China
Africa
Explore chapters and articles related to this topic
Magmatism and Magmatic Rocks
Published in Aurèle Parriaux, Geology, 2018
The ability of magma to move toward the surface depends on the presence of preferential pathways, or fractures. In general, the lithosphere is not very deformable, which explains why the great majority of magma remains trapped in the crust, never reaching the surface. Plutonism is the process of crystallization at great depth. Solidification takes thousands to several millions of years. As a result, the molten mass has plenty of time to form well-developed crystals. The texture of a plutonic rock is thus said to be granular, or coarse-grained, meaning that all the minerals are well crystallized. They are visible to the naked eye (Fig. 6.25).
Magmatism and Magmatic Rocks
Published in Aurèle Parriaux, Geology, 2018
The ability of magma to move toward the surface depends on the presence of preferential pathways, or fractures. In general, the lithosphere is not very deformable, which explains why the great majority of magma remains trapped in the crust, never reaching the surface. Plutonism is the process of crystallization at great depth. Solidification takes thousands to several millions of years. As a result, the molten mass has plenty of time to form well-developed crystals. The texture of a plutonic rock is thus said to be granular, or coarse-grained, meaning that all the minerals are well crystallized. They are visible to the naked eye (Fig. 6.25).
Early Permian strike-slip basin formation and felsic volcanism in the Manning Group, southern New England Orogen, eastern Australia
Published in Australian Journal of Earth Sciences, 2019
R. J. Manton, S. Buckman, A. P. Nutman
This ca 295 Ma age for crystallisation is younger than the ca 302 Ma crystallisation age for the Hillgrove Plutonic Supersuite (Collins et al., 1993; Kent, 1994) but older than the Bundarra Plutonic Supersuite at 286 ± 13 Ma (whole-rock Rb–Sr; Flood & Shaw, 1977). Within the Hillgrove Plutonic Supersuite, zircon U–Pb crystallisation ages have been calculated for the Abroi granodiorites (302 ± 4 Ma; Collins et al., 1993), Tia granodiorites (302 ± 4 Ma; Collins et al., 1993), Rockvale Monzogranite (295.6 ± 2.4 Ma; McKibbin et al., 2017) and the Harnham Grove Porphyriritc Microtonalite (295 ± 2 Ma), the youngest in the supersuite (Black, 2007). Slightly older zircon ages have been reported by McKibbin et al. (2017) for the Bakers Creek Suite gabbros (299.3 ± 3.1 Ma) and the Charon Creek Diorite (290.4 ± 3.2 Ma). McKibbin et al. (2017), used the correction of ages from zircon ion-microprobe reference material (SL13 and AS3) to recalculated the age for the I-type Halls Creek Volcanics to 295.7 ± 2.2 Ma. I-type plutonism has been described along the western portion of the Anawian terrane and include the Glenburnie Leuco-adamellite (ca 295 Ma; Kemp et al., 2009), the Jibbinbar Granite (298.1 ± 2 Ma) and the Bullaganang Granite (291.5 ± 2.2 Ma) (Cawood et al., 2011; Donchak, Bultitude, Purdy, & Denaro, 2007). Based on data outlined here, the Ramleh Volcanics are closely associated with the Hillgrove Plutonic Supersuite and we suggest they are comagmatic.
Recognition of mid-Paleozoic volcanism in New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2018
Rose E. Turnbull, Quinten H. A. van der Meer, Andy J. Tulloch, Jahandar Ramezani, Martin J. Whitehouse, Tom H. Andersen, Tod E. Waight
The main conclusions of this paper are: Rhyolite clast P81091 from the Permian Pupu Conglomerate (Parapara Group) represents c. 362 Ma volcanism likely associated with S-type Ridge Suite magmatism. Along with the 363 Ma Merrie Granite, this is the oldest episode of Ridge Suite magmatism so far recognised within New Zealand;Dacite clast P42694 from the Cretaceous Seek Cove Formation (Puysegur Group) represents 359 Ma volcanism that was also likely associated with Ridge Suite magmatism;The U–Pb ages of between 359 and 362 Ma of the volcanic clasts reveal that S-type silicic magmatism occurred between the two major episodes of currently recognised S-type plutonism of the Karamea (371–368 Ma) and Ridge (355–340) suites. These results indicate that the current age limits of Ridge Suite magmatism need to be revised, and that this episode of volcanic magmatism likely represents the fore-runner of Ridge Suite activity;
