Dark, windblown (eolian) sand on Mars has produced significant geologic effects throughout Martian history. Although local and regional sand sources have been identified, a primary origin, or genesis, for Martian sand has not been demonstrated. This knowledge gap was recently heightened by the discovery of widespread sand motion, implying breakdown of grains to sub-sand sizes. To address the question of sand genesis, we investigated the source(s) of sand in Aeolis Dorsa (AD), the westernmost Medusae Fossae Formation, using comparisons to sand potentially sourced from multiple regions, each connoting a different sand genesis. Our methods included comparison of (1) AD sand mineralogies with those of possible sand source features, and (2) mapped AD sand deposits and inferred emplacement directions with modeled sand deposit locations and transport pathways. The results point to a time-transgressive unit, interpreted as pyroclastic, as a source of dark sand. High-resolution images of this unit reveal outcrops with dark sand weathering out of lithified bedrock. Given the extent of interpreted pyroclastic deposits on Mars, this sand genesis mechanism is likely widespread today and operated throughout Martian history. Whereas this work identified olivine-rich sand, a range of original pyroclastic lithologies would account for the mineralogic variability of dune fields on Mars. These findings can be tested through analyses of other pyroclastic deposits and potentially by data from the NASA Curiosity rover in nearby Gale crater.Windblown (or eolian) sand has been a pervasive influence on Mars. Loose and lithified sand deposits and sand-eroded forms are observed globally and locally (Diniega et al., 2021), evidencing wind-driven sand over geologic time.The primary origin(s)—or genesis—of Martian sand is(are) unknown (Diniega et al., 2021). This knowledge gap in our understanding of Martian source-to-sink sedimentology (Grotzinger and Milliken, 2012; Kocurek and Ewing, 2012) is highlighted by detection of widespread dune movement today (Diniega et al., 2021), during which the more energetic saltating grain impacts are inferred to break down to sub-sand sizes (Sagan et al., 1977). Whereas local and regional sources for sand have been inferred, the primary mechanism(s) that originated the sand-sized grains remains(remain) a key area of inquiry.Multiple mechanisms might create sand on Mars, including glacial grinding, chemical precipitation, fluvial and lacustrine deposition, and volcanism (Greeley and Iversen, 1985). Volcaniclastic deposits, including products of explosive volcanism and weathering of effusive lavas, are consistent with the low albedo and mafic signature of Martian dunes and have analogs on Earth (Edgett and Lancaster, 1993).We tested for the source(s) of sand in the Aeolis Dorsa (AD) region (0°–8°S, 147.5°E–156°E; Fig. 1C), the westernmost part of the Medusae Fossae Formation (MFF; Fig. 1A; Greeley and Guest, 1987; Tanaka et al., 2014). The AD region, named for the numerous ridges (dorsa) of inverted fluvial deposits (Burr et al., 2021), shows erosional and depositional eolian