Analysis of cone structure at North of Olympus Mons Aureole, Mars R.Parekh, A.Rust, N.Teanby School of Earth Sciences, University of Bristol, Bristol, UK Introduction and Geological setting of study region Objectives :
• Locate and identify cone Background: 36⁰N
Flow Plain features. • Cone structures are common phenomena that are found on Earth and • Describe morphology and Mars. Terrestrial cones are used as an analogue to study Mars cones. size. • Depending upon formation process the cones are categorized into: • Compare its
34⁰N characteristics to different 1. Scoria Cones: Small cones built from particles and blobs of congealed Fig. 1 A) region of Mars where lava ejected from a vent; ejected material breaks into small fragments, Overview of cone fields are analysed. gets solidify and fall as scoria, e.g.: Coprates Chasma [Broz & Mars. B) Enlarge • Propose a formation Hauber, 2013]. view of study region mechanism for cones. 2. Tuff/Ring cones: Made up of fine grain particles, formed due to 32⁰N with footprints of interaction between ascending magma and subsurface water/ice, e.g.: datasets used and Nephentes region [Broz & Hauber, 2013]. flow feature 3. Rootless cones: Lava ground ice interaction, a rootless eruption, e.g.: (high-lighted in Why it is important Tartarus Colles [Hamilton et al., 2010c,2011]. black doted line). to study? 4. Pingos: Periglacial feature, form a mound structure under cold climatic 30⁰N Base MOLA elevation data. • Presence of cone field is condition, e.g.: Utopia basin [Pablo & Komatsu, 2009]. 140⁰ W 135⁰ W • Region consists of high elevated rough plains and low elevated smooth plain (potential evidence of an aqueous environment. • Distinct morphological features provide knowledge about the flow feature). • Origin of deposit is unclear (may be due to landslide that triggered from the failure of • Possibly suitable site for geological context, thus cones act as a key to specify nature of the astrobiological activities. surface. flank of Olympus Mons [Helgason, 1999]. It is difficult to assess the source of material that sculpted the terrain of Aureole and the source of formed cones. • Helpful to enhance current • Usually cones fields are located on younger surface of Mars (dominant knowledge regarding on northern plain) [Fagents et al., 2002]. • Cones were identified as ‘rootless cones’ [Fagent et al., 2007] without further supporting evidence. Olympus Mons formation. Observations and Results Cone identification Key: cluster or in group + conical shape with flank feature+ Fig. 2 Base of CTX images crater at summit+ located on flow feature. (~6m/pixel) Cone Classification: overlapped by elevation data 1. Radially Symmetric cones generated from • Out of 6491 total, 2185 identified as radially symmetric. CTX stereo pairs • Usually young with pristine signature. using online • Commonly the craters have an inward slope. MarsSI tool. • Crater walls are rough in texture with some blocky grainy material located at the foothill of the Below are the histograms of each rim or at the centre. region from the Fig 3. A) Clusters image. A clear of cone fields. variation in size of Cones are well crater diameter is preserved with seen in different crater rim at top areas. (F04_037285_213 7_XI_33N135W). B) Boulder material at the Area B bottom of rim Area A (PSP_007814_21 350 50 45 45_ RED).
300 40
250 35 2. Composite Cones 30 200 25 • Not perfectly circular but is elongated or has uneven structure . 150 20 • Many of them are adjoined shoulder to shoulder with multiple crater system. Frequency 15 • Few show collapsed parts of rim structure or no traces of rims. 100 Fig. 4 A)
Frequency 10 • Shows mounds like structure and/or a cone at the floor of the crater, known as Adjoined cones 50 5 double cone (DC). with partially 0 0 • Similar to those identified on Central Elysium Planitia [Noguchi & Kurita, 2015]. destroyed rim (PSP_007814_ 50 100 200 300 400 500 50 100 200 300 400 500 2145_RED). Crater Dia.(m) Crater Dia.(m) B) and C) Examples of Area C Area D DC 140 30 (ESP_012363_ 2145,
120 25 P13_006166_2
100 20 128_XN_32N1 80 35W). 15 D) Elevation
60 B profile of cone Frequency
Frequency 10 40 from image C. 20 5 B C 0 0 50 100 200 300 400 500 50 100 200 300 400 500 A D Crater Dia.(m) Crater Dia.(m) • Cones with large craters are typically found in region B, at lower elevation (between – 2290 m to -3025 m). • Region B has the highest proportion of large crater cones and lacks craters with <100 m diameter. • At high elevation (>-2280 m) cones with smaller craters are dominant. • Crater >300 m in diameter not at all present in southern part, region D. D • Area A,C,D show mixed populated cratered cone, but lack of large cones (>400 m).
Conclusion Christopher Hamilton, LPL,UA for constructive discussions. • Morphologic similarities to the rootless cones in Acidalia Planitia (100-400m carter possibly acted as a basin where the material flown down Special thanks to Chevening Scholarships, the UK dia.) [Fagents et al., 2002] lead us to conclude that these cones are mainly rootless from the higher elevated region and get collected. government’s global scholarship programme, funded by the cones. Enormous resources can be a factor for the large cratered Foreign and Commonwealth Office (FCO) and partner cones. organizations to fund my postgraduate study. • Radially symmetric cones are very well preserved relatively, and possibly formed in recent past(mid to late Amazonian). Adjoining complex cone is result of • At this stage we have no proper explanation that can justify current result about why majority of the cones are References: turbulent flood and might have formed during moving flow[Burr et al,2005]. (1) Broz & Hauber (2013), JGR, 118,1-20. (2) Burr et al.(2005), Thus, the process of cone formation has likely to occur during flow emplacement. located at the edge. Icarus 178, 56–73. (3) Fagents et al.(2002), Geol. Soc. London, • DC structures are like those on Central Elysim Planitia. It has been interpreted as 295-317.(4) Fagents et al.(2007), Camb. Uni. Press, 151-177. (5) multiple-collapsed structure[Noguchi & Kurita, 2015]. So one can conclude this Acknowledgment: Hamilton et al.(2010c), JGR, 115, 1991-2002.(6) Hamilton et al. (2011), JGR, 116(3), 1991-2012.(7) Helgason J. (1999), Geology, phenomena as time lapse event. We would like to thank Frances Boreham, doctorate student at UoB for 2(3), 231-234. (8) Noguchi & Kurita (2015), PSS, 44–54 (9) • Entire region is located on relatively lower elevation than surrounding, thus it suggestions. We appreciate Prof. Katharine Cashman at UoB and Dr. Pablo de & Komatsu (2009), Icarus, 199(1),49-74.