scholarly journals Stratigraphy and structural framework of the Sub-Himalaya, Bagmati River region, Central Nepal

1996 ◽  
Vol 13 ◽  
Author(s):  
T. P. Adhikary ◽  
L. N. Rimal
Keyword(s):  
Sedimentary Rocks ◽  
Middle Part ◽  
Central Nepal ◽  
Structural Framework ◽  
River Region ◽  
Siwalik Group ◽  
Bagmati River ◽  
Basic Rocks ◽  
First Time

The Sub-Himalaya in the Bagmati River region of central Nepal consists of two groups of rocks very different in age and characters. The Bagmati Group, an assemblage of pre-Siwalik rocks are found within the Siwalik Group. The Bagmati Group consists of sedimentary rocks, metasediments and basic rocks. The Siwalik Group is divided into the Lower, Middle and Upper Siwaliks. The Upper Siwalik is further subdivided into the Gadhan Khola, Chiruwa Khola and Bhainse Khola Formations. Vertebrate fossils were found in the lower and middle part of the Upper Siwaliks. An index fossil identified as Elephas planifrons was discovered for the first time in this region from a massive sandstone bed belonging to the upper part of the Upper Siwaliks. A conglomerate horizon with predominantly Siwalik sandstone clasts occur at the uppermost level of the Siwalik Group exposed in the southern belt. They in turn are unconformably overlain by flat lying younger Dun gravels. The Sub-Himalayan rocks are distributed into the northern and the southern belts, separated by the Chaura-Marin Thrust. The northern belt is characterised by a number of thrusts and faults resulting in the cropping out of the Bagmati Group sediments and the repetition of the formations of the Siwalik Group. The southern belt shows largely north dipping sequences from the Lower to the Upper Siwaliks. Both the belts show plunging folds in the vicinity of the thrusts. Several NW-SE, NE-SW and N-S trending faults have cut across the entire Siwalik Range.

Palinostratigraphy and Paleoenvironments in the Gorodishchi Section (Middle Volga River Region, Kimmeridgian–Hauterivian)

2021 ◽  
Vol 62 (07) ◽  
pp. 765-789
Author(s):  
E.B. Pestchevitskaya
Keyword(s):  
Middle Part ◽  
Trophic Conditions ◽  
Volga River ◽  
River Region ◽  
Biostratigraphic Subdivision ◽  
Middle Volga ◽  
Definition Of ◽  
First Time ◽  
Regressive Events ◽  
Biostratigraphic Units

Abstract —Eight dinocyst-based and three spore- and pollen-based biostratigraphic units are defined in the Kimmeridgian, Volgian, and Hauterivian of the Gorodishchi section, based on a biostratigraphic analysis of the successions of marine and terrestrial palynomorphs. Algological assemblages are described in more detail, and additional criteria for the definition of dinocyst zones established by previous researches are given. A more detailed biostratigraphic subdivision of the middle part of the Volgian is proposed. A local dinocyst zone in the Hauterivian and a biostratigraphic succession of spore–pollen units in the entire section are described for the first time. The research results demonstrate that the boundaries of many palynostratigraphic units exhibit a considerable correlation potential. Based on a biofacies analysis of the microphytoplankton, the dynamics of transgressive–regressive events is studied in relation to the accompanying oxygen and trophic conditions. Possible relationships between marine paleoenvironments and climatic changes reconstructed on the basis of spore–pol­len data are discussed.

scholarly journals Petrography of the Siwalik sandstones, Amlekhganj-Suparitar area, central Nepal Himalaya

2003 ◽  
Vol 28 ◽  
Author(s):  
Naresh Kazi Tamrakar ◽  
Shuichiro Yokota ◽  
Suresh Das Shrestha
Keyword(s):  
Middle Miocene ◽  
Foreland Basin ◽  
Early Pleistocene ◽  
Nepal Himalaya ◽  
Central Nepal ◽  
Present Study Area ◽  
Mean Grain Size ◽  
Siwalik Group ◽  
Variation Trends ◽  
The Himalaya

Middle Miocene to early Pleistocene sedimentary sequence deposited in the foreland basin of the Himalaya is represented by the Siwalik Group. In the present study area the Siwalik Group extends in a NW-SE direction and well-exposed. Forty­four sandstone samples were studied for texture, fabric and composition in order to assess their petrographic properties and variation trends of these properties in stratigraphic levels. Sandstones were classified into sublitharenite, subarkose, lithic arenite, arkosic arenite and feldspathic graywacke and further thirteen sub-clans. Mean grain size (M) and Trask sorting coefficient (So) increase up-section. Recalculated quartz, matrix, modified maturity index (MMI), total cement (Ct), cement versus matrix index (CMI) and ratio of strong cement over total cement ((Cfc/Cs)/Ct) also increase, whilst packing proximity (PP), packing density (PD) and consolidation factor (Pcc) decrease up-section showing distinct trends, and therefore, these properties are promising in recognizing the older sandstones from the younger ones.

