首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 62 毫秒
1.
The Beaver-Harrison, Utah chondrite (find July 24, 1979), a single, shock-veined stone of 925 grams, consists of major olivine (Fa25.0), low-Ca pyroxene (En77.3Fs21.1Wo1.6) and metallic nickel-iron; minor troilite and plagioclase (Ab82.6An11.1Or6.3), accessory high-Ca pyroxene (En47.0Fs8.5Wo44.5), chromite (Cm8.7Sp10.6Uv9.4Pc0.6Hc0.7), chlorapatite and whitlockite; and hydrous ferric oxide of terrestrial weathering origin. Mineral compositions indicate L-group classification, and homogeneity of minerals, highly recrystallized texture and presence of clear plagioclase suggest that the meteorite belongs to petrologic type 6.  相似文献   

2.
Abstract— The Loxton meteorite is a single stone of 22 g found in South Australia in 1968. It has been classified as an L5 chondrite, shock facies ‘a,’ and contains olivine (Fa24), orthopyroxene (Fs21–22), clinopyroxene (Wo44.7En45.9Fs9.4), nickel-iron, troilite, chromite and chlorapatite.  相似文献   

3.
Abstract— A stony meteorite fell near the Fuc Bin village, Vietnam, in July, 1971. Based on optical microscopy, scanning electron microscopy and electron probe microanalysis, the meteorite is classified as an L5 chondrite that contains olivine (Fa23.6), low-Ca pyroxene (Fs20.3 Wo1.3), high-Ca pyroxene (Fs7.5 Wo44.2), plagioclase (Ab83.8 Or5), chlorapatite, merrillite and opaque minerals: chromite, troilite, kamacite, taenite, tetrataenite and native copper.  相似文献   

4.
Abstract— The Yaringie Hill meteorite is a new H5 ordinary chondrite found in the Gawler Ranges, South Australia. The meteorite, which shows only minor signs of terrestrial weathering, is predominantly composed of olivine (Fa17.2), orthopyroxene (Fs15.1Wo1.1), and three distinct phases of nickeliferous iron metal (kamacite, taenite, tetrataenite). Other minerals include troilite, plagioclase (Ab81An16Or3), clinopyroxene (En52Wo42Fs6), chlorapatite, merrillite, ilmenite, and native copper. Three types of spinel with distinctive textures (coarse, skeletal aggregates, rounded aggregates) and with compositions close to the join MgAl2O4‐FeCr2O4 are also present. Chondrules within the Yaringie Hill meteorite, which often have poorly defined boundaries, are placed in a recrystallized matrix. Shock indicators suggest that the meteorite experienced only weak shock metamorphism (S3).  相似文献   

5.
The Loop meteorite was found in 1962 in Gaines County, Texas, at a location very close to that where the Ashmore chondrite was found in 1969. The two specimens were assumed to be fragments of the same meteorite. The Loop meteorite is a type L6 chondrite composed of olivine (Fo75.4Fa24.6), orthopyroxene (En77.6Wo1.5Fs20.9), clinopyroxene (En47.5Wo45.1Fs7.4), plagioclase (Ab84.3Or5.5An10.2), Fe-Ni metal, troilite, and chromite. Fe-Ni metal is represented by kamacite (5.8-6.4 wt % Ni, 0.88-1.00 wt % Co), taenite (30.0–52.9 wt % Ni, 0.16-0.34 wt % Co), and plessite (16.8–28.5 wt % Ni, 0.38-0.54 wt % Co). Native copper occurs as rare inclusions in Fe-Ni metal. Both chondrules and matrix have similar mineral compositions. The mineral chemistry of the Loop meteorite is quite different from that of the Ashmore, which was classified as an H5 chondrite by Bryan and Kullerud (1975). Therefore, the Ashmore and Loop meteorites are two different chondrites, even though they were recovered from the same geographic location.  相似文献   

