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NWA 1463

Chondrite, ungrouped (type 5+)
previously Winonaite (primitive) or ‘W Chondrite’
standby for northwest africa 1463 photo
Purchased November 27, 2000
no coordinates recorded Three fragments having a combined weight of 1,001 g were found and subsequently sold in Erfoud, Morocco to Canadian collector D. Gregory. This meteorite was analyzed and classified through a collaboration with UCLA and Washington University in St. Louis, and it was determined to be a primitive winonaite. A 23 g specimen of NWA 1463 is curated by UCLA, while the 975 g type specimen is on deposit with the Royal Ontario Museum.

Although the mineral composition of NWA 1463 is typical for the primitive achondrite group designated winonaites, it has a more primitive, more chondritic texture than most other members of the group, equilavent to a petrologic type 5 chondrite (Benedix et al., 2003). In contrast to most other winonaites, NWA 1463 does not exhibit features related to igneous fractionation processes; such features had supported the original designation of winonaites as primitive achondrites. NWA 1463 contains abundant relict chondrules, which are found infrequently in only a few anomalous winonaite members (e.g., Pontlyfni, Mount Morris) embedded within a recrystallized groundmass. By contrast, most other winonaites have features consistent with extensive thermal metamorphism, e.g., a texture consisting of uniform-sized grains forming 120° triple junctions. standby for winonaite comparison photo
Textural comparison of four winonaites, L to R: NWA 1463 (with relict chondrule), Winona, Tierra Blanca, HaH 193
Image credit: Floss et al., MAPS, vol. 43, #4, p. 660 (2008)
‘Evolution of the winonaite parent body: Clues from silicate mineral trace element distributions’
(http://dx.doi.org/10.1111/j.1945-5100.2008.tb00676.x)
The O-isotope composition of NWA 1463 plots on an extension of the winonaite trend line. However, the high abundance of FeNi-metal and troilite, as well as the absence of metallic and sulfide veining, attests to a lower equilibration temperature than that of other winonaites. standby for o-isotopic diagram
Diagram credit: Bunch et al., 41st LPSC, #1281 (2010) Based on similar silicate textures, reduced mineral chemistry, and O-isotopes, it is presumed that the winonaites and the IAB complex irons originated on a common parent body. Because of its highly primitive nature, NWA 1463 might closely resemble the chondritic precursor material of the typical winonaites and silicate inclusions in IAB complex irons. In a similar way, it was determined by Hidaka et al. (2015) that FeNi-metal in the winonaite Y-8005 retains a near chondritic composition likely representative of the precursor material of the parent body. Utilizing a Ge/Ni vs. Au/Ni coupled diagram, they found that metal in this winonaite plots in the field of the sLL subgroup of the IAB complex irons. In view of these findings, Hidaka et al. (2015) suggest that the sLL subgroup rather than the main group of the IAB complex represents the primitive metal of the IAB–winonaite parent body, with the main group possibly representing a partial melt of the sLL subgroup. In a subsequent analysis of the IAB iron complex, Worsham et al. (2017) demonstrated that the Mo isotope data for the two winonaites they studied, Winona and HaH 193, also attest to a common parent body for winonaites and the MG/sLL irons.

The winonaite NWA 1463 does not fit into the scheme that has commonly been used to define the primitive achondrite group, and it could be instrumental in the future in redefining the metamorphic progression of chondrites to primitive achondrites. To that end, Irving et al. (2005) described this meteorite as possibly representing the regolith of the winonaite parent body. Furthermore, they argued that the occurrence of distinct chondrules precludes the use of the term achondrite to describe this meteorite, and suggest that the term metachondrite or ‘W chondrite’ would be more appropriate to describe this texturally-evolved meteorite pairing group (Irving et al., 2005; Irving and Rumble III, 69th MetSoc, #5288 [2006]).