scholarly journals Occurrences of mineral resources in Bandipur Gondrang area of Tanahun district, central Nepal, Lesser Himalaya

2014 ◽  
Vol 2 ◽  
pp. 24-35
Author(s):  
Kabiraj Paudyal
Keyword(s):  
Mineral Resources ◽  
Mineral Deposits ◽  
Lesser Himalaya ◽  
Geological Investigation ◽  
Central Nepal ◽  
Metallic Mineral ◽  
Geological Map ◽  
Geological Control ◽  
Basic Rocks

A detailed geological investigation was carried out to assess the distribution of minerals and their geological control in Bandipur-Gondrang area of Tanahu district, a part of Lesser Himalaya in central Nepal. The area is found rich in both metallic and non-metallic mineral deposits. The main metallic minerals found are iron in Phalamdada and Labdi Khola, copper in Bhut Khola and poly-metallic deposits including suspected gold in Bhangeri Khola and Jaubari Khola-Bar Khola sections. A large deposit of inorganic carbon is found around the Gondrang-Watak area. Similarly, a good quality of green marble (metabasite) is found as decorative stone in Bagar Khola area and good quality of roofing stone in Bandipur area. In addition to these economic deposits other several sub economic to non-economic mineral are also located in the geological map of the area. Categorization of these mineral deposits is based on the probable reserve and laboratory analysis of related samples. Geological control of mineral deposits is considered to be the stratigraphic, structural, metamorphic and hydrothermal. Iron mineralization of the area is found stratigraphical control, copper deposits by magmatism of basic rocks (amphibolites), and poly-metallic deposits are related to the hydrothermal processes.

scholarly journals Species diversity, distribution and status of fishes in Chitwan district and adjacent areas, Nepal

2018 ◽  
Vol 30 ◽  
pp. 85-101
Author(s):  
Dilip Kumar Jha
Keyword(s):  
Species Diversity ◽  
Fish Species ◽  
Aquatic Systems ◽  
Adjacent Area ◽  
River Systems ◽  
Aquatic Resources ◽  
Number Of Species ◽  
Central Nepal ◽  
The People ◽  
First Time

Chitwan district is endowed with varied aquatic resources which harbor diverse fish species in central Nepal. A total of 111 fish species were collected from different sampling sites of several tributaries of Trisuli, Rapti and Narayani river systems in Chitwan district and adjacent areas from August 2011 to July 2016. These species belong to 9 orders, 27 families and 72genera. Among the orders, Cypriniformes had the highest number of species (49%) followed by Siluriformes (30%), Perciformes (12%), Synbranchiformes (3%), Osteoglossiformes (2%) while Anguiliformes, Beloniformes, Clupeiformes and Tetraodontiformes represented each by about 1%. Cyprinidae has the highest number of species (40%) among the families followed by Sisoridae (12%), Bagridae (7%), Cobitidae (5.4%), Schilbeidae (4.5%), Channidae (3.6%), Balitoridae (2.7%), Mastacembelidae (2.7%), Siluridae (2.7%), Notopteridae (1.8%), Ambassidae (1.8%), Nandidae (1.8%) and Mugilidae (1.8%). Other families accounted forabout 1% were Anguillidae, Belonidae, Clupeidae, Psilorhynchidae, Anabantidae, Gobiidae, Belontidae, Synbranchidae, Amblycipitidae, Pangasidae, Clariidae, Heteropneustidae, Chacidae and Tetraodontidae. The Botia geto was reported for the first time from Rapti river of Chitwan and adjacent area. Different fish species are naturally maintained in aquatic systems and support livelihoods of the people. Catches of major food fishes are declining due to overexploitation of resources, therefore, appropriate measures are needed at once to maintain and conserve the indigenous stock.

scholarly journals Periphytic Actinella Lewis (Ochrophyta, Bacillariophyceae) species from an Environmental Protection Area in the Brazilian Amazon

2018 ◽  
Vol 30 (0) ◽  
Author(s):  
Luís Gustavo de Castro Canani ◽  
Rebecca da Silva Fraia ◽  
Sérgio de Melo
Keyword(s):  
Light Microscopy ◽  
Environmental Protection ◽  
Brazilian Amazon ◽  
Acidic Ph ◽  
Diagnostic Features ◽  
Negro River ◽  
River Region ◽  
Environmental Protection Area ◽  
Protection Area ◽  
First Time

