Determination of Thermal Alteration Index from color of exinite (pollen, spores)

Staplin, Frank L.

doi:10.2110/scn.82.07.0007

Cited by 22 publications

(8 citation statements)

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“…The described angiosperm-like pollen grains are very rare, representing <1% of the pollen counts. In the studied sections palynomorphs are well preserved and show no sign of thermal alteration (Thermal Alteration Index <2; Staplin, 1982); however, they are strongly compressed. Contamination of the samples can be excluded since recent pollen grains would be three-dimensionally preserved and the described pollen types differ from superficially similar grains from Cretaceous and younger sediments.…”

Section: Methodsmentioning

confidence: 87%

Angiosperm-like pollen and Afropollis from the Middle Triassic (Anisian) of the Germanic Basin (Northern Switzerland)

Hochuli¹,

Feist-Burkhardt²

2013

Front. Plant Sci.

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Here we report on angiosperm-like pollen and Afropollis from the Anisian (Middle Triassic, 247.2–242.0 Ma) of a mid-latitudinal site in Northern Switzerland. Small monosulcate pollen grains with typical reticulate (semitectate) sculpture, columellate structure of the sexine and thin nexine show close similarities to early angiosperm pollen known from the Early Cretaceous. However, they differ in their extremely thin inner layer (nexine). Six different pollen types (I–VI) are differentiated based on size, reticulation pattern, and exine structure. The described pollen grains show all the essential features of angiosperm pollen. However, considering the lack of a continuous record throughout the lower part of the Mesozoic and the comparison with the oldest Cretaceous finds we suggest an affinity to an angiosperm stem group. Together with the previously published records from the Middle Triassic of the Barents Sea area the angiosperm-like pollen grains reflect a considerable diversity of the parent plants during the Middle Triassic. Sedimentological evidence and associated palynofloras also suggest a remarkable ecological range for these plants. Associated with these grains we found pollen comparable to the genus Afropollis. Representatives of this genus are commonly recorded in Lower Cretaceous sediments of low latitudes, but until now had no record from the lower part of the Mesozoic.

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Section: Methodsmentioning

confidence: 87%

Angiosperm-like pollen and Afropollis from the Middle Triassic (Anisian) of the Germanic Basin (Northern Switzerland)

Hochuli¹,

Feist-Burkhardt²

2013

Front. Plant Sci.

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“…Individual specimens do not exhibit any obvious signs of post-depositional degradation. Thermally unaltered conditions of the organic matter (OM) are indicated by the virtually unchanged colouring of the palynomorphs with a thermal alteration index (TAI) <2 after Staplin (1982) as well as by moderate to strong UV fluorescence of the amorphous organic matter (AOM).…”

Section: Palynology and Palynofacies Analysismentioning

confidence: 99%

Coastal sediments from the Algarve: low-latitude climate archive for the Aptian-Albian

Heimhofer

Adatte

Hochuli

et al. 2007

Int J Earth Sci (Geol Rundsch)

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The Late Aptian to Early Albian transition has previously been identified as a possible example of substantial climate cooling within the mid-Cretaceous greenhouse period. To study the response of continental weathering and terrestrial vegetation to this cooling episode at low-to mid-latitudes, marine nearshore deposits from the Algarve Basin (SW Portugal) have been investigated with a combined approach including palynology, clay mineralogy and bulk-rock geochemistry. In the Lower Aptian part of the succession, quartz-rich sandstone facies is accompanied by high abundances of early diagenetic kaolinite, which is interpreted to reflect episodes of enhanced humidity and high meteoric flow-through. In contrast, the Late Aptian to Early Albian deposits are characterized by high abundances of detrital clay minerals (mica and chlorite) indicating the dominance of physical weathering processes in the source area, most probably related to low precipitation rates in conjunction with tectonically enhanced erosion. Palynological data show a strong dominance of Classopollis pollen associated with low pteridophyte spore abundances, suggesting warm semi-arid to arid palaeoenvironments. Changes in sedimentation patterns from varicoloured lagoonal marls to thick-bedded shallow-water carbonates are neither expressed in the spore-pollen assemblages nor in the distributions of clay minerals which both remain essentially stable throughout the Late Aptian to Early Albian. These relatively stable patterns are in contrast with various lines of evidence, predominantly from high-latitude areas, that suggest a significant cooling during this time interval. Our study demonstrates that terrestrial environments of low-to mid-latitude regions were not significantly affected by the Late Aptian -Early Albian ''cold snap''.

