Crystallization of Poikilo-macro-spherulitic Feldspar in a Rhum Peridotite

  title={Crystallization of Poikilo-macro-spherulitic Feldspar in a Rhum Peridotite},
  author={Colin H. Donaldson and Harald Irving Drever and Robert Johnston},
Here we define and describe a new macrocrystalline radiate texture in a major layered intrusion. This occurrence is inconsistent with the much applied adcumulus crystal growth hypothesis which dominates current thinking on the derivation of ultrabasic rocks from basaltic magmas. Some radical alternative mechanisms of origin are proposed. 
Finger structures in the Lille Kufjord layered intrusion, Finnmark, Northern Norway
Highly irregular contacts are developed between peridotite and troctolite in layers forming the uppermost part of a transition zone between two of the cyclic units of the Lille Kufjord intrusion. TheExpand
The structure and petrology of ultrabasic rocks in the southern part of the Cuillin Igneous Complex, Isle of Skye
The ultrabasic rocks of the southern portion of the Early Tertiary Cuillin Igneous Complex, Isle of Skye, are recognised as forming a Peridotite Series s.l. and have been separated into six distinctExpand
Ultrabasic rocks of Rhum and Skye: the nature of the parent magma
  • F. Gibb
  • Geology
  • Journal of the Geological Society
  • 1976
Rocks from the peridotite dykes of southern Skye (Gibb 1968) are virtually identical to those found in the large layered intrusions of Rhum and Skye, suggesting that they may have been formed in aExpand
Geochemical studies on cumulus phases of some layered igneous rocks
This thesis presents the results of an investigation into the non-equilibrium distribution of trace constituents as a function of crystal growth. The ultrabasic igneous complex of Rhum (Scotland)Expand
Petrology and evolution of the Northern part of the Rhum Ultrabasic Complex
The central region of the Rhum ul-trabasic complex comprises three major sequences of olivine, and plagioclase-olivine cirulates: (i) the westerly continuation of the Eastern Layered Series; (ii) theExpand
Dynamics of evolving magma chambers: textural and chemical evolution of cumulates at the arrival of new liquidus phases
Abstract Basaltic magma chambers are best exemplified by layered intrusions – fossilized natural laboratories that historically constrain most fundamental principles of igneous petrology. ProgressiveExpand
The Rhum Layered Complex, Inner Hebrides, Scotland
The lower Eocene Rhum Central complex has a core of ultra-basic rocks and gabbros which formed at a late stage in the centre’s evolution. Three major components are recognised: the Eastern LayeredExpand
Intergrowths of Feldspars with Other Minerals
A brief summary of the detailed historical treatment in 2, 553–647 is augmented here by a review of the post-1973 literature. Feldspar is intergrown with quartz in (1) myrmekite, a symplectiteExpand
Ultrabasic Breccias in Layered Intrusions: The Rhum Complex
Two previously unmapped ultrabasic breccias-the Harris Bay and Ard Mheall breccias, in the Rhum layered complex-formed by upward intrusion of feldspathic peridotite magmas rather than by settling ofExpand
Snowflake troctolite in the Hettasch intrusion, Labrador: Evidence for magma-mixing and supercooling in a plutonic environment
The snowflake troctolite (SFT) in the Hettasch intrusion is a thin (0–10 m) zone of melatroctolite concordant with the normal leucotroctolites on one limb of the Hettasch intrusion. The textures ofExpand


The layered ultrabasic rocks of south-west Rhum, Inner Hebrides
  • W. Wadsworth
  • Biology
  • Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
  • 1961
The present study was initiated in the Harris area, which covers the south-western part of the ultrabasic tract, because it was believed that the rocks exposed there represented a different level in the original intrusion, and that they would provide further evidence of the mode of formation. Expand
Metastable Growth Patterns in Some Terrestrial and Lunar Rocks
With reference to new information on the textures in some terrestrial mafic and ultramafic igneous rocks of Tertiary age, textural patterns attributable to metastable crystallization are described,Expand