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Integrated biostratigraphy of the Jurassic strata of the Wagad Uplift, Kachchh, western India

Rai J., Garg S., Gupta M., Singh A., Pandey D. K., Fürsich F. T., Alberti M., Garg R.

Volumina Jurassica

2015

Vol. 13, no. 2

55--80

An integrated study based on calcareous nannofossils, organic-walled dinoflagellate cysts, and ammonites from the Washtawa and Kanthkot formations of the Wagad Uplift have allowed a detailed documentation of the stratigraphic position of these formations within the Oxfordian and Kimmeridgian sediments of the Kachchh Basin, western India. The nannofossil assemblages from the lower part of the Nara Shale Member exposed in the Nara and Washtawa domes, the Kanthkot Ammonite Beds along the Trambau River section, and the Patasar Shale Member exposed along the Trambau River section and the Patasar Tank section in the eastern part of the Wagad Uplift belong to the NJ 14 Cyclagelosphaera margerelli Zone of the Early Oxfordian, the NJ 15a Lotharingius sigillatus Zone of the Middle Oxfordian, and the NJ 15b Cretarhabdus conicus of Early Kimmeridgian age, respectively. Zonation schemes, based on calcareous nannofossils, dinoflagellate cysts, and ammonites were calibrated highlighting their biostratigraphic potential. These studies may represent a reference biochronology for Oxfordian–Kimmeridgian age strata applicable to the Tethyan realm of which India was a part during Late Jurassic times.

Thermally stimulated depolarization current investigations of copolyesteramide (Vectra B 950) polymer liquid crystal

Quamara J. K., Mahna S. K., Garg S.

Materials Science Poland

2010

Vol. 28, No. 3

679--691

Thermally stimulated depolarization current (TSDC) characteristics of copolyesteramide (Vectra B950), a polymer liquid crystal having a monomeric composition of 60/20/20 mol % of 6-hydroxy-2 -naphthoic acid (HNA), terethalic acid (TA) and 4-aminophenol (AP) were investigated in the tempera-ture range 20-250 °C in function of polarizing temperature (80-190 °C), polarizing field (2.77-13.88 kV/cm), polarization time (0.5-2 h) and storage time (1 - 100 h). The TSDC spectra in general comprise four maxima, namely ß', ß, ?, and ? with their respective locations around 30°C, 110 °C, 160 °C and 220 °C. The ß peak was attributed to the dipolar nature of the carbonyl group (> C = O) present in HNA and TA non liquid crystalline phase of Vectra B, whereas the ß' peak is due to the dipolar nature of the ester group. The ? peak was assigned to a space charge trapping mechanism. A major contribution towards ? relaxation comes from interfacial polarization arising from liquid crystalline phase inVectra B. A high temperature of the ? relaxation is associated with the onset of melting due to the movement of large segmental groups of liquid crystalline phase.