landforms that testify to extensive wind transport of sand (Fig. S1 in the Supplemental Material1). Yardangs, formed via erosion by wind-driven sand, are pervasive. Dark sand deposits are visible in some yardang troughs, adjacent to topographic features, and in Aeolis Chaos (Fig. 1C), an ~500-m-deep depression adjacent to the highlands. Geologic mapping (Burr et al., 2021) of the AD region and its regional geologic context enable testing of four source regions for AD sand (Fig. 1B). The Cerberus Plains region, northeast of the AD study area, is composed of effusive lavas crosscut by the Cerberus Fossae, where sand ripples (Roberts et al., 2012) and extensive wind streaks (Greeley and Iversen, 1985) attest to sand production. The Elysium Mons edifice north of AD has effusive lava and explosive sedimentary deposits (Tanaka et al., 2014), both of which could break down to produce epiclastic and pyroclastic sand, respectively. The southern highlands host many dune fields (Tirsch et al., 2011), from which sand could be transported northward into the AD study area. Last, the AD sand could originate from locales within the AD region, where the Aeolis and Zephyria Plana units, coinciding with MFF (Fig. 1C), share the interpretation of a pyroclastic deposit (Tanaka et al., 2014; Burr et al., 2021), generically modeled to include sand-sized sediments (Wilson and Head, 1994). To discover the primary origin of this sand, we evaluated each of these four potential sand source regions as a source of AD sand.This evaluation involved first mapping sand deposits in Aeolis Dorsa. Grain sizes for these dark deposits were estimated from nighttime infrared measurements, yielding sand sizes (Table S1). We then collected mineralogical data both from AD sand and from sand source features (e.g., craters, talus slopes; Supplemental Dataset 1) in the three other potential sand source regions for comparison, expecting AD sand source(s) to show the greatest mineralogic similarity to AD sand. Data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) were used to make these mineralogical identifications.We also conducted potential sand flux modeling. Spatial continuity between those time-integrated fluxes, or potential sand transport vectors, indicated possible sand transport pathways, which were compared to sand-mobilizing wind directions inferred from bed-form morphologies. Areas of convergent or near-zero potential sand transport were inferred to indicate sites of sand deposition, and these sites were compared to dark sand locations from mapping. More information is provided in the Supplemental Material.Mineralogies from the four potential sand source regions showed different compositions (Fig. 2). The potential sand source features in the highlands showed the most variability, including pyroxene and hydrated phases (Table S1; Fig. S2). The spectra from the Cerberus Plains showed a mixed mafic signature. The spectra from the Elysium Mons region are indicative of pyroxene, olivine, and/or glass. Spectra from the dark (non-dusty) sands within the AD Plana units, corresponding to MFF deposits, showed more olivine