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The Compass: Journal of Sigma Gamma Epsilon

Volume 86 Issue 2 Article 1

10-13-2014

Evidence of Large Scale Tectonic Processes on the Rise,

Genevieve Kidman Southern Utah University, [email protected]

John S. MacLean Southern Utah University, [email protected]

David Maxwell Southern Utah University, [email protected]

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Recommended Citation Kidman, Genevieve; MacLean, John S.; and Maxwell, David (2014) "Evidence of Large Scale Tectonic Processes on the Tharsis Rise, Mars," The Compass: Earth Science Journal of Sigma Gamma Epsilon: Vol. 86: Iss. 2, Article 1. Available at: https://digitalcommons.csbsju.edu/compass/vol86/iss2/1

This Article is brought to you for free and open access by DigitalCommons@CSB/SJU. It has been accepted for inclusion in The Compass: Earth Science Journal of Sigma Gamma Epsilon by an authorized editor of DigitalCommons@CSB/SJU. For more information, please contact [email protected]. EVIDENCE OF LARGE SCALE TECTONIC PROCESSES ON THE THARSIS RISE, MARS

Genevieve Kidman1, John S. MacLean2, and David Maxwell3 Department of Physical Science Southern Utah University 351 West University Boulevard Cedar City, UT 84720 [email protected] [email protected] [email protected] ABSTRACT

Past observations of Mars have led scientists to believe that tectonic kinematics stopped early in its planetary development. Recent has led to new theories that support an active tectonic regime on the Tharsis rise. With the advancement of new imagery and technologies such as Thermal Emission Imaging System, High Resolution Imaging Science Experiment satellite imagery, the Mars Orbital Altimeter, and interactive software such as J-Mars and Esri GIS, we have identified additional large-scale surface features in the Tharsis Rise and surrounding areas. Large-scale lineations, folds, and conjugate joints can be compared to similar structures on Earth to interpret potential plate boundaries. For example, a northeast-trending set of lineations with significant left-lateral strike-slip displacement and conjugate jointing located to the northeast of the Tharsis Rise could accommodate transform motion between two plates. Our observations allow the designation of multiple potential plate margins in the region. We propose a tectonic model showing relative motions along plate boundaries in a potentially active multiple-plate system on Mars.

Key Words: astrogeology, astro-, thermal emission imaging systems, Esri GIS software, J- Mars software, planetary , planetary tectonics

INTRODUCTION unmanned rovers trekking across the surface. During the past twenty , The close similarity between geological exploration of surface has grown by structures on Earth and Mars has enabled leaps and bounds. Mars does not disappoint in scientists to apply known geological scientific its promise for breathtaking scientific theory to uncover the past history of Mars. With breakthroughs. Two primary research topics on all the recent technological advances at our Mars, life and , have been frontrunners in fingertips, another basic geological question the Martian scientific community. Sedimentary about Mars can be asked; is there currently a markers of , rivers, and streambeds show form of on Mars? that the Martian paleoenvironment was quite The Tharsis rise, an area on the western different than today. Although conclusive hemisphere of Mars that is smaller than about evidence has not been found yet, the search for one third of the , was the focus of this life is ongoing through surface missions with research (fig. 1). The rise boasts some of the

The Compass: Earth Science Journal of Sigma Gamma Epsilon, v. 86, no. 2, 2014 Page 36 largest volcanoes in the including THEMIS camera is capable of taking visual , as well as features such as images at 59 feet or 18 meters per pixel. Mars (fig. 2). The technology used to Odyssey was later followed by the Mars analyze the surface of the Tharsis rise in this Reconnaissance Orbiter, launched in 2005 with study includes the following satellite missions. the High Resolution Imaging Science In 1996 The Jet Propulsion Laboratory launched Experiment (HiRISE) satellite imagery, which is the with scientific capable of taking images down to a 1 meter instruments that included the Mars Orbital Laser scale (NASA). Using J-Mars version 3.0, a Java Altimeter, as well as a and Mission-planning and Analysis for Remote electron reflectometer. Mars Global Surveyor Sensing GIS program specifically developed for allowed digital maps to be taken of the the study of Mars through State surface as well as a measurement of the University's Mars Space Flight Facility, images characteristics on Mars. In 2001 of Mars from THEMIS, and HiRISE, has made Thermal Emission Imaging System (THEMIS) it possible to view detailed satellite imagery. was carried by the satellite MOLA images were also used as background with one of its missions to investigate detailed maps for mapping on Esri ArcMap Version geological formations on the surface. The 10.2.

