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megabreccia

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Journal Article
Journal: Economic Geology
Published: 07 March 2022
Economic Geology (2022)
... as a Ni-Cu-PGE megabreccia deposit ( Holwell et al., 2017a ). The clasts of the sulfide breccia comprise mafic and ultramafic fragments as well as abundant apatite and carbonate, interpreted to be derived from the surrounding igneous host rocks ( Blanks, 2021 ). However, this sulfide-matrix breccia is now...
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Series: Geological Society, London, Special Publications
Published: 14 April 2020
DOI: 10.1144/SP490-2019-9
EISBN: 9781786205155
... was cut by normal faults which controlled the palaeogeography of the platform and the sediment input into the adjacent basin in which thick, resedimented, carbonate megabreccia and turbidites were deposited. These carbonates represent exploration targets in similar settings worldwide. Aims, data...
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Series: GSA Field Guide
Published: 04 December 2019
DOI: 10.1130/2019.0056(01)
EISBN: 9780813756561
... faults are where the gravity slides moved southward up and over the former land surface at least 35 km. The Paunsaugunt thrust faults resulted from gravitational spreading of the Marysvale volcanic field prior to emplacement of the slides. Note distribution of Markagunt Megabreccia (what we now call...
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Journal Article
Published: 01 October 2019
Italian Journal of Geosciences (2019) 138 (3): 333–354.
...-investigated subject. This normal faulting was apparently widespread at a super-regional scale, and the Narni-Amelia Ridge carries direct and indirect evidence for this episode of revived deformation: (i) the occurrence of limestone megabreccias (“Mt. Cosce Breccia”) resting unconformably, through an erosional...
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Journal Article
Journal: Economic Geology
Published: 01 August 2012
Economic Geology (2012) 107 (5): 909–934.
..., is characterized by discrete, Cu-Ag-Au–rich magnetite-sulfide veins and lesser pyrite disseminations within distal propylitic and proximal potassic to sodic alteration zones. The Polymetallic zone is hosted by a chaotic assemblage of gabbro and tuff bodies interpreted as a talus megabreccia. Several lines...
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Journal Article
Journal: Geology
Published: 01 March 2008
Geology (2008) 36 (3): 195–198.
... megabreccia unconformably overlain by sediments deposited during two Noachian-age phases of aqueous activity. A lighter-toned lower unit exhibiting phyllosilicates was deposited in a long-lived, quiescent distal alluvial or lacustrine setting. An overlying darker-toned and often blocky upper unit drapes...
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Journal Article
Journal: Geosphere
Published: 01 February 2008
Geosphere (2008) 4 (1): 75–106.
... section, we review field relationships from key localities where the Caetano caldera displays thick intracaldera tuff, steep caldera margins where pre-caldera and intracaldera units are abruptly truncated against each other, megabreccia and mesobreccia, a resurgent dome/intrusion, and a ring-fracture...
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Series: GSA Field Guide
Published: 01 January 2008
DOI: 10.1130/2008.fld011(06)
EISBN: 9780813756110
.... (A) Grand Wash trough. QTc—Colorado River sediments; Tby—early Pliocene basalts (e.g., 4.4 Ma Sandy Point basalt; Th, 11−6 Ma Hualapai Limestone; Ts—Sandstone-siltstone facies; Tgy—gypsum; Tcg—conglomerate derived from Gold Butte block; Tbr—megabreccia of Proterozoic or Paleozoic rock; Ths—tuffaceous...
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Series: GSA Field Guide
Published: 01 January 2008
DOI: 10.1130/2008.fld011(10)
EISBN: 9780813756110
... megabreccia, produced by the Alamo Impact Event, is as thick as 100 m and may be the best exposed proven bolide impact breccia on Earth. It contains widespread intervals generated by the seismic shock, ejecta curtain, tsunami surge, and runoff generated by a major marine impact. Newly interpreted crater-rim...
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Journal Article
Journal: GSA Bulletin
Published: 01 March 2007
GSA Bulletin (2007) 119 (3-4): 329–342.
... of the ignimbrite of Ruth Mountain then led to a second trap-door collapse as the first-phase partial ring fault propagated to the south to completely enclose the caldera. Wall-rock breccias are intercalated as lenses and megabreccia blocks in both ignimbrites. The minimum intracaldera volume is 55–60 km 3...