Northwest Africa 1463 contains certain features that are unique compared to most other winonaites, and while it is plausible that this meteorite may represent the winonaite precursor material, it has been conjectured that it may instead have originated on a separate parent body (Floss et al., 2008). These unusual features include the lowest degree of metamorphism of all winonaites, an anomalous chromite composition, an anomalous O-isotopic composition, a lack of graphite, the presence of merrillite rather than apatite, and an abundance of incompatible trace elements intermediate to other winonaites. The variability in Ar–Ar ages obtained for some winonaites indicates they may have been excavated from different depths over an extended period of time (Scott et al., 2014). Furthermore, cooling rates standardized at ~500°C were determined for a number of winonaites and IAB irons, and the results demonstrate that a wide continuum exists:

  • Pontlyfni—1,000–10,000°C/m.y.
  • Winona—200°C/m.y.
  • NWA 1463—100°C/m.y.
  • Fortuna and QUE 94535—30°C/m.y.
  • IAB irons—10–25°C/m.y.

Based on the oxygen isotope data obtained by Hunt et al. (2012) for silicate inclusions in IAB irons, along with the observed volatile element depletions, it can be inferred that the winonaite precursor likely had a volatile-depleted carbonaceous chondrite-like composition. From results of their trace element analyses of a broad sampling of winonaites, Hunt et al. (2017) recognized that CM chondrites represent the closest match; however, the important differences that exist indicate that the precursor to winonaites is unlike any meteorite class currently known. In another study employing Mo and W isotope data (e.g., Kruijer et al., 2017) demonstrate that the IAB complex irons, and thus the genetically-related winonaites, accreted in the non-carbonaceous reservoir (see the Appendix, Part III for further details). Preliminary data based on Al–Mg chronometry show that NWA 725 was formed ~1.4 m.y. after CAIs. This age is consistent with Hf–W ages in the range of 1.5–5 m.y. that were calculated for more highly metamorphosed winonaites (Hidaka et al., 2014).

New analyses were conducted by Worsham et al. (2017) for IAB complex irons, along with two winonaites (Winona and HaH 193), a lodranite (GRA 95209), the primitive achondrite NWA 725, and other selected meteorite groups. Employing precise Mo, W, and Os isotope data along with HSE and other literature data, they ascertained that the IAB complex irons represent at least three distinct parent bodies and at least three impact-generated metal–silicate segregation events (see top schematic diagram below). Moreover, they ascertained that the Mo isotope data, as well as the chemical and mineralogical data, attest to a common parent body for the winonaites and the MG/sLL irons. Importantly, they demonstrated that the Mo isotope values of NWA 725 do not plot with the IAB MG/sLL/winonaites, and that the values are all higher than those of the lodranite in their study. Notably, the Mo isotope values of NWA 725 plot within the field of the magmatic sHL and sHH irons, which are not genetically related to the other IAB parent bodies (see bottom diagram below). Oxygen isotope data for the sHL and sHH irons could help resolve whether any potential genetic relationship exists with the NWA 725 pairing group. standby for iab iron formation diagram

CRE-corrected Mo Isotopic Compositions of Meteorite Groups
(µ notation denotes deviation from terrestrial standards in parts per million)
standby for chinga mo diagram
click on photo for a magnified view

Diagrams credit: Worsham et al., Earth and Planetary Science Letters, vol. 467, pp. 157–166 (2017)
‘Characterizing cosmochemical materials with genetic affinities to the Earth: Genetic and chronological diversity within the IAB iron meteorite complex’
(https://doi.org/10.1016/j.epsl.2017.02.044)
There is convincing evidence that NWA 1463 is paired with NWA 725, NWA 1052, NWA 1054, and NWA 1058 (Irving and Rumble III, 2006); a further pairing was found in 2007 and designated NWA 4835 (T. Bunch, NAU). Further details about this pairing group can be found on the NWA 725 page. Shown above are two views of a 0.12 g cut fragment of NWA 1463 which show its chondritic texture and relatively fresh fusion crust. This specimen was kindly provided by Dr. David Gregory.


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NWA 1058

Chondrite, ungrouped (type 5+)
previously Achondrite, ungrouped
originally Primitive Achondrite (MetBull 87)

standby for northwest africa 1058 photo
Purchased 2001
no coordinates recorded A 180 g stone was purchased in Erfoud, Morocco and subsequently sold to a meteorite dealer. The meteorite was submitted to the Institut für Planetologie in Münster and given the designation NWA 1058. Although initially considered to be an acapulcoite, NWA 1058 was classified in a broad terminology as a primitive achondrite by Russell et al. (2003) due to its anomalous O-isotopic composition. On an O-isotope plot it falls on the terrestrial fractionation line similar to the winonaites, but with O-isotopes that are more 16O-rich than most winonaites.

