| Title | The geochemistry of Middle Jurassic dykes associated with the Straumsvola-Tvora alkaline plutons, Dronning Maud Land, Antarctica and their association with the Karoo large igneous province |
| Author | Riley, T.R.; Curtis, M.L.; Leat, P.T.; Millar, I.L. |
| Author Affil | Riley, T.R., Natural Environment Research Council, British Antarctic Survey, Cambridge, United Kingdom. Other: NERC Isotope Geosciences Laboratory, United Kingdom |
| Source | Mineralogical Magazine, 73(2), p.205- 226, . Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0026- 461X |
| Publication Date | Apr. 2009 |
| Notes | In English. 36 refs. GeoRef Acc. No: 297265 |
| Index Terms | Antarctica--Queen Maud Land; absolute age; alkaline earth metals; Antarctica; Ar/Ar; basanite; chemical ratios; concentration; dates; dike swarms; emplacement; geochemistry; igneous rocks; intrusions; isotope ratios; isotopes; Jurassic; Jutulstraumen Rift; Karoo Supergroup; large igneous provinces; magmas; magnetic anomalies; major elements; Mesozoic; metals; Middle Jurassic; minor elements; Nd- 144/Nd-143; neodymium; P-T conditions; phonolites; plutonic rocks; plutons; Queen Maud Land; rare earths; Sr-87/Sr-86; stable isotopes; Straumsvola Pluton; strontium; syenites; tephrite; Tvora Pluton; volcanic rocks; western Queen Maud land |
| Abstract | Jurassic dykes of western Dronning Maud Land (Antarctica) form a minor component of the Karoo large igneous province. An extensive local dyke swarm intrudes Neoproterozoic gneisses and Jurassic syenite plutons on the margins of the Jutulstraumen palaeorift in the Svedrupfjella region. The dykes were intruded in three distinct episodes (~204, ~176 and ~170 Ma). The 204 Ma dykes are overwhelmingly low-Ti, olivine tholeiites including some primitive (picritic) compositions (MgO ›12 wt.%; Fe2O3 ›12 wt.%; Cr ›1000 ppm; Ni ›600 ppm). This 204 Ma event precedes the main Karoo volcanic event by ~25 Ma, so any correlations to the wider province are difficult to make. However, it may record the earliest phase of rift activity along the Jutulstraumen. The 176 Ma dyke event is more intimately associated with the two syenite plutons. The dykes are alkaline (basanite/tephrite) and were small-degree melts from an enriched, locally derived source and underwent at least some degree of interaction with a syenitic contaminant. This ~176 Ma dyke event is widespread elsewhere in the Karoo (Southern Africa and Dronning Maud Land). Later-stage (170 Ma) felsic (phonolite-comendite) dykes intrude the 176 Ma basanite-tephrite suite and represent the last phase of magmatic activity in the region. |
| URL | http://hdl.handle.net/10.1180/minmag.2009.073.2.205 |
| Publication Type | journal article |
| Record ID | 87545 |