enrichment, and the aggregate AD sand composition was statistically separable from those of the other three potential source regions (Supplemental Dataset 1).Potential sand flux modeling showed limited potential sand pathways into the AD study area (Fig. 3). Sand from Elysium Mons and the Cerberus Plains would encounter transverse flows that would block transport into the AD region, whereas flux northward from the southern highlands would largely be captured by the Aeolis Chaos depression.Analyses within the study area (Fig. 1C) provided additional insight into AD sand sources. For the Aeolis Chaos sands (Fig. S3C), modeling showed northward potential transport over the southern edge of the depression. Within the depression, potential sand flux vectors and wind directions inferred from morphologies both indicated southward flow, substantiated by subtle southward ripple motion (S1 Animation). Sand mineralogies throughout the Aeolis Chaos were consistent with a highlands-like sand composition. On these bases, we interpreted Aeolis Chaos sand to be predominately sourced from the highlands and reworked by winds within the depression.In eastern Aeolis Planum (Fig. S3D), dark sand is visible among yardangs, suggesting that accelerated winds keep that sand freer of dust. To the west, the brighter land surface and a dusty CRISM spectrum provide evidence of dust, whereas limited potential sand flux and scour marks around one side of knobs (cf. Bishop, 2011) indicate underlying sand (Fig. S1B). Thus, we infer that sand in AD is more extensive than is surficially apparent, but its mineralogy is unclear in these locations due to dust.On central Zephyria Planum (Fig. S3E), sand locations and potential transport directions imply sourcing from Zephyria Planum itself. The most extensive dark sand is visible within an ~28 × 1.5 km linear trough (Fig. S1C) along a unit contact. Despite high potential sand transport over Zephyria Planum, sand is found only within this trough and as isolated interyardang deposits ~85 km to the northwest (Fig. S3F). Whereas mineral identifications were limited and nondiagnostic, any potential sand transport directions would permit sand only from the planum. Sand could also be sourced from abrasion of the walls of the troughs or yardangs, consistent with its topographic confinement.In southern Zephyria Planum (Fig. S3G), dark sand is visible within yardang troughs (Fig. S1A). The orientations of the potential sand transport vectors in this location (approximately transverse to the yardangs) likely do not reflect the actual transport direction, as the best available input topographic data for the modeling did not resolve the yardangs. In contrast to sand elsewhere in the study area, the mineralogical identifications in southern Zephyria Planum reflected a uniquely olivine-rich signature (Figs. 1C and 2), implying minimal mixing and/or transport from a local source.Local sources for the Zephyria Planum sand require a mechanism for sand genesis. The MFF, of which Zephyria Planum is a part, has been interpreted as an ignimbrite (Mandt et al., 2008) potentially sourced from Apollinaris