Geomorphological Analysis of Mass Balances of Martian Valley Networks in Western Terra Sirenum

In recent years, there has been a great deal of interest in Martian valley networks. Especially when [1] and how and among witch circumstances they have been formed [2] has been discussed up to now. On the whole, at what time Martian valley networks have been generated and that water might has been the forming agent is pretty certain now. A substantial amount of research by a lot of studies is published about that issue. However, a central question that needs to be addressed in this context is, how much water was required to create valley networks on early Mars. The intention of this study focuses on a geologic and geomorphological analysis of valley networks in the Western part of Terra Sirenum presenting calculations of discharge, transportation and erosion rates to improve the insight in a time there must have been other environmental and climate conditions, whose processes are still not sufficiently explored and understood

Runoff, runoff balancing, and derivation of climatic conditions based on regional studies at the impact craters Newton and Bakhuysen

Diese Arbeit beschäftigt sich mit der hydromorphologischen Untersuchung von Trockenbetten der Kraterinnenränder von Newton und Bakhuysen. Dabei liegt der Fokus auf dem nordöstlichen Kraterinnenrand Newtons. Durch die Auswertung verwendeter Bilddaten von HRSC (High Resolution Stereo Camera), CTX (Context Camera), HiRISE (High Resolution Imaging Science Experiment) und MOC (Mars Orbiter Camera), digitaler Höhenmodelle von MOLA (Mars Orbiter Laser Altimeter) und HRSC, berechneter Durchflussraten, Abflussspenden und potentiellen Abschmelzraten sowie verwendeter fluvialstatistischer Methoden wird auf die Morphologie und Struktur der fluvialen Systeme qualitativ und quantitativ Bezug genommen. Die untersuchten Trockenbettsysteme am Nordostinnenrand Newtons erreichen eine hohe Komplexität ihres Integrationsgrades der Zuflüsse bei Strahler-Ordnungen bis 5 und Taldichten zwischen 0,05 km^-1 und 0,32 km^-1 bei Ausbildung dendritischer Abflussmuster an der Zeitgrenze Noachium/Hesperium bis maximal spätes Hesperium. Ihre Bifurkationsverhältnisse liegen im Allgemeinen zwischen 2 und 5, während ihre Tallängenverhältnisse zwischen 1 und 4 schwanken. Da terrestrische Flusssysteme Werte in derselben Größenordnung zeigen, kann auf ähnliche erosive Abläufe auch auf dem Mars geschlossen werden. Bei der Untersuchung ihrer Profillinien ließ sich allerdings ein nur unausgeglichener Verlauf feststellen. Dem Abfluss war es nicht möglich einen Ausgleich zwischen Erosion, Transport und Akkumulation zu erreichen, was auf sporadische Entwässerung deutet. Die Hochwasserspitzen in Newton liegen an den Mündungen der Vorfluter zwischen 145 m³/s bis 1.200 m³ /s bei Einzugsgebieten bis über 4.000 km²; die mittleren Durchflussraten betragen etwa 10 m³/s bis 230 m³/s. Das entspricht Abflussspenden pro Tag, die im einstelligen Zentimeterbereich für jene und im einstelligen Millimeterbereich für diese sich befinden. Eine Ausprägung eindeutiger Mäander wurde unterdrückt. Vielmehr wechseln sich Abschnitte mit Konzentrationsabfluss in ausgebildeten Talstrecken und Flussverwilderung in intramontanen Ebenen ab. Schüttungskörper in Newton konnten aufgrund unzureichender Auflösung des verwendeten Datenmaterials nicht zweifelsfrei bestimmt werden. Im Vergleich mit Newton erreichen die Trockenbetten des Kraters Bakhuysen höchstens Strahler-Ordnungen von 4. Die Taldichten für die größten Trockenbettsysteme schwanken in Bakhuysen zwischen 0,46 km^-1 und 0,6 km^-1 und liegen damit etwa doppelt so hoch wie diejenigen des Newton-Kraters. Ihre Bifurkationsverhältnisse bewegen sich zwischen 2 und 4 für mittelgroße Systeme (Strahler 3) und bis 5 für die größten Systeme (Strahler 4); die Tallängenverhältnisse schwanken dagegen in der Regel zwischen 1 und 2 und befinden sich somit im unteren Feld der Messungen im Newton-Krater. Auch hier lassen sich Rückschlüsse auf ähnliche Erosionsabläufe in einer Aktivitätsphase bis in frühamazonische Zeit schließen, worauf Altersbestimmungen der Schüttungskörper schließen lassen; auch die Längsprofile der Täler sind ähnlich unausgeglichen wie die Newtons. Aufgrund der um eine Dimension kleineren Einzugsgebiete Bakhuysens (< 400 km²) werden geringere maximale und mittlere Durchflussraten erreicht. Diese liegen für die größten Einzugsgebiete zwischen 200 m³/s und 290 m³/s für die Maximalwerte und 20 m³/s bis 30 m³/s für die Durchschnittswerte. Ihre Abflussspenden liegen jedoch in derselben Größenordnung wie bei Newton. Flussverwilderungsabschnitte fehlen fast ganz und zu Materialzwischenlagerungen kam es kaum. Daher wurde das Material bis in den Krater hineintransportiert, worauf erhaltene Schüttungskörper im Nordosten hindeuten. Die Entstehung der Trockenbetten wird mit einem regionalen thermodynamischen