Mineralogy and geochemistry of hydrothermal sediments from the serpentinite-hosted Saldanha hydrothermal field (36°34′N; 33°26′W) at MAR

Dias, Ângelo José Burla; Barriga, Fernando J.A.S.

doi:10.1016/j.margeo.2005.07.013

Cited by 105 publications

(65 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Talc-rich fault rocks are particularly common on detachment surfaces where they localize shear stress during the tectonic uplift of Oceanic Core Complexes at slow-and ultraslow-spreading ridges (Escartín et al 2003;Boschi et al 2006b;MacLeod et al 2009). Similar rocks have been documented in (or near) oceanic fracture zones and within non-transform offset zones where ultramafic rocks are exposed on the seafloor (Kimball et al 1985;Bach et al 2004;D'Orazio et al 2004;Dias and Barriga 2006). In contrast to talc-schist in detachment faults, talc mimicking serpentinite mesh textures indicates that Si-metasomatism can proceed under static conditions ).…”

Section: Silica-metasomatism Of Seafloor Serpentinitesupporting

confidence: 57%

“…Dashed line marks pre-metasomatic contact between the rock body and the rock enclosing it the adjacent serpentinite. If fluid flow is massive, like in hydrothermal upflow zones, steatite pipes will develop such as seen in the basement underlying peridotite-hosted hydrothermal systems (Dias and Barriga 2006). Thus silicametasomatism can be infiltrational where the Si is derived from fluid rock-reactions outside the peridotite and transported along faults, or diffusional where metasomatic mass transport of silica is promoted along a geochemical potential gradient between contrasting lithologies.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Metasomatism Within the Ocean Crust

Bach

Jöns

Klein

2012

Lecture Notes in Earth System Sciences

View full text Add to dashboard Cite

From ridge to trench, the ocean crust undergoes extensive chemical exchange with seawater, which is critical in setting the chemical and isotopic composition of the oceans and their rocky foundation. Although the overall exchange fluxes are great, the first-order metasomatic changes of crustal rocks are generally minor (usually <10% relative change in major element concentrations). Drastic fluid-induced metasomatic mass transfers are limited to areas of very high fluid flux such as hydrothermal upflow zones. Epidotization, chloritization, and serizitization are common in these upflow zones, and they often feature replacive sulfide mineralization, forming significant metal accumulations below hydrothermal vent areas. Diffusional metasomatism is subordinate in layered (gabbroicdoleritic-basaltic) crust, because the chemical potential differences between the different lithologies are minor. In heterogeneous crust (mixed mafic-ultramafic lithologies), however, diffusional mass transfers between basaltic lithologies and peridotite are very common. These processes include rodingitization of gabbroic dikes in the lithospheric mantle and steatitization of serpentinites in contact to gabbroic intrusions. Drivers of these metasomatic changes are strong across-contact differences in the activities of major solutes in the intergranular fluids. Most of these processes take place under greenschist-facies conditions, where the differences in silica and proton activities in the fluids are most pronounced. Simple geochemical reaction path models provide a powerful tool for investigating these processes. Because the oceanic crust is hydrologically active throughout much of its lifetime, the diffusional metasomatic zones are commonly also affected by fluid flow, so that a clear distinction between fluid-induced and lithology-driven

show abstract

Section: Silica-metasomatism Of Seafloor Serpentinitesupporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Metasomatism Within the Ocean Crust

Bach

Jöns

Klein

2012

Lecture Notes in Earth System Sciences

View full text Add to dashboard Cite

show abstract

“…Metalliferous sediments are found in close association with mid-ocean ridges and seamounts and their distribution is widespread with known occurrences in the Red Sea (Pierret et al, 2010), along the East Pacific Rise (Barrett et al, 1987;Bodei et al, 2008;German et al, 1999;Sayles and Bischoff, 1973), along the Mid-Atlantic Ridge (Dias and Barriga, 2006;Dias et al, 2008;German et al, 1993), in the Indian Ocean (Bostrom, 1973), in the Gulf of California (Lonsdale et al, 1980) and on many seamounts (Mascarenhas-Pereira and Nath, 2010). Modern metalliferous sediments however, occur in locations with low…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Neoproterozoic iron formation: An evaluation of its temporal, environmental and tectonic significance

et al. 2013

View full text Add to dashboard Cite

Neoproterozoic iron formation (NIF) provides evidence for the widespread return of anoxic and ferruginous basins during a time period associated with major changes in climate, tectonics and biogeochemistry of the oceans. Here we summarize the stratigraphic context of Neoproterozoic iron formation and its geographic and temporal distribution. It is evident that most NIF is associated with the earlier Cryogenian (Sturtian) glacial epoch. Although it is possible that some NIF may be Ediacaran, there is no incontrovertible evidence to support this age assignment. The paleogeographic distribution of NIF is consistent with anoxic and ferruginous conditions occurring in basins within Rodinia or in rift-basins developed on its margins. Consequently NIF does not require whole ocean anoxia. Simple calculations using modern day iron fluxes suggest that only models that invoke hydrothermal and/or detrital sources of iron are capable of supplying sufficient iron to account for the mass of the larger NIF occurrences. This conclusion is reinforced by the available geochemical data that imply NIF record is a mixture of hydrothermal and detrital components. A common thread that appears to link most if not all NIF is an association with mafic volcanics.Word Count: 11,011

show abstract

“…These phyllosilicates are aluminum-rich and unlikely to be abundant in the primitive altered oceanic crust of the Hadean. The Hadean seafloor was mainly formed of mafic and ultramafic rocks, such as basalt, komatiite and peridotite, which hydrothermal alteration has been widely studied through (i) petrological and mineralogical observations of samples collected in oceanic hydrothermal settings (Alt and Honnorez, 1984;Buatier et al, 1993;Hunter et al, 1999;Buatier et al, 2001;Alt and Teagle, 2003;Dias and Barriga, 2006;Lackschewitz et al, 2006;Mas et al, 2008); (ii) experimental alteration of bulk rocks (Humphris, 1978;Mottl and Holland, 1978;Mottl et al, 1979;Seyfried and Bischoff, 1979;Seyfried and Dibble, 1980;Seyfried and Bischoff, 1981;Seyfried and Mottl, 1982;Marcaillou, 2011;Lazar et al, 2012); and (iii) mineral evolution (Hazen et al, 2008;Hazen and Sverjensky, 2010;Hazen, 2013;Hazen et al, 2013). All above studies suggested that Fe-Mg rich phyllosilicates along with various oxides, hydroxides, anhydrites and sulfides are the major alteration minerals formed.…”

Section: Introductionmentioning

confidence: 99%