A new petrogenetic grid for low‐grade metabasites

Frey, Martin; Capitani, Christian de; Liou, J. G.

doi:10.1111/j.1525-1314.1991.tb00542.x

Cited by 230 publications

(171 citation statements)

References 41 publications

Supporting

Mentioning

146

Contrasting

Unclassified

Order By: Relevance

“…For both rock extracts and hydropyrolysates, the Carawine Dolomite hosted significantly higher concentrations of PAHs and diamondoids than the underlying Jeerinah Formation black shale samples. Like the PAHs and diamondoids that previous studies reported in Archean rock extracts and hydropyrolysates (3,21,24,28), the low molecular mass aromatics (≤C 16 ) predominate over high molecular mass PAHs (>C 16 …”

Section: Resultsmentioning

confidence: 97%

“…AIDP-2 and AIDP-3 recovered organicrich sedimentary rocks from the two zones of lowest regional metamorphism known in the Pilbara (15). According to previous studies of mineral assemblage and organic matter reflectivity, these zones are within the prehnite−pumpellyite metamorphic facies and anthracite coal rank, implying maximum burial temperatures and pressures of 200-300°C and <7 kbar (1 bar = 100 kPa), respectively (15)(16)(17)(18). Core AIDP-2 was drilled in the Ripon Hills region (21°16'51"S, 120°50'2"E) in the same locality as the RHDH2A core, which was recovered in 1985 using conventional…”

Section: Sample Collectionmentioning

confidence: 99%

See 1 more Smart Citation

Reappraisal of hydrocarbon biomarkers in Archean rocks

French

Hallmann

Hope

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

243

178

View full text Add to dashboard Cite

Hopanes and steranes found in Archean rocks have been presented as key evidence supporting the early rise of oxygenic photosynthesis and eukaryotes, but the syngeneity of these hydrocarbon biomarkers is controversial. To resolve this debate, we performed a multilaboratory study of new cores from the Pilbara Craton, Australia, that were drilled and sampled using unprecedented hydrocarbon-clean protocols. Hopanes and steranes in rock extracts and hydropyrolysates from these new cores were typically at or below our femtogram detection limit, but when they were detectable, they had total hopane (<37.9 pg per gram of rock) and total sterane (<32.9 pg per gram of rock) concentrations comparable to those measured in blanks and negative control samples. In contrast, hopanes and steranes measured in the exteriors of conventionally drilled and curated rocks of stratigraphic equivalence reach concentrations of 389.5 pg per gram of rock and 1,039 pg per gram of rock, respectively. Polycyclic aromatic hydrocarbons and diamondoids, which exceed blank concentrations, exhibit individual concentrations up to 80 ng per gram of rock in rock extracts and up to 1,000 ng per gram of rock in hydropyrolysates from the ultraclean cores. These results demonstrate that previously studied Archean samples host mixtures of biomarker contaminants and indigenous overmature hydrocarbons. Therefore, existing lipid biomarker evidence cannot be invoked to support the emergence of oxygenic photosynthesis and eukaryotes by ∼2.7 billion years ago. Although suitable Proterozoic rocks exist, no currently known Archean strata lie within the appropriate thermal maturity window for syngenetic hydrocarbon biomarker preservation, so future exploration for Archean biomarkers should screen for rocks with milder thermal histories.oxygenic photosynthesis | eukaryotes | cyanobacteria | Great Oxidation Event | Pilbara

show abstract

Section: Resultsmentioning

confidence: 97%

Section: Sample Collectionmentioning

confidence: 99%

Reappraisal of hydrocarbon biomarkers in Archean rocks

French

Hallmann

Hope

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

243

178

View full text Add to dashboard Cite

show abstract

“…The equilibrium assemblage diopside + anorthite + clinochlore (chl75) + H 2 O = tremolite + clinozoisite has an upper stability limit of approximately 430°-540°C at pressures of 0.5-5 kb ( Fig. 12; Connolly, 1990;Frey et al, 1991) and provides a minimum temperature estimate for the early hydrothermal alteration in the Site 895 gabbros. This range in temperatures is consistent with oxygen isotope fractionation temperatures for plagioclase-chlorite pairs (discussed above) and the temperature constraints deduced for the formation of antigorite, lizardite, chlorite, tremolite and talc in the ultramafic rocks.…”

Section: Metamorphism In the Mafic Rocks And Conditions Of Incipient mentioning

confidence: 99%

“…This range in temperatures is consistent with oxygen isotope fractionation temperatures for plagioclase-chlorite pairs (discussed above) and the temperature constraints deduced for the formation of antigorite, lizardite, chlorite, tremolite and talc in the ultramafic rocks. Experimental and thermodynamic data indicate that prehnite has a stability range of approximately 220°-420°C Frey et al, 1991;Connolly and Kerrick, 1985) and essentially overlaps the (poorly constrained) stability field of hydrogrossular (Yoder, 1950;Pistorius and Kennedy, 1960;Coleman, 1967). Phase equilibria in the pure CaO-MgO-Al 2 O 3 -SiO 2 -H 2 O system predicts that prehnite is stable at low pressures below the invariant point for quartz-clinozoisite-garnet-prehnite-H 2 O at 1.35 kb, 420°C, and that prehnite-forming reactions occur at distinctly lower temperatures than for tremolite-diopside-chlorite assemblages ( Fig.…”