6.
Northwest Africa (NWA) 1950 is a new member of the lherzolitic shergottite clan of the Martian meteorites recently found in the Atlas Mountains. The petrological, mineralogical, and geochemical data are very close to those of the other known lherzolitic shergottites. The meteorite has a cumulate gabbroic texture and its mineralogy consists of olivine (Fo66 to Fo75), low and high‐Ca pyroxenes (En78Fs19Wo2‐En60Fs26W14; En53Fs16Wo31‐En45Fs14Wo41), and plagioclase (An57Ab41Or1 to An40Ab57Or3; entirely converted into maskelynite during intense shock metamorphism). Accessory minerals include phosphates (merrillite), chromite and spinels, sulfides, and a glass rich in potassium. The oxygen isotopic values lie on the fractional line defined by the other SNC meteorites (Δ17O = 0.312 %o). The composition of NWA 1950 is very similar to the other lherzolitic shergottites and suggests an origin from the same magmatic system, or at least crystallization from a close parental melt. Cosmogenic ages indicate an ejection age similar to those of the other lherzolitic shergottites. The intensity of the shock is similar to that observed in other shergottites, as shown by the occurrence of small melt pockets containing glass interwoven with stishovite.  相似文献   

7.
Nepheline and sodalite have been found in association with glass in a barred olivine chondrule from the Allende C3V meteorite. The major minerals of the chondrule are olivine (Fo80–88), bronzite (En85Fs12Wo3), and chromite. Olivine bars are separated by glass of nearly pure plagioclase composition (An81–99). Olivine composition is more Fe-rich than predicted by olivine-liquid equilibria (Fo96). Conditions of non-equilibrium are implied from this and the presence of plagioclase glass and small amounts of subcalcic diopside (En75Fs12Wo13) in the chondrule. The properties of this chondrule are consistent with liquid condensation, but melting of an amoeboid olivine aggregate or similar object could also have generated the chondrule-forming liquid. Nepheline and sodalite appear to have crystallized from this liquid under non-equilibrium conditions.  相似文献   

8.
Abstract– Northwest Africa (NWA) 4797 is an ultramafic Martian meteorite composed of olivine (40.3 vol%), pigeonite (22.2%), augite (11.9%), plagioclase (9.1%), vesicles (1.6%), and a shock vein (10.3%). Minor phases include chromite (3.4%), merrillite (0.8%), and magmatic inclusions (0.4%). Olivine and pyroxene compositions range from Fo66–72,En58–74Fs19–28Wo6–15, and En46–60Fs14–22Wo34–40, respectively. The rock is texturally similar to “lherzolitic” shergottites. The oxygen fugacity was QFM?2.9 near the liquidus, increasing to QFM?1.7 as crystallization proceeded. Shock effects in olivine and pyroxene include strong mosaicism, grain boundary melting, local recrystallization, and pervasive fracturing. Shock heating has completely melted and vesiculated igneous plagioclase, which upon cooling has quench‐crystallized plagioclase microlites in glass. A mm‐size shock melt vein transects the rock, containing phosphoran olivine (Fo69–79), pyroxene (En44–51Fs14–18Wo30–42), and chromite in a groundmass of alkali‐rich glass containing iron sulfide spheres. Trace element analysis reveals that (1) REE in plagioclase and the shock melt vein mimics the whole rock pattern; and (2) the reconstructed NWA 4797 whole rock is slightly enriched in LREE relative to other intermediate ultramafic shergottites, attributable to local mobilization of melt by shock. The shock melt vein represents bulk melting of NWA 4797 injected during pressure release. Calculated oxygen fugacity for NWA 4797 indicates that oxygen fugacity is decoupled from incompatible element concentrations. This is attributed to subsolidus re‐equilibration. We propose an alternative nomenclature for “lherzolitic” shergottites that removes genetic connotations. NWA 4797 is classified as an ultramafic poikilitic shergottite with intermediate trace element characteristics.  相似文献   

