Hypervelocity collisions into continental crust composed of sediments and an underlying crystalline basement: comparing the Ries (∼24 km) and Chicxulub (∼180 km) impact craters

The Chicxulub and Ries impact craters were excavated from layered continental terrains that were composed of carbonate-bearing sedimentary sequences and underlying crystalline silicate basement materials. The Chicxulub and Ries impact events were sufficiently large to produce complex peak-ring impact craters. The walls of transient craters and excavation cavities, with diameters of 12-16 km for the Ries and 90-100 km for Chicxulub, collapsed to form final crater diameters of ∼24 and ∼180 km, respectively. Debris from both the sedimentary and crystalline layers was ejected during crater formation, but the bulk of the melting occurred at depth, in the silicate basement. The volume of melt and proportion of melt among shock-metamorphosed debris was far larger at Chicxulub, producing a central melt sheet ∼3 km in depth. The central melt sheet was covered with melt-bearing polymict breccias and, at the Ries, similar breccias (crater suevites) filled the central cavity. Also at the Ries (and presumably at Chicxulub), large hill-size megablocks of crystalline basement material were deposited near the transient crater rim. Blocks and megablocks of sedimentary lithologies were ejected into the modification zone between the peak ring and final crater rim, while additional material was slumping inward during crater growth, and buried beneath a fallout deposit of melt-bearing polymict breccias. The melt and surviving clasts in the breccias are dominantly derived from the deeper, basement lithologies. At greater distances, however, the ejecta is dominated by near-surface sedimentary lithologies, large blocks of which landed with such high energy that they scoured and eroded the pre-existing surface. The excavation and ejecta pattern produced lithological and chemical variations with radial distance from the crater centers that evolve from basement components near the crater centers to sedimentary components far from the crater centers. In addition, carbonate (and anhydrite in the case of Chicxulub) was vaporized, producing environmentally active gases. The vaporized volume produced by the Ries impact event was too small to dramatically alter the evolution of life, but the vaporized volume produced by the Chicxulub impact event is probably a key factor in the Cretaceous-Tertiary boundary mass extinction event.     

Buried impact basins,the evolution of planetary surfaces and the Chicxulub multi‐ring crater

Impact craters are distinctive landforms on Moon, Mars, Venus and other bodies of the Solar System. In contrast, the Earth has few craters, due to the dynamic nature of the planet, where craters and other geological structures are destroyed, modified or covered. Planetary missions have also shown that in other worlds where craters are numerous and well preserved, the crater record has been modified, through the identification of buried structures. Studies of the concealed crater record have major implications for the crater‐size frequency distribution and crater‐counting chronologies. On Earth, Chicxulub is an example of a large multi‐ring buried basin. Its study provides clues for the investigation other planetary surfaces. In addition, geophysical surveys have unravelled its deep 3‐D structure, providing data and constraints for new planetary missions.     

Stratigraphy at Ground Zero: A Contemporary Evaluation of Well Data in the Chicxulub Impact Basin

Evidence of “Upper Cretaceous” sediments above the melt rock/breccia assemblage at Chicxulub has been used to dispute the link between this large impact crater and the Cretaceous-Tertiary (KT) extinction horizon. We have evaluated core samples and well logs from the Petróleos Mexicanos (Pemex) Yucatan No. 6 exploratory well located ～50 km from ground zero. Despite previous reports to the contrary, the sequence of crystalline rocks and breccias located at depths exceeding 1000 m below sea level are characteristic of the upper lithological sequence observed at other large impact basins such as the 220 km Sudbury structure. Furthermore, the “Upper Cretaceous” sediments overlying the melt rocks and impact brecias at Chicxulub contain abundant glass shards and shocked minerals, demonstrating conclusively that these are reworked debris involved in the impact event, and not normal marine sediments. Core samples straddling the KT boundary indicate that the impact event created a basin several hundred meters deep.     