Further petrographic and compositional analyses have determined that NWA 1058 is very similar to the primitive acapulcoite GRA 98028 (Patzer et al., 2004), and that the anomalous O-isotopic composition might actually be due to terrestrial weathering effects (W2–3). A high abundance of relict chondrules are observed in NWA 1058, which is also a feature of some primitive acapulcoites. However, while most acapulcoites have similar CRE ages of ~6 m.y. (16.8 m.y. for TIL 99002), that calculated for NWA 1058 is significantly higher at 38.2 m.y. (Patzer et al., 2003). Nevertheless, the noble gas abundances of NWA 1058 remain high with 36Ar/132Xe ratios that are similar to the ‘Q’ component, characteristics which are more consistent with acapulcoites.

A study was undertaken by Eugster and Lorenzetti (2005) in which they determined a possible structure for the acapulcoite parent body. They specifically analyzed a number of new acapulcoites, as well as NWA 1058. They found that the data on the whole were more consistent with NWA 1058 being a winonaite rather than an acapulcoite: 1) NWA 1058 is more Mg-poor and Fe-rich than any acapulcoite; 2) its O-isotope composition plots outside the acapulcoite field; 3) its CRE age is much higher than any other acapulcoite (38.9 ±4.0 m.y.), with all except one acapulcoite having almost identical CRE ages of ~6 m.y.

Therefore, this meteorite appears to be neither a typical winonaite nor a typical acapulcoite. Utilizing a diagram that compares the Δ17O to the Fa content of olivine, Rumble III et al (2005) found that the winonaites and the acapulcoite–lodranite clan meteorites were readily resolved, and that NWA 1058 plots within the winonaite field. In addition, Moggi-Cecchi et al (2011) published a diagram (42nd LPSC, #1398 [2011]) that plots the Cr content of diopside vs. Mg# of olivine, and the acapulcoite–lodranite clan is clearly distinguished from the winonaite group.

standby for aca/lod/win diagram photo

Moggi-Cecchi et al (2011) also published a diagram showing the reduction state of the samples (Fe# in orthopyroxene vs. Mg# of olivine), and it distinguishes three separate clusters: the acapulcoites, lodranites, and winonaites. To that end, Irving et al. (2005) described NWA 1058 as a metamorphosed chondrite probably representing the regolith of the winonaite parent body. Furthermore, they argued that the occurrence of distinct chondrules precludes the use of the term achondrite to describe this meteorite, and suggest that the term metachondrite or ‘W chondrite’ would be a more appropriate term to describe this texturally-evolved meteorite pairing group (Irving et al., 2005; Irving and Rumble III, 69th MetSoc #5288 [2006]).

New analyses were conducted by Worsham et al. (2017) for IAB complex irons, along with two winonaites (Winona and HaH 193), a lodranite (GRA 95209), the primitive achondrite NWA 725 (considered a pairing to NWA 1058), and other selected meteorite groups. Employing precise Mo, W, and Os isotope data along with HSE and other literature data, they ascertained that the IAB complex irons represent at least three distinct parent bodies and at least three impact-generated metal–silicate segregation events (see top schematic diagram below). Moreover, they ascertained that the Mo isotope data, as well as the chemical and mineralogical data, attest to a common parent body for the winonaites and the MG/sLL irons. Importantly, they demonstrated that the Mo isotope values of NWA 725 do not plot with the IAB MG/sLL/winonaites, and that the values are all higher than those of the lodranite in their study. Notably, the Mo isotope values of NWA 725 plot within the field of the magmatic sHL and sHH irons, which are not genetically related to the other IAB parent bodies (see bottom diagram below). Oxygen isotope data for the sHL and sHH irons could help resolve whether any potential genetic relationship exists with the NWA 725 pairing group. standby for iab iron formation diagram

CRE-corrected Mo Isotopic Compositions of Meteorite Groups
(µ notation denotes deviation from terrestrial standards in parts per million)
standby for chinga mo diagram
click on photo for a magnified view

Diagrams credit: Worsham et al., Earth and Planetary Science Letters, vol. 467, pp. 157–166 (2017)
‘Characterizing cosmochemical materials with genetic affinities to the Earth: Genetic and chronological diversity within the IAB iron meteorite complex’
(https://doi.org/10.1016/j.epsl.2017.02.044)
There is convincing evidence that NWA 1058 is paired with NWA 725, NWA 1052, NWA 1054, and NWA 1463 (Irving and Rumble III, 2006); a further pairing was found in 2007 and designated NWA 4835 (T. Bunch, NAU). The partial slice of NWA 1058 shown above weighs 0.9 g.


