Open Access Repository

Mafic volcanic rocks on King Island, Tasmania: evidence for 579 Ma break-up in east Gondwana


Downloads per month over past year

Meffre, S, Direen, NG, Crawford, AJ and Kamenetsky, VS 2004 , 'Mafic volcanic rocks on King Island, Tasmania: evidence for 579 Ma break-up in east Gondwana' , Precambrian Research, vol. 135, no. 3 , pp. 177-191 , doi: 10.1016/j.precamres.2004.08.004.

[img] PDF
PreC_Res2004.pdf | Request a copy
Full text restricted
Available under University of Tasmania Standard License.


The eastern coast of King Island in southeastern Australia exposes a thick, well-preserved sequence of latest Neoproterozoic volcanic, and related shallow intrusive rocks. These rocks are associated with shallow marine carbonates and siltstones and pass up into massive conglomerates representing a marine flooding event and unconformity, during continental break-up and subsequent volcanic passive margin formation. Unusual differentiated sills (Grimes Intrusive suite) with extreme internal variation (wehrlite to andesite compositions) intrude deformed Proterozoic metasediments of the Rodinian basement. A thin, basal tholeiitic basaltic volcanic unit (City of Melbourne Volcanics) is less contaminated than the underlying sills, and preceded eruption of a thick sequence of highly depleted picritic pillows, sub-aerial flows and hyaloclastites (Shower Droplet Volcanics). The picrite sequence is overlain by thick tholeiitic basalts and reworked volcanogenic conglomerates (Bold Head Formation) that show a strong compositional similarity to enriched mid ocean ridge basalts. Both the picrites and the upper tholeiitic basalts are not crustally contaminated and have an Nd-Sm isochron age of 579 +/- 16 Ma with initial epsilonNd of +4.2. The lithostratigraphy and range of compositions represented are analogous to early magmatism associated with continental break-up and volcanic passive margin formation, including voluminous Seaward Dipping Reflector Sequences, in the Mesozoic North Atlantic volcanic margins.

Item Type: Article
Authors/Creators:Meffre, S and Direen, NG and Crawford, AJ and Kamenetsky, VS
Keywords: continental break-up; crustal contamination; large igneous province; picrite; rodinia; tasmania; southeastern australia
Journal or Publication Title: Precambrian Research
DOI / ID Number: 10.1016/j.precamres.2004.08.004
Item Statistics: View statistics for this item

Actions (login required)

Item Control Page Item Control Page