The melt rocks of the Vredefort impact structure - Vredefort Granophyre and pseudotachylitic breccias: Implications for impact cratering and the evolution of the Witwatersrand Basin

The unique combination of its large size (250-300 km diameter), deep levels of erosion (>7 km), and widespread regional mining activity make the Vredefort impact structure in South Africa an exceptional laboratory for the study of impact-related deformation phenomena in the rocks beneath giant, complex impact craters. Two types of impact-generated melt rock occur in the Vredefort Structure: the Vredefort Granophyre - impact melt rock - and pseudotachylitic breccias. Along the margins of the structure, mining and exploration drilling in the Witwatersrand goldfields has revealed widespread fault-related pseudotachylitic breccias linked to the impact event. There, volumetrically limited melt breccia occurs in close association with cataclasite or mylonitic zones associated with bedding-parallel normal dip-slip faults that formed during inward slumping of the crater walls, and in rare subvertical faults oriented radially to the center of the structure. This association is consistent with formation of pseudotachylites by frictional melting. On the other hand, rocks in the Vredefort Dome - the central uplift of the impact structure - contain ubiquitous melt breccias that range in size from sub-millimeter pods and veinlets to dikes up to tens of meters wide and hundreds of meters long. Like fault-related pseudotachylites in the goldfields and elsewhere in the world, they display a close geochemical relationship to their wallrocks, indicating local derivation. However, although mm/cm- to, rarely, dm-scale offsets are commonly found along their margins, they do not appear to be associated with broader fault zones, are commonly considerably more voluminous than most known fault-related pseudotachylites, and show no consistent relationship between melt volumes and slip magnitude. Recent petrographic observations indicate that at least some of these melt breccias formed by shock melting, with or without frictional melting. Consequently, the non-genetic term “pseudotachylitic breccia” has been adopted for these Vredefort occurrences. These breccias formed during the impact in rocks at temperatures ranging from greenschist to granulite facies, and were subsequently annealed to varying degrees during cooling of the central uplift.In addition to the pseudotachylitic breccias, nine clast-laden impact melt dikes (Vredefort Granophyre), each up to several kilometers long, occur in vertical radial and tangential fractures in the Vredefort Dome. Unlike the pseudotachylitic breccias, they display a remarkably uniform bulk composition and clast populations that are largerly independent of their wallrocks, and they contain geochemical traces of the impactor. They represent intrusive offshoots of the homogenized impact melt body that originally lay within the crater. U-Pb single zircon and Ar-Ar dating indicates that the Vredefort Granophyre and pseudotachylitic breccias, and the Witwatersrand pseudotachylites all formed at 2020±5 Ma - the age of the impact event, making the breccias a convenient time marker in the evolution of the structurally complex Witwatersrand basin with its unique gold deposits.     

撞击过程和内太阳系撞击历史

在太阳系的形成和演化过程中,发生在天体物质间的撞击作用是最重要的地质过程之一.撞击构造是地外天体表面最常见的地貌单元,大部分天体的地貌演化主要受撞击作用控制.撞击过程产生的温度、压力和应变速率比岩石圈内的其他地质过程高多个数量级,形成广泛分布的撞击产物,如气化物、熔融物、冲击变质和变形等.虽然撞击过程转瞬即逝,撞击作用向天体注入能量并改变其内、外结构,对天体的圈层系统产生长远影响.持续撞击在天体表面累积了大量的撞击坑,撞击坑的空间分布反映了受外来撞击的历史.内太阳系在～3. 8 Ga前的撞击频率更高,但是大量撞击盆地是否灾变式的密集形成仍在持续争议;～3. 8 Ga以来的撞击频率趋于稳定,但是缺乏具有明确事件指代性的标定样品.在同一天体上,撞击坑的空间密度指示了相应地质单元的形成时间,因此撞击坑统计常被用于估算地外天体表面地质单元的相对年龄.基于月球软着陆探测任务返回的样品,前人已约束了不同直径的月球撞击坑的形成频率,进而建立了使用撞击坑统计估算月球表面地质单元的绝对模式年龄的方法.另外,内太阳系天体可能经历了相似的撞击历史,因此地-月系统的撞击频率已被缩放至其他类地行星.撞击坑统计是探索太阳系天体的撞击历史、遥估地外天体表面的相对和绝对年龄的主要方法,也是行星地质研究的基本工具.该方法的整体可靠性已得到大量实验的验证.同时,该方法在理论基础和技术细节上还存在大量的不确定性.修正该方法是完善太阳系撞击历史的重要研究内容,也是未来采样返回探测任务的重要科学目标.     

