Geological and geochemical record of 3400-million-year-old terrestrial meteorite impacts

Journal Article · Fri Sep 01 04:00:00 EDT 1989 · Science (Washington, D.C.); (USA)

DOI:https://doi.org/10.1126/science.245.4921.959· OSTI ID:6967324

Lowe, D R ^[1]; Byerly, G R ^[2]; Asaro, F ^[3]; Kyte, F T ^[4]

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1. Stanford Univ., CA (USA)
2. Louisiana State Univ., Baton Rouge (USA)
3. Lawrence Berkeley Lab., CA (USA)
4. Univ. of California, Los Angeles (USA)

Beds of sand-sized spherules in the 3400-million-year-old Fig Tree Group, Barberton Greenstone belt, South Africa, were formed by the fall of quenched liquid silicate droplets into a range of shallow- to deep-water depositional environments. The regional extent of the layers, their compositional complexity, and lack of included volcanic debris suggest that they are not products of volcanic activity. The layers are greatly enriched in iridium and other platinum group elements in roughly chondritic proportions. Geochemical modeling based on immobile element abundances suggests that the original average spherule composition can be approximated by a mixture of fractionated tholeiitic basalt, komatiite, and CI carbonaceous chondrite. The spherules are thought to be the products of large meteorite impacts on the Archean earth. 21 refs., 4 figs., 1 tab.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6967324
• Journal Information: Science (Washington, D.C.); (USA), Journal Name: Science (Washington, D.C.); (USA) Vol. 245:4921; ISSN SCIEA; ISSN 0036-8075
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AFRICA
DATA
DEPOSITION
EXPERIMENTAL DATA
GEOLOGIC MODELS
INFORMATION
METEORITES
NUMERICAL DATA
OXYGEN COMPOUNDS
SILICATES
SILICON COMPOUNDS
SOUTH AFRICA