Geology of a region connecting the lower and higher levels of the Vastitas Borealis Formation boundary: Assessment of the Hesperian hydrologic activity and long-wavelength topographic changes on Mars

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The primary goal of our study is to investigate in detail the western discontinuity of the Vastitas Borealis Formation (VBF) contact between its Deuteronilus and Nilosyrtis segments, a region between Utopia Planitia and Acidalia Planitia that connects the two distinct levels of the outer edge of the Vastitas Borealis Formation (VBF) within the northern plains. Results of this research are crucially important for the assessment of the topographic configuration and mode of emplacement of the VBF. The VBF covers vast parts of the northern lowlands and has been continuously interpreted to be a depositional residue of a past northern ocean. The morphologic setting and topographic configuration of the VBF edges are of particular interest as they share similarities with terrestrial coastal contacts. The results of this study could help to increase our knowledge about the extent, timing and duration of the postulated northern ocean on Mars. Our study is aimed to address the following scientific questions closely related to various aspects of the Martian ocean hypothesis: Does the topographic and morphologic setting in this region provide evidence that the VBF consists of a series of sequential units suggesting multiple episodes of its emplacement? Is its elevation changed continuously between the lower and the higher levels? Or, does it show a regional-scale break of slope somewhere within the gap? Is there evidence suggesting that the higher and lower segments of the contact are disconnected and represent independent features? Are they consistent with the interpretation of the VBF as a sublimation residue of a former ocean or of multiple sea-scale standing bodies of water?How do the results of crater counts in selected areas along the VBF boundary constrain the time interval of the VBF emplacement?