Abstract Aim The aim of this study is to present the Actinella species found in periphytic samples collected from an Environmental Protection Area in Santarém (PA, Brazil), to comment on their morphology by comparing them with existing records, and to increase knowledge of the distribution of the genus in Pará State. Methods Ten periphytic samples were collected from seven sampling stations in the Alter do Chão Environmental Protection Area (Santarém, Pará, Brazil) in October 2015 and February and July 2016. Dissolved oxygen, pH, conductivity and water temperature were measured in the field at sites from which samples were collected in 2016. Samples were oxidized and analyzed by light microscopy. Results The sampled water bodies presented low conductivity and an acidic pH. We identified 12 Actinella taxa, several of which had originally been described from samples collected from the Amazon in the mid-20th century, mainly in the lower Tapajós River region. Actinella rionegrensis is recorded for the first time in the State of Pará, outside of its type locality (Negro River, near Manaus, AM, Brazil), and the species habitus (wisp-shaped colonies) is recorded for the first time. Conclusion Our results indicate that the Environmental Protection Area has been effective in conserving the aquatic ecosystem, since Actinella species identified in the mid-20 th century are still present. Taxonomic issues for some species of this genus need clarification and revision, since overlapping diagnostic features occur among species and with species belonging to the genus Eunotia.

HYDROCARBON POTENTIAL OF THE MESOZOIC AND BASAL TERTIARY OF THE GIPPSLAND BASIN: A STRATIGRAPHIC ANALYSIS

1972 ◽  
Vol 12 (1) ◽  
pp. 138 ◽  
Author(s):  
T. R. Haskell
Keyword(s):  
Upper Cretaceous ◽  
Sedimentary Rocks ◽  
Economic Potential ◽  
The West ◽  
Stratigraphic Analysis ◽  
Structural Framework ◽  
Marine Influence ◽  
Gippsland Basin ◽  
North And South ◽  
Early Upper

A thick sequence of uppermost Jurassic, Cretaceous and basal Tertiary non-marine sedimentary rocks underlies the Gippsland area of Victoria. The older part of this sequence is extensively exposed in the west of the Gippsland area, but elsewhere it is known dominantly from well intersections. Although several hiates are recognised, palynological data indicate that a comparatively complete Cretaceous section can be compiled from this sequence in the Gippsland area.The uppermost Jurassic to Paleocene rocks can be divided into three units. The oldest unit is uppermost Jurassic and Lower Cretaceous in age. It consists of variably compacted greywackes and lithic sandstones, minor arkoses and interbedded siltstones and mudstones. The overlying early Upper Cretaceous and Paleocene units are distinguishable paleontologically and consist of quartzose sandstones, carbonaceous siltstones and mudstones.There is no indication of marine influence on sedimentation present in the microfossil content of any of the palynotogical preparations from samples taken throughout most of the sequence. Several species of microplankton are common in the oldest unit, but they are indicative of the lacustrine conditions under which the unit was deposited.Minor hydrocarbon shows have been recorded from the oldest unit, but the sandstones are characteristically tight. More significant shows have been reported from the two younger units that contain relatively clean sandstones interbedded with siltstones and mudstones. These units possess the greatest economic potential of all of the pre-Eocene rocks of the Gippsland Basin.The structural framework of the region is composed of separate series of north-easterly and easterly trending faults or monoclines and a south-easterly regional dip. Differential movements of blocks defined by this fault-monocline pattern appears to have resulted in erosion of the more prospective early Upper Cretaceous and Paleocene strata from all but two subrectangular areas respectively immediately north and south of Seaspray.

scholarly journals Lithofacies and depositional environment of the Siwalik Group in Samari-Sukaura River area, Central Nepal

2013 ◽  
Vol 16 ◽  
pp. 53-64 ◽  
Author(s):  
Dev Kumar Syangbo ◽  
Naresh Kazi Tamrakar
Keyword(s):  
Depositional Environment ◽  
Foreland Basin ◽  
River System ◽  
Nepal Himalaya ◽  
Meandering River ◽  
Fine Grained ◽  
Architectural Elements ◽  
Central Nepal ◽  
Eastern Zone ◽  
Siwalik Group

Thick sedimentary sequence deposited in the foreland basin of the Nepal Himalaya is represented by the Siwalik Group. The Siwalik Group is well exposed in the Samari-Sukaura River area. The present study is focused in southern portion of the MBT around the Samari-Sukaura area for its depositional environment. The Middle Siwaliks of the Sukaura Road sections is overlained by the Lower Siwaliks which is separated by the Karki Khola Thrust. Extension of the Lower Siwaliks in the Jyamire Khola and the Bundal Khola becomes wider in the eastern Zone. Repetition of the Lower Siwaliks along the southern margin of the MBT is recognized. Depending on lithofacies assemblage and facies analysis, the two broad facies assemblages FA1 and FA2 have been distinguished. FA1 shows SB, FF, LA, LS and CH architectural elements and is interpreted as a product of the fine-grained meandering river system. FA2 shows SB, FF, LA, DA and CH architectural elements and is interpreted as a product of sandy mixed-load meandering river system. DOI: http://dx.doi.org/10.3126/bdg.v16i0.8884   Bulletin of the Department of Geology Vol. 16, 2013, pp. 53-64