Lunar impact breccias: petrology,crater setting,and bombardment history of the Moon

Two general classes of lunar impact breccias have been recognised: fragmental breccias and melt breccias. Fragmental breccias are composed of clastic-rock debris in a finely comminuted grain-supported matrix of mineral and lithic fragments. Impact melt breccias have crystalline to glassy matrices that formed by cooling of a silicate melt. Most lunar impact breccias in our collection probably sample ejecta from large complex craters or multi-ring basins, although linking individual breccias to specific impact events has proven surprisingly difficult. A long-standing problem in lunar science has been distinguishing clast-poor impact melt breccias from igneous rocks produced by melting of the lunar interior. Concentrations and relative abundances of highly siderophile elements derived from the meteoritic impactor provide a useful discriminant, especially when combined with petrologic and geochemical evidence for mechanical mixing. Most lunar impact melt breccias have crystallisation ages of 4.0?–?3.8 Ga, corresponding to an episode of intensive crustal metamorphism recorded by whole-rock U?–?Pb isotopic compositions of lunar anorthosites. This may reflect a short-lived spike in the cratering rate, although other explanations are possible. The question of whether or not a cataclysmic bombardment struck the Earth and Moon at ca 3.9 Ga remains open and the subject of continuing investigations.     

The Sudbury Structure (Ontario,Canada): a tectonically deformed multi-ring impact basin

The occurrence of shock metamorphic features substantiates an impact origin for the 1.85 Ga old Sudbury Structure, but this has not been universally accepted. Recent improvements in knowledge of large-scale impact processes, combined with new petrographic, geochemical, geophysical (LITHOPROBE) and structural data, allow the Sudbury Structure to be interpreted as a multi-ring impact structure. The structure consists of the following lithologies: Sudbury Breccia —dike breccias occurring up to 80 km from the Sudbury Igneous Complex (SIC); Footwall rocks and Footwall Breccia — brecciated, shocked crater floor materials, in part thermally metamorphosed by the overlying SIC; Sublayer and Offset Dikes, Main Mass of the SIC and Basal Member of the Onaping Formation (OF) — geochemically heterogeneous coherent impact melt complex ranging from inclusion-rich basal unit through a dominantly inclusion-free to a capping inclusion-rich impact melt rock; Grey Member of OF — melt-rich impact breccia (suevite); Green Member of OF — thin layer of fall back ejecta; Black Member of OF — reworked and redeposited breccia material; Onwatin and Chelmsford Formations — post-impact sediments. Observational and analytical data support an integrated step-by-step impact model for the genesis of these units. Analysis of the present spatial distribution of various impact-related lithologies and shock metamorphic effects result in an estimated original rim-to-rim diameter of the final crater of 200 or even 280 km for the Sudbury Structure, prior to tectonic thrusting and deformation during the Penokean orogeny.     

Peering inside the peak ring of the Chicxulub Impact Crater—its nature and formation mechanism

The IODP‐ICDP Expedition 364 drilled into the Chicxulub crater, peering inside its well‐preserved peak ring. The borehole penetrated a sequence of post‐impact carbonates and a unit of suevites and clast‐poor impact melt rock at the top of the peak ring. Beneath this sequence, basement rocks cut by pre‐impact and impact dykes, with breccias and melt, were encountered at shallow depths. The basement rocks are fractured, shocked and uplifted, consistent with dynamic collapse, uplift and long‐distance transport of weakened material during collapse of the transient cavity and final crater formation.     

