Protoliths of the 3.8–3.7 Ga Isua greenstone belt, West Greenland

Myers, John S.

doi:10.1016/s0301-9268(00)00108-x

Cited by 156 publications

(79 citation statements)

References 25 publications

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“…3.8 Ga chert and BIF at amphibolite facies metamorphic grade are tectonically interleaved with amphibolite that locally preserves pillow structures (Myers, 2001). The BIF consists predominantly of quartz and magnetite, with cummingtonite and/or grunerite, actinolite, hornblende, and calcite (Dymek and Klein, 1988).…”

Section: Eoarchean Bifsmentioning

confidence: 99%

Iron Formation: The Sedimentary Product of a Complex Interplay among Mantle, Tectonic, Oceanic, and Biospheric Processes

Bekker¹,

Krapež²,

Slack³

et al. 2010

Economic Geology

852

494

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Iron formations are economically important sedimentary rocks that are most common in Precambrian sedimentary successions. Although many aspects of their origin remain unresolved, it is widely accepted that secular changes in the style of their deposition are linked to environmental and geochemical evolution of Earth. Two types of Precambrian iron formations have been recognized with respect to their depositional setting. Algoma-type iron formations are interlayered with or stratigraphically linked to submarine-emplaced volcanic rocks in greenstone belts and, in some cases, with volcanogenic massive sulfide (VMS) deposits. In contrast, larger Superior-type iron formations are developed in passive-margin sedimentary rock successions and generally lack direct relationships with volcanic rocks. The early distinction made between these two iron-formation types, although mimimized by later studies, remains a valid first approximation. Texturally, iron formations were also divided into two groups. Banded iron formation (BIF) is dominant in Archean to earliest Paleoproterozoic successions, whereas granular iron formation (GIF) is much more common in Paleoproterozoic successions. Secular changes in the style of iron-formation deposition, identified more than 20 years ago, have been linked to diverse environmental changes. Geochronologic studies emphasize the episodic nature of the deposition of giant iron formations, as they are coeval with, and genetically linked to, time periods when large igneous provinces (LIPs) were emplaced. Superior-type iron formation first appeared at ca. 2.6 Ga, when construction of large continents changed the heat flux at the core-mantle boundary. From ca. 2.6 to ca. 2.4 Ga, global mafic magmatism culminated in the deposition of giant Superior-type BIF in South Africa, Australia, Brazil, Russia, and Ukraine. The younger BIFs in this age range were deposited during the early stage of a shift from reducing to oxidizing conditions in the ocean-atmosphere system. Counterintuitively, enhanced magmatism at 2.50 to 2.45 Ga may have triggered atmospheric oxidation. After the rise of atmospheric oxygen during the GOE at ca. 2.4 Ga, GIF became abundant in the rock record, compared to the predominance of BIF prior to the Great Oxidation Event (GOE). Iron formations generally disappeared at ca. 1.85 Ga, reappearing at the end of the Neoproterozoic, again tied to periods of intense magmatic activity and also, in this case, to global glaciations, the so-called Snowball Earth events. By the Phanerozoic, marine iron deposition was restricted to local areas of closed to semiclosed basins, where volcanic and hydrothermal activity was extensive (e.g., backarc basins), with ironstones additionally being linked to periods of intense magmatic activity and ocean anoxia.Late Paleoproterozoic iron formations and Paleozoic ironstones were deposited at the redoxcline where biological and nonbiological oxidation occurred. In contrast, older iron formations were deposited in anoxic oceans, where ferrous iron oxid...

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Section: Eoarchean Bifsmentioning

confidence: 99%

Iron Formation: The Sedimentary Product of a Complex Interplay among Mantle, Tectonic, Oceanic, and Biospheric Processes

Bekker¹,

Krapež²,

Slack³

et al. 2010

Economic Geology

852

494

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“…In 62 this paper we follow this holistic approach, and apply it to the c. 3700 Ma portion of 63 the Isua supracrustal belt (West Greenland; Fig. 1 the Anshan area of northeastern China; for summaries of these see Schiøtte et al, 79 1989; Nutman et al, 1991Nutman et al, , 1996Kinny & Nutman, 1996; Bowring & Williams, 1999; 80 Iizuka et al, 2007;Liu et al, 2007;O'Neil et al, 2007 andHorie et al, 2010 Archaean (Friend et al, 1987(Friend et al, , 1988 Nutman et al, 1989, Nutman & Friend, 2007 97 Crowley, 2002; Friend & Nutman, 2005b components can be sampled separately (e.g., Baadsgaard et al, 1986a; Nutman et al, 107 1996 Nutman et al, 107 , 1999 Friend et al, 2002;Crowley et al, 2002;Polat et al, 2002; Polat & 108 Hofmann, 2003; Bennett et al, 1993 Bennett et al, , 2003 Bennett et al, , 2007Hiess et al, 2009) by 3820-3795 Ma tonalite protoliths (Nutman et al, 1996(Nutman et al, , 1997(Nutman et al, , 2000 Crowley et al, 121 2002;Crowley, 2003; et al, 1984Myers, 2001 , 1984;1997Komiya et al, 1999;Solvang, 1999; Furnes et al, 2007). …”

