SANTA FILOMENA

Stony

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DESCRIÇÃO:

CHONDRITE

ORDINARY

H-L-LL

H

5-6

S4

W0

BRAZIL - PE

2020

Equilibrated Ordinary Chondrite H5-6, Shock Stage S4 and Weathering W0.

PETROGRAFIA:

Five thin polished sections from brecciated and unbrecciated masses were examined. The unbrecciated specimen is composed of medium gray colored lithology and shows some scattered, faint, texturally equilibrated chondrules set within a recrystallized groundmass. The mean visible chondrule diameter is 0.5mm. The main phases are olivine and orthopyroxene. Olivine shows mosaicism, planar fractures and darkening. Small and rare feldspar grains are present and show undulatory extinction. Opaque phases include metals (kamacite, taenite) and troilite. Other accessory phases include phosphate and chromite. The brecciated lithology consists of a chondritic texture with medium-gray chondritic clasts in a dark-gray chondritic host that has similar texture and composition, but much darker in color. Plagioclase grains are present with sizes up to 50 microns in diameter. Highly recrystallized fragments (type 6) coexist with areas showing a chondritic texture (type 5) and fragments of impact darkening. No melt pockets or veins are present. Olivine shows weak mosaicism and darkening indicating shock stage S4. Kamacite is predominantly found in single crystals with well-defined and distorted Neumann lines.Troilite shows multiple twinning also indicating a shock stage S4.

GEOQUÍMICA:

Electron microprobe analysis yields: unbrecciated lithology: olivine Fa18.8.5 ± 0.4 (25), low Ca pyroxene Fs17.1 ± 0.4 Wo1.2 ± 0.8 (18), plagioclase Ab71.9 ± 9.3 An12.7 ± 6.3 Or15.3 ± 13.0 (10), Co in Kamacite 0.112 ± 0.02 (22). Equilibrated clasts: Fa19.6 ± 0.5 (57), low Ca pyroxene Fs17.3 ± 0.6 (93), plagioclase Ab75.3 ± 9.2 An10.9 ± 2.7 Or13.8 ± 11.4 (15). Oxygen isotopes (K. Ziegler, UNM) (linearized, all per mil rel. to V-SMOW, TFL slope=0.528): A total of 3 untreated (i.e., no acid-wash) fragments/subsamples were analyzed by laser fluorination. Sample weights for each measurement were between 1.5 and 2.5 mg. δ18O = 4.366, 4.618, 4.452; δ17O = 2.958, 3.161, 3.115; Δ17O = 0.652, 0.723, 0.731, all permil

CLASSIFICAÇÃO:

H5-6 breccia ordinary chondrite. Weathering (W0) and moderately shocked (S4)

CLASSIFICADORES:

M. E. Zucolotto and A. A. Tosi

HISTÓRIA:

A bright fireball appeared on the western region of Pernambuco state, Brazil, on August 19, 2020, 13:18:17 UTC. Four cameras from a weather forecast company named "Clima Ao Vivo" recorded the bolide in the cities of Floresta, Salgueiro, Belém de São Francisco and São José do Belmonte. The GOES-16 satellite also captured the bolide flash. Using the video data, the BRAMON (Brazilian Meteor Observation Network) performed the bolide triangulation and orbit calculation. The meteoroid entered the Earth atmosphere at 15.36 km/s, in a 43.1° inclination (relative to ground) travelling 61.3 km in 4 " and extinguished at 20.9 km height, 7.5 km east of the city of Santa Filomena. The meteoroid orbit was calculated as follows: semi-major axis 2.0 AU, eccentricity 0.94, inclination 0.26°, pericenter longitude 143.5° and ascending node 146.7°. Stones were recovered within a 16.0 × 2.7 km elipse compared to the predicted strewn field of 40 × 4 km as calculated by Jim Goodall. Santa Filomena is located nearly at the middle of the strewn field. The majority of the stones, by weight, were recovered by local people. A 38.2 kg mass was found ~7 km from Santa Filomena on the Pernambuco-Piaui state border. A 2.81 kg oriented nosecone hammered a house in front of the main city church and plaza. Another 1.5 kg stone hit a Cohab house ~1 km NE of the plaza. Other stones were witnessed to fall by residents of the village of Caramari located few hundred meters North of the Cohab house. Stones were also found by researchers and meteorite hunters: Andre L. R. Moutinho (4 pcs, 57 g), "Meteoriticas" - UFRJ (3 pc, 83.2 g), Robert Ward (1 pc, 34 g), José C. Medeiros - Astro Agreste (3 pcs, 62 g), Cartier Ramalho and Evandro Peixoto - CASF (3 pcs, 243g) and Luiz F. Castro - GASF (2 pcs, 118 g).

Todas as informações que não possuírem fonte especifica, foram extraídas do Meteoritical Bulletin Database.

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