9.
Abstract— Dar al Gani 476, the 13th martian meteorite, was recovered from the Sahara in 1998. It is a basaltic shergottitic rock composed of olivine megacrysts reaching 5 mm (24 vol%) set in a finegrained groundmass of pyroxene (59 vol%) and maskelynitized plagioclase (12 vol%) with minor amounts of accessory phases (spinel, merrillite, ilmenite). Dar al Gani 476 is similar to lithology A of Elephant Moraine A79001 (EETA79001) in petrography and mineralogy, but is distinct in several aspects. Low‐Ca pyroxenes in the Dar al Gani 476 groundmass are more magnesian (En76Fs21 Wo3～En58Fs30Wo12) than those in lithology A of EETA79001 (En73Fs22Wo5～En45Fs43Wo12), rather similar to pyroxenes in lherzolitic martian meteorites (En76Fs21 Wo3～En63Fs22Wo15). Dar al Gani 476 olivine is less magnesian and shows a narrower compositional range (Fo76‐58) than EETA79001 olivine (Fo81‐53), and is also similar to olivines in lherzolitic martian meteorites (Fo74‐65). The orthopyroxene‐olivine‐chromite xenolith typical in the lithology A of EETA79001 is absent in Dar al Gani 476. It seems that Dar al Gani 476 crystallized from a slightly more primitive mafic magma than lithology A of EETA79001 and several phases (olivine, pyroxene, chromite, and ilmenite) in Dar al Gani 476 may have petrogenetic similarities to those of lherzolitic martian meteorites. Olivine megacrysts in Dar al Gani 476 are in disequilibrium with the bulk composition. The presence of fractured olivine grains in which the most Mg‐rich parts are in contact with the groundmass suggests that little diffusive modification of original olivine compositions occurred during cooling. This observation enabled us to estimate the cooling rates of Dar al Gani 476 and EETA79001 olivines, giving similar cooling rates of 0.03‐3 °C/h for Dar al Gani 476 and 0.05‐5 °C/h for EETA79001. This suggests that they were cooled near the surface (burial depth shallower than about 3 m at most), probably in lava flows during crystallization of groundmass. As is proposed for lithology A of EETA79001, it may be possible to consider that Dar al Gani 476 has an impact melt origin, a mixture of martian lherzolite and other martian rock (Queen Alexandra Range 94201, nakhlites?).  相似文献   

10.
Abstract Melnikovo is a relatively unweathered 545.6-g LL6 chondrite that was found in 1983. Only a few poorly defined chondrules are discernable in the examined sections; two of these are enriched in chromite. The meteorite contains olivine (Fa27,8), low-Ca pyroxene (Fs24,4), plagioclase, rare clinopyroxene, chlorapatite, merrillite and opaque minerals, which have a modal abundance (in wt%) of troilite (3.9%), kamacite (0.4%), taenite plus tetrataenite (0.7%), chromite (0.8%), and trace amounts of ilmenite and Mn-ilmenite. The meteorite appears unbrecciated on a centimeter scale.  相似文献   

11.
Abstract— The Wilder chondrite, a single stone of 1970 g, was found in southwestern Idaho in 1982. A classification of H5 is indicated by the mean compositions of olivines (Fa18.4) and orthopyroxenes (Fs16.3), and the narrow range in mineral compositions, recrystallized nature of the matrix, and mean Wo content of the orthopyroxenes (Wo1.34).  相似文献   

12.
The only two Nakhlite meteorites, Nakhla and Lafayette, are identical in mineral composition, consisting of augite (Wo39En38Fs23), olivine (Fo32–35), plagioclase (An27), K-feldspar (Or75Ab22An3), titaniferous magnetite with exsolved ilmenite, iddingsite (?), and minor amounts of fluor-chlorapatite, FeS, pyrite, chalcopyrite, and K-rich glass. The texture is suggestive of a cumulative origin.  相似文献   

13.
The iron‐bearing phases in a ureilite fragment (AS#051) from the Almahata Sitta meteorite are studied using Mössbauer spectroscopy, X‐ray diffraction (XRD), and electron microprobe analysis (EMPA). AS#051 has a typical ureilite texture of medium‐ to coarse‐grained silicates (olivine, orthopyroxene, and pigeonite) with minor opaques (Fe‐Ni metal, troilite, and graphite). The silicate compositions, determined by EMPA, are homogeneous: olivine (Fo90.2), orthopyroxene (En86.3Fs8.6Wo5.1), and pigeonite (En81.6Fs8.9Wo9.5), and are similar to those of magnesian ureilites. The modal abundance of mineral phases was determined by Rietveld refinement of the powder XRD data. The Mössbauer spectra at 295 K and 78 K are composed of two sharp well‐defined paramagnetic doublets superimposed on a well‐resolved magnetic sextet and other weak absorption features. The two paramagnetic doublets are assigned to olivine and pyroxene (orthopyroxene and pigeonite), and the ferromagnetic sextet to kamacite (magnetic hyperfine field ≈ 33.2 T), in agreement with the XRD characterization. The Mössbauer results also show the presence of small amounts of troilite (FeS) and cohenite ([Fe,Ni,Co]3C). Using the Mössbauer data, the relative abundance of each Fe‐bearing phase is determined and compared with the results obtained by XRD.  相似文献   

