PARAMBU

Stony

TIPO:

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CHONDRITE

ORDINARY

H-L-LL

LL

-

5

-

-

BRAZIL - CE

1967

According to the mineralogy and petrological description, Parambu is an ordinary chondrite LL5, characterized by presenting an advanced polymictic brecciated structure.

PETROGRAFIA:

The main characteristic of the Parambu meteorite is its broken texture. The rock consists of a fine matrix with varying grain sizes, which contains defined cores with varied texture (barred, radial, porphyritic and others). Most of the matrix contains fragments of clasts, which are varied in size, color, shape and texture. Some are dark, due to the spread of opaque phases, such as FeNi and troilites. Other fragments are clear due to the high recrystallization of plagioclases. The texture is typical of a regolith-like breccia, with clasts varying in shape from angular to rounded. According to Levi-Donati and Sighinolfi (1974), the lytic portion represents 91.5% of the meteorite and the opaque ones correspond to 8.5%. Source: Gomes & Keil (1980).

GEOQUÍMICA:

The meteorite basically consists of olivine, orthorhombic and monoclinic pyroxene, FeNi and troilite. Plagioclase and chromite are the least constituent constituents. It has in rare quantities grains of maskelinite, whitlockite, ilmenite and petlandite. Levi-Donati & Sighinolfi (1974) listed Fa27-28, Fs22-23 and An10 values through refractive indices. The composition for Ca-rich pyroxene and plagioclase are, respectively, En46.4 Fs10.6 Wo43.0 and Ab80.2 An10.6 Or9.3. Wet chemical analysis provided the following results in% by weight: Si 19.07, Mg 14.66, Fe (total) 18.95, Al 1.12, Ca 1.45, Na 0.757, K 0.091, Mn 0.257, Ni 0.87, Co 0.068, S 2.23. The total iron content of 18.95% is lower than in normal L group chondrites and especially metallic iron is very low. Only 0.5% of metallic iron was found in the meteorite set. The ratio of total iron to silica is 0.46, that of metallic iron to total iron is 0.025 and that of silica to magnesium oxide is 1.68. These reasons are consistent with the reasons given by Van Schumus & Wood for the LL group of chondrites. The analysis of the heavy elements gave the following results in ppb: W 110, Re 48, Os 620, Ir 360, Pt 740, Au 140. The abundances of these elements in Parambu are considerably less than their abundances in Mocs (L6) and Holbrook (L6). This also supports Parambu's classification for being an LL chondrite. Source: Gomes & Keil (1980).

CLASSIFICAÇÃO:

According to the mineralogy and petrological description, Parambu is an ordinary chondrite LL5, characterized by having an advanced genomic breccia structure. Parambu is a breccia formed in the regolith of its parental body, with equilibrated and unequilibrated stony components of the LL group, which mechanically mixed in the meteorite. Source: Gomes & Keil (1980).

CLASSIFICADORES:

A. Barreto, Z. Fonseca de Mello, G. R. Levi-Donati e G. P. Sighinolfi (1973. The Meteorite Shower of Parambu, Ceara State, Brazil: Mineralogy and Petrology (Abstract). Meteoritics 8, 324. M.) e Shima, G. P. Sighinolfi, K. P. Jochum and H. Hintenberger. (1973. The Parambu Meteorite: Bulk Chemistry and Heavy Trace Metals by Spark Mass Spectroscopy (Abstract). Meteoritics 8, 440-441).

HISTÓRIA:

A meteorite shower fell on July 24, 1967 at around 5.30 pm on the Novo Exú farm. A bolide was seen traveling from SW to NE followed by a thunderous noise that lasted a few seconds and culminated in a major detonation. Prof. A. Barreto was doing rutile research in Independência when he watched the bolide pass. The next day, he headed for the area where he had estimated the meteorite to have fallen, but the searches were unsuccessful. He was later informed that he had fallen close to Parambu. Over the weekend, he gathered around 30 men who worked for him and managed to recover 14 samples making up approximately 1.5 kg of meteorite. He donated about 100g to Moacyr Vasconcelos from DNPM and the largest fragment of approximately 450g stayed with Mr. Horácio, owner of the farm. A sample of approximately 300g went to SUDENE and the Museum of Rocks, which would be in Juazeirinho. Other reports indicate that more than 27 specimens were recovered, the largest weighing 594.6 g. Description obtained in the documents of National Museum.

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