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1.
Abstract— The discovery of 34 new stony meteorites is reported from those areas of the Nullarbor Region, Western Australia named after Mundrabilla, Forrest, Reid and Deakin sidings on the Trans Australian Railway line. The recoveries include 15 H-, and 15 L-group equilibrated (types 4–6) ordinary chondrites, two distinct H3 chondrites (Mundrabilla 003 and Forrest 003), a genomict H-group chondrite breccia (Reid 011) comprising types 3–6, and one structurally anomalous chondrite (Deakin 001). Seventy-eight distinct meteorites are now known from the region.  相似文献   

2.
Abstract— To date, 24 possibly distinct meteorites have been reported from the Nullarbor Region in South Australia and many more recoveries remain to be described. Following Bevan and Binns (1989), the system of nomenclature for meteorites from the Western Australian Nullarbor has been extended into the South Australian Nullarbor. For the purposes of nomenclature, the South Australian Nullarbor has been divided into 27 named “areas.” Henceforth, distinct meteorites will take the name of the area in which they were found and a number (e.g., 001). The names of previously documented meteorites from the region remain unchanged.  相似文献   

3.
Abstract— This Meteoritical Bulletin is again dominated by meteorite finds from hot and cold deserts: 99 from the Nullarbor, 12 from the Sahara, and 35 from Antarctica. Besides 161 ordinary chondrites, it lists 5 irons (Cotton, Hidden Valley, Miles, Tagounite, Tres Castillos), 2 ureilites (FRO90168, Hughes 009), 1 howardite (ALH 88135), 1 CV3 (Axtell), 1 CK4 (Sleeper Camp 006), and 2 enstatite chondrites (ALH 88070, Forrest 033). Three of the meteorites are falls.  相似文献   

4.
Abstract— Over 4450 meteorite specimens with a total mass of 168 760 g have been found in the Gold Basin (L4) strewn field over an area of 225 km2. The meteorite is a breccia, composed only of fragments of L‐chondrite materials. The parent meteoroid had a kinetic energy equivalent to ～5 to 50 ktons when it hit the top of the atmosphere. Cosmogenic nuclide studies indicate the meteorite has a terrestrial age of 15 000 ± 600 years, corresponding to the Late Pinedale portion of the Wisconsin Glaciation. Conditions in the Gold Basin, which is now part of the Mojave Desert, were wetter and cooler at the time of the fall. Mössbauer analyses indicate the sample is 30 to 35% oxidized. This is less than that in meteorites with similar ages found in eastern New Mexico, but comparable to that found in meteorites from the Sahara and the Nullarbor Region. Oxidation is likely to have occurred soon after the fall, when exposure to precipitation was at its maximum. Four other new meteorites were also found in the Gold Basin strewn field.  相似文献   

5.
Two new large iron meteorites, weighing 840 kg and 800 kg respectively, have been recovered from the Nullarbor Plain in the vicinity of the original Mundrabilla meteorite site, and are now at the Western Australian Museum in Perth. Numerous small knucklebone-shaped irons were also found at Tookana Rock Hole in the vicinity of Eucla. X-ray fluorescence spectrometry of these meteorites confirms that the additional finds are members of the Mundrabilla meteorite shower.  相似文献   

6.
Abstract— We classified ten new ordinary chondrites found in 1993 in the Nullarbor Region of Western Australia, seven of which were found in the Reid area (Reid 018–024) and three in the Hughes area (Hughes 027–029). Six of these are H and four are L chondrites, with petrologic types ranging from 4 to 6 and shock classifications from S2 to S4. All of the samples are small and, in most cases, heavily weathered, making pairing difficult.  相似文献   

7.
In the five years from June, 1967, to June, 1972, a total of 99 meteorites were found in Roosevelt County, New Mexico and in adjoining Curry County. Of this number, 74 were found by one man. The finds include two achondrites, one pallasite, one carbonaceous chondrite, and 95 chondrites. They appear to represent more than 50 separate meteorite falls. The finding of a large number of meteorites in a small area provides data for an estimate of the probable quantity and average size of the meteorite specimens reaching the earth. The problems involved in allocating a total of 17 available local place names among more than 50 meteorite falls are discussed.  相似文献   

8.
To improve the labelling value of meteoritic names, new meteorites should be assigned geographical names which are not used for other meteorites, which are simple, and, if possible, of mnemonic value. A Committee on Meteoritic Nomenclature should be established to supervise the assignment of new meteorite names, and to assist in the work necessary to confirm that new meteorite finds are not paired with meteorites which were previously cataloged.  相似文献   

9.
Abstract– In this edition of The Meteoritical Bulletin, a total of 506 newly approved meteorite names with their relevant data are reported. These include 354 from northwest Africa, 31 from the Americas, 15 from Antarctica (Koreamet), 85 from Asia, 20 from Australia, and 1 from Europe. Among these meteorites are 2 falls, Grimsby (Canada) and Santa Lucia (2008) (Argentina). Also described are a CM with low degree of alteration, new ungrouped chondrites and achondrites, and 4 Martian meteorites.  相似文献   

