Vitrinite reflectance, illite crystallinity and tectonics: results from the Northern Apennines (Italy)

Reinhardt, M.

doi:10.1016/0146-6380(91)90075-u

Cited by 11 publications

(9 citation statements)

References 4 publications

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“…The T conditions of the metamorphic peak estimated in this study with different methods are coherent with those reported in previous studies where the T is regarded as ranging from 230 to 300°C (Ellero et al, 2001;Leoni et al, 1996;Reinhardt, 1991;Venturelli & Frey, 1977). The P conditions in the range from 0.6 to 0.9 GPa are the first quantitative geobaric estimates for the IL units Similarly, a deformation of the IL units in a transpressional zone is also unlikely.…”

Section: Discussion and Con Clus I Onsupporting

confidence: 91%

Subduction signature in the Internal Ligurian units (Northern Apennine, Italy): Evidence from P–T metamorphic peak estimate

Meneghini,

Di Rosa,

Marroni

et al. 2023

Terra Nova

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The Internal Ligurian units (Northern Apennine) represent deformed and metamorphosed fragments of the oceanic lithosphere of the Ligure–Piemontese oceanic basin. Different tectonic models have been proposed for the geodynamic setting in which the deformation and metamorphism have been acquired. However, the lack of updated, clear, thermo‐barometric data has made it hard to unambiguously discriminate between these different proposed models. In this article, we provide evidence for the deformation of the Palombini Shale, i.e., pelagic deposits belonging to the Internal Ligurian units, under P and T peak conditions of 230–300°C. and 0.6–0.9 GPa, respectively. These data indicate that the Internal Ligurian units were affected by a blueschist facies metamorphism achieved during the underplating within the accretionary wedge developed during the Late Cretaceous—Early Tertiary Alpine subduction. These data support the hypothesis of a unique, pre‐Oligocene orogenic system for the Alpine belt and the westernmost sector of the Northern Apennines belt.

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Section: Discussion and Con Clus I Onsupporting

confidence: 91%

Subduction signature in the Internal Ligurian units (Northern Apennine, Italy): Evidence from P–T metamorphic peak estimate

Meneghini,

Di Rosa,

Marroni

et al. 2023

Terra Nova

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“…This stage also corresponds to the influence of stress (Bustin et al, 1995;Han et al, 2017;Wilks et al, 1993) on the studied anthracite samples. This observation is, further, supported by the study carried out by Reinhardt (1991) who suggested that the high amplitude of tectonic shear stress coupled with heating phase would enhance the parallel alignment of the aromatic lamellae inducing high bireflectance of the vitrinite grains. Taylor et al (1998) opined that the shearing plays effectively in promoting the maximum reflectance and anisotropy of the vitrinite grains, which, additionally, substantiate the enhanced bireflectance values observed in this work.…”

Section: Optical Anisotropy Of the Maceralssupporting

confidence: 61%

“…degree of bireflectance (Reinhardt, 1991), the strong correlation between the B w and R am parameters put an additional evidence on the optical transformations of the maceral grains in response to the deformation events of the Himalaya.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Petrographic and Raman spectroscopic characterization of coal from Himalayan fold-thrust belts of Sikkim, India