14.
Abstract— We report a previously undocumented set of high‐pressure minerals in shock‐induced melt veins of the Umbarger L6 chondrite. High‐pressure minerals were identified with transmission electron microscopy (TEM) using selected area electron diffraction and energy‐dispersive X‐ray spectroscopy. Ringwoodite (Fa30), akimotoite (En11Fs89), and augite (En42Wo33Fs25) were found in the silicate matrix of the melt vein, representing the crystallization from a silicate melt during the shock pulse. Ringwoodite (Fa27) and hollandite‐structured plagioclase were also found as polycrystalline aggregates in the melt vein, representing solid state transformation or melting with subsequent crystallization of entrained host rock fragments in the vein. In addition, Fe2SiO4‐spinel (Fa66‐Fa99) and stishovite crystallized from a FeO‐SiO2‐rich zone in the melt vein, which formed by shock melting of FeO‐SiO2‐rich material that had been altered and metasomatized before shock. Based on the pressure stabilities of the high‐pressure minerals, ringwoodite, akimotoite, and Ca‐clinopyroxene, the melt vein crystallized at approximately 18 GPa. The Fe2SiO4‐spinel + stishovite assemblage in the FeO‐SiO2‐rich melts is consistent with crystallization of the melt vein matrix at the pressure up to 18 GPa. The crystallization pressure of ?18 GPa is much lower than the 45–90 GPa pressure one would conclude from the S6 shock effects in melt veins (Stöffler et al. 1991) and somewhat less than the 25–30 GPa inferred from S5 shock effects (Schmitt 2000) found in the bulk rock.  相似文献   

15.
Abstract— The petrographic and chemical characteristics of a fresh Indian meteorite fall at Sabrum are described. Its mean mineral composition is defined by olivine (Fa31.4), orthopyroxene (Fs25.1,Wo2.0), clinopyroxene (Wo45En45.6Fs9.4) and plagioclase (An10.6Ab83.6Or5.8). The meteorite shows moderate shock features, which indicate that it belongs to the S4 category. Based on mineralogical and chemical criteria the meteorite is classified as an LL6 brecciated veined chondrite. Several cosmogenic radioisotopes (46Sc, 7Be, 54Mn, 22Na and 26Al), noble gas (He, Ne, Ar, Kr and Xe), nitrogen isotopes, and particle tracks density have been measured. Concentrations of cosmogenic 21Ne and 38Ar indicate that its cosmic‐ray exposure age is 24.8 Ma. Small amounts of trapped Kr and Xe, consistent with petrologic class 5/6, are present. The track density in olivines is found to be (1.3 ± 0.3) × 106/cm2. Activities of most of the short‐lived isotopes are lower than those expected from solar cycle variation. 22Na/26Al (1.12 ± 0.02) is found to be significantly anomalous, being ?25% lower than expected from the Climax neutron monitor data. These results indicate that the cosmic‐ray flux during the terminal segment of the meteoroid orbit was low. The activities of 26Al and 60Co and the track density indicate small meteoroid size with a radius ?15 cm.  相似文献   