Patera (Kerber et al., 2011), and terrestrial basaltic ignimbrites exhibit sand-rich layers tens of centimeters thick (Fisher et al., 1993; Scarpati et al., 2015; Valentine et al., 2019). Sand layers are also documented for terrestrial pyroclastic deposits that are pumiceous (de Vleeschouwer et al., 2005). Based on these terrestrial examples of endogenous sand layers in pyroclastic deposits, we examined high-resolution images on all plana units (Fig. 1C) for dark sandy layers (see Methods in the Supplemental Material). This examination yielded 31 examples of dark strata with submeter thickness above dark slopes with characteristics of gravitational sand deposition (Figs. 4A–4C; Supplemental Dataset 2; see the supplemental Methods). An olivine-rich mineralogy for one such outcrop (Fig. 4D), in contrast to the regional mixed mafic signatures, argues against entrainment of olivine sand grains from the Martian surface during pyroclastic flow. The presence of native olivine as sand-sized phenocrysts in terrestrial basaltic ignimbrites (Clemens et al., 2011; Martí et al., 2017) also supports the inference that the olivine-rich sand is native to the Zephyria Planum bedrock.Where sand genesis from strata was not detected, such as along the sand-rich unit contact on Zephyria Planum (Fig. S1C), eolian abrasion may be liberating sand that is more homogeneously distributed within the outcrop, as documented for lithics and crystals in the terrestrial Campo Piedra Pomez ignimbrite (de Silva et al., 2013). Other possible explanations for sand in this location are its transport from the topographically higher planum unit to the southwest, consistent with the secondary northward component of the modeled potential sand transport, or formation as a lag deposit, consistent with scattered 1-km-scale dark sand deposits (Fig. S1C) on the planum. Any of these three possibilities implies that sand originated from the Zephyria Planum bedrock. The suggestion of sand distributed within the Zephyria Planum bedrock and the identification of discrete sand strata both show how the light-toned MFF could be a source for dark sand.The vast MFF, the westernmost extent of which maps to Zephyria Planum bedrock (Fig. 1C), is interpreted as a pyroclastic deposit on the basis of erosional morphology, draping of underlying topography, density, compositional information, and multiple radar data sets (Brož et al., 2021). Given the distribution of pyroclastic deposits on Mars (Kerber et al., 2012; Tanaka et al., 2014), the discovery of a pyroclastic source for the Zephyria Planum sand provides a mechanism for the wide-spread distribution of Martian sand from local sources. Explosive deposits with sand-sized grains are widespread on Mars (Wilson and Head, 1994; Kerber et al., 2012; Brož et al., 2021). Though fine sands will fall very close to the vent (Kerber et al., 2012), the potential for saltative sand transport at moderate wind speeds (Sullivan and Kok, 2017; Andreotti et al., 2021) allows for further distribution. Pyroclastic deposits have been inferred globally (Tanaka et al., 2014), identified regionally (Mandon et