{{Short description|Martian dune field}} {{Use dmy dates|date=June 2025}} [[File:ESP 035924 2620 MRGB North Polar Scarp in Abalos Undae with Basal Exposure and Dunes rotated.jpg|thumb|300px|Abalos Undae dunes at Abalos Scopuli, the scarp of ''[[Abalos Mensa]]''. The ice layers on the cap and [[Basal sliding|basal formations]] are also visible. The picture was taken by the [[HiRISE]] camera on board the [[Mars Reconnaissance Orbiter]] and was enhanced by [[NASA]] in [[RGB]] colour.]]
'''Abalos Undae''' ([[Latin]] for "Abalos Waves") is a [[dune field]] on [[Mars]] in the periphery of [[Planum Boreum]], the Martian North pole. It is one of the [[Classical albedo features on Mars|officially named]] northern circumpolar dune fields, along with [[Olympia Undae|Olympia]], [[Hyperboreae Undae|Hyperboreae]], and [[Siton Undae]], and also one of the densest of the region.<ref name="USGS"/><ref name="hirise.lpl">{{cite web|author1=Kate Fishbaugh|title=Dunes in Abalos Undae|url=https://hirise.lpl.arizona.edu/PSP_010219_2785|date=19 November 2008}}</ref> Its northernmost boundary is located in the southwest channel that separates the [[Abalos Colles]] formation from the main polar ice cap, and from there the dune field extends southwest all the way to the lowlands of [[Vastitas Borealis]].<ref name="hirise.lpl"/><ref name="Icarus"/><ref name="Icarus(2008)"/>
It is theorised that the dunes of the Abalos field may have resulted from erosion of ''[[Rupes Tenuis]]'' ({{langx|la|Thin Cliff}}), the polar [[Escarpment|scarp]].<ref name="hirise.lpl"/><ref name=NASAimage/> Its name was approved by the [[International Astronomical Union]] in 1988.<ref name="USGS"/> It extends from latitude 74.94°N to 82.2°N and from longitude 261.4°E to 283.03°E (76.97°W – 98.6°W). Its origin is located at classical [[albedo feature]] with coordinates 72°N, 70°W and has a diameter of 442.74 km.<ref name="USGS">{{cite web|website= Gazetteer of Planetary Nomenclature|title=Abalos Undae|url=https://planetarynames.wr.usgs.gov/Feature/5?__fsk=-1259906441|publisher=[[USGS]]}}</ref>
==Location and formation characteristics== [[File:Distribution of dune fields in the Planum Boreum region.PNG|thumb|250px|[[Stereographic projection]] map showing the density distribution of dune fields in the Planum Boreum region. The grey regions are lower density fields. The four densest dune fields including Abalos Undae are shown in black. The [[prime meridian]] is at the bottom of the map. Abalos Undae is the smaller black region at centre left, between longitude 261.4°E to 283.03°E (76.97°W – 98.6°W).]] Abalos Undae is a [[dune field]] on [[Mars]], in the periphery of Planum Boreum, the Martian north pole. It is a part of the northern circumpolar dune fields, along with Olympia, Hyperboreae, and Siton Undae, which are officially named after nearby [[Classical albedo features on Mars|classical albedo features]].<ref name="hirise.lpl"/> It is located in the southwest channel that separates the Abalos Colles formation remnant from the main ice cap, and continues all the way to the channel's southern boundary.<ref name="hirise.lpl"/><ref name="Icarus(2008)">{{cite journal |author=Niels Hovius |author2=Andrew Lea-Cox |author3=Jens M. Turowski |title=Recent volcano–ice interaction and outburst flooding in a Mars polar cap re-entrant|journal=Icarus|date=29 May 2008|volume=197 |issue=197|pages=24–38|doi= 10.1016/j.icarus.2008.04.020|url=https://www.researchgate.net/publication/223390157|bibcode=2008Icar..197...24H}}</ref> The dunes of the Abalos field may have formed from erosion of ''Rupes Tenuis'', the polar [[Escarpment|scarp]].<ref name="hirise.lpl"/><ref name=NASAimage>[https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA20607 NASA] quote: "Today's image location is slightly east of Monday's image. In this image the polar scarp (called Tenuis Rupes) bisects the image.</ref> Abalos Undae has its northernmost boundary in the neighbourhood of [[Abalos Mensa]] and continues in a south-eastward direction after it emerges from the western end of a narrow channel separating Rupes Tenuis from Abalos Mensa.<ref name="Icarus">{{cite journal |author=Kenneth L. Tanaka |author2=J. Alexis P. Rodriguez |author3=James A. Skinner Jr |author4=Mary C. Bourke |author5=Corey M. Fortezzo |author6=Kenneth E. Herkenhoff |author7=Eric J. Kolb |author8=Chris H. Okubo |title=North polar region of Mars: Advances in stratigraphy, structure, and erosional modification|journal=Icarus|date=28 February 2008|volume=196 |issue=2 |pages=318–358|doi=10.1016/j.icarus.2008.01.021|url=https://www.researchgate.net/publication/235137809|access-date=25 August 2017|ref=YICAR 8602|bibcode=2008Icar..196..318T}}</ref>
Enhanced colour images obtained by the [[HiRISE|High Resolution Imaging Science Experiment]] (HiRISE) camera on board the [[Mars Reconnaissance Orbiter]] highlight the areas of the dunes where different materials are present.<ref name="hirise.lpl"/> The blue areas indicate the presence of dunes of [[basaltic]] origin, while the light-colour areas are probably dust. The pictures are of sufficient resolution to show ripples on the dune surface.<ref name="hirise.lpl"/> The ripples are generated by winds, as are the dunes.<ref name="hirise.lpl"/> The dunes are considered stationary as a unit, with only small ripple movements present.<ref name="hirise.lpl"/>
