Serpentines Close-Up and Intimate: An HRTEM View

Dódony, István; Buseck, Peter R.

doi:10.2747/0020-6814.46.6.507

Cited by 48 publications

(31 citation statements)

References 67 publications

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“…HRTEM studies on ion-thinned sections reveal a complex pattern of ordered lizardite intergrown with a minor amount of curled TO-layers (Fig. 3a) as already reported from other localities (Dódony & Buseck, 2004). Stacking defects and intercalation of 1T and 2H polytypes are common (Fig.…”

Section: Characteristics Of the Sample Materialsmentioning

confidence: 53%

Dehydroxylation kinetics of lizardite

Trittschack¹,

Grobéty²

2012

ejm

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Abstract:The thermally induced dehydroxylation of lizardite and its phase transformation to forsterite were studied by hightemperature X-ray diffraction (HT-XRD), thermogravimetry (TGA) and Fourier-transformed infrared spectroscopy (FTIR). Primary sample characteristics like chemical composition and crystallographical structure were determined by combined (HR)TEM-EDX, electron-microprobe analyses (EMPA) as well as conventional X-ray diffraction (XRD). Isothermal HT-XRD and non-isothermal TGA data were treated with the classical Avrami-Erofe'ev method and more advanced isoconversional methods in order to obtain kinetic data of a multi-step decomposition reaction. A highly precise activation energy E a versus reaction progress (a) dependency based on non-isothermal TGA data of lizardite is provided and associated mechanisms are discussed. Here, the main focus is on recently published ab initio calculations from the phase transformation of other phyllosilicates. Moreover, the calculated overall apparent activation energy is compared with discrepant data from the literature and discussed. Especially, the usability of overall activation energies of multi-step decomposition reactions is critically discussed. The presented and discussed reaction steps of water formation from different hydroxyl species in lizardite can be used to improve ab initio calculations, especially the pre-selection of reacting hydroxyl species in hydrous sheet like minerals.

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Section: Characteristics Of the Sample Materialsmentioning

confidence: 53%

Dehydroxylation kinetics of lizardite

Trittschack¹,

Grobéty²

2012

ejm

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“…Serpentinites by definition contain a significant amount of serpentine group minerals, and other volumetrically minor products that form during the hydration process (e.g., brucite and magnetite) . Serpentine minerals are hydrous phyllosilicates and have the theoretical formula Mg 3 Si 2 O 5 (OH) 4 . The three main forms of serpentine—lizardite, chrysotile, and antigorite—are widely found in natural samples, and two other intermediate serpentine varieties (polygonal serpentine and polyhedral serpentine) are less frequently reported …”

Section: Introductionmentioning

confidence: 99%

Submicron Raman spectroscopy mapping of serpentinite fault rocks

Rooney

Tarling

Smith

et al. 2017

J Raman Spectroscopy

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Submicron Raman spectroscopy mapping is able to unambiguously distinguish the main serpentine minerals within their in situ microstructural context. The high spatial resolution (~370 nm), large‐area coverage (up to hundreds of micrometres in each dimension), and ability to map directly on polished thin sections allows novel interpretations to be made regarding the nature and evolution of serpentinite fault rock textures. The potential of this method is illustrated by examining submicron‐scale textures of scaly serpentinites (e.g., dissolution seams, mineral growth in pressure shadows, distribution, and intergrowth of serpentine minerals) from a lithospheric‐scale shear zone in New Zealand and a subduction‐related serpentinite body in California, USA.

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“…3A). Pore formation is likely the result of several factors such as imperfect packing of randomly orientated serpentine grains as typically observed in serpentinite mesh cores (22), chrysotile nanopores (22,23), prolonged exposure to upwelling subduction zone fluids inducing mineral dissolution, and/or decompression cracking during upward migration along faults or within the mud volcano conduit. Mesh rims are typically characterized by fewer, micrometer-sized pores ( Fig.…”

Section: Serpentinite Clasts From the South Chamorro Mud Volcanomentioning

confidence: 99%

Subduction zone forearc serpentinites as incubators for deep microbial life

Plümper

Geisler

et al. 2017

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

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Serpentinization-fueled systems in the cool, hydrated forearc mantle of subduction zones may provide an environment that supports deep chemolithoautotrophic life. Here, we examine serpentinite clasts expelled from mud volcanoes above the Izu-BoninMariana subduction zone forearc (Pacific Ocean) that contain complex organic matter and nanosized Ni-Fe alloys. Using time-of-flight secondary ion mass spectrometry and Raman spectroscopy, we determined that the organic matter consists of a mixture of aliphatic and aromatic compounds and functional groups such as amides. Although an abiotic or subduction slab-derived fluid origin cannot be excluded, the similarities between the molecular signatures identified in the clasts and those of bacteria-derived biopolymers from other serpentinizing systems hint at the possibility of deep microbial life within the forearc. To test this hypothesis, we coupled the currently known temperature limit for life, 122°C, with a heat conduction model that predicts a potential depth limit for life within the forearc at ∼10,000 m below the seafloor. This is deeper than the 122°C isotherm in known oceanic serpentinizing regions and an order of magnitude deeper than the downhole temperature at the serpentinized Atlantis Massif oceanic core complex, MidAtlantic Ridge. We suggest that the organic-rich serpentinites may be indicators for microbial life deep within or below the mud volcano. Thus, the hydrated forearc mantle may represent one of Earth's largest hidden microbial ecosystems. These types of protected ecosystems may have allowed the deep biosphere to thrive, despite violent phases during Earth's history such as the late heavy bombardment and global mass extinctions.deep biosphere | serpentinization | subduction zone | forearc

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Serpentines Close-Up and Intimate: An HRTEM View

Cited by 48 publications

References 67 publications

Dehydroxylation kinetics of lizardite

Dehydroxylation kinetics of lizardite

Submicron Raman spectroscopy mapping of serpentinite fault rocks

Subduction zone forearc serpentinites as incubators for deep microbial life

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