mJv-lZqDpH4 Pahoehoe lava at PuuOo, Kilauea volcano (Hawaii), 2012 Morphological transition from pahoehoe to `a`a lavas Video 2a: Lava at Pacaya (slope) https://youtu.be/NQkdUxQ_drM PACAYA Cerro Cerro 1 km Chino Grande 14 9 11 107 El Patrocinio 12 8 15,16 13 McKenney 2000m Soldati et al. 2014. Bull Volc. El Rodeo Cone 4 5,6 Pacaya Viejo 1500m Collapse Scar 3 1 Pahoehoe to `a`a lava flow at flank of Pacaya volcano STUDIED FLOW (Guatemala), 2014 HISTORICAL FLOW 18,19 17 CONTOUR LINE Guatemala SCARP City 1 SAMPLE Los Pocitos Pacaya CRATER VILLAGE Morphological transition from pahoehoe to `a`a lavas Video 02b: Aa at Pacaya (terminus) https://youtu.be/Oa8TYOVoow0 “Mercury Kraken” `A`a lava flow (terminus) at Pacaya volcano (Guatemala), 2014 Viscosity q depends on temperature (T) q depends on composition (X) q depends on crystal (Φc) and bubble (Φb) fraction As lavas cool, they will crystallize q crystal fraction (Φc) increases q changes residual liquid composition (X) Ø changes residual liquid viscosity (η) Lavas change their flow behavior throughout cooling Morphological transition from pahoehoe to `a`a lavas Peterson & Tilling, 1980 Whether pahoehoe or rough, jagged surface `a`a is formed appears to moves slowly lower in temperature be a critical relationship high viscosity involving both viscosity and rate of deformation η 1,000,000 Pa s • at high strain rates low viscosity -> pseudo-plastic η < 1,000 Pa s smooth moves relatively fast relatively hot Viscosity and strain rate relationship of low viscosity pahoehoe to `a`a transition determined by Robert et al. 2014. Bull Volc. Sehlke et al. 2014. Bull. Volc. Viscosity • Resistance of a fluid to flow, in Pa s • Ratio of applied shear stress (!) to its rate of deformation (ε) y ) le ing lk hinn u ar-t (Pa) B l- she e ( σ h tic low η c las rs op ity e ud os H se sc P vi η = σ / h ig • : h Flow curves illustrated in an ni to w Shear stress, e the diagram on the right N ity cos vis ow n: l • Slope in these curves nia wto determines the viscosity high η Ne (η) dσ σy . dε σy . Strain rate, ε (s-1) Viscosity – viscous flow • Newtonian fluids: slope is linear, therefore independent on the applied stress y ) • Pseudoplastic fluids are not le ing lk hinn u ar-t (Pa) B l- she e ( linear. Deformation depends σ h tic low η c las rs op ity e ud os on the applied stress. Viscosity H se sc P vi h ig is lower at high strain rates : h an ni to w Shear stress, e • Flow curves may not intersect N in the origin. Deformation ity cos vis requires minimum stress that ow n: l nia wto needs to be overcome high η Ne -> Yield strength (σ ) y dσ σy . dε σy . Strain rate, ε (s-1) Viscosity – viscous flow • Newtonian fluid (Water, Oil) y ) le ing lk hinn u ar-t (Pa) B l- she e ( σ h tic low η c las rs op ity • Bingham fluid (Toothpaste) e ud os H se sc P vi h ig : h an ni to w Shear stress, e N ity cos vis ow • Pseudoplastic fluid n: l nia wto high η Ne dσ σy . dε σy . Strain rate, ε (s-1) Rheological transition from pahoehoe to `a`a lavas For Hawaiian lava: Morphology and physical properties quantified. Coincidence? à Needs to be checked for other flow of different lava type Craters of the Moon National Monument and Preserve, Idaho Video 03: Blue Dragon Flow (COTM) https://youtu.be/jyiKsEBk2b0 Near spatter cones (volcanic vents) SE of lava lake (white patches disappeared) Near terminus Digital Terrain Model (DTM) Terminus High resolution (~ 5 cm per pixel) Mapped flow from near vent to toe, Sampled over ~2.75 km length (Summer 2016) Additional levee and depth samples (Summer 2017) Total of 35 samples Spatter cones