1-20 OF 143 RESULTS FOR

Tyndall Group

Results shown limited to content with bounding coordinates.
Follow your search
Access your saved searches in your account

Would you like to receive an alert when new items match your search?
Close Modal
Sort by
Journal Article
Journal: Economic Geology
Published: 01 August 2001
Economic Geology (2001) 96 (5): 1073–1088.
... and hyaloclastic dacites associated with interbedded carbonates and calcareous volcaniclastic sandstones located at the Mount Read Volcanics Tyndall Group-Central Volcanic Complex boundary. The alteration zone forms a subvertically dipping tabular sheet over 3 km in length and between 10 and 100 m in width...
FIGURES | View All (16)
Journal Article
Journal: Economic Geology
Published: 01 May 1992
Economic Geology (1992) 87 (3): 597–619.
... alteration studies.Three calc-alkaline suites (one extending to shoshonitic compositions) and two tholeitiic suites have been distinguished within the Mount Read belt. Suite I is voluminous and includes the Eastern sequence, Central Volcanic Complex, Tyndall Group, the intrusive quartz-feld-spar porphyries...
Journal Article
Journal: Economic Geology
Published: 01 August 2001
Economic Geology (2001) 96 (5): 1089–1122.
... of the Owen Group. Small lead-zinc-rich massive sulfide lenses, together with lenses of fossil-rich limestone, characterize the exhalative zone, which is hosted within submarine volcaniclastic breccias and sandstones in the basal part of the late Middle Cambrian Tyndall Group at Comstock. The upper part...
FIGURES | View All (20)
Journal Article
Journal: Economic Geology
Published: 01 May 1992
Economic Geology (1992) 87 (3): 564–586.
... to active felsic volcanism which produced widespread crystal- and pumice-rich mass-flow deposits of the Southwell Subgroup and Tyndall Group. GeoRef, Copyright 2006, American Geological Institute. Abstract, Copyright, Society of Economic Geologists 1992 ...
Journal Article
Journal: Economic Geology
Published: 01 July 1997
Economic Geology (1997) 92 (4): 438–447.
... at the base of the Tyndall Group, a sequence of rhyolite lavas and crystal-rich volcaniclastics. Fossiliferous sediments and welded ignimbrites within this group are indicative of a local shallow-water environment. Mineralization occurs in a conformable package of altered rocks in the footwall of a major...
Journal Article
Journal: Economic Geology
Published: 01 March 2015
Economic Geology (2015) 110 (2): 445–468.
... to underlie the Mount Read Volcanics. Magmatism in the central Mount Read Volcanics lasted at least 12.7 m.y., from 506.8 ± 1.0 Ma for a massive dacite unit in the lower part of the Central Volcanic Complex to 496.0 ± 0.9 Ma for a welded ignimbrite in the lower Tyndall Group. Together with previous age...
FIGURES | View All (10)
Journal Article
Journal: Economic Geology
Published: 01 August 2004
Economic Geology (2004) 99 (5): 987–1002.
...Nicholas C. Williams; Garry J. Davidson Abstract The Basin Lake copper-gold prospect lies in western Tasmania’s Mount Read Volcanics and is hosted in a series of calc-alkaline andesites, quartz-feldspar porphyries, mudstones, carbonates, and sandstones between the Tyndall Group and the Central...
FIGURES | View All (8)
Journal Article
Journal: Economic Geology
Published: 01 August 1993
Economic Geology (1993) 88 (5): 1176–1197.
... of magmatic zircons and hornblendes, respectively, from different parts of the Mount Read Volcanics yields a concordant age of 502.6 + or - 3.5 Ma (1Sigma ), which constrains the time of volcanogenic massive sulfide mineralization. The Comstock Tuff from the Tyndall Group in the upper part of the volcanic...
Image
Simplified lithostratigraphic units of the MRV showing the approximate stratigraphic positions of the major mineral deposits within the belt. Note that these appear to conform to two major mineralizing periods; the older period is in the NCVC at the top of the CVC while the younger period is in the SCVC and located at the base of the Tyndall Group. Colours as in Figure 1. Source: modified from Mortensen et al. (2015).
Published: 05 September 2024
is in the SCVC and located at the base of the Tyndall Group. Colours as in Figure 1 . Source: modified from Mortensen et al. (2015) .
Image
Fig. 4. Comparative diagrammatic cross sections of the Comstock and North Lyell areas showing stratigraphic relationships. Note preservation of upper part of alteration system beneath Tyndall Group rocks at Comstock and of a segment of this part of the system in a displaced schist mass at North Lyell. Most of the upper part of the system in the North Lyell-Prince Lyell area was eroded off prior to the Haulage unconformity. Form of alteration zone and associated chert and sulfide bodies on downthrown side of Great Lyell fault is purely speculative.
Published: 01 August 2001
F ig . 4. Comparative diagrammatic cross sections of the Comstock and North Lyell areas showing stratigraphic relationships. Note preservation of upper part of alteration system beneath Tyndall Group rocks at Comstock and of a segment of this part of the system in a displaced schist mass at North
Image
