Chronological and Archaeometric Evaluation of Bricks from Archaeological Sites of Upper Assam, Northeast India: Estimation of the Firing Temperature and Civilization History Raktim Ranjan Saikia, Chaitra Dhar Taye, Nurul Amin, Sorat Konwar, Laura Panzeri, Anna Galli Applied Sciences Switzerland, 2024 This study aimed to uncover the chronology and production technologies of ancient bricks unearthed from various locations in Upper Assam, Northeast India. To achieve this goal, complementary spectroscopic techniques such as Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) coupled with Energy Dispersive Spectrometer (EDS), as well as Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL/IRSL) dating, were applied. FTIR and XRD analyses revealed the presence of quartz, feldspar (microcline, orthoclase, albite), kaolinite, chlorite, cerussite, palygorskite, magnetite, hematite, and organic carbon. The mineralogical composition indicates two distinct groups with firing temperatures below 650 °C and above ~800 °C. These two groups could be the first indication of the presence of two civilizations or at least two different production technologies involving different firing temperatures and kiln atmospheric conditions. Further, the SEM-EDS study suggests that both calcareous and non-calcareous clays were used in brick making, which have low and high refractory properties, respectively. The internal morphology of the samples shows the existence of micropores and microfractures, indicating the influence of higher-temperature firing. Absolute dating techniques associate the two brick groups with different age ranges: a firing temperature above ~800 °C indicates a superior technology corresponding to a production period between the 7th and 10th centuries CE. In contrast, a temperature below 650 °C indicates a technologically less advanced group of people, with the age group dated between the 11th and 14th centuries CE.
Petrography and Geochemistry of the Lower Sylhet Sandstone Member (Therria Sandstone) of Jaintia Group Exposed Along Jowai-Badarpur Road Section, Jaintia Hills District, Meghalaya: Implication for Provenance and Palaeoclimate Ananya Chutia, Dimple Moni Kachari, Chaitra Dhar Taye Journal of the Geological Society of India, 2024 The Paleogene sediments of the Shillong Plateau are exposed in the southern part of Meghalaya and are designated as the Jaintia Group. The Lower Sylhet Sandstone Member (LSSM) (Therria Sandstone) is the lowermost member of the Shella Formation of Jaintia Group. To understand the depositional history of the studied sandstones, petrographic and geochemical approaches have been made. Petrographically, these sandstones are classified as quartz arenite and quartz wacke. They were derived from intermediate to upper rank metamorphic and plutonic source which were deposited in a craton interior and quartzose recycled tectonic setting. The paleoweathering indices of CIA, CIW, PIA and ICV indicate that the weathering at the provenance was intense. The tectonic discrimination diagrams suggest passive margin setting for their sedimentation and climatic condition during the deposition was humid in nature. The studied sediments were deposited in non-marine conditions as evidenced by the geochemical proxies and primary sedimentary structures existing in the LSSM.
Petrography and Clay Mineralogical Study of the Siwalik Group of Rocks Exposed along Pasighat-Mariyang Road Section, East Siang District, Arunachal Pradesh, Northeast India Ananya Chutia, Chaitra Dhar Taye, Jagriti Daimari, Debasish Chutia Journal of the Geological Society of India, 2020 Abstract The Neogene (Mio-Pliocene) molassic sediments occur as a linear belt along the foot hills of Arunachal Pradesh, are designated as the Siwalik Group. Petrography, heavy mineral and clay mineralogical characteristics of these rocks exposed along Pasighat-Mariyang road section, East Siang district, Arunachal Pradesh, India is presented here. These massive and well bedded rocks are detached from alluvium by HFT and remarkably from Yinkiong Group of rocks by MBT. The present study reveals the presence of lower as well as middle-upper Siwalik in the study area. Petrographic study of the sandstones has shown that these rocks are mainly sub-arkose and sub-lith-arenite with lithic and feldspathic greywacke in subordinate amount, which are medium to coarse grained and composed mainly of quartz, feldspar, mica and rock fragments as their detrital constituents. Argillaceous and siliceous matrix as well as argillaceous, carbonate and siliceous cement are binding the framework grains. These sediments were derived mainly from middle to upper grade metamorphic rocks. During deposition these rocks have undergone shallow depth as well as deeper level diagenesis and the climate prevailed was humid and tropical.
Provenance of the Yinkiong Group exposed along Pasighat-Mariyang Road section, East Siang District, Arunachal Pradesh: A petrographic, heavy mineral and clay mineralogical approach Indian Journal of Geosciences, 2019