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Journal Article
Journal: Geology
Published: 01 January 2007
Geology (2007) 35 (1): 57–60.
... abrupt deepening above the upper megabreccia. Poorly preserved Cretaceous planktic foraminifers reworked from the Colorado Plateau (e.g., Merriam and Bandy, 1965 ) are present near the top of the Mud Hills member (Fig. 2) . Cretaceous tonalite at the base of the section is overlain by a thin (∼0–40...
FIGURES
Journal Article
Journal: Economic Geology
Published: 01 March 2006
Economic Geology (2006) 101 (2): 431–451.
... that the breccia was formed and dolomitized prior to deposition of the upper Takakkaw Tongue. F ig . 10. Dolomitization features at the top of a megabreccia of the Takakkaw Tongue at Monarch Cirque. A. Dolomitized megaclast of the Cathedral Formation in dolomite breccia that is in contact with ribbon...
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Journal Article
Published: 27 September 2005
Canadian Journal of Earth Sciences (2005) 42 (6): 1033–1044.
... called the study area, located in a remote part of the Wernecke Mountains of northern Yukon (Figs.  1–3 ). In the study area, hydrothermal megabreccias crosscut metamorphosed and deformed strata of the Paleoproterozoic Wernecke Supergroup ( Delaney 1981 ; Bell 1986 ; Thorkelson 2000 ). These breccias...
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Series: GSA Reviews in Engineering Geology
Published: 01 January 2002
DOI: 10.1130/REG15-p379
EISBN: 9780813758152
...; at top, crossed by arrow, is vertical wall of Split Mountain megabreccia. Figure 6. Closer view of contact between red and gray sturzstrom mass and overlying Split Mountain sturzstrom deposit. Arrow points to 3 m-thick. sediment-filled stream channel formed between the two sturzstrom events...
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Journal Article
Journal: GSA Bulletin
Published: 01 September 1999
GSA Bulletin (1999) 111 (9): 1350–1370.
..., and megabreccia (somewhat >15.5 to somewhat <13.9 Ma) dominate the unconformably overlying sedimentary succession. Decreasing dip angles in progressively younger strata through this volcanic-sedimentary succession, and angular unconformities between units, form corroborative evidence with geochronologic...
Journal Article
Published: 01 May 1998
Canadian Journal of Earth Sciences (1998) 35 (5): 495–503.
..., suggesting that volcanic activity began shortly after formation of the Boulder basin, the extensional basin in which the informally named red sandstone unit was deposited. The red sandstone unit is at least as old as 11.70 ± 0.08 Ma and contains megabreccia deposits younger than 12.93 ± 0.10 Ma. This result...
Journal Article
Published: 01 September 1997
Journal of Sedimentary Research (1997) 67 (5): 792–804.
... as a prolonged interaction with depositional substrate. As such, the basal contacts were not frictionless, and basal shear stresses probably were transmitted through the breccia mass during transport. If so, then many common features of megabreccia deposits, including long run-out, inherited stratigraphy...
Journal Article
Published: 01 January 1997
Environmental & Engineering Geoscience (1997) III (4): 501–512.
..., clastic dikes, and basal striations. The three stratigraphically lower sheets range between 5 and 10 m thick, whereas the highest sheet is approximately 75 m thick. Breccia clasts in the sheets consist predominantly of Paleozoic carbonate. The source area for the megabreccia is the Clark Mountains...
Journal Article
Journal: Geology
Published: 01 May 1996
Geology (1996) 24 (5): 411–414.
... the Appalachian Meguma terrane boundary in Nova Scotia, Canada, where a Late Carboniferous fault megabreccia contains Devonian (369 Ma: U-Pb zircon) granulite-grade mylonite fractured by veins filled with Visean amphibole (ca. 335 Ma: Ar-Ar). This fractured mylonite was later mixed with Early Carboniferous...
Journal Article
Journal: Geology
Published: 01 November 1995
Geology (1995) 23 (11): 1003–1006.
... marine carbonate megabreccia exposed on land. It covers ≈4,000 km 2 , averages ≈70 m thick, and contains more than 250 km 3 of carbonate-platform debris that was deposited by a giant submarine slide. The breccia is a single bed with the characteristics of a chaotic debrite at the base evolving upward...