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“…Thermally immature conditions of sedimentary organic matter derived from the Crato Formation have been reported by Baudin & Berthou (1996) based on pyrolysis data. The colour of palynomorphs (thermal alteration index <2 after Staplin, 1982) and the occurrence of intact, thin‐walled angiosperm pollen provide further evidence for the generally low degree of thermal alteration and exclude deep burial of these deposits. These observations are in line with the results from petrographic inspection of the Nova Olinda laminites.…”

Section: Interpretation and Discussionmentioning

confidence: 92%

Deciphering the depositional environment of the laminated Crato fossil beds (Early Cretaceous, Araripe Basin, North-eastern Brazil)

Heimhofer¹,

Ariztegui

Lenniger³

et al. 2010

Sedimentology

102

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The laminated limestones of the Early Cretaceous Crato Formation of the Araripe Basin (North-eastern Brazil) are world-famous for their exceptionally well-preserved and taxonomically diverse fossil fauna and flora. Whereas the fossil biota has received considerable attention, only a few studies have focused on the sedimentary characteristics and palaeoenvironmental conditions which prevailed during formation of the Crato Fossil Lagerstä tte. The Nova Olinda Member represents the lowermost and thickest unit (up to 10 m) of the Crato Formation and is characterized by a pronounced rhythmically bedded, pale to dark lamination. To obtain information on palaeoenvironmental conditions, sample slabs derived from three local stratigraphic sections within the Araripe Basin were studied using highresolution multiproxy techniques including detailed logging, petrography, l-XRF scanning and stable isotope geochemistry. Integration of lithological and petrographic evidence indicates that the bulk of the Nova Olinda limestone formed via authigenic precipitation of calcite from within the upper water column, most probably induced and/or mediated by phytoplankton and picoplankton activity. A significant contribution from a benthonic, carbonate-secreting microbial mat community is not supported by these results. Deposition took place under anoxic and, at least during certain episodes, hypersaline bottom water conditions, as evidenced by the virtually undisturbed lamination pattern, the absence of a benthonic fauna and by the occurrence of halite pseudomorphs. Input of allochthonous, catchmentderived siliciclastics to the basin during times of laminite formation was strongly reduced. The d18 O values of authigenic carbonate precipitates (between )7AE1 and )5AE1&) point to a 18 O-poor meteoric water source and support a continental freshwater setting for the Nova Olinda Member. The d13 C values, which are comparatively rich in 13 C (between )0AE1 and +1AE9&), are interpreted to reflect reduced throughflow of water in a restricted basin, promoting equilibration with atmospheric CO 2 , probably in concert with stagnant conditions and low input of soil-derived carbon. Integration of lithological and isotopic evidence indicates a shift from closed to semi-closed conditions towards a more open lake system during the onset of laminite deposition in the Crato Formation.

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Determination of Thermal Alteration Index from color of exinite (pollen, spores)

Cited by 22 publications

References 0 publications

Angiosperm-like pollen and Afropollis from the Middle Triassic (Anisian) of the Germanic Basin (Northern Switzerland)

Angiosperm-like pollen and Afropollis from the Middle Triassic (Anisian) of the Germanic Basin (Northern Switzerland)

Coastal sediments from the Algarve: low-latitude climate archive for the Aptian-Albian

Deciphering the depositional environment of the laminated Crato fossil beds (Early Cretaceous, Araripe Basin, North-eastern Brazil)

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