Fig. 14. Carbon and oxygen stable isotopes from carbonates associated with the Henty alteration and regional Tyndall Group-upper Central Volcanic Complex carbonates. Modeled carbon and oxygen isotope data is from the equations of Zengh and Hoefs (1993), predicting carbonate composition due to precipitation as a result of the mixing of two fluids, in this case a magmatic fluid (δ13C = –5permil;, δ18O = 5.5permil;; Davidson, 1997) and seawater (δ13C = 0permil;, δ18O = 0permil;; Davidson, 1997). Cambrian marine limestone field from Veizer and Hoefs (1976).
Published: 01 August 2001
F ig . 14. Carbon and oxygen stable isotopes from carbonates associated with the Henty alteration and regional Tyndall Group-upper Central Volcanic Complex carbonates. Modeled carbon and oxygen isotope data is from the equations of Zengh and Hoefs (1993) , predicting carbonate composition due
Image
Fig. 15. Carbon and oxygen stable isotopes from carbonates associated with the Henty alteration and regional Tyndall Group-upper Central Volcanic Complex carbonates. Modeled carbon and oxygen isotope data is from the equations of Zengh and Hoefs (1993) for fluid-rock interaction between a preexisting carbonate (δ13C = 1.2permil;, δ18O = 17permil;) and a later, mixed magmatic seawater-derived hydrothermal fluid (δ13C = –10permil;, δ18O = 5.5permil; Davidson, 1997) with changing water/rock (w/r) ratios. Cambrian marine limestone field from Veizer and Hoefs (1976).
Published: 01 August 2001
F ig . 15. Carbon and oxygen stable isotopes from carbonates associated with the Henty alteration and regional Tyndall Group-upper Central Volcanic Complex carbonates. Modeled carbon and oxygen isotope data is from the equations of Zengh and Hoefs (1993) for fluid-rock interaction between
Journal Article
Published: 15 January 2024
Journal of the Geological Society (2024) 181 (1): jgs2023-081.
... (565.22 ± 0.89 Ma) and the Stretton Shale Formation, Long Mynd (566.6 ± 2.9 Ma). Correlations to West Avalonia include the time-equivalent Fermeuse Formation, St John's Group, eastern Newfoundland (564.13 ± 0.65 Ma). The data presented here establish the biota of the Llangynog Inlier as a lateral...
FIGURES | View All (5)
Series: Special Publications of the Society of Economic Geologists
Published: 01 January 2018
DOI: 10.5382/SP.20.02
EISBN: 9781629496399
... compositions and classified them as group 1 (formerly basaltic) and group 2 (formerly micaceous) kimberlites. Mitchell (1995) pointed out that the group 1 kimberlites contained abundant megacryst minerals (e.g., picroilmenite, Ti-rich pyrope, large chrome diopsides) crystallizing in the low-velocity zone...
FIGURES | View All (11)
Image
Photograph looking west at the Libbey Glacier fault across the Tyndall Glacier. Location is in Figure 3. This outcrop was only observed from across the Tyndall Glacier, and the rocks in the hanging wall could be Cretaceous Yakutat Group mélange (Kym) or sedimentary rocks of the Yakutat microplate such as Tertiary Poul Creek Formation (Tpc). Tk—Kulthieth Formation. Light-colored slope wash obscures darker brown to reddish-brown rocks in the footwall of the fault that cuts the fold in the upper indeterminate unit.
Published: 01 February 2012
Figure 8. Photograph looking west at the Libbey Glacier fault across the Tyndall Glacier. Location is in Figure 3 . This outcrop was only observed from across the Tyndall Glacier, and the rocks in the hanging wall could be Cretaceous Yakutat Group mélange (K ym ) or sedimentary rocks
Journal Article
Published: 05 September 2024
Geochemistry: Exploration, Environment, Analysis (2024) 24 (3): geochem2024-008.
... is in the SCVC and located at the base of the Tyndall Group. Colours as in Figure 1 . Source: modified from Mortensen et al. (2015) . ...
FIGURES | View All (17)
Journal Article
Journal: Economic Geology
Published: 01 August 2001
Economic Geology (2001) 96 (5): 1123–1132.
... with the felsic-intermediate sequence. This unit is characterized by the presence of up to 5 percent of 1- to 2-mm quartz phenocrysts and resembles the Tyndall Group. The quartz-porphyritic volcanic unit is in contact with hematitic, clast- and matrix-supported, pebble-cobble conglomerate of the Owen Group...
FIGURES | View All (7)
Journal Article
Journal: GSA Bulletin
Published: 01 September 2014
GSA Bulletin (2014) 126 (9-10): 1317–1339.
... happen if the Tyndall ichthyosaurs swam, and likely also hunted, in packs composed of different size classes. A group behavior in ichthyosaurs has previously been hypothesized by Hauff (1953) , Massare (1988) , and Hogler (1992) . Even a cooperative foraging strategy was speculated, or herding...
FIGURES | View All (10)
Journal Article
Published: 01 April 2019
Earth Sciences History (2019) 38 (1): 28–42.
...), James T. Gardner (1842–1912) and Clarence King (1842–1901) ( Figure 4 ). D. Stanley Tarbell and Ann T. Tarbell pointed out that the coming together of this group of talented individuals was not accomplished as a result of some long-range plan but was due instead to luck. They note: By chance, King...
FIGURES | View All (8)
Journal Article
Journal: Geosphere
Published: 01 February 2012
Geosphere (2012) 8 (1): 105–126.
...Figure 8. Photograph looking west at the Libbey Glacier fault across the Tyndall Glacier. Location is in Figure 3 . This outcrop was only observed from across the Tyndall Glacier, and the rocks in the hanging wall could be Cretaceous Yakutat Group mélange (K ym ) or sedimentary rocks...
FIGURES | View All (17)