Porphyroblastic Metasediments

Title

Porphyroblastic Metasediments

Alternative Title

Hybrid rock

Identifier

KBR-12

Description

The porphyroblastic metasediments/hybrid rocks were interpreted by Eales and his co-workers to be metamorphosed "Red Beds" Formation sediments but could be magmatic in origin. The samples illustrate the range in textures; see KBR 13 and KBR 14 to note this range. This sample has an aphanitic porphyritic texture. There are unfoliated coarse-grained metasediments (2 mm- 4 mm) and subhedral muscovite phenocrysts (2 mm - 3 mm) as well as red anhedral phenocrysts. There is a rusty-looking weathered surface. In thin section, radiating pyroxenes are clearly visible.
Thin sections are shown in plain polarized light and cross polarized light at 40x magnification.
The rock is comprised of 70% plagioclase, 22% pyroxene (mainly augite), and 8% opaques.

Date

No date given.

Contributor

Western Minerals, Inc.

Is Part Of

http://www.geosciencecollections.milne-library.org/collections/show/17

Spatial Coverage

Karoo- Birds River, Eastern Cape, South Africa

Temporal Coverage

183-179 Ma (Jurassic)

Accrual Method

Purchased from Western Minerals, Inc.

Unit

Lesotho Formation

Number of Thin Sections

1

Geolocation