10.
Abstract— Studies of 52 specimens recovered from the find site of the original Travis County meteorite reveal the presence of two distinct meteorites. Travis County (a), which includes the original Travis County meteorite, is the more abundant meteorite and is classified as an H5(S4) shock-blackened chondrite. Travis County (b) is classified as an H4(S2) chondrite with rare chondritic clasts of H group parentage, indicating that the meteorite is a breccia.  相似文献   

11.
One of the most productive and well‐sampled dense collection areas for meteorites on Earth is the “Franconia strewn field” in Mohave County, Arizona, which since 2002 has yielded hundreds of meteorites in an ellipsoidal area approximately 5 × 16 km across. Based on petrographic, mineral‐chemical, and terrestrial age data, we conclude that among 14 meteorites examined, there are at least 6 and possibly 8 distinct meteorites represented, which fell over a period of approximately 0–20 kyr ago. These include equilibrated H‐chondrites such as Franconia (H5) and Buck Mountains (BM) 001 (H6); H3–6 breccias such as Buck Mountains Wash and BM 004; and L6 chondrites such as BM 002 and BM 003 (which may be paired), Palo Verde Mine, and BM 005. To confidently pair such meteorites often requires thorough petrographic examination, mineral‐chemical analyses, and terrestrial ages. We estimate that 50 ± 10% of the larger specimens in this area are paired, yielding a relatively high value of approximately 2.3–2.9 distinct meteorites km?2. The meteorite flux estimated for Franconia area is higher than the flux inferred from contemporary fireball data for larger masses. We suggest that one large H3–6 meteoroid fell in the area, most likely that of Buck Mountains Wash approximately 4 kyr ago, which produced an elliptical strewn field with masses generally increasing toward one end, and which raised the meteorite productivity in the recovery area.  相似文献   

12.
Abstract– We report the use of Doppler weather radar as a tool for locating meteorites, both at the time of a fall and from archived radar data. This asset is especially useful for meteorite recovery as it can provide information on the whereabouts of falling meteorites in “dark flight” portion of their descent where information on their flight paths cannot be discerned from more traditional meteorite location techniques such as eyewitness accounts. Weather radar data can provide information from detection in three distinct regimes: (A) direct detection of the rapidly moving, optically bright fireball by distant radars, (B) detection of falling debris to include hand‐sample sized rocks, and (C) detection of dust produced by detonation events that can occur tens of minutes and many kilometers laterally removed from the actual fireball locality. We present examples of each, as well as comparisons against man‐made debris from a re‐entering Soyuz rocket and the Stardust Sample Return Capsule. The use of Doppler weather radar as a supplement to traditional meteorite recovery methods holds the promise of improving both the speed and total number of meteorite recoveries, thereby increasing the number of freshly fallen meteorites for scientific study.  相似文献   

13.
We describe the geological, geomorphological, and paleoclimatic setting of the Sahara of North Africa in particular, focused on the main meteorite dense collection areas (DCA; Morocco, Algeria, Tunisia, and Libya). We report on the outcome of several meteorite recovery field expeditions in Morocco and Tunisia since 2008, by car and by foot, that applied systematic search methods. The number of meteorites collected is 41 ordinary chondrites and one brachinite. The statistics of unpaired ordinary chondrites indicates that H chondrites are more abundant (21) than L chondrites (12), while LL chondrites are rare (2). Our meteorite density estimates for Tunisia and Morocco are in the order of magnitude of 1 met km?2. An estimate of the total maximum number of meteorites that could be recovered from the Sahara is 780,000 meteorites. We selected 23 meteorites from Aridal, Bou Kra, Bir Zar, and Tieret DCAs for 14C dating. The results show a wide range of terrestrial ages from 0.4 to more than 40 kyr with a majority of meteorites showing ages between 0.4 and 20 kyr. The weathering degree of these meteorites is ranges from minor (W1) to strong (W4). The highest weathering grades result from repeated oscillations between high and low humidity in the Sahara. However, there appears to be no correlation between weathering grade and terrestrial age of meteorites.  相似文献   

14.
Abstract— A catalog of Chinese meteorites is presented. The catalog updates Bian Depei's 1981 catalog and is complete through 1990 October. It includes data for 54 stone meteorites, 30 iron meteorites and a stony-iron meteorite. Many of the meteorites were previously unknown in the West.  相似文献   

15.
Abstract— A new meteorite find from the Nullarbor Plain in Australia was studied using optical, SEM, and electron microprobe techniques. The meteorite, Nullarbor 018, is an orthodox L6 chondrite that experienced minor-to-moderate alteration of metal during terrestrial weathering (grade A–B to B). During weathering, troilite was preferentially altered, and roughly 20% of the original complement of S in the meteorite was removed. Shock metamorphic effects corresponding to shock stage S4 (or shock facies d) are found, including the presence of some diaplectic feldspar (maskelynite). The meteorite is not obviously paired with other finds from the Nullarbor region, but the possibility that it is paired cannot be excluded.  相似文献   

