lower Amazonian

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Journal Article
Journal: Geosphere
Published: 01 August 2015
Geosphere (2015) 11 (4): 1042-1061.
... Neoproterozoic or early Cambrian, and some may have been deposited ca. 510 Ma. Continental rifting ended ca. 560 Ma at the longitude of our study, so the transition from rifting to subduction at this location in eastern Laurentia may have lasted only 50 M.y. Lower Ordovician arc intrusions into these rocks...
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Journal Article
Journal: Geology
Published: 01 September 2014
Geology (2014) 42 (9): 763-766.
... of Mars being lower than is typical, in comparison to the long-term average over much of the Middle to Late Amazonian. This supports Laskar et al.’s (2004) statistical prediction that the long-term average obliquity on Mars (∼35° during the past 250 m.y., ∼38° over the past 4 b.y.) was higher than its...
Series: Geological Society, London, Special Publications
Published: 01 January 2008
DOI: 10.1144/SP294.10
EISBN: 9781862395428
... of schists and phyllites scatter around 1600–1700 Ma. Facies analysis of low-grade metasedimentary rocks from drill cores suggests a sedimentary environment of basin floor and lower- to upper-slope turbidites. Nearby sources are indicated by the textural and mineralogical immaturity; together with structural...
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Journal Article
Journal: Geology
Published: 01 February 1994
Geology (1994) 22 (2): 119-122.
...Paul A. Mueller; Ann L. Heatherington; Joseph L. Wooden; Robert D. Shuster; Allen P. Nutman; Ian S. Williams AbstractA Gondwanan origin for the pre-Cretaceous basement of Florida is suggested by U- Pb ages of 515 to 2860 Ma for single zircons separated from subsurface samples of lower Paleozoic...
Series: GSA Memoirs
Published: 01 January 1953
DOI: 10.1130/MEM58-p1
... of the western part of South America. Continental plant-bearing strata of Mississippian age are described, and their known distribution is indicated. Great sequences of marine Pennsylvanian and Permian strata were studied over a large area. The Pennsylvanian is represented mainly by the Atokan stage, lower...
Journal Article
Journal: Geology
Published: 01 May 2008
Geology (2008) 36 (5): 411-414.
... of several lobes onto the current surface of the LVF indicates that a phase of alpine glaciation followed the lowering of the valley glacial system. These data suggest that the Late Amazonian glaciation that produced LVF in this region involved significantly larger amounts of ice than previously thought...
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Journal Article
Published: 04 June 2010
Canadian Journal of Earth Sciences (2010) 47 (5): 591-620.
... Laurentian crust, products of a long-lived Mesoproterozoic continental-margin arc and associated back arc, and remnants of one or more accreted mid-Mesoproterozoic island-arc terranes. A potential suture, preserved in Grenvillian inliers of the southeastern USA, may separate rocks of Laurentian and Amazonian...
Published: 01 December 2016
DOI: 10.5724/gcs.15.35.0038
EISBN: 978-1-944966-10-2
... boundaries are refined each year as additional well data is incorporated in the database and new information comes to light. The Mesozoic super-sequences of Olson et al. (2015) are also shown for reference. Figure 3. Chronostratigraphic well control (upper maps) and pseudowell control (lower...
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Series: GSA Field Guide
Published: 01 January 2012
DOI: 10.1130/2012.0029(09)
EISBN: 9780813756295
... of the lower metaconglomerate horizons yields detrital zircons of latest Middle Cambrian age. This stratigraphy is interpreted to record the Rheic rift-drift sequence on the trailing edge of an Ediacaran-Cambrian arc terrane as it pulled away from the Amazonian craton in Middle Cambrian–Furongian time...
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Journal Article
Journal: GSA Bulletin
Published: 01 November 2007
GSA Bulletin (2007) 119 (11-12): 1506-1520.
... Amazonian foreland basin indicates that widespread, restricted marine ingressions shaped western Amazonia throughout the Miocene. The late Lower–early Upper Miocene sedimentary series (Pebas Formation) consists of stacked, 3- to 10-m-thick, tidally influenced, brackish to freshwater, bay-margin sequences...
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Journal Article
Journal: Economic Geology
Published: 01 May 2006
Economic Geology (2006) 101 (3): 585-605.