Figure 1. MOLA map of the surface of Mars (NASA, Mars global data set). The Tharsis rise is located in the western half and has prominent features such as volcanoes, ranges, and deep . Tharsis rise is the predominantly areas in the western hemisphere.

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Figure 2. Tharsis Rise regional map. Background imagery from NASA.

Through these technologies and the work of and Phillips, 2005), likely contributed to other scientists, there have been recent the creation of the Tharsis Rise. discoveries on Mars that have shed light on the  Tectonic episodic slab rollback (Yin, possibility of ancient and active Martian 2012a), including the necessary tectonics. These discoveries include the components of a core, mantel, and , following: would facilitate the heat needed for  The Mars Global Surveyor found a mechanics and tectonism. remnant crustal magnetic field on Mars  The linear northeast trend of the Tharsis (Stanley, et al., 2008) that may indicate Montes, Arasia Mons, , a driving mechanism for ancient plate and , as well as tectonics. numerous , suggest the  One or more large hotspots involving likelihood of a spreading center on the volcanic construction on the Tharsis Rise (Zimbelman and Edgett, (, et al., 2004) (Kiefer and Li 1992) (Comer, et al., 1985) (Borgia and 2007 and 2009), possibly paired with the Murray, 2010). creation of the Hellas Basin (Johnson  Transtensional, left lateral strike-slip movement with 150 kilometers of

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displacement shows modern tectonism magnetized rocks showed evidence that at one in Valles Marineris (Yin, 2012a). time there was a strong global magnetic field  Evidence of apparently recent faulting is created by an ancient Martian core (Stanley, et exposed, implying recent and possibly al., 2008). While this does not explain a ongoing tectonic processes (Andrews- mechanism for modern plate tectonics on Mars Hanna, et al., 2008) (Petrowsky, et al., today, it does give a mechanism for a previously 2009) (Allemand, et al., 2006) hot interior that could continue to affect (Kronberg and Hauber, 2009) (Ferrill, et boundaries seen today. al., 2011).  Linear features called “wrinkle ridges” Creation of the Tharsis Rise interpreted as thrust faults are aligned The Tharsis Rise may have begun to perpendicular to Tharsis Rise form by the Nochian, the earliest on Mars, (Golombek ,1990). at least by 3500 Ma (Johnson and Phillips, 2005)  The Tharsis Rise volcanoes show (Yin, 2012b). Recently a new model for the evidence of activity in the past million creation of the Tharsis Rise has been proposed years. In geologic time, it is possible for involving the start of early planetary tectonic these dormant volcanoes to still be kinematics (Yin, 2012b). of a plate active (Neukum, et al., 2004). to the northwest of the Tharsis rise could have  Relative age dating and remote sensing been triggered by a large impact, such techniques of different units on the as the Argyre impactor, during the heavy Tharsis Rise allow comparison of bombardment period. This impact would have relative movements (Tanaka and Scott, pushed the Tharsis rise region up and over its 1987). neighboring plate to the northwest. With This study focused on three questions subduction started, a slab rollback model would stemming from the discoveries listed above to be able to create the Tharsis rise that is seen explore the possibility of current plate tectonics today. Moving from southeast to northwest, this on Mars. First, are there Earth analogs to rollback model includes evidence such as features that could be used to differences in structural trends, morphologies, identify tectonic processes? Second, is it spacing of volcanoes, as well as a lack of crustal possible to use Martian surface features to magnetization and different faulting and crustal identify types of plate boundaries on Mars? styles bounding Olympus Mons (Yin, 2012b). Third, it is possible to discern relative plate Both theories involve active tectonic processes motions? taking place from the Nochian through early epochs. These tectonic processes GEOLOGIC SETTING AND PREVIOUS imply zones of weaknesses that would give RESEARCH current tectonic processes preexisting weaknesses to utilize. Magnetic field The Tharsis Rise region may be During its lifespan, Mars Global influenced by plumes. The plume Surveyor was able to take measurements of the influence hypothesis is supported by mantle strength of the magnetic field around Mars. It convection models and observations of indicated there is no global magnetic field lithospheric thicknesses from anomalies, presently on Mars, but a “remnant crustal topography, and tectonic structures (Kiefer and magnetic field” created by highly magnetized Li, 2007 and 2009). Additionally, magnetization rocks in the southern hemisphere exists. These

