# Presentation: 089015

## Visit NE Syrtis Major!  

- Visit NE Syrtis Major!
- Win Valuable Martian Geological History!

**Ralph P. Harvey**
**Case Western Reserve University**
**Planetary Time Share Specialist**

**Notes:**
I submitted my abstract at the last minute,  not wanting to get involved in this high-stakes, speculative market.  But after nearly two days of indoctrination,  I’m ready to be a seller,  not a buyer.   And what I want to sell you is NE Syrtis Major as a place that MSL can land, and not only investigate “habitability” but also, with a little luck,  solve some really major Martian problems.

## Geologically speaking,  the ideal site includes: 

- •A “walkable” cross-section of Martian history including periods of assumed high habitability.
- •Recognizable global stratigraphic markers.
- •Both “Stay Home” and “Go To”

- _For safe operations,  the ideal site includes:_
- •Low dust (low albedo?) and high TI.
- •Flat on the relevant scales (km to cm).
- •Low altitude and near equatorial to help Skycrane.
- •No ice or water in case Skycrane needed help.

## Syrtis 

- Syrtis
- Major

**Notes:**
This is the place in the presentation where a real time-share salesman would lock the doors,  and have the next 4 hours to break you down with an endless litany of descriptions of amazing features.   Our hosts have given me 10 minutes,  so I’ll keep the primer on Syrtis Major to a minimum.

Like the other volcanoes in the circum-Hellas region,  it is of Hesperian age,  superimposed on the ancient Noachian southern highlands of Mars.  Most accepted relative chronologies say this should correspond to a time a minimum of 3.3 billion years ago.  Remember this for the climax of this talk.
 •Please note that this information and a lot more in this talk comes from the brilliant characterization of Syrtis Major by Heizinger and Head (2004),  and I strongly suggest that anyone interested in Syrtis Major start by reading that article   

## 20 km

## Physical properties

- After Heisinger and Head (2004)

**Notes:**
Let's move on to the physical properties
•Although often described as "basaltic" Syrtis Major does not exhibit the profile of a typical basaltic shield. like the other circum-hellas volcanoes, Syrtis Major is stunningly flat.   
--- Flank slopes are very shallow;  at its peak Syrtis Major rises only 500 m above the inferred regional northward-sloping Southern Highlands surface. 
--Long, thin lava flows are prevalent,  with good evidence for flooding of nearby Nili Fossae, Antoniadi crater and the Isidis basin. 

## A

- A'

- After Heisinger and Head (2004)

- From Kiefer (2004)

**Notes:**
•But Syrtis Major doesn't lie on TOP of the local surface,  it's cut into it.  As can be seen from the top profile, Syrtis lava plains lie significantly below the inferred regional surface, particularly along the southern margin.  This suggests significant thermally erosion of the local regolith, something very hard to do without a very, very hot magma. 

•Also note the complex caldera (actually two calderas) actually lies significantly below the altitude of the margins of the volcano.  This is not typical basaltic shield behavior and relatively unique even among these circum-Hellas volcanoes.  The best explanation for it is collapse after solidification of a deep, dense, presumably ultramafic magma chamber.

## From Bibring et al., 2005

**Notes:**
a concentration of high-Ca pyroxene,  as we see in Omega data.  While there's always some ambiguity in spectroscopy,  it's fair to say that Syrtis Major seems to be a  place where lava flows are px dominated,  and in particular hi-Ca px dominated.

## After Mustard et al. 
(LPSC 36, 2005), Hamilton et al., (2003) 
and Hoefen et al., (2003)

- (LPSC 36, 2005), Hamilton et al., (2003)
- and Hoefen et al., (2003)

**Notes:**

•  So here's a summary of the spectroscopically-derived mineralogy of Syrtis Major and the adjacent regions of Nili Fossae;  

•Ancient highlands enriched in low-Ca pyroxene

•Hesperian volcanism characterized by 2-pyroxene composition, enriched in high-Ca pyroxene

•Highly localized Olivine Mg-rich in Nili Fossae and Fe-rich in Syrtis Major.

## Interpretation: 

- •Syrtis Major is a differentiated ultramafic volcanic complex-  basaltic (gabbroic) or even more felsic units overlying abundant pyroxene- and olivine- rich lithologies (e.g, Skaergaard, Bushveld, Theo's Flow, etc.).
**Give me an hour,  I’ll convince Phil C.*
- _Why care?:_
- • It’s in _good global context_ and it’s border with Mg-rich opx and olivine-bearing, layered rocks in Nili Fossae defines _global environmental change_.