Ghosh

Rodrigues

Varma

et al. 2018

International Journal of Coal Geology

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The present study focuses on the investigation of the optical anisotropy, optical sign, textural heterogeneity and deformational features of the maceral grains along with the Raman spectral characteristics of the seven coal samples collected from the Himalayan fold-thrust belts of Sikkim State, India. The coal samples were extremely fragile and pulverized due to the intense tectonic deformation. The maceral composition revealed the dominance of semifusinite over collotelinite grains. The calculated maximum vitrinite reflectance (5.94 -8.66 %) and mean random reflectance (4.11 -5.36 %) suggest anthracite A rank of the coal samples following ISO 11760:2005. The proximity of the intermediate reflectance axis value (R INT ) to maximum reflectance axis value (R MAX ) as well as the range of Reflectance Indicating Surface (RIS) style (R st ) values (-9.98 to -19.37) indicates the biaxial negative optical texture of the vitrinite grains. The augmented bireflectance values due to enhancement of the R MAX associated with strong decline in R MIN may suggest the commencement of pregraphitization. In addition, the strong linear correlation (r = 0.94) of the RIS-anisotropy (R am ) parameter with the bireflectance values may imply the role of tectonic stress on the optical transformations of the samples. The range of the peak temperature (334.94 -369.01 ℃) calculated from mean random vitrinite reflectance may suggest the effect of thermo-stress coupling on the metamorphism of these coal samples. Microlithotype study combined with deformational aspects of macerals shows the presence of "deformed", "sheared" and "smashed" grains within each sample, which may, additionally, document the tectonic stress influence on the coal particles. Moreover, relatively, larger area of 'defect band 1 (D 1 )' than that of 'graphitic band (G)' along with the broad G band in the first order Raman spectra may indicate the considerable presence of structural dislocations and aromatic compounds with disordered bond angle within the microstructure induced by the tectonic deformation. The lowest intensity of the 'defect band 4 (D 4 )' may suggest the preferential removal of aliphatic compounds from the samples in response to the tectonic stress degradation. In addition, the relative area ratio calculated from the D 1 and the G bands (AD 1 /(AD 1 +AG)) may indicate that the studied anthracite samples would have attained the metamorphic temperature ranging from 325.12 -387.89 ℃.

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“…Mählmann (1995Mählmann ( , 1996 had ear lier emphasised the sig nif i cant role of heat ing and its du ra tion on coalification in the Alps of east ern Swit zer land. Reinhardt (1991) de scribed the vari abil ity of R r o val ues in nappes of the east ern Apennines. He in ter preted signs of graphitisation in ar eas with the great est es ti mated tem per atures (~300°C; R max 4-7%) as due to the fact that large rock units were first bur ied to a depth of ~5 km be fore be ing rap idly thrust over large dis tances.…”

Section: Carpathian Orogen and The Alpsmentioning

confidence: 99%

Organic-matter vitrinite reflectance variability in the Outer Carpathians, Poland: relationship to tectonic evolution

Zielińska

2016

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Zieliñska, M., 2017. Or ganic-mat ter vitrinite reflectance vari abil ity in the Outer Carpathians, Po land: re la tion ship to tec tonic evo lu tion. Geo log i cal Quar terly, 61 (1): 214-226, doi: 10.7306/gq.1338 Ran dom vitrinite reflectance of allochthonous plant ma te rial var ies through out all the flysch sed i men tary units of the Outer West ern Carpathians. The vitrinite reflectance of coalified phytogenic mat ter is vari able even within the same lithostratigraphic unit. There is no clear re la tion ship be tween ran dom vitrinite reflectance and stra tig ra phy (age of par tic u lar strata) within sur face sam ples. The typ i cal pat tern of in creas ing ran dom reflectance with depth in bore holes is un set tled by R r o "jumps" which oc cur within folds and overthrusts. How ever, this study re vealed a trend of in creas ing ran dom vitrinite reflectance from north to south in the area of the Magura Unit. A compressional re gime in volv ing phases of up lift and burial, vary ing from place to place in the flysch ba sin, was the main fac tor in flu enc ing coalification. The ini tial ma tu rity of or ganic mat ter trans ported to the ma rine en vi ron ment was a sec ond ary fac tor. A de gree of coalification had oc curred in the flysch sed i ments prior to the main stage of fold-and-thrust move ments as so ci ated with the phase of max i mum tec tonic sub si dence at the end of the Eocene. It is gen er ally as sumed that coalified plant ma te rial dis persed in sed i men tary rocks ex pe ri enced the same phys i cal and chem i cal changes as those in larger ac cu mu la tions of coal. Coalification of phytogenic ma te rial co eval with flysch in the Outer Carpathians cor re sponds to the in ter val from sub-bi tu mi nous to low-me dium-rank bi tu mi nous coal.

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Vitrinite reflectance, illite crystallinity and tectonics: results from the Northern Apennines (Italy)

Cited by 11 publications

References 4 publications

Subduction signature in the Internal Ligurian units (Northern Apennine, Italy): Evidence from P–T metamorphic peak estimate

Subduction signature in the Internal Ligurian units (Northern Apennine, Italy): Evidence from P–T metamorphic peak estimate

Petrographic and Raman spectroscopic characterization of coal from Himalayan fold-thrust belts of Sikkim, India

Organic-matter vitrinite reflectance variability in the Outer Carpathians, Poland: relationship to tectonic evolution

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