地月系统不同成因环形构造及其影像特征

环形构造是一种常见的地质现象,特别是在月球上分布更为普遍。本文论述了三种成因的环形构造,即:侵入岩成因的环形构造,火山成因的环形构造,以及小天体撞击形成的撞击坑。文中详细介绍了它们的成因与结构特征,指出侵入岩成因的环形构造主要由岩浆冷凝收缩形成,在遥感影像上主要表现为影像色调的不同;火山成因的环形构造为火山口,在遥感影像上具有环形结构;而小天体撞击形成的撞击坑形态复杂,如碗形坑、中心锥环形坑与多环撞击坑,撞击坑的坑沿外缓内陡,遥感影像上表现为环形或弧形构造,有些撞击坑具有辐射纹。     

Impact ejecta and carbonate sequence in the eastern sector of the Chicxulub crater

The Chicxulub 200 km diameter crater located in the Yucatan platform of the Gulf of Mexico formed 65 Myr ago and has since been covered by Tertiary post-impact carbonates. The sediment cover and absence of significant volcanic and tectonic activity in the carbonate platform have protected the crater from erosion and deformation, making Chicxulub the only large multi-ring crater in which ejecta is well preserved. Ejecta deposits have been studied by drilling/coring in the southern crater sector and at outcrops in Belize, Quintana Roo and Campeche; little information is available from other sectors. Here, we report on the drilling/coring of a section of 34 m of carbonate breccias at 250 m depth in the Valladolid area (120 km away from crater center), which are interpreted as Chicxulub proximal ejecta deposits. The Valladolid breccias correlate with the carbonate breccias cored in the Peto and Tekax boreholes to the south and at similar radial distance. This constitutes the first report of breccias in the eastern sector close to the crater rim. Thickness of the Valladolid breccias is less than that at the other sites, which may indicate erosion of the ejecta deposits before reestablishment of carbonate deposition. The region east of the crater rim appears different from regions to the south and west, characterized by high density and scattered distribution of sinkholes.     

U–Pb isotopic dating of titanite microstructures: potential implications for the chronology and identification of large impact structures

Identifying and dating large impact structures is challenging, as many of the traditional shock indicator phases can be modified by post-impact processes. Refractory accessory phases, such as zircon, while faithful recorders of shock wave passage, commonly respond with partial U–Pb age resetting during impact events. Titanite is an accessory phase with lower Pb closure temperature than many other robust chronometers, but its potential as indicator and chronometer of impact-related processes remains poorly constrained. In this study, we examined titanite grains from the Sudbury (Ontario, Canada) and Vredefort (South Africa) impact structures, combining quantitative microstructural and U–Pb dating techniques. Titanite grains from both craters host planar microstructures and microtwins that show a common twin–host disorientation relationship of 74° about <102>. In the Vredefort impact structure, the microtwins deformed internally and developed high- and low-angle grain boundaries that resulted in the growth of neoblastic crystallites. U–Pb isotopic dating of magmatic titanite grains with deformation microtwins from the Sudbury impact structure yielded a ²⁰⁷Pb/²⁰⁶Pb age of 1851?±?12 Ma that records either the shock heating or the crater modification stage of the impact event. The titanite grains from the Vredefort impact structure yielded primarily pre-impact ages recording the cooling of the ultra-high-temperature Ventersdorp event, but domains with microtwins or planar microstructures show evidence of U–Pb isotopic disturbance. Despite that the identified microtwins are not diagnostic of shock-metamorphic processes, our contribution demonstrates that titanite has great potential to inform studies of the terrestrial impact crater record.     