Microscopic Studies of Gold Deposit of Southern Ashaly in Eastern Kazakhstan

2013 ◽  
Vol 828 ◽  
pp. 1-10
Author(s):  
Adilkhan Baibatsha ◽  
Kulyash Dyussembayeva ◽  
Aimkhan Kassenova
Keyword(s):  
Gold Mineralization ◽  
Sedimentary Rocks ◽  
Sulfide Deposit ◽  
Carbonaceous Shales ◽  
Microscopic Studies ◽  
Middle Carboniferous ◽  
Gold Sulfide ◽  
First Time ◽  
Tuff Breccia ◽  
Eastern Kazakhstan

The gold-sulfide deposit Southern Ashaly is localized in carbonaceous terrigenous formation (black shale strata) of the middle carboniferous (Bukon suite, which is the ore-hosting for super large deposit Bakyrchik). The Southern Ashaly is at the exploration stage and according to preliminary estimates of the expected resources belongs to a large deposit in scale. Ore gold mineralization of such level as Southern Ashaly in southwestern Kalba is found for the first time and gives hope for the discovery of such objects in the Boko Vassilyevskoye ore field. Ore-hosting at the field Southern Ashaly is carbonaceous terrigenous formation of the middle carboniferous, with no visible signs of volcanic formations. But, it was revealed, at microscopic research by us, paragenetic relation of the gold mineralization with small intrusions of plagiogranites and zones of plagiogranite porphyry dykes and found volcano-sedimentary rocks (aleuritic tuffsandstone, tuff breccia) which have undergone hydrothermal-metasomatic changes. The vein-disseminated gold-sulfide mineralization is associated with beresitizated plagiogranites and plagigranite-porphyries and hydrothermally altered tuff sandstones, tuff breccia and carbonaceous shales. Southern Ashaly unlike Bakyrchik deposit which contains invisible gold in sulfides, all the gold is concentrated in the pyrite mainly in the form of micro-sized (1-5 µm or less) in arsenopyrite is noted rarely.

Lower jaws, lower tetrapods–a review based on the Devonian genus Acanthostega

1998 ◽  
Vol 89 (1) ◽  
pp. 11-46 ◽  
Author(s):  
Per Erik Ahlberg ◽  
Jennifer A. Clack
Keyword(s):  
Phylogenetic Analysis ◽  
Wide Distribution ◽  
Middle Part ◽  
Crown Group ◽  
Lower Jaw ◽  
Stem Group ◽  
Early Tetrapods ◽  
First Time

AbstractThe lower jaw of the Devonian tetrapod Acanthostega is described for the first time. Redescriptions are provided for the lower jaws of the elpistostegid Panderichthys, the Devonian tetrapods Elginerpeton, Obruchevichthys, Metaxygnathus, Ventastega and Ichthyostega, and the Carboniferous tetrapods Crassigyrinus, Megalocephalus and Gephyrostegus. The character distri- butions thus revealed differ considerably from previous accounts, particularly in the wide distribution of certain primitive characters. Meckelian ossification in the middle part of the jaw is widespread among Devonian tetrapods, being demonstrably absent only in Acanthostega. Among Carboniferous tetrapods, a tooth-bearing parasymphysial plate is shown to be present in Crassigyrinus and Megalocephalus (having already been demonstrated by other authors in Whatcheeria and Greererpeton). A phylogenetic analysis of 26 early tetrapods including all the aforementioned genera, scored for 51 lower jaw characters, produces at least 2,500 equally parsimonious trees. However, the lack of resolution lies largely in a big top end polychotomy containing anthracosaurs, temnospondyls, seymouriamorphs, microsaurs and a nectridean-amniote clade. Below this polycho- tomy, which may correspond approximately to the tetrapod crown group, there is a well-resolved stem-group containing, in descending order, Megalocephalus, Greererpeton, Crassigyrinus, (jaws associated with) Tulerpeton, Whatcheeria, Acanthostega, Metaxygnathus, Ichthyostega, Ventastega and Metaxygnathus (unresolved), an Elginerpeton-Obruchevichthys clade, and Panderichthys. This conflicts with recently published phylogenies by Coates and Lebedev & Coates, which place Tulerpeton and all post-Devonian tetrapods in the amphibian or amniote branches of the tetrapod crown group.

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