The Compass: Earth Science Journal of Sigma Gamma Epsilon, v. 86, no. 2, 2014 Page 39 data from Mars Global Surveyor indicates that three volcanoes that make up the Tharsis thermal uplift and the creation of the Hellas Montes, , Pavonis Mons, and Basin, antipodal to the Tharsis Rise, could have Ascraeus Mons, and their associated fissures or contributed greatly to the creation of the rise flank vents indicate a axis oriented N40E (Johnson and Phillips, 2005). (Zimbelman and Edgett, 1992) (Comer, et al., 1985). The Tharsis rise has also been compared Linear Trends and Spreading Centers with the terrestrial Mount Etna, a gravitational Large scale linear features have been spreading that shows strong similarities, identified on the Tharsis rise, including the albeit on a smaller scale, to the Tharsis Rise alignment of the (fig. 3). The (Borgia and Murray, 2010).

Figure 3. The Tharsis Montes, a range of aligned volcanoes on the Tharsis Rise trending N40W. Background imagery from NASA.

Large escape structures created by dilatational extensional forces resulting in the overlying faults and fractures have created pit craters that sediments flowing down into the newly open are not unlike those found on Earth and other spaces below. One of the known methods to planetary bodies (fig. 4). These pit craters are create pit craters on an escape structure would created when a fracture of experiences be in a tectonic environment (Ferrill, et al.,

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2011). Numerous grabens are common on the general direction of northeast 45-60 degrees Tharsis rise, (fig. 5) and are found trending in a (Kronberg and Hauber, 2009).

Figure 4.

Escape structures forming pit craters on the northern edge of the Tharsis Rise (J-Mars, 2013).

HiRISE Images:

ESP_028449_2105_Red, ESP_027460_2105_Red, PSP_004912_2110-Red. Located at 260.62E 31.11.

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Figure 5. Conjugate jointing of two escape structures (J-Mars 2013). HiRISE Images: ESP_017268_1915_Red, ESP_017413_1915_Red. Located at 237.34E 11.54

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Valles Marineris 2012b). The episodic slab rollback theory The creation of the 4000 km long Valles explains the ’s left lateral movement and Marineris canyon in the southeast Tharsis Rise displacement along the canyon as back-arc region has been a point of varying hypotheses. extension (Yin, 2012b). There is recent tectonic Recent evidence suggests the canyon is currently activity in the area, accommodated by 150 km of a large transtensional left lateral strike slip displacement in the Melas . Fault scarps boundary that forms half of an east-facing V- cross-cutting young talus slopes indicate shaped conjugate strike-slip system with the recent tectonic movement in the area (Yin, fault (fig. 6) (Yin, 2012a and 2012a).

Figure 6. The Valles Marineris and Claritas Fossae strike slip system. Background imagery from NASA.

Other Prominent Faults 2012b). The southern Thaumasia Highlands Well known faults include the show evidence of shortening within a crater (fig. Thaumasia thrust on the southeast side of the 7). Other surficial linear features along the conjugate strike slip system, the Lycus thrust perimeter of the Tharsis Rise are likely strike northwest of Olympus Mons, the Northern and slip faults with displacement (Andrews-Hanna, Southern Tharsis graben zone, the Claritas fault, et al., 2008). One of the strike slip faults on and the Solis-Lunae and thrust belt (Yin, Labitas Fosse on the northwest side of the

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Tharsis Rise shows a large amount of faults show classic features that accompany displacement (fig. 8). Faulting has also been large-scale plate boundaries such as identified through the deformation of craters displacement, mountain ranges, depressions, and within the southern area of the rise (Allemand, et age differences in lithology of the Martian al., 2006) (Petrowsky, et al., 2009). All of these surface (fig. 2).