mentioning

confidence: 99%

“…Strontium, Nd and Hf radiogenic isotope data from the rare surviving oldest rocks 37 (4000-3600 Ma; approximately a millionth of the present crust) indicate that they 38 represent largely juvenile Eoarchaean crust (Moorbath, 1975;Hamilton et al, 1978; Consequently, a multidisciplinary data set offers the best constraints on the 60 geodynamic setting of crust formation and provides insight into the meaning of The oldest geological record and the Isua supracrustal belt 71 The Eoarchaean geological record 72 The rare occurrences of 4000-3600 Ma (Eoarchaean) rocks reflect the small 73 volume of them that have survived more than 3.5 billion years of plate tectonics, 74 weathering and erosion (Nutman, 2006 origin (Nutman et al, 1984(Nutman et al, , 1996(Nutman et al, , 2002(Nutman et al, , 2007Myers, 2001 also preserve pillow structures (Solvang, 1999), and these have yielded a single 241 oscillatory-zoned prismatic zircon with an age of 3709 ± 9 Ma (Nutman et al, 2010).…”

mentioning

confidence: 99%

The emergence of the Eoarchaean proto-arc: evolution of a c. 3700 Ma convergent plate boundary at Isua, southern West Greenland

Nutman

Bennett

Friend³

2013

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Eoarchaean juvenile crust formed as 'proto-arcs' . The northern side of the Isua supracrustal belt is an archetypal proto-arc, with ≥3720 Ma boninites, c. 3720 Ma basalts and gabbros, 3720-3710 Ma andesites, diorites and mafic tonalites, 3710-3700 Ma intermediate-felsic volcanic and sedimentary rocks and 3700-3690 Ma chemical sedimentary rocks. On its northern side there is an extensive body of 3700-3690 Ma tonalite. During its evolution, the c. 3700 Ma Isua volcanic-sedimentary assemblage was partitioned into tectonic slices, with intercalation of mantle dunites with pillow basalts, prior to intrusion of c. 3710 Ma quartz diorites. Partitioning also occurred at 3690-3660 Ma, when the 30-20 million years life of the c. 3700 Ma Isua proto-arc was terminated by juxtaposition with the c. 3800 Ma terrane that occurs along the south of the Isua supracrustal belt. The trace element chemistry for all the ≥3720-3700 Ma mafic to intermediate volcanic rocks indicates fluid-fluxing mantle melting. The c. 3690 Ma tonalites have signatures showing melting of garnet-bearing mafic (eclogite) sources. The Isua c. 3700 Ma assemblage developed at an intra-oceanic convergent plate boundary, and it has a life-cycle broadly analogous to (but not identical to) an oceanic island arc eventually accreted against older crust.Keywords boundary, plate, ma, isua, southern, 3700, west, c, greenland, evolution, convergent, arc, proto, eoarchaean, emergence, GeoQuest (Moorbath, 1975;Hamilton et al., 1978; 39 Baadsgaard et al., 1986a;Collerson et al., 1991; Bennett et al., 1993 Bennett et al., , 2007 Caro et al., 40 2005;Hiess et al., 2009) Polat et al., 2002; Polat & Hoffman, 2003; Jenner et al., 2009; 45 Nagel et al., 2012 Nutman Komiya et al., 1999), whole rock geochemistry signatures (e.g., 56Nutman Polat & Hofmann, 2003;Hoffmann et al., 2011a) and accurate 57 and precise absolute dates (particularly by U-Pb zircon methods) should be integrated 58 with the isotopic data (e.g., Bennett et al., 2007;Hoffmann et al., 2011b). 59Consequently, a multidisciplinary data set offers the best constraints on the 60 geodynamic setting of crust formation and provides insight into the meaning of 61 changing palaeogeographic settings (such as marine transgressions and regressions). In 62 this paper we follow this holistic approach, and apply it to the c. 3700 Ma portion of 63 the Isua supracrustal belt (West Greenland; Fig. 1 the Anshan area of northeastern China; for summaries of these see Schiøtte et al., 79 1989; Nutman et al., 1991Nutman et al., , 1996Kinny & Nutman, 1996; Bowring & Williams, 1999; 80 Iizuka et al., 2007;Liu et al., 2007;O'Neil et al., 2007 andHorie et al., 2010 Archaean (Friend et al., 1987(Friend et al., , 1988 Nutman et al., 1989, Nutman & Friend, 2007 97 Crowley, 2002; Friend & Nutman, 2005b components can be sampled separately (e.g., Baadsgaard et al., 1986a; Nutman et al., 107 1996 Nutman et al., 107 , 1999 Friend et al., 2002;Crowley et al., 2002;Polat et al., 2002; Polat & 108 Ho...