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NWA 725

Chondrite, ungrouped (type 5+)
previously Winonaite (primitive) or ‘W Chondrite’
originally Acapulcoite (MetBull 85)

standby for northwest africa 725 photo
Found July 4, 2000
30° 36′ N., 5° 3′ E. Eleven pieces of a Moroccan meteorite, having a combined weight of 3,824 g (total weight of the entire pairing group is ~5.1 kg), were recovered by a French team under the organization of Bruno Fectay and Carine Bidaut. Although the coordinates of the recovery location in Tissemoumine, Morocco were recorded by GPS equipment, a NWA-series designation was accepted as the name for this meteorite by the Meteoritical Society NomCom. This primitive meteorite is of great interest due to its abundance of relict chondrules.

*Previously, Floss (2000) and Patzer et al. (2003) proposed that the acapulcoite/lodranite meteorites should be divided based on metamorphic stage:

  1. primitive acapulcoites: near-chondritic (Se >12–13 ppm [degree of sulfide extraction])
  2. typical acapulcoites: Fe–Ni–FeS melting and some loss of sulfide (Se ~5–12 ppm)
  3. transitional acapulcoites: sulfide depletion and some loss of plagioclase (Se <5 ppm)
  4. lodranites: sulfide, metal, and plagioclase depletion (K <200 ppm [degree of plagioclase extraction])
  5. enriched acapulcoites (addition of feldspar-rich melt component)

A similar distinction could be made among the winonaites in our collections, although there is not yet an analog of the IAB complex irons for the acapulcoite/lodranite PB. Northwest Africa 1463 (and pairing group) ranks as the most primitive member of the winonaites, containing intact chondrules comparable to a petrologic type 5 chondrite (Benedix et al., 2003). However, most winonaites experienced extensive thermal metamorphism involving incipient sulfide melting and exhibit highly recrystallized textures, characteristics analogous to the ‘typical’ acapulcoites. Metamorphic progression in other winonaites led to partial loss of the low-melting phases FeS and plagioclase, and these are designated as a ‘transitional’ stage in the acapulcoite/lodranite metamorphic continuum. Those winonaites which experienced the highest temperatures ultimately crystallized from residual melt material, and they exhibit significant depletions in FeS, FeNi-metal, and plagioclase (including plagiophile trace elements). Samples representing this advanced metamorphic stage are known as lodranites in the acapulcoite/lodranite metamorphic sequence, while the term ‘evolved’ could be used to represent a similar metamorphic stage in the winonaite group (e.g., Tierra Blanca; Hunt et al., 2017). Although NWA 725 was initially classified as an acapulcoite, an O-isotopic analysis of a portion of the main mass (from the collection of S. Turecki) by the Open University, UK resolves the material within the winonaite field: ‘In particular, the Δ17O value of -0.431 is in reasonable agreement with the mean value of -0.48 for the winonaite–IAB complex group determined by Clayton and Mayeda (1996).’ In addition, when plotted on a diagram comparing Δ17O vs. Fa mol% in olivine (Rumble III et al, 2005), NWA 725 (Fa6.1) and the winonaites NWA 1463 (Fa7.4; Δ17O = -0.45‰), NWA 1457 (Fa5; Δ17O = -0.40 [±0.03]‰), and NWA 1058 (Fa6.5; Δ17O = -0.53‰) all plot very close together within the winonaite field. The inference can thus be made that NWA 725 is actually a winonaite, likely paired with the primitive winonaites NWA 1463 and 1058 (NWA 1052 and NWA 1054 are also possible members of this pairing group; see Irving and Rumble III, 69th MetSoc, #5288 [2006]).