Zirkulationsmodell erklärt, dass durch die Orographie bedingt wurde. Schneefälle in den Hochlagen und der Verbleib als Schnee- und Eisrücklage über lange Zeiträume bedingen in wärmeren Epochen (Interglazialen) ein Abschmelzen derselben aus Nivationsnischen und Hochebenen. Die Bestimmung potentieller Abschmelzraten ergaben maximale Abflussspenden im unteren einstelligen Zentimeterbereich pro Tag und besitzen damit die gleiche Dimension der ermittelten Werte, die sich aus den Durchflussraten und ihren Einzugsgebieten an den Vorflutermündungen bestimmen ließen. Durch Eisrindeneffekt und „thermische Erosion“ war es abfließendem Wasser möglich eine zügige Eintiefung der Flüsse in den Untergrund zu bewerkstelligen. Die Beobachtungen, Messungen und Berechnungen zeigen, dass die Trockenbetten und Talsysteme des Mars sich in relativ kurzen Zeitperioden unter kaltklimatischen Bedingungen entwickeln konnten.This work deals with hydro-morphological investigations of channel and valley networks of the inner rims of Newton and Bakhuysen Crater on Mars, while focusing on the northeastern inner rim of Newton Basin. Image data (HRSC, CTX, MOLA, HiRISE, MOC), digital elevation models (MOLA, HRSC), calculation of discharge, runoff and potential thawing rates, and fluvial-statistic methods with qualitative and quantitative reference to the morphology of the fluvial systems were used for the analyses. The investigated channels and valleys at the northeastern inner rim of Newton Crater are characterized by a high degree of complexity and integration of the tributaries. These dendritic systems reach stream orders of up to 5 and channel/valley densities between 0.05 km^-1 and 0.32 km^-1 at the Noachian-Hesperian-Boundary up to the Late Hesperian. Their bifurcation ratios vary between 2 to 5 and their stream length ratios yield 1 to 4. As terrestrial river systems show values in the same order, erosive processes on Early Mars can assumed to be quite similar. The unbalanced longitudinal profiles indicate that the channels did not evolve to the maturity level. The lack of balance of erosion, transport, and sedimentation, indicates sporadic drainage. The flood peaks in Newton range between 145 m³/s and 1,200 m³/s at the mouths. The mean discharge rates are about 10 m³/s to 230 m³/s. This corresponds to runoff rates of some centimeters per day (peak discharge rates) and some millimeters per day (mean discharge rates). River meandering was mainly suppressed. Rather, fluvial sections alternate with single stream channels within well preserved valleys and segments of anastomosing fluvial structures within inner mountain plains. A potential alluvial fan or delta could not be determined unambiguously due to insufficient resolution of the data. In contrast to Newton Crater, stream orders up to 4 have been determined at the inner rim of Bakhuysen Crater. The channel/valley densities vary between 0.46 km^-1 and 0.6 km^-1. Hence, they are roughly twice as high as those of Newton Crater. The bifurcation ratios vary between 2 and 4 in medium-sized networks (stream order 3) and up to 5 for the largest systems (stream order 4). Their stream length ratios usually range between 1 and 2 and, thus, correspond to the lower field of the Newton Crater measurements. Conclusions can be drawn that erosion processes occurred in a similar way at other locations on Mars and at other times up to Early Amazonian. This is proved by age determinations of fluvial deposits. Longitudinal profiles of the Bakhuysen channels are likewise unbalanced as the Newton ones. Due to the smaller catchments of Bakhuysen Crater (< 400 km²), peak and mean discharge rates reach lower values. Largest catchment areas show peak discharge values of 200 m³/s to 290 m³/s and mean discharge rates of 20 m³/s to 30 m³/s. These runoff rates range in the same dimension as those of Newton Crater. In general, there is hardly evidence for sedimentation of material in inner mountain plains. Thus, the material was transported into the crater which is documented by deposits in the northeast of Bakhuysen. The formation of the channels and valleys is explained by a local thermodynamic circulation model generated by the orography. Snowfall in high altitudes and accumulation of snow and ice in nivation hollows or at elevated areas over long periods cause thawing and melt water runoff during warmer periods (interglacial). The determination of potential thawing rates yields maximum runoff rates of some centimeters per day. They have the same dimension as those runoff values, which were calculated from the discharge rates, deduced from catchment area size. A rapid incision of the channel and valley networks was enabled by the effect of the “eisrinde” and “thermal erosion”. The observations and calculations show that channel and valley networks on Mars can evolve intensively in relative short time periods under cold climate conditions