Abstracts from the 2017–2018 Mineral Deposits Studies Group meeting
Published in Applied Earth Science, 2018
L. Santoro, St. Tshipeng Yav, E. Pirard, A. Kaniki, G. Arfè, N. Mondillo, M. Boni, M. Joachimski, G. Balassone, A. Mormone, A. Cauceglia, N. Mondillo, G. Balassone, M. Boni, W. Robb, T. L. Smith, David Currie, Finlay Stuart, John Faithfull, Adrian Boyce, N. Mondillo, C. Chelle-Michou, M. Boni, S. Cretella, G. Scognamiglio, M. Tarallo, G. Arfè, F. Putzolu, M. Boni, N. Mondillo, F. Pirajno, N. Mondillo, C. Chelle-Michou, M. Boni, S. Cretella, G. Scognamiglio, M. Tarallo, G. Arfè, Saltanat Aitbaeva, Marina Mizernaya, Boris Dyachkov, Andrew J Martin, Iain McDonald, Christopher J MacLeod, Katie McFall, Hazel M Prichard, Gawen R T Jenkin, B. Kennedy, I. McDonald, D. Tanner, L. Longridge, A. M. Borst, A. A. Finch, H. Friis, N. J. Horsburgh, P. N. Gamaletsos, J. Goettlicher, R. Steininger, K. Geraki, Jonathan Cloutier, Stephen J. Piercey, Connor Allen, Craig Storey, James Darling, Stephanie Lasalle, A. Dobrzanski, L. Kirstein, R. Walcott, I. Butler, B. Ngwenya, Andrew Dobrzanski, Simon Howard, Lore Troalen, Peter Davidson, Rachel Walcott, Drew Drummond, Jonathan Cloutier, Drew Drummond, Adrian Boyce, Robert Blakeman, John Ashton, Eva Marquis, Kathryn Goodenough, Guillaume Estrade, Martin Smith, E. Zygouri, S. P. Kilias, T. Zack, I. Pitcairn, E. Chi Fru, P. Nomikou, A. Argyraki, M. Ivarsson, Adrian A. Finch, Anouk M. Borst, William Hutchison, Nicola J. Horsburgh, Tom Andersen, Siri Simonsen, Hamidullah Waizy, Norman Moles, Martin Smith, Steven P. Hollis, Julian F. Menuge, Aileen L. Doran, Paul Dennis, Brett Davidheiser-Kroll, Alina Marca, Jamie Wilkinson, Adrian Boyce, John Güven, Steven P. Hollis, Julian F. Menuge, Aileen L. Doran, Stephen J. Piercey, Mark R. Cooper, J. Stephen Daly, Oakley Turner, Brian McConnell, Hannah S. R. Hughes, Hannah S. R. Hughes, Magdalena M. Matusiak-Małek, Iain McDonald, Ben Williamson, James Williams, Guy Dishaw, Harri Rees, Roger Key, Simon Bate, Andy Moore, Katie McFall, Iain McDonald, Dominque Tanner, Manuel Keith, Karsten M. Haase, Daniel J. Smith, Reiner Klemd, Ulrich Schwarz-Schampera, Wolfgang Bach, Sam J Walding, Gawen RT Jenkin, Daniel James, David Clark, Lisa Hart-Madigan, Robin Armstrong, Jamie Wilkinson, Gawen RT Jenkin, Hugh Graham, Daniel J Smith, Andrew P Abbott, David A Holwell, Eva Zygouri, Robert C Harris, Christopher J Stanley, Hannah L.J. Grant, Mark D. Hannington, Sven Petersen, Matthias Frische, Fei Zhang, Ben J. Williamson, Hannah Hughes, Joshua Smiles, Manuel Keith, Daniel J. Smith, Chetan Nathwani, Robert Sievwright, Jamie Wilkinson, Matthew Loader, Daryl E. Blanks, David A. Holwell, W.D. Smith, J.R. Darling, D.S. Bullen, R.C. Scrivener, Aileen L. Doran, Steven P. Hollis, Julian F. Menuge, John Güven, Adrian J. Boyce, Oakley Turner, Sam Broom-Fendley, Aoife E Brady, Karen Hudson-Edwards, Oakley Turner, Steve Hollis, Sean McClenaghan, Aileen Doran, John Güven, Emily K. Fallon, Richard Brooker, Thomas Scott
Titanite CaTi[SiO4](O,OH,F) is an accessory phase common to propylitic assemblages, and can incorporate trace amounts of uranium and thorium into its structure making it a useful geochronometer. In-situ LA-ICP-MS U-Pb analysis of hydrothermal titanite within propylitically altered rock samples from across the OT district identified distinct multiple episodes of titanite growth at approximately 370 Ma, 340 Ma, 320 Ma and 290 Ma. These dates are consistent with known major intrusive events in the district including porphyry emplacement and mineralisation in the late Devonian, the intrusion of granodiorite plutons, andesite dykes, and rhyolite dykes and sills in the early Carboniferous, a second pulse of granodiorite and granite plutonism later in the Carboniferous, and finally emplacement of the Khanbogd Granite in the Permian. Propylitic titanite records episodic growth in the OT district. Propylitic assemblages at OT may therefore be associated with porphyry mineralisation, or could be associated with later non-mineralising magmatic activity. Through titanite petrochronology it is now possible to definitively classify porphyry and non-porphyry alteration in a rock sample. The ability to classify alteration in this way is critical in the development of geochemical vectoring tools, as we can be confident that alteration observed in the rock is the same age as known mineralisation in a porphyry camp.