16.
Abstract— We have performed petrologic and geochemical studies of Patuxent Range (PAT) 91501 and Lewis Cliff (LEW) 88663. PAT 91501, originally classified as an L7 chondrite, is rather a unique, near total impact melt from the L‐chondrite parent body. Lewis Cliff 88663 was originally classified as an “achondrite (?)”, but we find that it is a very weakly shocked L7 chondrite. PAT 91501 is an unshocked, homogeneous, igneous‐textured ultramafic rock composed of euhedral to subhedral olivine, low‐Ca pyroxene, augite and chrome‐rich spinels with interstitial albitic plagioclase and minor silica‐alumina‐alkali‐rich glass. Only ～10% relic chondritic material is present. Olivine grains are homogeneous (Fa25.2–26.8). Low‐Ca pyroxene (Wo1.9–7.2En71.9–78.2Fs19.9–20.9) and augite (Wo29.8–39.0En49.2–55.3Fs11.8–14.9) display a strong linear TiO2‐Al2O3 correlation resulting from igneous fractionation. Plagioclase is variable in composition; Or3.0–7.7Ab79.8–84.1An8.2–17.2.‐Chrome‐rich spinels are variable in composition and zoned from Cr‐rich cores to Ti‐Al‐rich rims. Some have evolved compositions with up to 7.9 wt% TiO2. PAT 91501 bulk silicate has an L‐chondrite lithophile element composition except for depletions in Zn and Br. Siderophile and chalcophile elements are highly depleted due to sequestration in centimeter‐size metal‐troilite nodules. The minerals in LEW 88663 are more uniform in composition than those in PAT 91501. Olivine grains have low CaO and Cr2O3 contents similar to those in L5–6 chondrites. Pyroxenes have high TiO2 contents with only a diffuse TiO2‐Al2O3 correlation. Low‐Ca pyroxenes are less calcic (Wo1.6–3.1En76.5–77.0Fs20.4–21.4), while augites (Wo39.5–45.6En46.8–51.1Fs7.6–9.4) and plagioclases (Or2.6–5.7Ab74.1–83.1An11.2–23.3) are more calcic. Spinels are homogeneous and compositionally similar to those in L6 chondrites. LEW 88663 has an L‐chondrite bulk composition for lithophile elements, and only slight depletions in siderophile and chalcophile elements that are plausibly due to weathering and/or sample heterogeneity.  相似文献   

17.
We performed a petrologic, geochemical, and oxygen isotopic study of the lowest FeO ordinary chondrite (OC), Yamato (Y) 982717. Y 982717 shows a chondritic texture composed of chondrules and chondrule fragments, and mineral fragments set in a finer grained, clastic matrix, similar to H4 chondrites. The composition of olivine (Fa11.17 ± 0.48 (1σ)) and low‐Ca pyroxene (Fs11.07 ± 0.98 (1σ)Wo0.90 ± 0.71(1σ)) is significantly more magnesian than those of typical H chondrites (Fa16.0‐20, Fs14.5‐18.0), as well as other known low‐FeO OCs (Fa12.8‐16.7; Fs13‐16). However, the bulk chemical composition of Y 982717, in particular lithophile and moderately volatile elements, is within the range of OCs. The bulk siderophile element composition (Ni, Co) is within the range of H chondrites and distinguishable from L chondrites. The O‐isotopic composition is also within the range of H chondrites. The lack of reduction textures indicates that the low olivine Fa content and low‐Ca pyroxene Fs content are characteristics of the precursor materials, rather than the result of reduction during thermal metamorphism. We suggest that the H chondrites are more compositionally diverse than has been previously recognized.  相似文献   

18.
Abstract– The Grove Mountains (GRV) 021663 meteorite was collected from the Grove Mountains region of Antarctica. The meteorite is composed primarily of olivine (Fa5.4), orthopyroxene (Fs4.7Wo3.0), chromian diopside (En53.6Fs2.4Wo44), troilite, kamacite, and plagioclase (Ab74.5Or4An21.5). Minor phases include schreibersite and K‐feldspar. The meteorite is highly weathered (W3) and weakly shocked (S2). We determine a whole rock oxygen isotopic composition of δ18O = 7.50‰, δ17O = 3.52‰. Comparisons of these data with other primitive achondrites have resulted in the reclassification of this meteorite as a member of the winonaite group. The occurrences of troilite, metal, and schreibersite in GRV 021663 indicate that these minerals were once completely molten. Euhedral inclusions of pyroxene within plagioclase further suggest that these may have crystallized from a silicate melt, while the depletion of plagioclase, metal, and troilite indicates that GRV 021663 could represent a residuum following partial melting on its parent asteroid. Trace element distributions in silicate minerals do not, however, confirm this scenario. As with other winonaite meteorites, the formation of GRV 021663 probably relates to brecciation and mixing of heterogeneous lithologies, followed by varying degrees of thermal metamorphism on the parent body asteroid. Peak metamorphic conditions may have resulted in localized partial melting of metal and silicate mineralogies, but our data are not conclusive.  相似文献   