Down flow changes in sample texture Spatter bomb (vent): • highly vesicular • Rounded bubbles • Low crystallinity, random order Down flow changes in sample texture Pahoehoe lobe: • vesicular • Rounded bubbles • Low crystallinity, random order Down flow changes in sample texture Pahoehoe lobe: • Less vesicular • Rounded/irregular bubbles • Low crystallinity, aligned Down flow changes in sample texture Pahoehoe slab: • Vesicular • Rounded bubbles • Low crystallinity, aligned Down flow changes in sample texture Pahoehoe rubble: • Vesicular • Rounded/irregular bubbles • High crystallinity, aligned Down flow changes in sample texture Pahoehoe rubble: • Vesicular • Rounded/ bubbles • high crystallinity, random order Down flow changes in sample texture `A`a rubble: • Vesicular • Irregular bubbles • Very high crystallinity, random order 1.00 Transition zone determined by field mapping 0.80 0.60 0.40 Crsytal fraction Crsytal 0.20 0.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Distance (m) Seeing trends with flow distance in • Crystallinity • Bulk density • Pore space Height profile through center of lava flow 1,810 extracted from DTM Lava Lake Area 1,800 1,790 1,780 1,770 Elevation (m) 1,760 1,750 1,740 Terminus 1,730 0 500 1,000 1,500 2,000 2,500 Flow distance (m) 1,800 1,780 Smooth patches 1,795 disappear 1,775 1,790 1,770 1,785 1,765 Elevation (m) 1,780 Elevation (m) 1,760 1,775 1,755 Pahoehoe ropes Transition Zone 1,770 1,750 500 600 700 800 900 1,000 1,000 1,100 1,200 1,300 1,400 1,500 Flow distance (m) Flow distance (m) 1,765 1,755 Terminus 1,760 1,750 1,755 1,745 1,750 1,740 Elevation (m) 1,745 Elevation (m) 1,735 1,740 1,730 Transition Zone `A`a 1,735 1,725 1,500 1,600 1,700 1,800 1,900 2,000 2,000 2,100 2,200 2,300 2,400 2,500 Flow distance (m) Flow distance (m) Roughness of Lava Flow Surface with Distance 0.018 y = 5E-06x + 0.0027 R² = 0.81223 0.016 0.014 0.012 0.010 height (m) 0.008 RMS 0.006 0.004 0.002 0.000 -500 0 500 1000 1500 2000 2500 3000 Flow distance (m) Height/elevation between each adjacent pixel averaged over length 50 meter. Based on center line profile. • Correlation between flow distance and roughness exists. • Correlation between flow distance and density and vesicularity exists Roughness vs Density 3,000 Linear R² = 0.55617 Real Case 2,500 R² = 0.58126 ) 2,000 3 - 1,500 0.018 0.016 0.014 1,000 0.012 Bulk density (kg m (kg density Bulk 0.010 0.008 0.006 500 Based on a single line profile: RMSD height (m) 0.004 biased (directional view!). Use the 0.002 0.000 2D/3D ratio instead 0 1000 2000 3000 0 Flow distance (m) 0.000 0.002 0.004 0.006 0.008 0.010 0.012 0.014 Roughness (RMS height, m) Surface roughness classification Area ratio Currently developed by Mallonee and Kobs Nawotniak at Idaho State University • RMS (root-mean-square) height, below • Area ratio (2D/3D), left Satellite imagery RMS height Thermo-Physical Properties of Lava Flows Looking at the morphology and estimate a temperature? Not impossible! ? Viscosity measurements High temp. Low temp. 1600ºC – 1000ºC – 500ºC 1150ºC high viscosity low viscosity 108 – 1013 Pa s 0.1 – 105 Pa s Viscosity of crystal-free lavas across the Solar System Sehlke and Whittington (2016). Geochim. Cosmochim. Acta Viscosity of crystal-free lavas across the Solar System Temperature (ºC) N = 494 Craters of the Moon Blue Dragon Lava (crystal-free) • Crystal-free lavas = Melts • Newtonian fluids y ) le ing lk hinn u ar-t (Pa) B l- she e ( σ h tic low η c las rs op ity e ud os H se sc P vi h ig : h an ni to w Shear stress, e N ity cos vis ow n: l nia wto high η Ne dσ σy .