Figure 7. Thaumasia Highlands with distorted and shortened craters. The crater on the right side of the east-west ridge is shortened and slightly shifted. There are also north- grabens cross-cutting many of the craters that result in the craters being pulled on in two directions. Themis IR 100m Global Mosaic V11.5 (J-Mars). Located at 280.649E, 27.912

Figure 8. Displacement on the Labitas Fosse. Themis Day IR 100m Global Mosaic V11.5 (J-Mars). Located at 280.649E, 27.912

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Wrinkle Ridges folds or fault propagation folding due to the Wrinkle ridges are macro scale different characteristics seen with this style of deformation in the surface over large thrust faulting. Due to their 50-meter spacing, the faults (fig. 9), often due to fault bend folding orientations of their dips, and the amount of (Plescia and Golombek, 1986). These linear shortening, these faults likely extend to the features are prevalent in the Solis-Lunae fold bottom of the lithosphere (Golombek, 1990). and thrust belt and near the Thaumasia thrust. Similar large scale-faulting is seen in the areas Stratigraphic relationships indicate these ridges of , Lunae Planum, Sinai Planum, were formed during Noacian through the early Solis Planum, and and is Amazonian with the bulk of their creation in the aligned perpendicular to the body of the (Andrews-Hanna, et al., 2008). It is Tharsis rise. unclear if these faults are a result of fault bend

Figure 9. faulting near the Thaumasia thrust. HiRISE Image ESP_024453_1570_Red (J- Mars). Located at 280.31E -22.63

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Volcanic Activity Mons and the creation of the Tharsis Rise to It is unknown whether volcanic activity possibly early Nochian Era (Neukum, et al., on Mars is a geologically active process. The 2004). The five that cap Olympus Mons past, general consensus of the volcanoes on the have been dated from 100-200 Ma, happening in Tharsis Rise is that they are extinct. With new short succession of each other with flows ability to analyze surface features with improved that cascaded over the Olympus Mons scarp technology allows a reevaluation of this dating from 2.4-115 Ma (Neukum, et al., 2004). hypothesis. By using High Resolution Stereo This suggests that it is a possibility that Camera imagery along the calderas and flanking Olympus Mons could have episodic activity in rift zones of the Tharsis Rise and Elysium Rise the future. volcanoes, it is possible to get an accurate age dating using crater counting. The very basic Age Dating premise of crater age dating states that more Geological maps of Mars have been craters found in an area equates to greater age. made based off of rock feature types and crater There is evidence that flows on Olympus Mons count age dating (NASA). The use of this map and Hecates spanned 80% of the in this study was beneficial in that tectonic geological history of Mars, dating Olympus relationships could be interpreted from the locations of various lithologies (fig. 10).

Figure 10. Geological Map of Mars (NASA).

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METHODS AND RESULTS general surface topography comparisons. By The Tharsis Rise, including Valles using satellite imagery such as HiRISE, Marineris, was mapped using Esri ArcMap10.2 THEMIS, Mars Orbiter Laser Altimeter and analyzed using traditional observations (MOLA), as well as interactive programs such similar to field geology. Plate margins were as Google Mars, and J-Mars, five categories of evaluated using lineations, feature displacement, plate margins were created within the Tharsis dramatic topographic differences, crater Rise region (table 1). deformation, different rock units by age, and

Table 1. Type of plate margins and their characteristics

Type of Plate Characteristics Margin

Linear features including volcanoes with regional spreading indicators such as flank fissures and parasitic calderas all Divergent aligned in the same trending direction. The age of the rock units are the same on either side of the .

There are sharp changes in elevation with a non-linear boundary between the two areas. Changes in surface topography are present from relatively rough to smooth surfaces. Conjugate joints are present near the boundary. There is a change in age of the rock units.

Sharp changes of elevation are present with a linear Oblique Obduction boundary. There is a difference in the age of the rock unit on either side. Conjugate jointing is present.

Strike Slip with Long lineations with displaced features on either side of the visible boundary. Sharp elevation changes within the lineation displacement itself.

Strike Slip without Long lineations without visible displacement on the surface. visible Sharp elevation changes within the lineation itself. displacement

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ArcMap was used to inspect the surface ArcMap using topology and a multiple ring for sharp lineations and known features buffer to evaluate directions of maximum described earlier. Conjugate joints were mapped horizontal compression (fig. 12). These analyses that were visible at a 1:1,000,000 scale. These allowed an interpretation of plate margins and were then grouped into specific areas using their kinematic motions, yielding a broad picture natural spacing where conjugate joints were not of plate tectonics on the Tharsis Rise (fig. 13). present (fig. 11). Within these areas, rose Five distinct areas with unique kinematic diagrams of structural indicators such as motions and closed plate margins were conjugate joints, wrinkle ridges, escape identified (table 1). structures, and grabens were constructed in

Figure 11. Mapped conjugate joints and rose diagram areas on the Tharsis rise. Background imagery from NASA.