Water and Martian habitability: Results of an integrative study of water related processes on Mars in context with an interdisciplinary Helmholtz research alliance “Planetary Evolution and Life”

A study in context with the Helmholtz Alliance ‘Planetary Evolution and Life’ focused on the (temporary) existence of liquid water, and the likelihood that Mars has been or even is a habitable planet. Both geomorphological and mineralogical evidence point to the episodic availability of liquid water at the surface of Mars, and physical modeling and small-scale observations suggest that this is also true for more recent periods. Habitable conditions, however, were not uniform over space and time. Several key properties, such as the availability of standing bodies of water, surface runoff and the transportation of nutrients, were not constant, resulting in an inhomogeneous nature of the parameter space that needs to be considered in any habitability assessment. The planetary evolution of Mars led to environmental changes, which in turn affected its habitability potential. Similarly, considerable variations in climate due to latitudinal or elevation effects combined with a diverse surface geology caused distinctively different local conditions that influenced the planet׳s habitable potential

Mineralogy and morphology of geologic units at Libya Montes, Mars: Ancient aqueous outcrops, mafic flows, fluvial features and impacts

There is ample evidence of ancient and long-lasting fluvial activity and chemical alteration in the Libya Montes region south of Isidis Basin. The region hosts Noachian to Amazonian aged surface rocks with extensive outcrops of olivine- and pyroxene-bearing material. Libya Montes also features surface outcrops and/or deposits hosting Fe/Mg-smectite, Fe/Mg-smectite mixed with carbonate and/or other Fe/Mg-rich phyllosilicates, and Al-smectite. These aqueous materials likely formed from chemical alteration connected with hydrothermal activity resulting from the formation of the Isidis Basin and/or the pervasive fluvial activity throughout this region. The morphology and stratigraphy of the aqueous and mafic minerals are described using High Resolution Imaging Science Experiment (HiRISE) and High Resolution Stereo Camera (HRSC) derived Digital Terrain Models (DTMs). Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) analyses show variations in the chemistry of the Fe/Mg-smectite from nontronite like exposures with spectral features near 2.29 and 2.4 μm more consistent with Fe3OH groups in the mineral structure, and saponite-like outcrops with spectral features near 2.31 and 2.38 μm characteristic of Mg2OH groups. These Fe/Mg-smectite bearing materials also have bands near 1.9 μm due to H2O and near 2.5 μm that could be due to the smectite, other phyllosilicates, and carbonates. All regions exhibiting carbonate features near 3.4-3.5 μm also have features consistent with the presence of olivine and Fe/Mg-smectite, indicating that the carbonate signatures occur in rocks likely containing a mixture of these minerals. The Al-smectite-bearing rocks have bands near 1.41, 1.91 and 2.19 μm that are more consistent with beidellite than other Al-phyllosilicates, indicating a higher-temperature or diurnally processed origin for this material. Our interpretation of the geologic history of this region is that ancient Noachian basaltic crustal materials experienced extensive aqueous alteration at the time of the Isidis impact, during which the montes were also formed, followed by emplacement of a rough olivine-rich lava or melt and finally the smooth pyroxene-bearing caprock unit