Mesozoic alkali basalts and felsic rocks in eastern Victoria, Australia
| DOI | 10.1201/NOE0415398992.ch9 |
|---|---|
| Aasta | 2006 |
| Raamat | Dyke Swarms - Time Markers of Crustal Evolution Selected Papers of the Fifth International Dyke Conference in Finland, Rovaniemi, Finland, 31 July- 3 Aug 2005 & Fourth International Dyke Conference, Kwazulu-Natal, South Africa 26-29 June 2001 |
| Toimetaja(d) | Hanski, E., Mertanen, S., Rämö, T., Vuollo, J. |
| Kirjastus | Taylor & Francis |
| Leheküljed | 131-146 |
| Tüüp | artikkel kogumikus |
| Eesti autor | |
| Keel | inglise |
| Id | 24059 |
Abstrakt
Southeastern Australia was part of Gondwana and experienced Jurassic magmatism that preceded the Gondwana break-up. Magmatism in this area belongs to the Ferrar low-Ti magmatic group, but mafic and felsic rocks of the Freestone and Benambra areas, Victoria, belong to alkali-rich associations. The 191 Ma Freestone dykes are basalts with alkalies around 6.5wt% at MgO contents of 4.5-8 wt%. The felsic rocks from Benambra (trachydacites, monzogranodiorites) are marginally older and have high alkali contents (12.5% at MgO contents of 0.1-0.9 wt%). 143Nd/ 144Nd ratios of Freestone and Benambra rocks are 0.512427-0.512449 and 0.51231- 0.51237, with ε Nd values of +0.7 to +1.4 and 0 to -1.1, respectively. The Freestone basalts can be modelled as fractionation products of small-degree melts of an enriched mantle source. The crustal contamination of the basaltic magma is insignificant. The felsic rocks may be low-pressure fractionation products of these mafic melts