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Figure 12. Rose Diagrams with maximum principal axes. Background imagery from NASA.

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Figure 13. Tharsis Rise with plate margins and maximum principal stress axes. There are five distinctive areas on the rise that show unique kinematic movement (areas labeled 1-5). Background Imagery from NASA.

DISCUSSION Slab rollback initiated by the Argyer impactor Martian tectonics surrounding the would have started early tectonics on Mars as it Tharsis Rise contains classic geological features could have on early Earth. During this similar to those seen on Earth that display a vast bombardment period, early in Mars’ history of geological change. Many of the areas developmental history, it was struck by a large across the Tharsis Rise show visible impactor that destroyed its current planetary displacement along tectonic features. Below is a magnetic field. With the destruction of the logical summary of the region’s tectonic history, Martian dynamo the planet lost much of its including the delineation of individual plates and and protection against the solar their current kinematic moments. . Although there is not presently a core- During the early Nochian, which spans driven magnetic field, there is enough evidence the Hadean and the Archean eon on Earth, Mars in the crustal magnetic field that Mars did at one was developing in a similar fashion as Earth. point have a working dynamo at its core. After

The Compass: Earth Science Journal of Sigma Gamma Epsilon, v. 86, no. 2, 2014 Page 50 this dynamo failed, hotspots of large plate boundaries on Earth such as strike-slip began to rise on the surface of Mars, possibly systems, mountain ranges, abrupt contacts of triggered by the impactor that created Hellas differing rock ages, and distinct topographic Planitia, antipodal to the Tharsis Rise. Hotspot features. Geological structures in the form of and its associated tectonic forces conjugate jointing, escape structures, wrinkle could have created and driven the Tharsis Rise ridge faulting, and strike-slip faulting yielded over billions of years. These two processes interpretations of plate motions. During this could easily set the stage for widespread faulting study, five distinct areas on the Tharsis Rise that created planes of weakness along which show evidence of movement in a unique movement could continue today. direction and have features we interpret as plate Slab rollback helps to explain the boundaries. Further questions for study include creation of Valles Marineris. Part of a 1000- continued recognition and analysis of conjugate kilometer-scale left lateral transtentional systems in and around the rise and conjugate strike slip system, Valles Marineris continued age dating of these conjugate joint shows evidence of modern kinematics through systems, which will yield a more accurate displacement of young talus slopes (Yin, 2012a). picture of kinematic processes over geological As the Tharsis Rise was created, back arc basins time. and crustal hot spot thickening could have enabled the build-up of the rise. Currently the REFERENCES CITED highest point of the rise measured by the Mars Allemand, P., Baratoux, D., and Mondoux, M., Orbital Laser Altimeter (MOLA) is at Olympus 2006. Eliptical craters in Thaumasia, Mars: Mons averaging at 22 kilometers above Martian Consequences on fault behavior. Lunar and level. This rise has created a large amount of , 2031.pdf. loading on the rocks on and around the rise. Using Mount Etna as a terrestrial analog, Tharsis Andrews-Hanna, J.C., Zuber, M.T., and Hauck, rise would be able to activate preexisting S.A., 2008. Strike-slip faults on Mars: faulting to break into plate-sized blocks that are Observations and implications for global pushed outward due to gravitational spreading tectonics and geodynamics. Journal of and expansion due to thermal plumes. Based on Geophysical Research, v. 113, p. 1-19. these interpretations and age dating of previous Borgia, A. and Murray, J. B., 2010. Is Tharsis flows, Olympus Mons could erupt again in the Rise, Mars, a spreading volcano? The future. Geological Society of America Special Paper CONCLUSION 470, p. 115-122. Although Mars’ geological past has not Comer, R. P., Solomon, S. C., and Head, J. W., been directly seen, it is possible to apply many 1985. Mars: thickness of the lithosphere from geological principals to explain its surficial the tectonic response to volcanic loads. Reviews features. Many scientists have put great effort of , v. 23, p. 61-92. into deciphering the Tharsis rise. Using the research of others, as well as using remote Ferrill, D. A., Wyrick, D. Y., and Smart, K. J., sensing to gather evidence of classic geological 2011. Coseismic, dilatational-fault and landforms, we conclude there are modern extension-fracture related pit chain formation in processes at work on the rise. We identified Iceland: Analog for pit chains on Mars. surface features that are closely correlated with Lithosphere, v. 3(2), p. 133-142.

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