Crustal evolution of the early earth: The role of major impacts

Impact cratering was an important — even dominant — process affecting the crustal evolution of the small terrestrial planets. The fundamental highlands/maria dichotomy of the Moon's surface can be traced to a late heavy bombardment by basin-forming, asteroid-sized bodies which produced not only a topographic division in the lunar crust but also localized the later eruptions of mare basalts. Major impact basins with diameters in excess of 200 km are recognized throughout the inner solar system from Mars to Mercury. Similar craters must have formed on the Earth prior to 4 Ga ago, and the minimum number of such basin-forming impacts can be calculated by scaling from the observed (minimum) number preserved on the Moon. When allowance is made for differences in impact velocity, gravitational cross-section and the effects of gravity on crater diameter, it is found that at least 50% of a presumed global sialic crust would have been converted into impact basins by 4 Ga ago. Among the effects resulting from the impact of an asteroidal object on the early crust were: (a) establishment of a topographic dichotmy of 3–4 km (after isostatic adjustment), (b) pressure-release partial melting of the upper mantle and rapid flooding of the basin floor by basalt, and (c) enhancement of thermal gradients in the sub-basin lithosphere and upper asthenosphere. Comparative planetary data such as impact scaling can be used as important constraints on models of the early terrestrial crust. For example, the topography resulting from impact bombardment produced discrete oceans and dry land by 4 Ga ago, making unreasonable models of a globe-encircling ocean on the Earth after that time.     

The Kotuikan ring structure as possible evidence for a large impact event in the northern Siberian craton

Remote-sensing, cosmogeological, tectonic, geophysical, structural, compositional, isotopic, and geochronological criteria permit identifying the Kotuikan ring structure in the northern Siberian Platform as a Paleoproterozoic large astrobleme, close in age to the Vredefort and Sudbury impact structures. Also, indirect evidence for two more large impact structures was obtained here. This confirms widely hypothesized massive bombardment of the early Earth by asteroids and a possible effect of large impact events on the Earth's mantle dynamics and rotation regime, that is, the tectonic evolution of our planet, including plate tectonics.     

Kaveri crater – An impact structure in the Precambrian terrain of southern India

The region to the east of Palghat gap is of low elevation and nearly circular in shape. It forms a part of the Kaveri river basin. The predominantly gneissic terrain is surrounded by the charnockitic hill ranges, prominent among which are Nilgiris and Biligirirangan to the north; and Anaimalai and Kodaikanal to the south. The charnockite massifs have a steep slope facing the circular feature and a gentler slope in the opposite direction. Fractures/faults/shear zones are noticed in many parts. The Bouguer anomaly in the gneissic terrain is elliptical in shape and positive, relative to the surrounding elevated region. The magnetic contours are also elliptical and the magnetic basement is deeper by about one km compared to regions in the periphery. The shallow seismic velocity picture from Chennimalai to Palani indicates a graben structure. The velocity structure also depicts a 4–5 km Moho upwarp near Chennimalai. Junction between the gneissic and charnockitic terrain and even beyond, is marked by the presence of pseudotachylites and breccia. Field and petrographic studies indicate presence of suevite, Planar Deformation Features (PDF), Planar Fractures, diaplectic glass of quartz and plagioclase and spherical inclusion in suevite. These evidences taken together point to an extra-terrestrial impact which created a crater of approximately 120 km in diameter. Several lines of indirect evidences point to Neoproterozoic age for the impact. Kaveri Crater is the fourth largest crater on the surface of the Earth; other larger craters being Vredefort (160 km), Chicxulub (150 km) and Sudbury (130 km).     