Similarly to the rest of the dune fields around the periphery of Planum Borealis, the Abalos dune field is considered to consist of [[lag deposit]]s resulting from the [[ablation]] of the sediment found in [[Basal sliding|basal units]].<ref name="Icarus(2008)"/> The Abalos dune field is considered one of the densest dune fields in the northern circumpolar region of Mars. Other fields of similar density in the region include the Olympia, Hyperboreae, and Siton Undae.<ref name="Tanaka">{{cite conference |author=K. L. Tanaka |author2=R. K. Hayward |title=Mars’ North Circum-Polar Dunes: Distribution, Sources, and Migration History.|url=http://www.lpi.usra.edu/meetings/dunes2008/pdf/7012.pdf|conference=Planetary Dunes Workshop: A Record of Climate Change |year=2008}}</ref><ref name="Earth and Planetary"/>
The Abalos dune field consists of transverse dune linear sequences that, overall, form platforms of sand ranging from approximately 10 metres to 200 metres thickness.<ref name="Tanaka"/> Abalos Undae, along with Hyperboreae and Siton Undae, is a sand tributary to mostly medium-density sand fields located east of [[Olympia Undae]] and extending to the [[prime meridian]] of Mars.<ref name="Tanaka"/> Image analysis, performed using the method of spectral derivatives, indicates that Abalos Undae, and the rest of the densest dunes fields in the periphery of Planum Borealis, Olympia Undae and Hyperboreae Undae, show the highest [[pixel density]] indicating the presence of [[gypsum]].<ref name="Earth and Planetary">{{cite journal |author=M. Massé |author2=O. Bourgeois |author3=S. Le Mouélic |author4=C. Verpoorter |author5=A. Spiga |author6=L. Le Deit |title=Wide distribution and glacial origin of polar gypsum on Mars |journal=Earth and Planetary Science Letters |date=2012 |volume=317–318 |pages=44–45 |doi=10.1016/j.epsl.2011.11.035|bibcode=2012E&PSL.317...44M }}</ref> The gypsum of Abalos Undae may be eroding due to scouring action by substrates of bedrock involved in plains formation.<ref name="Tanaka"/> {{clear}}
==Images by HiRISE and THEMIS== <gallery widths="180px" heights="180px"> File:PSP 009367 2620 RED Aeolian Source Layers Exposed in Northwestern Abalos Scopuli.jpg|Abalos Undae at Abalos Scopuli, the scarp of [[Abalos Mensa]] File:PSP 010501 2615 MIRB Abalos Undae map-projected.jpg|Gypsum deposits in the dunes of Abalos Undae map-projected in IRB colour File:Dunes in Abalos Undae.jpeg|Dunes in Abalos Undae. The blue areas indicate the presence of dunes of basaltic origin, while the light-colour areas are probably dust. File:Sample of Abalos Undae Gypsum.jpeg|Gypsum deposits in the dunes of Abalos Undae File:Dunes in Abalos Undae, Mars.jpg|Dunes in Abalos Undae File:PSP 010501 2615 MRGB Abalos Undae Gypsum map projected.jpg|The dunes of Abalos Undae with gypsum deposits map-projected in RGB colour File:PSP 010501 2615 MIRB Abalos Undae with scale.jpg|The dunes of Abalos Undae with gypsum deposits map-projected in IRB colour with scale File:PSP 010501 2615 Abalos Undae Gypsum.jpg|The dunes of Abalos Undae with gypsum deposits map-projected in IRB colour File:ESP 035924 2620 MRGB North Polar Scarp in Abalos Undae with Basal Exposure and Dunes.jpg|North Polar Scarp in Abalos Undae with Basal Exposure and Dunes map-projected in RGB colour and distance scale File:ESP 035924 2620 RED North Polar Scarp in Abalos Undae with Basal Exposure and Dunes black and white.jpg|North Polar Scarp in Abalos Undae with Basal Exposure and Dunes in black and white File:ESP 034500 2620 RED North Polar Scarp in Abalos Undae with Basal Exposure and Dunes black and white with scale.jpg|North Polar Scarp in Abalos Undae with Basal Exposure and Dunes in black and white with scale File:ESP 034500 2620 RED North Polar Scarp in Abalos Undae with Basal Exposure and Dunes black and white.jpg|North Polar Scarp in Abalos Undae with Basal Exposure and Dunes in black and white File:Abalos Undae dunes and crater.png|Abalos Undae dunes and crater File:Polar cap scarp in Abalos Undae THEMIS IOTD 20160511.jpg |The edge of the dark dunes of Abalos Undae shown just below the polar scarp and cap File:ESP 035924 2620 North Polar Scarp in Abalos Undae with Basal Exposure and Dunes.jpg|Abalos Undae dunes with brightness adjusted </gallery> {{clear}}
== See also == * [[Classical albedo features on Mars]] * [[Hagal dune field]] * [[Nili Patera dune field]] * [[Hyperboreae Undae]] * [[Aspledon Undae]] * [[Ogygis Undae]]
== References == {{reflist|30em}}
== External links == * [https://www.uahirise.org/ESP_034500_2620 HiRISE entry for North Polar Scarp in Abalos Undae with Basal Exposure and Dunes]
{{Geography of Mars}} {{Portal bar|Solar System}} {{Authority control}} {{Use British English|date=June 2025}}
[[Category:Dunes on Mars]] [[Category:Mare Boreum quadrangle]]