19.
Abstract— In this paper we reconstruct the heterogeneous lithology of an unusual intrusive rock from the acapulcoite‐lodranite (AL) parent asteroid on the basis of the petrographic analysis of 5 small (<8.3 g) meteorite specimens from the Frontier Mountain ice field (Antarctica). Although these individual specimens may not be representative of the parent‐rock lithology due to their relatively large grain size, by putting together evidence from various thin sections and literature data we conclude that Frontier Mountain (FRO) 90011, FRO 93001, FRO 99030, and FRO 03001 are paired fragments of a medium‐ to coarse‐grained igneous rock which intrudes a lodranite and entrains xenoliths. The igneous matrix is composed of enstatite (Fs13.3 ± 0.4 Wo3.1 ± 0.2), Cr‐rich augite (Fs6.1 ± 0.7 Wo42.3 ± 0.9), and oligoclase (Ab80.5 ± 3.3 Or3.2 ± 0.6). The lodranitic xenoliths show a fine‐grained (average grain size 488 ± 201 μm) granoblastic texture and consist of olivine Fa9.5 ± 0.4 and Fe,Ni metal and minor amounts of enstatite Fs12.7 ± 0.4 Wo1.8 ± 0.1, troilite, chromite, schreibersite, and Ca‐phosphates. Crystals of the igneous matrix and lodranitic xenoliths are devoid of shock features down to the scanning electron microscope scale. From a petrogenetic point of view, the lack of shock evidence in the lodranitic xenoliths of all the studied samples favors the magmatic rather than the impact melting origin of this rock. FRO 95029 is an acapulcoite and represents a separate fall from the AL parent asteroid, i.e., it is not a different clast entrained by the FRO 90011, FRO 93001, FRO 99030, and FRO 03001 melt, as in genomict breccias common in the meteoritic record. The specimen‐to‐meteorite ratio for the AL meteorites so far found at Frontier Mountain is thus 2.5.  相似文献   

20.
Abstract— We describe the mineralogy, petrology, oxygen, and magnesium isotope compositions of three coarse‐grained, igneous, anorthite‐rich (type C) Ca‐Al‐rich inclusions (CAIs) (ABC, TS26, and 93) that are associated with ferromagnesian chondrule‐like silicate materials from the CV carbonaceous chondrite Allende. The CAIs consist of lath‐shaped anorthite (An99), Cr‐bearing Al‐Ti‐diopside (Al and Ti contents are highly variable), spinel, and highly åkermanitic and Na‐rich melilite (Åk63–74, 0.4–0.6 wt% Na2O). TS26 and 93 lack Wark‐Lovering rim layers; ABC is a CAI fragment missing the outermost part. The peripheral portions of TS26 and ABC are enriched in SiO2 and depleted in TiO2 and Al2O3 compared to their cores and contain relict ferromagnesian chondrule fragments composed of forsteritic olivine (Fa6–8) and low‐Ca pyroxene/pigeonite (Fs1Wo1–9). The relict grains are corroded by Al‐Ti‐diopside of the host CAIs and surrounded by haloes of augite (Fs0.5Wo30–42). The outer portion of CAI 93 enriched in spinel is overgrown by coarse‐grained pigeonite (Fs0.5–2Wo5–17), augite (Fs0.5Wo38–42), and anorthitic plagioclase (An84). Relict olivine and low‐Ca pyroxene/pigeonite in ABC and TS26, and the pigeonite‐augite rim around 93 are 16O‐poor (Δ17O ～ ?1‰ to ?8‰). Spinel and Al‐Ti‐diopside in cores of CAIs ABC, TS26, and 93 are 16O‐enriched (Δ17O down to ?20‰), whereas Al‐Ti‐diopside in the outer zones, as well as melilite and anorthite, are 16O‐depleted to various degrees (Δ17O = ?11‰ to 2‰). In contrast to typical Allende CAIs that have the canonical initial 26Al/27Al ratio of ～5 × 10?5 ABC, 93, and TS26 are 26Al‐poor with (26Al/27Al)0 ratios of (4.7 ± 1.4) × 10?6 (1.5 ± 1.8) × 10?6 <1.2 × 10?6 respectively. We conclude that ABC, TS26, and 93 experienced remelting with addition of ferromagnesian chondrule silicates and incomplete oxygen isotopic exchange in an 16O‐poor gaseous reservoir, probably in the chondrule‐forming region. This melting episode could have reset the 26Al‐26Mg systematics of the host CAIs, suggesting it occurred ～2 Myr after formation of most CAIs. These observations and the common presence of relict CAIs inside chondrules suggest that CAIs predated formation of chondrules.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号