This study presents geochemical characteristics of glauconites in estuarine deposits within the Maastrichtian Lameta Formation in central India. Resting conformably over the Bagh Group, the Lameta Formation consists o...This study presents geochemical characteristics of glauconites in estuarine deposits within the Maastrichtian Lameta Formation in central India. Resting conformably over the Bagh Group, the Lameta Formation consists of ~4-5 m thick arenaceous, argillaceous and calcareous green sandstones underlying the Deccan Traps. The sandstone is friable, medium-to coarse-grained, well-sorted and thoroughly crossstratified, and contains marine fossils. Detailed petrography, spectroscopy and mineral chemistry indicates unique chemical composition of glauconite with high KO, MgO, AlOand moderate TFeO. Glauconite is formed by the replacement of K-feldspars, initially as stringers in the cleavages and fractures of feldspars. Incipient glauconite subsequently evolves fully, appearing as pellets. Fully-evolved glauconite pellets often leave tiny relics of K-feldspar. XRD exhibits characteristic peak of 10A from basal(001)reflection of glauconite, indicating the "evolved" character. The KO content of glauconites in the Lameta Formation varies from 5.51% to 8.29%, corroborating the "evolved" to "highly-evolved" maturation stage.The TFeOcontent of glauconite varies from 12.56% to 18.90%. The PASS-normalized-REE patterns of glauconite exhibit a "hat-shape" confirming the authigenic origin of glauconites. The slightly-negative to slightly-positive Ce anomaly value and the moderate TFeOcontent of glauconite agree well with a suboxic,estuarine condition. The replacement of K-feldspar by the glauconite contributes towards the high KO content. Compositional evolution of glauconites in the Lameta Formation is similar to those observed in many Precambrian sedimentary sequences.展开更多
Almost complete skulls of most derived titanosaurs which provide complete teeth row are rare. Saraikimasoom vitakri is the smallest sized, the most derived titanosaurian sauropod based on very small sized 15 - 18 cm l...Almost complete skulls of most derived titanosaurs which provide complete teeth row are rare. Saraikimasoom vitakri is the smallest sized, the most derived titanosaurian sauropod based on very small sized 15 - 18 cm long and 7 - 9 cm high partial skull. Dorsal profile of skull inclined 40°anteriorly. It provides full teeth row with dental formula 4, 13/9-13. Saraikimasoom is the smallest titanosaur so far found from Indo-Pakistan subcontinent. Its height is about 2 meter, length 8 - 10 meter and weight about 5 tons. Saraikimasoom vitakri shows Gondwanan paleobiogeographic link with some endemic elements.展开更多
Indo-Pakistan subcontinent is lucky to host the smallest, medium and large sized titanosaurian sauropod dinosaurs. Saraikimasoom is the smallest sized, and Gspsaurus is the medium sized transversely stocky, Pakisaurus...Indo-Pakistan subcontinent is lucky to host the smallest, medium and large sized titanosaurian sauropod dinosaurs. Saraikimasoom is the smallest sized, and Gspsaurus is the medium sized transversely stocky, Pakisaurus and Isisaurus are the large sized titanosaurs of South Asia. Pakisaurus balochistani is a slender type of pakisaurid titanosaurian based on associated vertebral and appendicular skeletons. Pakisaurus balochistani includes key elements like transversely thin or narrow tibia and ventrally not reduced tall caudal vertebrae, along with other elements which are significant for cladistic analysis.展开更多
Vitakrisaurus saraiki abelisauroid theropod dinosaurs reported from Pakistan and extended distribution into India. Vitakrisaurus saraiki is medium to large sized theropod which is represented by associated vertebral a...Vitakrisaurus saraiki abelisauroid theropod dinosaurs reported from Pakistan and extended distribution into India. Vitakrisaurus saraiki is medium to large sized theropod which is represented by associated vertebral and limb elements and especially hand elements. Out of 14 small to large bodied theropods from Indo-Pakistan subcontinent, only less than half of these are restricted to some common elements. Vitakrisaurus saraiki theropod of Pakistan is based on associated vertebral and limb elements especially hand including articulated carpals, metacarpals, phalanges and claws which are significant for Gondwanan paleobiogeographic link, comparisons and systematic.展开更多
基金Ministry of Mines, Government of India for financial support through grant F No. 14/77/2015Met. IV
文摘This study presents geochemical characteristics of glauconites in estuarine deposits within the Maastrichtian Lameta Formation in central India. Resting conformably over the Bagh Group, the Lameta Formation consists of ~4-5 m thick arenaceous, argillaceous and calcareous green sandstones underlying the Deccan Traps. The sandstone is friable, medium-to coarse-grained, well-sorted and thoroughly crossstratified, and contains marine fossils. Detailed petrography, spectroscopy and mineral chemistry indicates unique chemical composition of glauconite with high KO, MgO, AlOand moderate TFeO. Glauconite is formed by the replacement of K-feldspars, initially as stringers in the cleavages and fractures of feldspars. Incipient glauconite subsequently evolves fully, appearing as pellets. Fully-evolved glauconite pellets often leave tiny relics of K-feldspar. XRD exhibits characteristic peak of 10A from basal(001)reflection of glauconite, indicating the "evolved" character. The KO content of glauconites in the Lameta Formation varies from 5.51% to 8.29%, corroborating the "evolved" to "highly-evolved" maturation stage.The TFeOcontent of glauconite varies from 12.56% to 18.90%. The PASS-normalized-REE patterns of glauconite exhibit a "hat-shape" confirming the authigenic origin of glauconites. The slightly-negative to slightly-positive Ce anomaly value and the moderate TFeOcontent of glauconite agree well with a suboxic,estuarine condition. The replacement of K-feldspar by the glauconite contributes towards the high KO content. Compositional evolution of glauconites in the Lameta Formation is similar to those observed in many Precambrian sedimentary sequences.
文摘Almost complete skulls of most derived titanosaurs which provide complete teeth row are rare. Saraikimasoom vitakri is the smallest sized, the most derived titanosaurian sauropod based on very small sized 15 - 18 cm long and 7 - 9 cm high partial skull. Dorsal profile of skull inclined 40°anteriorly. It provides full teeth row with dental formula 4, 13/9-13. Saraikimasoom is the smallest titanosaur so far found from Indo-Pakistan subcontinent. Its height is about 2 meter, length 8 - 10 meter and weight about 5 tons. Saraikimasoom vitakri shows Gondwanan paleobiogeographic link with some endemic elements.
文摘Indo-Pakistan subcontinent is lucky to host the smallest, medium and large sized titanosaurian sauropod dinosaurs. Saraikimasoom is the smallest sized, and Gspsaurus is the medium sized transversely stocky, Pakisaurus and Isisaurus are the large sized titanosaurs of South Asia. Pakisaurus balochistani is a slender type of pakisaurid titanosaurian based on associated vertebral and appendicular skeletons. Pakisaurus balochistani includes key elements like transversely thin or narrow tibia and ventrally not reduced tall caudal vertebrae, along with other elements which are significant for cladistic analysis.
文摘Vitakrisaurus saraiki abelisauroid theropod dinosaurs reported from Pakistan and extended distribution into India. Vitakrisaurus saraiki is medium to large sized theropod which is represented by associated vertebral and limb elements and especially hand elements. Out of 14 small to large bodied theropods from Indo-Pakistan subcontinent, only less than half of these are restricted to some common elements. Vitakrisaurus saraiki theropod of Pakistan is based on associated vertebral and limb elements especially hand including articulated carpals, metacarpals, phalanges and claws which are significant for Gondwanan paleobiogeographic link, comparisons and systematic.
