6/15/2023 0 Comments Oolite deutsch![]() The Ancorichnus ichnofabric reflects lower offshore condition of deposition. The ichnofabric Ophiomorpha 1 with syn-sedimentary faulting exemplifies high energy conditions typical of lower shoreface environment, whereas the Ophiomorpha 2 ichnofabric typifies upper shoreface envi- ronment. The ichnofabric analysis divulges five distinct ichnofabrics, each typifying distinct depositional environment within shallow marine conditions. bolbiterminus, Phycodes palmatus, Planolites beverleyensis, Rhizoco- rallium isp., Rosselia rotatus, R. Jamesonichnites hein- bergi, Imponoglyphus kevadiensis, Laevicyclus mongraensis, Monocraterion tentaculatum, Ophiomorpha nodosa, Palaeophycus tubularis, P. The Kolar Dongar Member represents a shallow marine succession that contains 16 ichnotaxa: Ancorichnus ancorichnus, Conichnus conicus, Gyrochorte comosa, cf. The ichnology and ichnofabric of the lower part of Bhadasar Formation (i.e., Kolar Dongar Member) belonging to Tithonian age are pre- sented and discussed. The shallow marine sedimentary sequence of the Jaisalmer Basin exhibits one of the important and well-developed Tithonian sedimentary outcrops for western India. Ichno-events like Chondrites-Zoophycos Assemblage Zoophycos assemblage Gyrophyllite – Diplocraterion assemblage Psilonichnus assemblage are useful in reconstructing paleooceanographic conditions of the entire Kachchh basin. Out of these ichnoevents, five of the ichnoevent serve as important stratigraphic markers these are (1) Zoophycos for Dhosa Oolite, (2) Teichichnus-Fugichnia Event for Middle Jhuran Shales (3) Phycodes horizon for demarcating Upper member and Katesar member boundary, (4) Cyclic bioturbated Horizons for Lower part of Ghuneri Member (5) Teredolite for differentiating base of the Ukra Member with upper part of Ghuneri Mb. These ichno events are: (1) Diplocraterion-Arenicolites (2) Astereosoma-Rhizocorallium (3) Zoophycos-Chondrites Assemblage (4) Zoophycos (5) Gastrochaeonolites (6) Zoophycos-Thalassinoides (7) Teichichnus-Fugichnia (8) Polykladichnus-Skolithos-Ophiomorpha (9) Phycodes (10) Fugichnia (11) Gyrophyllite – Diplocraterion (12) Psilonichnus and (13) Teredolite ichnoassemblages and (14) Cyclic Bioturbated Horizons. These events are spatially extensive in nature and thus helps in short-distance, intra-basinal stratigraphic correlation of the various sections of the western Kachchh. Ichnologically, fourteen major ichnological events are recorded in entire Mesozoic sections of Western Kachchh. Thus the Mesozoic sediments of Western Kachchh are represented by nearly continuous section from Middle Jurassic to Cretaceous. ![]() These sedimentary fills are represented by well exposed and age constrained (1) Umia Ammonite Band, (2) Katesar Member and (3) Ukra Member, sedimentary units. Although, in the central and eastern part of the basin these important hiatus are present whereas in western part of the basin these breaks/hiatus is completely filled. Post rift stage is characterized by another major hiatus corresponding to Tithonian. The Syn-rift basin Stratigraphy is marked by one major hiatus corresponding to Late Oxfordian. The Syn-rift stage is further divided into Early syn-rift and rift climax stages. Sedimentation in the Kachchh basin occurred in three distinct phases (1) Pre-Rift, (2) Syn-Rift and (3) Post-Rift. The Mesozoic sediments are well exposed in the Kachchh basin and shows sedimentary breaks in the western part of the Basin. The sedimentological and ichnological data analysis revealed seven distinctive depositional regimes ranging from shelfal below storm wave base to middle shoreface. The bathymetric control of the trace fossils exhibited development of Skolithos, Cruziana and Zoophycos ichnofacies type condition. Seventeen ichnoguilds are demonstrated based on the space utilization for characterising the ecological complexity of ichnoassemblages. These trace fossils represents five ethological categories and six ichnoassemblages. 34 ichnogenera were identified and analysed paleoecologically. Certain exceptional bands of ripple-marked calcareous sandstone shale and oolitic limestone facies are rich in ammonites, belemnites, brachiopods and bivalves. The sequence as based on sedimentological characteristics, exhibits six sedimentary facies and four subfacies. The Middle to Late Jurassic succession of the Jhura Dome (Jhurio and Jumara formations) of the Mainland Kachchh, western India, comprises ~500 m thick succession of clastic carbonate and mixed siliciclastic-carbonate, intercalated with shales.
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