Section: Metamorphism In the Mafic Rocks And Conditions Of Incipient mentioning

confidence: 99%

Petrologic and Stable Isotope Constraints on Hydrothermal Alteration and Serpentinization of the EPR Shallow Mantle at Hess Deep (Site 895)

Früh-Green¹,

Plas²,

Lécuyer³

1996

Proceedings of the Ocean Drilling Program

106

View full text Add to dashboard Cite

Leg 147 of the Ocean Drilling Program recovered sections of the East Pacific Rise lower crust and shallow mantle ( l Ma), tectonically exposed at the western end of the Cocos-Nazca propagator of the Hess Deep Rift Valley. These rocks record a polyphase history of hydrothermal alteration and provide new constraints on the depth and mechanisms of hydrothermal circulation at fast-spreading ridges. A complex sequence of harzburgite-dunite-troctolite-gabbro recovered at Site 895 is considered to be the result of processes of melt migration and wall-rock reaction close to the mantle/crust boundary. The peridotites are extensively serpentinized (50%-100%) and are cut by multiple generations of fracture-filling veins. In the gabbros, progressive alteration under greenschist to zeolite facies conditions is characterized by tremolite + chlorite + diopside + anorthjte ± prehnite assemblages in the least altered samples, and incipient rodingitization to prehnite + hydrogrossular + zeolite + clays as Cataclastic deformation and veining increases.Oxygen isotope ratios of mineral separates from the gabbros and peridotites from Site 895 show a depletion in I8O relative to mantle values and are consistent with high-temperature exchange with aqueous fluids. Dunite/harzburgite ratios of chlorite, serpentine, and tremolite, together with δ' 3 C values of CO 2 extracted from completely serpentinized dunites, suggest at least two, but possibly three, components of the hydrothermal fluids: hydrothermally altered seawater; magmatic volatiles; and H 2 released during serpentinization. These data combined with structural data imply that penetration of seawater and high-temperature hydrothermal alteration produced a low 18 O shallow mantle sequence at some distance off-axis of the East Pacific Rise, but at an early stage in the propagation of the Cocos-Nazca rift and formation of the Hess Deep Rift Valley. Mineral assemblages in the gabbroic rocks and the presence of antigorite at Hess Deep, combined with oxygen isotope ratios, suggest that faulting associated with the Cocos-Nazca propagator enhanced seawater penetration and hydrothermal alteration at temperatures above 350°C in this segment of the East Pacific Rise oceanic lithosphere. The results of this study suggest that seawaterperidotite interactions and high-temperature serpentinization processes may be an important contribution to the overall 18 Obudget in the oceanic lithosphere nd may represent a significant sink for mantle CO 2 and source of H 2 .

show abstract

“…In particular, the late prehnite-bearing veins indicate the final M 5 stage occurred at temeprature between 200 and 280 • C for pressure less than 0.3 GPa. Furthermore, presence of wairakite-free zeolitic assemblages (heulandite) poses an upper limit for the temperature and pressure conditions during M 5 (T < 250 • C and P < 0.2 GPa; Frey et al, 1991).…”

Section: -To-m 5 Stagementioning

confidence: 99%

Metamorphic history and geodynamic significance of the Early Cretaceous Sabzevar granulites (Sabzevar structural zone, NE Iran)

et al. 2011

View full text Add to dashboard Cite

Abstract. The Iranian ophiolites are part of the vast orogenic suture zones that mark the Alpine-Himalayan convergence zone. Few petrological and geochronological data are available from these ophiolitic domains, hampering a full assessment of the timing and regimes of subduction zone metamorphism and orogenic construction in the region. This paper describes texture, geochemistry, and the pressuretemperature path of the Early Cretaceous mafic granulites that occur within the Tertiary Sabzevar ophiolitic suture zone of NE Iran. Whole rock geochemistry indicates that the Sabzevar granulites are likely derived from a MORB-type precursor. They are thus considered as remnants of a dismembered dynamo-thermal sole formed during subduction of a back-arc basin (proto-Sabzevar Ocean) formed in the upper-plate of the Neotethyan slab. The metamorphic history of the granulites suggests an anticlockwise pressuretemperature loop compatible with burial in a hot subduction zone, followed by cooling during exhumation. Transition from a nascent to a mature stage of oceanic subduction is the geodynamic scenario proposed to accomplish for the reconstructed thermobaric evolution. When framed with the regional scenario, results of this study point to diachronous and independent tectonic evolutions of the different ophiolitic domains of central Iran, for which a growing disparity in the timing of metamorphic equilibration and of pressuretemperature paths can be expected to emerge with further investigations.

show abstract

A new petrogenetic grid for low‐grade metabasites

Cited by 230 publications

References 41 publications

Reappraisal of hydrocarbon biomarkers in Archean rocks

Reappraisal of hydrocarbon biomarkers in Archean rocks

Petrologic and Stable Isotope Constraints on Hydrothermal Alteration and Serpentinization of the EPR Shallow Mantle at Hess Deep (Site 895)

Metamorphic history and geodynamic significance of the Early Cretaceous Sabzevar granulites (Sabzevar structural zone, NE Iran)

Contact Info

Product

Resources

About