Northwest Africa 725 and pairings contain relict intact chondrules, and accordingly it was grouped among the most primitive winonaites with near chondritic composition. However, the meteorite has experienced extensive heating and possibly a low degree of partial melting resulting in a depletion of certain trace elements. The features of this meteorite suggest that winonaites are actually metamorphosed chondrites. It was suggested by Irving et al. (2005) that the term ‘metachondrites’ be used for such metamorphosed chondrites, including several newly recognized chondrule-free, texturally evolved meteorites with elemental ratios and O-isotopic compositions showing affinities to existing chondrite groups. It was also suggested that the term ‘W-chondrites’ be used for those winonaites like NWA 725 that contain relict chondrules.

Oxygen isotope data for IAB silicate inclusions, along with observed volatile element depletions, led to the inferrence that the winonaite precursor had a volatile-depleted carbonaceous chondrite-like composition (Hunt et al., 2012). It has been demonstrated that two distinct reservoirs existed in the early protoplanetary disk—carbonaceous chondrite (CC) and non-carbonaceous (NC). These were segregated by the rapid accretion of proto-Jupiter and reflect differences in the contribution of p-, r-, and s-process material (Bermingham et al., 2018). Subsequent studies employing Mo and W isotope data (e.g., Kruijer et al., 2017) reveal that the IAB complex irons, and thus the genetically-related winonaites, accreted in the non-carbonaceous reservoir (see the Appendix, Part III for further details). Preliminary data based on Al–Mg chronometry show that NWA 725 was formed ~1.4 m.y. after CAIs. This age is consistent with Hf–W ages in the range of 1.5–5 m.y. that were calculated for more highly metamorphosed winonaites (Hidaka et al., 2014).

New analyses were conducted by Worsham et al. (2017) for IAB complex irons, along with two winonaites (Winona and HaH 193), a lodranite (GRA 95209), the primitive achondrite NWA 725, and other selected meteorite groups. Employing precise Mo, W, and Os isotope data along with HSE and other literature data, they ascertained that the IAB complex irons represent at least three distinct parent bodies and at least three impact-generated metal–silicate segregation events (see top schematic diagram below). Moreover, they ascertained that the Mo isotope data, as well as the chemical and mineralogical data, attest to a common parent body for the winonaites and the MG/sLL irons. Importantly, they demonstrated that the Mo isotope values of NWA 725 do not plot with the IAB MG/sLL/winonaites, and that the values are all higher than those of the lodranite in their study. Notably, the Mo-isotopic values of NWA 725 plot within the field of the magmatic sHL and sHH irons, which are not genetically related to the other IAB parent bodies (see bottom diagram below). Oxygen isotope data for the sHL and sHH irons could help resolve whether any potential genetic relationship exists with the NWA 725 pairing group. standby for iab iron formation diagram

CRE-corrected Mo Isotopic Compositions of Meteorite Groups
(µ notation denotes deviation from terrestrial standards in parts per million)
standby for chinga mo diagram
click on photo for a magnified view

Diagrams credit: Worsham et al., Earth and Planetary Science Letters, vol. 467, pp. 157–166 (2017)
‘Characterizing cosmochemical materials with genetic affinities to the Earth: Genetic and chronological diversity within the IAB iron meteorite complex’
(https://doi.org/10.1016/j.epsl.2017.02.044)
Schmitz et al. (2016) conducted a Cr-isotopic analysis on a xenolithic inclusion from the L6 chondrite Villalbeto de la Peña, and on chrome-spinel grains from both the winonaite NWA 725 and the L6 chondrite Lundsgard. They demonstrated through a coupled Δ17O vs. ε54Cr diagram (shown below) that the Villalbeto de la Peña clast plots with NWA 725 in the winonaite field. Northwest Africa 725 Chromium vs. Oxygen Isotope Plot
standby for o-cr diagram
click on photo for a magnified view

Diagram credit: Schmitz, B. et al., Nature Communications, vol. 7, p. 4 (2016, open access link)
‘A new type of solar-system material recovered from Ordovician marine limestone’
(https://doi.org/10.1038/ncomms11851)’
Further information about the classification of this meteorite and its probable pairings can be found on the NWA 1058 page. The NWA 725 specimen pictured above is a 1.3 g partial slice showing many distinct, intact chondrules. The photo below is an excellent petrographic thin section micrograph of NWA 725, shown courtesy of Peter Marmet. standby for lodran photo
click on photo for a magnified view
Photo courtesy of Peter Marmet