Porphyroblastic Metasediments

Title

Porphyroblastic Metasediments

Alternative Title

Hybrid rock

Identifier

KBR-14

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 12 and KBR 13 to note this range. This sample is medium grained, holocrystalline, and has a hypidiomorphic-granular texture. It has dark gray crystals, ranging from < 1 mm- 3 mm. Dramatic labradorite-like striations cover about half of the rock. Groups of striations are roughly at right angles to one another. The rusty looking weathered surface is more vibrant on this rock (than the other samples).
The thin sections shown in plain polarized Light and cross polarized light at 40x magnification.
The rock is 60% plagioclase, 40% pyroxenes (mainly enstatite), and <1% 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