Editing Noctis Labyrinthus (section)

===Mineralogical diversity===

An unnamed depression near the southernmost extent of the Noctis Labyrinthus system, near the divide of [[Syria Planum]] and [[Sinai Planum]] and at the western end of the [[Valles Marineris]], was found to be one of the most mineralogically diverse sites yet observed on the planet. These deposits, dated to the late Hesperian, post-date most Martian deposits of hydrated minerals.<ref name=thollot2012>{{cite journal |last1=Thollot |first1=P |last2=Mangold |first2=N |last3=Ansan |first3= V |last4=Le Mouélic |first4=S. |last5=Milliken |first5=RE |last6=Bishop |first6=JL |last7=Weitz |first7=CM |last8=Roach |first8=LH |last9=Mustard |first9=JF |last10=Murchie |first10=SL|s2cid=6739191 |date=2012 |title=Most Mars minerals in a nutshell: Various alteration phases formed in a single environment in Noctis Labyrinthus |journal=Journal of Geophysical Research |volume=117 |issue=E00J06 |pages= n/a|doi=10.1029/2011JE004028 |bibcode=2012JGRE..117.0J06T |doi-access=free }}</ref> Based on [[Compact Reconnaissance Imaging Spectrometer for Mars|CRISM]] spectral imagery, authors studying this depression have interpretatively identified the presence of:
*iron-rich minerals such as [[hematite]] and [[goethite]]<ref name=thollot2012 />
*Polyhydrated iron sulfates ([[copiapite]] and [[coquimbite]]), monohydrated iron sulfates ([[szomolnokite]] and possibly [[kieserite]]), hydroxylated iron sulfates ([[melanterite]] and hydronium [[jarosite]]), and possibly anhydrous iron sulfates ([[mikasaite]]).<ref name=thollot2012 />
*aluminum [[phyllosilicates]] ([[kaolinite]]s like hydrated [[halloysite]]/endeillite, or perhaps a combination of kaolinite and [[montmorillonite]])<ref name=thollot2012 />
*iron [[smectite]]s ([[nontronite]])<ref name=thollot2012 />
*[[opal#Noncrystalline opal|opaline silica]] (opal-A to the [[diagenesis|diagenetically]]-altered opal-CT), found to be comparable in spectral signature to some [[Iceland]]ic volcanic glass [[lapilli]]<ref name=thollot2012 />

Of the hydrated iron sulfate minerals observed in the basin, some of them - such as [[copiapite|ferricopiapite]] - are not stable in modern Martian conditions. However, researchers have suggested that they appear to coexist because the different deposits may have been exposed to the open atmosphere at different times, and some of these minerals do only fully dehydrate under Martian conditions over the course of many years.<ref name=thollot2012 /> Furthermore, opaline silica deposits observed within this depression display spectra that may occasionally suggest interpersal with the iron sulfate mineral [[jarosite]] and the phyllosilicate mineral montmorillonite. The latter material is interpreted as such from an unusual doublet shape resolved on its spectra.<ref name=thollot2012 />

The minerals in this basin were most likely formed as a result of an initially acidic [[hydrothermal alteration]] of basaltic terrain, with the dissolution of [[plagioclase]] and calcium-rich pyroxenes increasing the pH steadily and causing the other minerals to precipitate. In this basin in particular, the [[mafic]] smectite layer overlays sulfates, aluminum phyllosilicate clays, and opaline silica deposits. The order of this layering is unique to the unnamed depression and is typically reversed in most Martian contexts, with the mafic smectites forming the bottom [[Noachian]]-age layer.<ref name=thollot2012 /> Some researchers have counterproposed that rather than a sequentially reversed depositional event, this basin formed in a single, highly heterogeneous event. This is not necessarily indicative of a global alterational phenomenon, but is most likely tied to a localized heat source such as a volcano or an impact crater.<ref name=thollot2012 /> In 2024, scientists Pascal Lee and Sourabh Shubham found evidence from CRISM, the [[HiRISE]] camera, and the [[Mars Orbital Laser Altimeter]] that this heat source was a volcano near the northeast end of the labyrinthus that they dubbed '''Noctis Mons''', which would be the seventh-highest mountain on Mars at {{cvt|9028|m|ft}}, and that the eastern part of its base was home to multiple [[glacier]]s with potential for hosting life, which could make it a highly valuable candidate target for [[astrobiology]] missions.<ref name="SETI Institute 2024">{{cite web | title=Giant Volcano Discovered on Mars | website=SETI Institute | date=March 13, 2024 | url=https://www.seti.org/press-release/giant-volcano-discovered-mars | access-date=March 20, 2024}}</ref><ref name="SETI Institute 2023">{{cite web | title=Remains of a Modern Glacier Found Near Mars’ Equator Implies Water Ice Possibly Present at Low Latitudes on Mars Even Today | website=SETI Institute | date=March 15, 2023 | url=https://www.seti.org/press-release/remains-modern-glacier-found-near-mars-equator-implies-water-ice-possibly-present-low-latitudes | access-date=March 20, 2024}}</ref>

Calcium-rich [[pyroxene]]s have been spectrally observed elsewhere in the northern reaches of the Noctis Labyrinthus fracture zone.<ref name=thollot2012 />