CERRO GORDO, AN ANALOG OF A MARTIAN COMPOSITE VOLCANO O. García Monasterio1 , J.S. Oliveira1, J.L. Mesa Uña1, S. F. Romero1, J.L. García Bueno2 and M. Diaz Michelena1 1Space Magnetism Area, Payloads and Space Sciences Department, National Institute for Aerospace Technology (INTA) 2Coordination and Plans Department, National Institute for Aerospace Technology (INTA), 28850 Torrejón de Ardoz, Spain *Corresponding author: [email protected] / [email protected]
INTRODUCTION ESA/Roscosmos ExoMars mission will soon deliver a surface platform and a rover to the Martian surface, at Oxia Planum [1]. Crustal magnetic field MARS EARTH information is crucial to better understand the surface and sub-surface N properties and geological history. Measuring the magnetic field signals is one of the objectives of the AMR (Anisotropic MagnetoResistance) sensor [2] part of the Meteorological package within Kazachok surface platform. The magnetic field signature of different terrestrial analogues will help to understand the future acquired magnetic field measurements on Mars and allow a better characterization of the local geology. Here we focus on Cerro Gordo (CG) volcano, proposed to be an analogue for some Martian volcanos, and the mixed volcanic structure magnetic signals. Figure 1 shows our targeted terrestrial analog, Cerro Gordo volcano, to the Ulysses Colles, Tharsis (Mars). It has to be remarked that in comparison, Martian strombolian volcanos are expected to be larger in size than their terrestrial counterparts given the different gravity and atmospheric 1 km conditions of both planets [3]. It is very likely that the Martian volcanoes Figure 2. Crustal magnetic field intensity of Mars at 150 area is magnetized, given the available information from spacecraft km constant altitude, using the model from [4]. The star altitudes [4]. However, satellite measurements provide large-scale symbol indicates the location of Ulysses Colles volcano signatures with limited spatial resolution in contrast to the upcoming Figure 1. (left) Ulysses Colles, Tharsis (Mars) and (right) Cerro Gordo, Campos de Calatrava, Spain. shown in Figure 1. near-ground and on ground measurements.
GEOLOGICAL DESCRIPTION A
CG volcano, from the Campos de Calatrava volcanic province, is located close to Ciudad Real, Spain (38.833073°N Figure 3. The structure of the CG volcano, according 3.743197°W). It is a volcano formed between 4.7 and 1.75 million years ago, related to an intraplate volcanism formed in a to the topography and volcanic deposits, can be lacustrine area with different types of eruptions. The volcanic building is found to be hosted on an Armorican quartzite lava flows divided into three main groups: the two large lava scoria main flows in the northwest zone, with the lowest relief, basement, composed of four main phases [5]: two phreatomagmatic and two strombolian phases, culminating in the bulding formation of some spatter lava flows on the southeastern slope of the volcano. which correspond to the most effusive phases of The principal geological structures such as lava flows, spatter flows, and the volcanic building, are highlighted in Figure 3. the second eruptive stage; a large central structure composed of large scoria deposits, which formed Similar geological events can be expected on Mars, and therefore the preparatory campaigns for the characterization of the cone in the second and last stage of eruptions; Martian volcanoes need to consider not only monogenic volcanoes but also mixed buildings [6][7]. and two smaller lava flows with a high positive Past studies [8] described the mineralogy of the volcano as olivine nephelinites, with high contents of mafic materials, highly spatter B relief, also called spatter lava flows, which are the
magnetised in both the northern lava and the spatter flows. We have collected 16 samples in total: 10 lavas-spatter and 6 800 most recent materials of the volcano. (Edited from
scorias, the most representative of each deposit. We show in the following laboratory analysis of a spatter sample. 750 B GoogleEarth). m A 1 km 2 km
MAGNETIC CHARACTERIZATION OF CERRO GORDO ROCKS GEOCHEMICAL CHARACTERIZATION We have measured the magnetic properties of a spatter sample from Cerro Gordo by means of a VSM (Vibrating Sample X Rays diffraction (XRD) analysis shows the presence of magnetic minerals in the Magnetometer). The hysteresis loop (Figure 4 left) presents a wasp-waist shape, which suggests the presence of two mineral rock such as: magnetite and pyrrhotite. It is also seen the titanium phases phases in the sample: a ferromagnetic phase and a paramagnetic or superparamagnetic (SP) phase that produces the narrowing responsible for the paramagnetic behavior. These results are consistent with the in the central zone. The position of the sample on the Day plot [9] in figure 4 (right), together with the geochemical structure in the hysteresis loop and the Day diagram. characterization results, confirm those phases. From the diagrams and the chemical data, it can be inferred that the ferromagnetic phase could be magnetite or pyrrhotite as the most common magnetic phases. Furthermore, the paramagnetic phase could be a titanium-rich phase (titanomagnetite).
