Cyclic units in the Somerset Dam layered gabbro intrusion, southeastern Queensland, Australia

AbstractDetailed remapping of the Palaeogene Ardnamurchan Centre 3 gabbros, NW Scotland, suggests that this classic sequence of ring-intrusions forms a composite layered lopolith. The area mapped by previous studies as the Great Eucrite gabbro intrusion comprises 70% by area of Centre 3. Field observations suggest that most of the other smaller ring-intrusions of Centre 3 (interior to the Great Eucrite) constitute either distinct petrological facies of the same intrusion, or included country-rock or peridotite blocks. These observations, together with syn-magmatically deformed inward-dipping modal layering, are used here to support the interpretation that significant central sagging occurred in the intrusion at a late stage in its crystallization history.

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Hollow apatites in a layered basic intrusion, Norway

Geological Magazine ◽

10.1017/s0016756800039765 ◽

1972 ◽

Vol 109 (5) ◽

pp. 385-392 ◽

Cited By ~ 3

Author(s):

P. M. Gardner

Keyword(s):

Magma Chamber ◽

Rapid Growth ◽

Mineral Phase ◽

Northern Norway ◽

Stages Of Growth ◽

Apatite Crystals ◽

Layered Gabbro ◽

Two Stages ◽

Gabbro Intrusion

SummaryCumulate apatite crystals with infilled tube-like cavities parallel to the c-axis are described from a layered gabbro intrusion in Northern Norway. These are considered to be skeletal crystals produced by rapid growth in the supercooled roof zone of the magma chamber. At least two stages of growth are suggested on the basis of the morphology of the apatites. The interiors of the crystals contain phases representing the trapped magma or the cumulus mineral phase within which they are enclosed. Recirculation of the apatite primocrysts by convection currents is indicated by the interrupted form of some of the tubes.

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The petrology of the layered gabbro intrusion, eastern gabbro, Coldwell alkaline complex, Northwestern Ontario, Canada: evidence for multiple phases of intrusion in a ring dyke

Lithos ◽

10.1016/s0024-4937(97)00030-3 ◽

1997 ◽

Vol 40 (2-4) ◽

pp. 243-259 ◽

Cited By ~ 13

Author(s):

Cliff S.J. Shaw

Keyword(s):

Alkaline Complex ◽

Northwestern Ontario ◽

Layered Gabbro ◽

Gabbro Intrusion ◽

Ring Dyke

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Developing a 3-D model for the Skaergaard intrusion in East Greenland: constraints on structure, mineralisation and petrogenetic models

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/geusb.v17.5015 ◽

1969 ◽

Vol 17 ◽

pp. 61-64 ◽

Cited By ~ 4

Author(s):

Troels F.D. Nielsen ◽

Símun D. Olsen ◽

Bo M. Stensgaard

Keyword(s):

North Atlantic ◽

North Atlantic Ocean ◽

Flood Basalts ◽

Skaergaard Intrusion ◽

East Greenland ◽

The North ◽

Layered Gabbro ◽

Systematic Evolution ◽

D Model ◽

Gabbro Intrusion

The Skaergaard intrusion (Fig. 1) is probably the most studied layered gabbro intrusion in the world (Wager & Deer 1939; Wager & Brown 1968; McBirney 1996; Nielsen 2004). The intrusion is c. 54.5 Ma old and was formed during the Palaeogene opening of the North Atlantic Ocean, intruding into the base of the East Greenland flood basalts. The intrusion is relatively small with a volume of c. 300 km3 (Nielsen 2004). Spectacular magmatic layering and systematic evolution in the compositions of liquidus phases and estimated melt compositions (e.g. Wager & Brown 1968) have made the intrusion the most studied example of the development of the ‘Fenner trend’ of iron enrichment in basaltic liquids (e.g. Thy et al. in press; Veksler in press).

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