- _But Wait,  There’s More....._

**Notes:**
•In a nutshell,  spectroscopy suggests that in many regions of Syrtis major a px-rich lithology,  possibly Ca-px-rich with Fe-rich olivine,  is exposed. 
•This is fully consistent with the physical geology suggestion of an ultramafic complex replete with early voluminous cumulate px and ol units and later more felsic lithologies 

## Interpretation:

- -Higher up,  numerous conformable strata, most NOT dust covered but high Albedo.
- -low crater density supports the highly degraded “look” of the land.
- -Beautifully exposed ancient fluvial channels
- _Interpretation:_
- -An ancient fluvial environment with significant (but varying) degrees of denudation.

## The John Grant Slide TM

| Lat/Long
Alt. | Name | Go To? | Potential Issues | Science objective |
| --- | --- | --- | --- | --- |
| 16.359° N, 77.383° E
-2807 m | NE Syrtis Major 1 | Mostly | No MOC coverage for most of ellipse; quickest access to Nili section | Hesperian / Noachian section |
| 16.085° N, 76.742° E
-2185 m | NE Syrtis Major 2 | Ditto | No MOC coverage for most of ellipse | Ditto |
| 16.265° N, 77.984° E
-3181 m | NE Syrtis Major 3 | Ditto | Ditto, with best Syrtis exposures (rougher) and “thermals” | Ditto |
| 17.086° N, 75.391° E
-1095 m | NE Syrtis Major 4 | Ditto | “cliffy”?  Nice Nili drainages.  | Ditto |
| 18.376° N
77.663° E
-2662 m | Nili Fossae Crater | Not | Big trap, for sediment and rovers both. | deltas |

**Notes:**
A major challenge facing ongoing studies of Mars is the absence of an absolute timescale. 

•While a number of consistent relative chronologies have been proposed for Mars , the uncertainties associated with these mean shifts of 109 years or more possible in absolute terms.  

•The result is a geological history of Mars that is not directly comparable to that of the Moon and Earth.  And no matter what problem you're working on regarding Mars, be it life or water or volcanism or tectonics,  it makes a big difference whether it happened 3 billion years ago or 1 billion.  

•In this sense, establishing an absolute timescale is, at least for geologists,  the "holy grail" of martian geology.

## 3

- 4

- NFC

## Slide 13

## Slide 14

## Slide 15

## Slide 16

## M02-01453

## M02-01453

## M02-01453

## Slide 20

## E11-02526

## E11-02526

## E11-02526

## E11-02526

## Slide 25

## R10-05024

## R10-05024

## Nili Fossae Crater

## Slide 29

## The bonus-  a possible absolute age?

- _The Nakhlites_
- FACT:  Nakhlites _unique_ among martian meteorites;  CPX cumulates with "disequilibrium" Fa-rich (25-35% Fo) olivine.
- FACT: Seven specimens,  all identical in crystallization age (1.3 ba) and ejection age (11 ma) .  _Both shared with Fo-rich Chassignites_.

## Northeast Syrtis Major Got it All.

- • Well-exposed stratigraphy (history), including:

- • Conservatively fits MSL goals and guidelines.

- -Hesperian volcanics, with hints of fluvial overprints.
- -The Hesperian / Noachian boundary.
- -layered Noachian terrain with high habitability potential
- -Can walk the section _Downhill_

- -”Safe” flat, equatorial, low altitude, low dust landing site .
- -Good rover access to all stratigraphic levels .
- -The full range of materials MSL can exploit explore, most low albedo / low TI.
- -no ice or water now.

- • ADDED BONUS:  A potential absolute age tie.

## The John Grant Slide TM

- _THANK YOU_
- --To the organizers of the workshop for making it accessible to “outsiders”.
- --To the data providers,  making outstanding image products available, and easier to access every day.

| Lat/Long
Alt. | Name | Go To? | Potential Issues | Science objective |
| --- | --- | --- | --- | --- |
| 16.359° N, 77.383° E
-2807 m | NE Syrtis Major 1 | Mostly | No MOC coverage for most of ellipse; quickest access to Nili section | Hesperian / Noachian section |
| 16.085° N, 76.742° E
-2185 m | NE Syrtis Major 2 | Ditto | No MOC coverage for most of ellipse | Ditto |
| 16.265° N, 77.984° E
-3181 m | NE Syrtis Major 3 | Ditto | Ditto, with best Syrtis exposures (rougher) and “thermals” | Ditto |
| 17.086° N, 75.391° E
-1095 m | NE Syrtis Major 4 | Ditto | “cliffy”?  Nice Nili drainages.  | Ditto |
| 18.376° N
77.663° E
-2662 m | Nili Fossae Crater | Not | Big trap, for sediment and rovers both. | deltas |