V v
Figure 4. (left) Hysteresis loop and virgin curve (inset) of a spatter sample from Figure 5. XRD of a CG spatter sample. The intensity and angle of incidence of the X-rays are Cerro Gordo. (right) Theoretical Day diagram for magnetite [9] where the red shown. point indicates the studied sample. MAGNETIC FIELD SIGNATURES OF CERRO GORDO VOLCANO A previous magnetic survey at 5 m constant altitude has been performed over two of the volcanic structures: the northern lava flow A and the northern spatter deposit [10]. The respective measured magnetic anomalies along the various flight tracks is shown in Figure 6. Over the northern lava flow region, the obtained magnetic anomaly reaches intensity values of up to 1500 nT. High spatial frequency signal is observed and can be the result of a worked agricultural land, where the rocks magnetic orientation does not remain original. Over the northern spatter deposit, the magnetic anomaly reaches intensity values around 3500 nT, showing a MAGNETICpattern, compatible with theFIELDhypothesis SIGNATURESof the spatter being formed, and OFconsequently CG magnetized when the global magnetic field was in the opposite direction of today's main field. Further magnetic surveys at 10 and 20 m altitudes will be performed along a horizontal line, crossing all the main building structure of the volcano. This future survey will allow a complete characterization of the magnetic signature of this analog.
Figure 6. Map of magnetic measurements with a small amount of data processing, obtained by B magnetic surveys along the CG Volcano. In red, the horizontal line crossing all the volcanic structures.
CONCLUSIONS/PERSPERCTIVES REFERENCES The CG volcanic edifice is magnetized, and the iron-rich rocks [1] Cathy Quantin-Nataf et al. (2021). Oxia Planum: The Landing Site for the ExoMars “Rosalind Franklin” Rover Mission: Geological Context and Prelanding Interpretation. Astrobiology, Volume 1, Number 3. [2] D. Rodríguez Díaz et al. (2019). AMR instrument for ExoMars 2020 scientific payload for stationary magnetic measurements on the surface of Mars. The tenth Moscow solar system have ferromagnetic phases. At first glance, different parts of the symposium (10M-S3) IKI RAS, Moscow, 7-11. [3] Petr Brož et.al (2015). Scoria cones on Mars: Detailed investigation of morphometry based on high-resolution digital elevation models. JGR volcano can be distinguished with the magnetic surveys. Planets, Volume 120, Issue 9 (1461-1595). [4] Benoit Langlais et al. (2019). A New Model of the Crustal Magnetic Field of Mars Using MGS and MAVEN. JGR Planets, Volume 124, Issue 6, pages 1471-1632. [5] Elena González et al. (2010). Aportaciones Recientes en Volcanología, 2005-2008zz. Bulletin of Volcanology. [6] Emily M. Stewart and James Head (2001). Ancient Martian volcanoes Further characterization of the properties of the magnetic in the Aeolis region: New evidence from MOLA data. JCR Planets, Volume 106, Issue E8, pages 17497-17698. [7] Sauro, Francesco et al. (2019). Book: Volcanic Caves of Lanzarote: A Natural phases, dating of the collected samples by K-Ar, and deep Laboratory for Understanding Volcano-Speleogenetic Processes and Planetary Caves. Springer. [8] Ancochea E. (1982) Evolución espacial y temporal del volcanismo reciente de España Central. processing of the magnetic surveys are the following steps of Thesis. [9] David J. Dunlop (2002). Theory and application of the Day plot (Mrs/Ms versus Hcr/Hc) 1. Theoretical curves and tests using titanomagnetite data. JGR Solid Earth, Volume 107, Issue B3. [10] Sergio Fernández et al. (2021). Vector Magnetometry Using Remotely Piloted Aircraft Systems: An Example of Application for Planetary Exploration. Remote Sens. , 13(3), 390. this work. A full characterization of the Cerro Gordo analogue will allow to relate geology with its magnetic signature, which will be a great advantage to understand the geology of ACKNOWLEDGEMENTS This project is funded by the project MagAres (reference: ESP2017-88930-R) of the Spanish Programme of Research, Development and Innovation oriented to the Challenges of the Society in the magnetized volcanic structures of Mars (thickness, structure, frame of the State Plan of Scientific and Technical Research and Innovation 2013-2016. The participation of J.S. Oliveira is funded by the European Union’s Horizon 2020 research and innovation etc.). programme under the Marie Skłodowska-Curie grant agreement SIGMA no 893304. zz The authors would like to thank to the PNOA-LiDAR project, Subdirectorate General of Geodesy and Cartography of the Spanish National Geographic Institute for the MDS data to make the Figure 1.