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| Titel: |
Relict textures of chromitites from New South Wales |
| Auteur: |
Golding, H. G. |
| Verschenen in: |
Australian journal of earth sciences |
| Paginering: | Jaargang 22 (1975) nr. 4 pagina's 397-412 |
| Jaar: |
1975 |
| Inhoud: |
Podiform chromitites from ultramafic belts in New South Wales are interpreted as modified cumulates of three principal textural types. In Type 1 the inferred cumulus units were chromite euhedra. Settling of euhedra was followed in sequence by sintering at points of grain contact, overgrowth, mutual impingement, and interface adjustment of the grains, and intergranular fracture of the aggregate. The final products range from sintered frameworks of chromite grains (60-80% chromite) to densified polygonal-granular aggregates with pull-apart texture (80-100% chromite). In Type 2 the inferred cumulus units were chromite spheroids comprising both single-crystal and polycrystalline varieties. Settled spheroids did not sinter, but deformed and recrystallized to ellipsoidal nodules with a polygonal-granular internal structure or rim. Type 2 chromitites include (i) nodular chromitites that are non-sintered frameworks or disseminations of intact nodules and (ii) nodule-derived chromitites consisting of the densified or disseminated products of nodule disaggrega-tion. In Type 3 chromitites, it is inferred that chromite euhedra and larger olivine euhedra settled together. The chromite grains together with intercumulus olivine formed a network between the large cumulus olivine grains. During extension of the total aggregate variations in the relative competencies of the network material and the large olivine grains resulted in a range of strongly lineated olivine chromitites. The remarkable variety of textures encountered in the chromitites suggests a complex history for the group in the upper mantle. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 4 van 11 gevonden artikelen
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