陨石撞击构造作用的研究现状与前景

当陨石撞击地球表面时, 它所引起的瞬时(1秒至1微秒)动态高压(数十至数百个吉帕)和高温(大于1500℃), 必然导致陨石撞击坑(astroblems)的生成并使周围岩石发生变质作用, 这便是撞击变质作用(impact metamorphism)。目前关于撞击构造(impact tectonics)作用研究的主要进展涵盖如下四个方面:1.撞击坑的构造形貌及形成机制; 2.撞击变质作用及撞击变质岩; 3.撞击作用的数值模拟和实验研究; 4.撞击作用的经济地质意义。陨击作用研究不仅具有学术意义, 还具有实际的经济地质意义。南非的Vredefort-Witwatersrand是最老的撞击构造, 它以丰富的金铀矿床而闻名; 加拿大的肖德贝里(Sudbury)以同撞击作用期的大型铜镍矿床著称; 如今北美、中美不少地区正在探索与陨击期后构造有关的油气储集。此外, 许多陨击变质岩可以供作建筑材料。不少撞击坑已经辟为旅游胜地, 如德国的Nordlingen Ries撞击坑。我国撞击构造的研究已有不少进展。20世纪90年代初发现了海南白沙陨击坑, 此外内蒙古的多伦、江苏的太湖和辽宁的岫岩罗圈里等地也发现有陨击构造的证迹, 不过, 都尚待进一步的工作予以证实。全球撞击构造研究经验可以借鉴的是, 在长期构造稳定区较易于发现陨击坑; 不少撞击构造被隐伏在第四纪或更老的沉积物之下, 所以采用人造卫星发回资料解译地球表面的照片, 加上地球物理勘探, 可以有效地确定研究靶区, 在此基础上再加强岩石学、构造学研究予以确认。      

月表构造与深部构造的关系

地球和月球很可能是通过大撞击形成的。在行星地质学中,研究月球的地质-构造现象,对了解月球、地球乃至太阳系的形成与演化历史都有很大帮助。月球的构造分为深部构造与月表构造,寻找它们在分布或成因上的关系,可以为月球甚至地月系的起源和演化历史提供重要参考。利用LROC的宽视角影像数据以及LOLA数据提取解译月表构造,结合深大断裂进行观察分析,并对月球的撞击盆地进行统计,最后以静海地区为例分析构造分布特征,发现月球的质量瘤盆地中具有环状分布的月岭,外侧具有近环状分布的深大断裂,自前酒海纪至酒海纪,具备上述特征的质量瘤盆地占总撞击盆地的比例突然有一个很大的提升,且静海地区西部具有该构造分布特征。推测该特征与撞击、月海沉降等有关,且在酒海纪与雨海纪期间月球有较多的月海玄武岩分布,由此判断静海西部存在质量瘤,发生过撞击与月海沉降。     

Identification of the projectile at the Brent crater,and further considerations of projectile types at terrestrial craters

Impact melt samples from drill hole B1-59 at the 3.8 km diameter Brent crater (Ontario) have been analysed for siderophile trace elements indicative of meteoritic contamination. Samples from the basal melt zone at 823–857 m depth are enriched in Ir, Os, Pd, Ni, Co, Cr and Se over basement, with the abundance pattern suggesting a chondritic projectile for Brent. From a Ni-Cr correlation of 10 melt samples an L or LL chondrite is inferred. The contribution of an ultramafic country rock (alnoite) in the melt is too small to significantly influence its $\text{Ni}\text{Cr}$ ratio. Glass-rich breccias from the allochthonous breccias filling the crater also contain a meteoritic component. Interelement ratios (e.g. $\text{Ni}\text{Cr}$) are, however, fractionated relative to the melt zone samples. This, as well as the low Au content of all Brent samples, is probably a product of alteration.Additional data on impact melts from the 65 km diameter crater Manicouagan still did not reveal a meteoritic component, as also for the Mistastin crater (28 km diameter) where Cr analyses set an upper limit of 1% of an achondritic projectile component in the melt. Irghizites (tektite like glasses) from the Zhamanshin impact structure have been found to contain high Ni and Co concentrations, and our data show that Ir is also enriched. It is however not possible to define the projectile-type. Enrichment of an Ivory Coast tektite in Ir is confirmed. There are large differences in siderophile element concentrations among tektites, with otherwise similar chemical composition.There are now four known craters formed by chondrites (Clearwater East, Lapparjärvi, Wanapitei, and Brent), with Brent being the smallest of these. For smaller craters the projectiles appear to be limited to iron or stony-iron meteorites, because of atmospheric destruction of relatively small stony meteorites. It appears, however, that all major classes of meteorites are represented among the projectiles at terrestrial impact craters.     