16.
The subgroups within the basaltic achondrite suite are defined using the structural criterion of Wahl (1952). The ‘monomict’ meteorites are samples of a single lithology while the polymict meteorites are those containing two or more lithologies. The ‘monomict’ subgroups eucrites, cumulate eucrites and diogenites are subdivided into both brecciated and unbrecciated meteorites. The polymict achondrites sample a petrological-compositional continuum that contains both mafic and ultramafic rock types and may be subdivided into several groups. Two groups of polymict basaltic achondrites, the polymict eucrites and howardites are separated using an arbitrarily defined criterion. The recommended criterion is based on the amount of magnesian ortho-pyroxenite (diogenite) component in the meteorite. Howardites contain more than 10% and polymict eucrites contain less than 10%. The criteria proposed (perhaps with minor variations), appear to reconcile the ambiguities caused by the polymict eucrites. These meteorites, using earlier structural criteria, are howardites, but using mineralogical-chemical criteria are eucrites. As a subgroup of the polymict achondrites, their relationship with the howardites is clear, and the preservation of the term ‘eucrite’ in their name highlights their modal affinity to the monomict eucrites.  相似文献   

17.
Abstract— The Meteoritical Bulletin, Number 74, contains listings for 190 meteorites, including 112 from North Africa, 63 from Antarctica and eight from Australia and six from the U.S. Among the meteorites described are 15 type 3 ordinary chondrites, most notably Roosevelt County 075 which is the lowest petrologic type H chondrite known to date, two very similar ureilites (Nova 1 and Nullarbor 010), a howardite (Old Homestead 001), a CK3 chondrite (Camel Donga 003), a CV3 chondrite (Denman 002) and a major new CR chondrite (Acfer 311 and 10 meteorites with which it is paired).  相似文献   

18.
This report presents bulk composition data for 10 lunar meteorite stones from Oman for which the names have been approved since June, 2012. On the basis of composition and reported find location, four new meteorites are represented among this group of stones. Data from neutron activation analysis of 371 subsamples of all lunar meteorites from Oman and Saudi Arabia analyzed in this laboratory are presented.  相似文献   

19.
Abstract— We determined terrestrial ages of ordinary chondrites from the Lewis Cliff stranding area, East Antarctica, on the basis of the concentrations of cosmogenic 10Be (t½; = 1.51 Ma), 26Al (t½; = 0.705 Ma), and 36Cl (t½; = 0.301 Ma). After an initial 26Al γ-ray survey of 91 meteorites suggested that many have terrestrial ages >0.1 Ma, we selected 62 meteorites for 10Be and 26Al measurements by accelerator mass spectrometry (AMS) and measured 36Cl in twelve of those. Low terrestrial ages (<0.1 Ma) were found for ～60% of the meteorites, whereas all others have ages between 0.1 and 0.5 Ma, except for one exceptional age of >2 Ma (Welten et al., 1997). Our major conclusions are: (1) The Lewis Cliff H-chondrites show similar ages to those from the Allan Hills icefields, but the L-chondrites are about a factor of 2 younger than those from Allan Hills, which indicates that Lewis Cliff is a younger stranding area. (2) The terrestrial age distributions at different parts of the Lewis Cliff stranding area generally agree with simple meteorite concentration models, although differences in weathering rate may also play a role. (3) We confirm that meteorites with natural thermoluminescence (TL) levels >80 krad are associated with low terrestrial ages (Benoit et al., 1992) but conclude that natural TL levels <80 krad can not be used to calculate the terrestrial age of a meteorite. Natural TL levels do seem useful to estimate relative terrestrial ages of large groups of meteorites and to determine differences in the surface exposure age of paired meteorite fragments. (4) Of the 62 meteorites measured with AMS, 31 were assigned to 11 different pairing groups, mainly on the basis of their cosmogenic nuclide record. The meteorites are estimated to represent between 42 and 52 distinct falls.  相似文献   

20.
Abstract— The Meteoritical Bulletin No. 96 contains a total of 1590 newly approved meteorite names with their relevant data. These include 12 from specific locations within Africa, 76 from northwest Africa, 9 from the Americas, 13 from Asia, 1 from Australia, 2 from Europe, 950 from Antarctica recovered by the Chinese Antarctic Research Expedition (CHINARE), and 527 from the American Antarctic program (ANSMET). Among these meteorites are 4 falls, Almahata Sitta (Sudan), Sulagiri (India), Ash Creek (United States), and Maribo (Denmark). Almahata Sitta is an anomalous ureilite and is debris from asteroid 2008 TC3 and Maribo is a CM2 chondrite. Other highlights include a lunar meteorite, a CM1 chondrite, and an anomalous IVA iron.  相似文献   

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