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“…Y aún en este registro tan antiguo, potenciales biofirmas (carbonatos precipitados biogénicamente) pudieran estar presentes (Nutman et al, 2010), lo cual sugiere que la biósfera podría ser varios millones de años más antigua que los estromatolitos y microfósiles más antiguos conocidos (~3500 Ma). Otras biofirmas putativas de más de 3500 Ma (glóbulos grafitizados asociados a apatita; ver McKeegan et al, 2007;Papineau et al, 2010aPapineau et al, , 2010b son también polémicas (véase Myers, 2001;van Zuilen et al, 2002;Fedo y Whitehouse, 2002;Papineau et al, 2011) dada su dudoso tiempo de formación, que pudo ser más reciente. Firmas biológicas de particular interés son las asociadas a las llamadas Banded Iron Formations (i.e.…”

Section: El Escenario De La Vida Tempranaunclassified

La vida temprana en la Tierra y los primeros ecosistemas terrestres

Beraldi-Campesi¹

2014

BSGM

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La vida temprana en la Tierra y los primeros ecosistemas terrestres 65 ResumenLos ecosistemas terrestres han sido considerados tradicionalmente como superficies dominadas por plantas, cuyos primeros registros datan del Fanerozoico temprano (< 550 Ma/millones de años). Sin embargo, la presencia de componentes biológicos mucho más antiguos que las plantas en hábitats tan distintos como suelos, turberas, estanques, lagos, arroyos y dunas, sugiere que los ecosistemas terrestres comenzaron a existir en la Tierra hace al menos 2700 Ma. Los microbios fueron abundantes hace ~3500 Ma y sin duda se adaptaron a vivir en condiciones subaéreas, en entornos intermareales y en zonas áridas y semiáridas, como lo hacen actualmente los microbios terrestres, y que tienen una enorme y rápida capacidad de adaptación a condiciones cambiantes. Todo ello está respaldado por el registro fósil. No obstante, esta evidencia es inusual e indirecta en comparación con fósiles de ambientes marinos, superficiales o profundos, y su registro ha sido poco atendido. En consecuencia, la noción de que fueron comunidades microbianas las que formaron los primeros ecosistemas terrestres no ha sido ampliamente difundido ni incorporado conceptualmente en la sociedad. Hoy conocemos un amplio registro fósil de biota marina somera y lacustre a partir de los ~3500 Ma, así como microbios colonizando ambientes costeros desde hace ~3450 Ma y evidencia indirecta de actividad biológica en paleosuelos de > 3400 Ma de edad. El tipo de ambientes, de donde proviene esta evidencia, sugiere que la vida terrestre se produjo casi en paralelo con la vida acuática en el Arqueano. Las rápidas adaptaciones observadas en microbios actuales, su excepcional tolerancia a condiciones extremas y fluctuantes, su rápida y temprana diversificación y su antiguo registro fósil, indican que los primeros ecosistemas terrestres fueron exclusivamente microbianos. Es factible que los microbios contribuyeran en la formación de los primeros suelos donde las plantas se desarrollaron más tarde. Comprender cómo la vida se diversificó y adaptó a las condiciones terrestres es fundamental para entender su impacto en los sistemas terrestres durante millones de años. Beraldi-Campesi 66 661. Introducción Definición de terrestreLos ambientes terrestres seguramente han existido a través de toda la historia geológica de la Tierra a menos que su superficie estuviera permanentemente bajo el agua, lo cual no es aceptablemente realista. La definición de 'terrestre' no es tan trivial como parece. Aunque aquí se define como un ambiente 'no acuático', la distinción entre lo marino y lo terrestre atraviesa un amplio espectro de ambientes transicionales, donde lo acuático y lo no-acuático evolucionan y superponen en el tiempo. Comúnmente se entiende que un entorno terrestre (sobre el nivel del mar), puede incluir ambientes acuáticos (lagos cubiertos o no de hielo, lagunas y humedales, turberas, ríos y arroyos, campos geotérmicos) y no-acuáticos (especialmente zonas con poca lluvia). Estos hábitats pueden experimen...

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Protoliths of the 3.8–3.7 Ga Isua greenstone belt, West Greenland

Cited by 156 publications

References 25 publications

Iron Formation: The Sedimentary Product of a Complex Interplay among Mantle, Tectonic, Oceanic, and Biospheric Processes

Iron Formation: The Sedimentary Product of a Complex Interplay among Mantle, Tectonic, Oceanic, and Biospheric Processes

The emergence of the Eoarchaean proto-arc: evolution of a c. 3700 Ma convergent plate boundary at Isua, southern West Greenland

La vida temprana en la Tierra y los primeros ecosistemas terrestres

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