... Amazonian craton. The mineralized areas are characterized by intense hydrothermal alteration of the monzogranite, comprising incipient autometasomatism, K silicate, sodic, Mn chlorite, phyllic, carbonate, and microcline alteration, with partial overprinting of the early alteration by later stages. A distal...
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Journal Article
Published: 01 February 1996
Canadian Journal of Earth Sciences (1996) 33 (2): 140-155.
...Joseph B. Whalen; George A. Jenner; Frederick J. Longstaffe; Ernst Hegner AbstractIn the Gander Zone, Ordovician to Devonian, metaluminous to slightly peraluminous plutons, with within-plate affinities, intrude a lower Paleozoic metasedimentary package. During the Siluro-Devonian, εNd(T) and δ18O...
Journal Article
Journal: Geophysics
Published: 21 July 2017
Geophysics (2017) 82 (5): J39-J60.
... parameters from magnetic and radiometric data in the shield area indicate sharp changes that follow the known geologic changes observable in the survey area. Observed large-scale anisotropy in the area seems to be autocorrelated with two different geochronological provinces of the Amazonian craton...
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Journal Article
Published: 01 May 2017
The Canadian Mineralogist (2017) 55 (3): 437-456.
...José de Arimatéia de Almeida; Roberto Dall'agnol; Marcílio Cardoso Rocha AbstractThe Mesoarchean Na-granitoids exposed in the Rio Maria domain, southeastern Amazonian craton, are represented by tonalite–trondhjemite and leucogranodiorite–granite suites. The 2.98–2.92 Ga tonalite–trondhjemites...
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Journal Article
Published: 01 December 2009
The Canadian Mineralogist (2009) 47 (6): 1441-1468.
...: implications for the genesis of Proterozoic A-type granites . Lithos 46 , 431 – 462 . Dall’Agnol , R. , Scaillet , B. & Pichavant , M ( 1999 ): An experimental study of a Lower Proterozoic A-type granite from the eastern Amazonian Craton, Brazil . J. Petrol . 40 , 1673 – 1698...
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Journal Article
Published: 02 November 2009
Geological Magazine (2009) 147 (3): 416-433.
... at the northern edge of West Gondwana after the 10–20 Ma period of tectonic quiescence that followed the terminal stage of the Cadomian collisions. Monotonous Młynowiec metagreywackes form the lower part of the succession, and the lithologically diverse schistose Stronie Formation forms its upper part. The change...
Series: GSA Special Papers
Published: 01 January 2007
DOI: 10.1130/2007.2423(07)
... Sensitive high-resolution ion microprobe (SHRIMP) U-Pb ages have been obtained from zircons separated from Upper Carboniferous to Lower Permian SiO 2 -rich volcanic and subvolcanic rocks of eleven drill sites. The volcanic rocks belong to a large volcanic province that formed during the initial...
Journal Article
Journal: GSA Bulletin
Published: 01 September 1978
GSA Bulletin (1978) 89 (9): 1290-1294.
... to be coeval and of early Proterozoic age and have been correlated with the upper and lower Birrimian rocks of West Africa. In West Africa the Birrimian sequence is underlain by basement rocks of the 2,700 m.y. B.P. Liberian event. These supracrustal rocks in both South America and West Africa are intruded...
Histogram illustrating interpreted outgassing of SO 2  through time on Mars...
in > Geology
Published: 01 May 2012
Figure 2. Histogram illustrating interpreted outgassing of SO 2 through time on Mars. Lower estimate is based on volcanic mapping (CG; Craddock and Greeley, 2009 ). Upper estimate is based on total crust production and magmatic SO 2 production (H-R; Righter et al., 2009 ; Hirschmann
Figure 4. A: Stratigraphic column (after  Scott and Tanaka, 1986 ); approxi...
in > Geology
Published: 01 February 2003
Figure 4. A: Stratigraphic column (after Scott and Tanaka, 1986 ); approximate timing of preaureole proto–Olympus Mons flow is indicated by arrow. Amazonian is youngest martian era; time of Hesperian-Amazonian boundary is ca. 3.5 Ga. B: Interpretive cross section. Surface is generated from Mars