Volatile enhanced dispersal of high velocity impact melts and the origin of tektites

In hypervelocity meteorite impacts, shock energies produce temperatures well above the melting point of a wide area of the impacted target rocks. This produces impact melt during excavation and expansion of the transient crater cavity. The vast majority of this melt is retained in the crater-fill stratigraphy where it may form coherent melt units and/or be variably mixed with non-molten target rocks. A small portion (1–3%) of this melt is ejected from the crater at very high velocities – potentially faster than the impactor itself – forming impact glasses and, in rare cases, tektites. Why only some impacts form large volumes of high velocity impact glass and even fewer form tektites remains poorly understood. Many of the expected theoretical controls on the production and dispersal of high-velocity impact melt (target rock type, impact size, impact angle) do not seem to apply; comparison of the volume and nature of ejected melt around complex and simple craters on Earth reveals no systematic relationship to any of these parameters. The geologic evidence suggests that there is another controlling mechanism that promotes production of high velocity impact melt and tektite formation in some impacts. The Darwin impact event shows clearly that the presence of water rich surface layers in the target stratigraphy enhances by orders of magnitude the production of high velocity ejected melt; as hinted at by some numerical models. For tektites from all four strewn fields, the presence of water rich surface layers at the impact site can be inferred and it seems this is the missing feature of the target stratigraphy required to explain tektite origin.     

Big returns on small samples: Lessons learned from the analysis of small lunar samples and implications for the future scientific exploration of the Moon

Samples returned from the surface of planetary bodies are both complementary to orbital and in situ observations and provide a unique perspective for understanding the nature and evolution of that body. This unique perspective is based on the scale the sample is viewed (mm-Å), the ability to manipulate the sample, the capability to analyze the sample at high precision and accuracy, and the ability to significantly modify experiments as logic and technology dictates over an extended period of time (decades). Unlike the Apollo missions, robotic sample return missions in the next decade will result in the return of relatively small sample mass. Such robotically returned samples are scientifically more valuable if they can be placed within a planetary context through orbital observations and if information concerning planetary-scale processes and conditions can be extracted from them. Conversely, samples give remotely sensed data ground truth. That is, they act as a “calibration standard” for these data allowing a much enhanced global view to be constructed.The Moon is an example that illustrates how information can be extracted from small samples and then extended to planetary and solar system scales. Three examples from the Moon illustrate this point. First, multi-analytical and experimental studies of minute (10-500 μm) glass beads representing near-primary magmas provide constraints on the composition and condition of the lunar mantle, the style of early planetary differentiation, the history and character of early mantle dynamics and melting, and the isolation of the lunar mantle from late-stages of lunar accretion. Second, trace element analysis of individual mineral grains via ion microprobe and isotopic analysis of small rock fragments representing some of the oldest and youngest periods of lunar magmatism illustrate their usefulness for both fingerprinting distinct episodes of lunar magmatism and reconstructing the evolution of lunar magmatism. Third, mechanisms for primitive planetary mantles degassing and volatile transport on airless bodies can be understood by the analysis of volatile coatings on glass and mineral fragments in the lunar regolith.As many of our insights about the Moon are based on samples that primarily were collected within a limited lunar terrain, our understanding of the Moon is somewhat biased. Future scientifically strategic sampling targets are young mare basalts (Roris basalt in Oceanus Procellarum), far-side mare basalts (Mare Moscoviense), large pyroclastic deposits and potential mantle xenoliths (Aristarchus plateau, Rima Bode) major unsampled crustal lithologies outside the Procellarum KREEP terrane (central peak in Tsiolkovsky crater, South-pole Aitken basin), basin and crater melt sheets (South-pole Aitken basin, Giordano Bruno) and H deposits in permanently shaded areas (South-pole Aitken basin). Sampling these locations would further our understanding of processes at work during the early evolution of the terrestrial planets, provide a comprehensive history of endogenous (e.g., primary volcanic degassing) and exogenous (e.g., solar wind, galactic cosmic rays, volatiles from comets) volatile reservoirs and volatile transport and would provide unique historical information about events and processes that affected the entire inner solar system, a record obscured on the Earth and Mars.