al., 2020, and references therein), and detected in situ (McCoy et al., 2008). The variety of mafic minerals in terrestrial basaltic ignimbrites (Clemens et al., 2011; Martí et al., 2017) provides a pyroclastic avenue for formation of the mixed mafic compositions of dune fields on Mars (Tirsch et al., 2011).This mechanism of sand liberation from a pyroclastic deposit, detected to be operating in the present-day Amazonian climate on Mars, also likely operated over much of Martian history. A decline in the generation of granular material from impact and volcanic processes (Grotzinger and Milliken, 2012) would imply that sand on Mars today is predominately recycled (e.g., Edgett et al., 2020). However, with high grain-impact velocities during the low-density atmospheric conditions of the past ~3.0 b.y. (Kok et al., 2012), sand genesis by eolian abrasion of pyroclastic bedrock could have been substantial throughout that epoch.Olivine phenocrysts in terrestrial basaltic ignimbrites are modeled to have formed during a low-pressure (<180 MPa) period in a shallow magma chamber (Clemens et al., 2011). Consistent with this low-pressure olivine formation, Martian magma has been modeled to result from near-surface partial melting (Schumacher and Breuer, 2007). The confinement of source rocks spectrally dominated by olivine to the early Noachian and the early Hesperian on Mars suggests a mid- to late Noachian mantle cooling that minimized olivine crystallization (Ody et al., 2013). The emplacement of the MFF was temporally extended, with the early Hesperian–age deposits younging to the east (Tanaka et al., 2014). Sand from other MFF members (Fig. 1A), or more broadly from other explosive deposits (Brož et al., 2021), by providing primary volcanogenic mineralogies of decreasing age, enables testing of the magmatic evolution on Mars.Sediment maturation, by which composition evolves over time, has broad utility on Earth but uncertain application to Mars (Diniega et al., 2021). Olivine has been suggested to characterize mature volcanogenic sand, based on in situ data from Icelandic sand sheets (Mangold et al., 2011) and the “El Dorado” ripple field in Gusev crater (Sullivan et al., 2008). Results from this work indicate that olivine can also characterize highly immature (locally to regionally sourced) sediments.The findings of this work are testable in other globally distributed pyroclastic deposits (Tanaka et al., 2014; Mandon et al., 2020, and references therein; Brož et al., 2021). The variably olivine-enriched eolian sands in nearby Gale crater are likely not sourced from the olivine-poor Stimson eolian sandstone (Rampe et al., 2018). Sand on Aeolis Mons most likely comes from the upper mound, a possible MFF outlier (Thomson et al., 2011).This work was initiated at the University of Tennessee (Knoxville, Tennessee, USA), on the traditional territory of the Tsalagi (Cherokee), the Tsoyaha (Yuchi, Muscogee Creek), and other Native peoples. The work was completed at Northern Arizona University (Flagstaff, Arizona), which sits on homelands sacred to the Hohokam Diné, Hopi, Western Apache, and other Native peoples. We honor the past, present, and future generations of these tribes on their ancestral lands. This work was supported by NASA grant NNX16AL47G through the Mars Data Analysis Program, and its presentation was improved through helpful reviews by Briony Horgan and Jim Zimbelman.

