Silica diagenesis: origin of inorganic and replacement cherts

Hesse, Reinhard

doi:10.1016/0012-8252(89)90024-x

Cited by 237 publications

(138 citation statements)

References 52 publications

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“…An example of mineral diagenesis that alters chert deposits with time is the transformation of primary opaline silica phases to microcrystalline quartz varieties through intermediary cryptocrystalline opal phases (Hesse, 1989). Recrystallization of primary aqueous mineral matrices often obliterates the fine-scale morphological features of microfossils, which are finer than the minimum grain size of the predominant diagenetic phase (e.g., microquartz by definition has an average grain size of 5-20 mm).…”

Section: Mineral and Biomolecule Diagenesismentioning

confidence: 99%

Morphological Biosignatures and the Search for Life on Mars

et al. 2003

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This report provides a rationale for the advances in instrumentation and understanding needed to assess claims of ancient and extraterrestrial life made on the basis of morphological biosignatures. Morphological biosignatures consist of bona fide microbial fossils as well as microbially influenced sedimentary structures. To be recognized as evidence of life, microbial fossils must contain chemical and structural attributes uniquely indicative of microbial cells or cellular or extracellular processes. When combined with various research strategies, high-resolution instruments can reveal such attributes and elucidate how morphological fossils form and become altered, thereby improving the ability to recognize them in the geological record on Earth or other planets. Also, before fossilized microbially influenced sedimentary structures can provide evidence of life, criteria to distinguish their biogenic from non-biogenic attributes must be established. This topic can be advanced by developing process-based models. A database of images and spectroscopic data that distinguish the suite of bona fide morphological biosignatures from their abiotic mimics will avoid detection of false-positives for life. The use of high-resolution imaging and spectroscopic instruments, in conjunction with an improved knowledge base of the attributes that demonstrate life, will maximize our ability to recognize and assess the biogenicity of extraterrestrial and ancient terrestrial life.

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Section: Mineral and Biomolecule Diagenesismentioning

confidence: 99%

Morphological Biosignatures and the Search for Life on Mars

et al. 2003

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“…The silica concentration of the pore fl uids, the chemical environment of the silicification, and the relative timing of the silicifi cation with respect to the other diagenetic events that affect the carbonate host rocks can be ascertained (Hesse, 1990).…”

Section: Introductionmentioning

confidence: 99%

Dolomitization and silicification in low-energy lacustrine carbonates (Paleogene, Madrid Basin, Spain)

Bustillo

Arribas

2002

Sedimentary Geology

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Repetitive sequences of carbonate deposits, occurrence include in the lower part of the Paleogene Carbonate Unit (northeast border of the Madrid Basin), have been studied, defining regressive lacustrine sequences and early diagenetic processes.Binocular microscopic examination, scanning electron microscopic/energy dispersive X-ray observations, and X-ray diffi-action analyses joint to isotopic studies dolomite precipitating -waters. The cherts included in palustrine limestones show j180 values of quartz that record more evaporated waters than those of the general stages of silicification.

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“…In this way, the local hydrogeological conditions are created, in a relatively confined environment, for the start of silicification. In littoral lacustrine environments with greater biological productivity, in which these hydrological conditions arise, the continual arrival of organic matter also contributes to a decrease in the pH of the diagenetic aqueous solutions (Siever 1962), favouring the precipitation of silica and increasing the solubility of calcite (Hesse 1989).…”

Section: Uranium Contentmentioning

confidence: 99%

The chert from the Castelltallat Formation (south-central Pyrenees): archaeometric characterisation and archaeological implications

Ortega

Pau

Ibáñez

et al. 2017

Archaeol Anthropol Sci

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Chert from the limestones and marly limestones of Castelltallat Formation (Ebro Basin) was widely used throughout prehistoric times in north-eastern Iberia to produce stone tools due to its properties and accessibility.A rough estimate indicates that this rock -either as raw material or as lithic products-was distributed mainly to the north of the outcrops, over an area of 6000-8000km 2 . However, other rocks in the area have similar characteristics which can lead to confusion in the interpretation of its prehistoric use and distribution. In order to establish useful archaeometric criteria for differentiating this chert from other similar, the Castelltallat chert is characterised in petrographic, mineralogical and geochemical terms.The chert nodules are found to be homogenous at the macro-and microscopic level, with a significant presence of bioclasts, thus indicating they might be formed in a freshwater lake environment by the early diagenetic replacement of carbonates in shallow waters. The mineralogical composition is homogeneously uniform and of a flint type, characterised by an almost exclusive predominance of quartz, without any opaline phases, and a variable proportion of moganite. The iron oxide content is very low, whereas its chemical composition is unusually high in uranium which correlates positively with carbonate content and negatively with silica.Archaeometrical parameters are provided to reach a proper identification of tools knapped with this chert. This way, chert from Castelltallat Formation turns out to be a valuable lithological marker to evaluate the range of mobility of the human groups who lived in the north-eastern Iberia and their contacts with neighbouring areas.

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Silica diagenesis: origin of inorganic and replacement cherts

Cited by 237 publications

References 52 publications

Morphological Biosignatures and the Search for Life on Mars

Morphological Biosignatures and the Search for Life on Mars

Dolomitization and silicification in low-energy lacustrine carbonates (Paleogene, Madrid Basin, Spain)

The chert from the Castelltallat Formation (south-central Pyrenees): archaeometric characterisation and archaeological implications

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