A major north-west dyke swarm zone in north Queensland

P. J. Stephenson, B. W. Chappell

    Research output: Contribution to journalArticle

    Abstract

    A zone of north-west trending dykes extends for over 600 km in the hinterland from Cairns to Mackay. In some regions the zone is up to 120 km wide. The context of the dyke swarm is the Tasman Orogenic Zone. Geological relationships indicated a wide span of ages for the intrusions in the dyke swarm zone. They intrude a range of volcanic and sedimentary rocks, and in some areas plutonic rocks. Older dykes, apparently part of the same regional swarm are intruded by some of the granites. These dykes cut various granites or older volcanic rocks. Four K/Ar determinations for granites in the Palm Islands gave 274 to 282 Ma. Older dykes in the volcanic rocks can be seen to be cut by these granites, but none were found to be suitable for age determination. Geological contexts in most other regions of the dyke swarm zone appear to be consistent with these Permian ages. However, the dykes in the Whitsunday region are much younger, since they cut Cretaceous granites. Dykes of this later age may be present elsewhere, since for example Cretaceous plutonism has been recognised recently west of Townsville. -from Authors

    Original languageEnglish
    Pages (from-to)817-822
    Number of pages6
    JournalUnknown Journal
    Publication statusPublished - 1987

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