中文翻译：

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火星Aeolis Dorsa暗沙的爆炸性火山起源

火星上的深色风沙（风成沙）在整个火星历史中产生了显着的地质影响。尽管已经确定了局部和区域砂源，但尚未证明火星砂的主要起源或成因。最近发现广泛的沙子运动加剧了这种知识差距，这意味着颗粒分解成亚沙粒大小。为了解决沙子成因的问题，我们调查了最西端的 Medusae Fossae 组 Aeolis Dorsa (AD) 的沙子来源，通过比较可能来自多个区域的沙子，每个区域都意味着不同的沙子成因。我们的方法包括将 (1) AD 砂矿物学与可能的砂源特征进行比较，(2) 用模拟的沙子沉积位置和运输路径绘制 AD 沙子沉积图和推断的就位方向。结果表明一个时间海侵单元，被解释为火山碎屑，是暗沙的来源。该单元的高分辨率图像显示出露头，其中暗沙从岩石化的基岩中风化出来。鉴于火星上被解释的火山碎屑沉积物的范围，这种沙子的成因机制可能在今天很普遍，并且在整个火星历史中都在运作。虽然这项工作确定了富含橄榄石的沙子，但一系列原始火山碎屑岩性将解释火星沙丘场的矿物学变异性。这些发现可以通过对其他火山碎屑沉积物的分析以及可能通过附近盖尔陨石坑的美国宇航局好奇号探测器的数据进行测试。风沙（或风成沙）对火星产生了普遍的影响。全球和局部都观察到松散和岩化的砂沉积和砂蚀形式（Diniega 等，2021），证明了地质时间上的风驱动砂。火星砂的主要起源或成因是（是）未知（Diniega 等人，2021 年）。我们对火星源-汇沉积学理解的这种知识鸿沟（Grotzinger 和 Milliken，2012 年；Kocurek 和 Ewing，2012 年）通过今天广泛的沙丘运动（Diniega 等人，2021 年）的检测突出显示，在此期间，更有活力跳跃的颗粒影响被推断为亚砂粒大小（Sagan 等，1977）。尽管已经推断出当地和区域的沙子来源，但产生沙子大小的颗粒的主要机制仍然（仍然）是一个关键的研究领域。多种机制可能在火星上产生沙子，包括冰川研磨、化学沉淀、河流和湖泊沉积以及火山作用（Greeley 和 Iversen，1985）。火山碎屑沉积物，包括爆发性火山活动和喷出熔岩风化的产物，与火星沙丘的低反照率和镁铁质特征一致，并且在地球上有类似物（Edgett 和 Lancaster，1993 年）。我们测试了沙丘的来源Aeolis Dorsa (AD) 区域（0°–8°S，147.5°E–156°E；图 1C），美杜莎窝组的最西端（MFF；图 1A；Greeley 和 Guest，1987；Tanaka等人，2014）。AD 地区以倒置河流沉积物的众多山脊（背脊）命名（Burr 等，2021），显示出侵蚀和沉积风成地貌，证明了沙子的广泛风运（图 1）。补充材料中的 S1）。风沙侵蚀形成的雅丹斯无处不在。在与地形特征相邻的一些 yardang 槽中可见深色砂沉积物，在与高地相邻的约 500 米深的洼地 Aeolis Chaos（图 1C）中可见。AD 地区的地质填图 (Burr et al., 2021) 及其区域地质环境能够测试 AD 砂的四个源区（图 1B）。AD 研究区东北部的 Cerberus 平原地区由 Cerberus Fossae 横切的喷涌熔岩组成，沙子波纹（Roberts 等人，2012 年）和广泛的风纹（Greeley 和 Iversen，1985 年）证明了沙子的产生。AD 以北的 Elysium Mons 大厦有喷涌的熔岩和爆炸性沉积物 (Tanaka et al., 2014)，两者都可能分解产生史诗碎屑和火山碎屑砂，分别。南部高地有许多沙丘田（Tirsch 等，2011），沙子可以从沙丘向北输送到 AD 研究区。最后，AD 砂可能起源于 AD 区域内的区域，其中 Aeolis 和 Zephyria Plana 单元与 MFF 重合（图 1C），共享对火山碎屑沉积物的解释（Tanaka 等，2014；Burr 等。 , 2021), 一般建模为包括沙子大小的沉积物 (Wilson and Head, 1994)。为了发现这种沙子的主要来源，我们评估了这四个潜在的沙子源区中的每一个作为 AD 沙子的来源。这项评估涉及首先绘制 Aeolis Dorsa 的沙子沉积物。这些深色沉积物的粒度是根据夜间红外测量估算的，得出砂粒大小（表 S1）。然后，我们收集了来自 AD 砂和其他三个潜在砂源区域的砂源特征（例如，陨石坑、距骨斜坡；补充数据集 1）的矿物学数据进行比较，期望 AD 砂源显示最大的矿物学相似性到AD沙。来自火星紧凑型侦察成像光谱仪 (CRISM) 的数据用于进行这些矿物学鉴定。我们还进行了潜在的沙通量建模。这些时间积分通量或潜在的沙子迁移向量之间的空间连续性表明了可能的沙子迁移路径，这与从床形形态推断的沙子流动风向进行了比较。推断会聚或接近零潜在沙子迁移的区域以指示沙子沉积地点，并将这些地点与测绘中的暗沙位置进行比较。补充材料中提供了更多信息。来自四个潜在沙源区域的矿物显示出不同的成分（图 2）。高地潜在的沙源特征表现出最大的可变性，包括辉石和水合相（表 S1；图 S2）。地狱犬平原的光谱显示出混合的镁铁质特征。Elysium Mons 地区的光谱表明辉石、橄榄石和/或玻璃。来自 AD Plana 单元内的暗（非尘埃）沙子的光谱（对应于 MFF 沉积物）显示出更多的橄榄石富集，并且 AD 沙子的总体成分在统计上与其他三个潜在来源区域的成分是可分离的（补充数据集 1）。潜在砂通量模型显示进入 AD 研究区的潜在砂通道有限（图 3）。来自 Elysium Mons 和 Cerberus 平原的沙子会遇到横向流动，阻碍向 AD 地区的运输，而从南部高地向北的流动将主要被 Aeolis Chaos 洼地捕获。研究区域内的分析（图 1C）提供了额外的深入了解 AD 沙源。对于 Aeolis Chaos 砂岩（图 S3C），模型显示了凹陷南部边缘向北的潜在输送。在洼地内，从形态推断出的潜在沙通量矢量和风向都表明向南流动，并由微妙的向南波纹运动证实（S1动画）。整个 Aeolis Chaos 的沙子矿物学与类似高地的沙子成分一致。在这些基础上，我们将 Aeolis Chaos 沙子解释为主要来自高地，并被洼地内的风改造。在 Aeolis Planum 东部（图 S3D），在 yardangs 中可以看到深色沙子，这表明加速的风使沙子更自由灰尘。在西部，较亮的地表和尘土飞扬的 CRISM 光谱提供了尘埃的证据，而旋钮一侧周围有限的潜在沙通量和冲刷痕迹（参见 Bishop，2011）表明底层沙子（图 S1B）。因此，我们推断 AD 中的沙子比表面明显的要广泛，但由于灰尘，这些位置的矿物学不清楚。