| Title | U-Pb geochronology of Late Silurian (Wenlock to Pridoli) volcanic and sedimentary rocks, central Newfoundland Appalachians: targeting the timing of transient extension as a prelude to Devonian orogenic
gold mineralization |
| |
| Author | Honsberger, I W ;
Bleeker, W; Kamo, S L; Sutcliffe, C N; Sandeman, H A
I |
| Source | Atlantic Geology 2022 p. 2015-237, https://doi.org/10.4138/atlgeo.2022.009 |
| Image |  |
| Year | 2022 |
| Alt Series | Natural Resources Canada, Contribution Series 20220005 |
| Publisher | Atlantic Geoscience Society |
| Document | serial |
| Lang. | English |
| Media | paper; digital; on-line |
| Related | NRCan photo(s) in this
publication |
| File format | pdf |
| Province | Newfoundland and Labrador |
| Area | Appalachians |
| Lat/Long WENS | -60.3928 -52.4114 51.8822 46.3836 |
| Subjects | economic geology; general geology; mineralogy; Nature and Environment; Science and Technology; uranium lead dating; volcanic rocks; sedimentary rocks; orogenies; gold; Silurian; Devonian |
| Illustrations | location maps; diagrams; photographs; photomicrographs; graphs |
| Program | Targeted Geoscience Initiative (TGI-6) Ore systems |
| Released | 2022 06 10 |
| Abstract | Bimodal igneous suites and associated immature clastic sedimentary rocks are diagnostic of orogenic gold-mineralized, crustal-scale fault zones. In the central Newfoundland Appalachians, the Rogerson
Lake Conglomerate belt and Botwood basin are Late Silurian, fault-controlled, magmatic suites and sedimentary rock sequences closely associated with orogenic gold mineralization; however, the spatio-temporal evolution of faulting and associated
magmatism and sedimentation are not fully resolved. U-Pb zircon geochronological results were obtained by using an integrated approach employing both LA-ICPMS (laser ablation-inductively coupled plasma mass spectrometry) and CA-ID-TIMS (chemical
abrasion-isotope dilution-thermal ionization mass spectrometry) on the same detrital samples. Using this approach, a maximum depositional age for the Rogerson Lake Conglomerate sequence is 421.9 ± 1.0 Ma, which confirms that it is younger than, and
stratigraphically overlies, ca. 422-420 Ma igneous rocks exposed along the central Newfoundland gold belt. Towards the stratigraphic middle of the Botwood basin in north-central Newfoundland, a tuffite layer intercalated with graded siltstone
produced a maximum depositional age of 427.9 ± 3.1 Ma. The age of emplacement of an autobrecciated, flow-banded rhyolite dome of the Charles Lake volcanic belt along the northwestern Botwood basin is 429.3 ± 0.7 Ma. Detrital zircon age distributions
for sedimentary rocks of the Rogerson Lake Conglomerate belt and Botwood basin are interpreted to represent a mixed Laurentian-Gondwanan provenance, whereas high-precision CA-ID-TIMS zircon data establish a clear link between Late Silurian magmatism
and sedimentation throughout central Newfoundland. Furthermore, these geochronological results are consistent with a structural model involving the southeastward advancement of a transient, intra-terrane, extensional fault system across strike of the
Exploits Subzone between ca. 429 and 418 Ma, with propagation along strike to the southwest (Rogerson Lake Conglomerate belt) at ca. 422 Ma. Extensional faulting may have contributed to Late Silurian basin formation, subsidence, and exhumation of
pre-Late Silurian rocks of the Exploits Subzone. Time-transgressive, extension-related magmatism and clastic sedimentation are compatible with Salinic slab rollback and break-off prior to compressional Acadian overprint; therefore, extension appears
to mark the transition between the Salinic and Acadian orogenic cycles along the central Newfoundland gold belt. Transient lithospheric extension may have been important for increasing heat and fluid flow in the crust as a prelude to Acadian crustal
thickening and Devonian orogenic gold mineralization. |
| Summary | (Plain Language Summary, not published)
This research constrains the timing and evolution of tectonic processes associated with the formation of igneous and sedimentary rocks that contain gold
deposits in central Newfoundland. This work contributes to the understanding of how and where gold deposits form. |
| GEOSCAN ID | 329937 |
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