The Mordor Complex: A highly differentiated potassic intrusion with kimberlitic affinities in central Australia
✍ Scribed by Alan P. Langworthy; Lance P. Black
- Book ID
- 104745528
- Publisher
- Springer
- Year
- 1978
- Tongue
- English
- Weight
- 1021 KB
- Volume
- 67
- Category
- Article
- ISSN
- 0010-7999
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✦ Synopsis
The Mordor Complex in central Australia consists of a suite of highly fractionated potassic rocks. Syenite and monzonite are intruded by phlogopite shonkinite and melamonzonite, which are in turn intruded by numerous plug-like bodies of phlogopiterich periodotite and pyroxenite, and by pegmatite dykes, and carbonate-rich breccia.
The consanguinity of the suite, cumulate texture of the ultramafic rocks, enrichment of the Complex in large-ion-lithophile (LIL) elements, mineral equilibrium data, and mineral and whole-rock Rb-Sr isochron data, indicate that the rocks were produced by fractional crystallization from an ultrapotassic mafic magma in an intermediate-level magma chamber. Magma genesis possibly involved modification during uprise of potassic partial melt derived from phlogopite-bearing atypical upper mantle source rock. Evidence for regional compositional heterogeneity in the upper mantle is discussed.