在 Zephyria Planum 中部（图 S3E），沙子位置和潜在的运输方向意味着来自 Zephyria Planum 本身. 在约 28 × 1.5 km 的线性槽内可见最广泛的深色沙子（图 3）。S1C) 沿单元触点。尽管在 Zephyria Planum 上空的沙子运输潜力很大，但沙子仅在这个槽内被发现，并且在西北约 85 公里处是孤立的 interyardang 沉积物（图 S3F）。尽管矿物鉴定有限且无法诊断，但任何潜在的沙子运输方向都只允许来自平面的沙子。沙子也可能来自槽壁或 yardangs 的磨损，与其地形限制一致。在 Zephyria Planum 南部（图 S3G），在 yardang 槽内可见深色沙子（图 S1A）。该位置潜在沙子输送矢量的方向（大约与 yardangs 相交）可能无法反映实际的输送方向，因为用于建模的最佳可用输入地形数据并未解决 yardangs。与研究区其他地方的沙子相比，Zephyria Planum 南部的矿物学鉴定反映了独特的富含橄榄石的特征（图 1C 和 2），这意味着来自当地来源的混合和/或运输极少。 Zephyria Planum 的当地来源沙子需要一种沙子生成机制。Zephyria Planum 是 MFF 的一部分，它被解释为可能来自 Apollinaris Patera（Kerber 等，2011）的火成岩（Mandt 等人，2008），而陆地玄武质火成岩表现出数十层富砂层厘米厚（Fisher 等人，1993；Scarpati 等人，2015；Valentine 等人，2019）。砂层也被记录为浮石的陆地火山碎屑沉积物（de Vleeschouwer 等，2005）。基于这些火山碎屑沉积物中内生砂层的陆地实例，我们检查了所有平面单元上的高分辨率图像（图 1C）中的暗沙层（参见补充材料中的方法）。该检查产生了 31 个暗斜坡以上具有亚米厚度的暗地层示例，具有重力砂沉积特征（图 4A-4C；补充数据集 2；见补充方法）。与区域混合镁铁质特征相比，这种露头的富含橄榄石的矿物学（图 4D）反对在火山碎屑流期间从火星表面夹带橄榄石砂粒。天然橄榄石作为沙粒大小的斑晶存在于陆地玄武质火成岩中（Clemens 等人，2011；Martí 等人，2017）也支持推断富含橄榄石的沙子原产于 Zephyria Planum 基岩。从地层未检测到，例如沿着 Zephyria Planum 上富含沙子的单元接触（图 S1C），风成磨损可能释放出在露头内分布更均匀的沙子，如陆地 Campo Piedra Pomez ignimbrite 中的岩石和晶体所记录的那样（de Silva et等人，2013）。这个位置的沙子的其他可能解释是它从地形较高的平面单元向西南迁移，与模拟的潜在沙子迁移的次生向北分量一致，或形成为滞后沉积物，与分散的 1 公里尺度暗平面上的砂沉积物（图S1C）。这三种可能性中的任何一种都意味着沙子来自 Zephyria Planum 基岩。沙子分布在 Zephyria Planum 基岩中的建议和离散沙地层的识别都表明浅色 MFF 如何成为深色沙子的来源。巨大的 MFF，其最西端映射到 Zephyria Planum 基岩（图 1）。 1C），根据侵蚀形态、下伏地形、密度、成分信息和多个雷达数据集（Brož 等人，2021 年）被解释为火山碎屑沉积物。鉴于火星上火山碎屑沉积物的分布（Kerber 等，2012；Tanaka 等，2014），Zephyria Planum 砂的火山碎屑源的发现为火星砂从当地来源的广泛分布提供了机制. 具有沙粒大小的爆炸性沉积物在火星上很普遍（Wilson 和 Head，1994；Kerber 等，2012；Brož 等，2021）。尽管细沙会落在非常靠近通风口的地方（Kerber 等人，2012 年），但在中等风速（Sullivan 和 Kok，2017 年；Andreotti 等人，2021 年）下，盐沙运输的潜力允许进一步分布。火山碎屑沉积物已在全球范围内进行推断（Tanaka 等人，2014 年），在区域上进行了识别（Mandon 等人，2020 年及其参考文献），并进行了原位检测（McCoy 等人，2008 年）。陆相玄武质火成岩中镁铁质矿物的多样性（Clemens 等人，2011；Martí 等人，2017）为火星沙丘区混合镁铁质成分的形成提供了火山碎屑途径（Tirsch 等人，2011）。从火山碎屑沉积物中释放沙子的机制，被检测到在当今火星上的亚马逊气候中运行，也可能在火星历史的大部分时间里运行。撞击和火山过程产生的颗粒物质减少（Grotzinger 和 Milliken，2012 年）意味着今天火星上的沙子主要是可回收的（例如，Edgett 等人，2020 年）。然而，在过去约 3.0 的低密度大气条件下（Kok 等人，2012 年），由于颗粒撞击速度很高，在整个那个时代，火山碎屑基岩的风成磨损可能会产生大量的沙子。陆地中的橄榄石斑晶玄武质火成岩被模拟为在浅层岩浆房的低压（<180 MPa）期间形成（Clemens et al., 2011）。与这种低压橄榄石地层一致，火星岩浆被模拟为近地表部分熔融的结果（Schumacher 和 Breuer，2007 年）。光谱上以橄榄石为主的烃源岩限制在火星上的早期 Noachian 和早期 Hesperian 表明，Noachian 中晚期地幔冷却使橄榄石结晶最小化（Ody 等，2013）。MFF 的就位时间延长，早期的 Hesperian 时代沉积物向东年轻化（Tanaka et al., 2014）。来自其他 MFF 成员（图 1A）或更广泛地来自其他爆炸性沉积物（Brož 等人，2021 年）的沙子，通过提供年龄递减的主要火山成因矿物学，能够测试火星上的岩浆演化。成分随着时间的推移而演变，在地球上具有广泛的用途，但在火星上的应用却不确定（Diniega 等人，2021 年）。橄榄石被认为是成熟火山砂的特征，基于冰岛沙层 (Mangold et al., 2011) 和 Gusev 火山口的“El Dorado”波纹场 (Sullivan et al., 2008) 的现场数据。这项工作的结果表明，橄榄石还可以表征高度不成熟（本地到区域来源）的沉积物。这项工作的发现可以在其他全球分布的火山碎屑沉积物中进行检验（Tanaka 等人，2014 年；Mandon 等人，2020 年和参考文献）其中；Brož 等人，2021）。附近盖尔陨石坑中富含橄榄石的风成砂可能不是来自贫橄榄石的 Stimson 风成砂岩（Rampe 等，2018）。Aeolis Mons 上的沙子很可能来自上丘，可能是 MFF 异常值（Thomson 等，2011）。这项工作是在 Tsalagi 传统领土上的田纳西大学（美国田纳西州诺克斯维尔）发起的。切诺基），Tsoyaha（Yuchi，Muscogee Creek）和其他土著民族。这项工作是在北亚利桑那大学（亚利桑那州弗拉格斯塔夫）完成的，该大学坐落在对 Hohokam Diné、霍皮人、西阿帕奇人和其他原住民来说是神圣的家园。我们在他们祖先的土地上向这些部落的过去、现在和未来的世代致敬。这项工作得到了 NASA 通过火星数据分析计划拨款 NNX16AL47G 的支持，并通过 Briony Horgan 和 Jim Zimbelman 的有益评论改进了其演示文稿。