Recent contributions on Falkland Islands bedrock geology, with an inventory of representative lithostratigraphical specimens held by the British Geological Survey

Stone, P.. 2014 Recent contributions on Falkland Islands bedrock geology, with an inventory of representative lithostratigraphical specimens held by the British Geological Survey. Nottingham, UK, British Geological Survey, 35pp. (OR/14/040) (Unpublished)

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Abstract/Summary

After completion of the Falkland Islands geological mapping project in 1998, geological work on the islands by the British Geological Survey continued in support of onshore mineral exploration projects and to provide correlative data for the offshore hydrocarbons exploration programme. Academic research from British institutions has declined over the last decade, but international interest has increased, with research visits by geologists from Brazil, Australia and the USA. Results arising from these disparate sources have extended knowledge of the Falkland Islands lithostratigraphy, biostratigraphy and depositional palaeoenvironments, with the latter aspect extensively researched in relation to the glacigenic Fitzroy Tillite Formation. A representative suite of lithostratigraphic specimens has been placed in the BGS collections, Keyworth, as have a number of fossil specimens. The fossil fauna of the Falkland Islands has been extended by new discoveries in both the Devonian and Permian strata; noteworthy examples are the Devonian ophiuroid from the Fox Bay Formation, the Cambrian archaeocyaths in erratic clasts of limestone from the Permo-Carboniferous Fitzroy Tillite Formation, and the bivalve fauna from the Permian Brenton Loch Formation. Studies of structural geology have generally been complementary to work offshore, and have focused in particular on the thermal history experienced by the Falklands rock succession. Ar-Ar radiometric dating of syntectonic mica has confirmed an Early Permian age for the onset of deformation, later stages of which involved previously unrecorded sinistral shear. In terms of the regional geology, one tentative structural reinterpretation suggests that the southern extremity of the North Falklands Basin may extend onshore in the Limpet Creek area of the East Falklands coast. An aeromagnetic survey radically revised interpretations of the Falkland Islands dyke swarms; follow-up radiometric dating of dykes from East Falkland confirmed the Early Jurassic ages previously reported from West Falkland, but also proved the existence of a previously unsuspected Early Cretaceous swarm with ages from three individual dolerite dykes ranging from ca 135 Ma to ca 121 Ma. This newly discovered swarm comprises dykes aligned north-south across both West and East Falkland, and extends offshore to the south-east of the islands. The Jurassic and Cretaceous dykes onshore are compositionally distinct, and both suites have likely igneous correlatives offshore in the Falkland Plateau Basin. Scientific publications on the themes mentioned above have been supplemented by historical studies and more popular articles.

Item Type:	Publication - Report
Funders/Sponsors:	NERC
Additional Information. Not used in RCUK Gateway to Research.:	This item has been internally reviewed but not externally peer-reviewed
Date made live:	04 Aug 2014 08:53 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/507998

Item Type:

Publication - Report

Funders/Sponsors:

NERC

Additional Information. Not used in RCUK Gateway to Research.:

This item has been internally reviewed but not externally peer-reviewed

Date made live:

04 Aug 2014 08:53 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/507998