Geophysical signatures of fluids in a reactivated Precambrian collisional suture in central India

The Central India Tectonic Zone （CITZ） marks the trace of a major suture zone along which the south Indian and the north Indian continental blocks were assembled through subduction-accretion- collision tectonics in the Mesoproterozoic. The CITZ also witnessed the major, plume-related, late Cretaceous Deccan volcanic activity, covering substantial parts of the region with continental flood basalts and associated magmatic provinces. A number of major fault zones dissect the region, some of which are seismically active. Here we present results from gravity modeling along five regional profiles in the CITZ, and combine these results with magnetotelluric （MT） modeling results to explain the crustal architecture. The models show a resistive （more than 2000 Ω. m） and a normal density （2.70 g/cm3） upper crust suggesting dominant tonalite-trondhjemite-granodiorite （TTG） composition. There is a marked correlation between both high-density （2.95 g/cm3） and low-density （2.65 g/cm3） regions with high conductive zones （〈80 Ω. m） in the deep crust. We infer the presence of an interconnected grain boundary network of fluids or fluid-hosted structures, where the conductors are associated with gravity lows. Based on the conductive nature, we propose that the lower crustal rocks are fluid reservoirs, where the fluids occur as trapped phase within minerals, fluid-filled porosity, or as fluid-rich structural conduits. We envisage that substantial volume of fluids were transferred from mantle into the lower crust through the younger plume-related Deccan volcanism, as well as the reactivation, fracturing and expulsion of fluids transported to depth during the Mesoproterozoic subduction tectonics. Migration of the fluids into brittle fault zones such as the Narmada North Fault and the Narmada South Fault resulted in generating high pore pressures and weakening of the faults, as reflected in the seismicity. This inference is also supported by the presence of broad gravity lows near these faults, as well as the low velocity in the lower crust beneath regions of recent major earthquakes within the CITZ.

Petrogenesis and Tectonic Significance of An Early Paleoproterozoic High-Mg Boninite-Norite-Diorite Suite of Rocks from the Bastar Craton, Central India

Mafic/ultramafic rocks derived from high siliceous(high-Si)high magnesium(high-Mg)mantle melts are an important feature observed during early Precambrian.They provide much important geological and petrological

Geochemical signatures of Mesoproterozoic siliciclastic rocks of the Kaimur Group of the Vindhyan Supergroup,Central India

The Upper Kaimur Group of the Vindhyan Supergroup in Central India,primarily consists of three rock types-DhandraulSandstone,Scarp Sandstone and Bijaigarh Shale.Mineralogically and geochemically,they are quartz arenite,sublitharenite to litharenite and litharenite to shale in composition,respectively.The A-CN-K ternary plot and CIA and ICV values suggest that the similar source rocks suffered severe chemical weathering,under a hot-humid climate in an acidic environment with higher PCO2,which facilitated high sediment influx in the absence of land plants.Various geochemical discriminants,elemental ratios like K2O/Na2O,Al2O3/TiO2,SiO2/MgO,La/Sc,Th/Sc,Th/Cr,GdN/YbN and pronounced negative Eu anomalies indicate the rocks to be of post-Archean Proterozoic granitic source,with a minor contribution of granodioritic input,in a passive margin setting.The sediments of the Upper Kaimur Group were probably deposited in the interglacial period in between the Paleoproterozoic and Neoproterozoic glacial epochs.

Petrogenesis of carbonatitic lamproitic dykes from Sidhi gneissic complex,Central India

Petrographic, mineral chemical and whole-rock geochemical characteristics of two newly discovered lamproitic dykes(Dyke 1 and Dyke 2) from the Sidhi Gneissic Complex(SGC), Central India are presented here. Both these dykes have almost similar sequence of mineral-textural patterns indicative of:(1) an early cumulate forming event in a deeper magma chamber where megacrystic/large size phenocrysts of phlogopites have crystallized along with subordinate amount of olivine and clinopyroxene;(2) crystallization at shallow crustal levels promoted fine-grained phlogopite, K-feldspar, calcite and Fe-Ti oxides in the groundmass;(3) dyke emplacement related quench texture(plumose K-feldspar, acicular phlogopites) and finally(4) post emplacement autometasomatism by hydrothermal fluids which percolated as micro-veins and altered the mafic phases. Phlogopite phenocrysts often display resorption textures together with growth zoning indicating that during their crystallization equilibrium at the crystal-melt interface fluctuated multiple times probably due to incremental addition or chaotic dynamic self mixing of the lamproitic magma. Carbonate aggregates as late stage melt segregation are common in both these dykes, however their micro-xenolithic forms suggest that assimilation with a plutonic carbonatite body also played a key role in enhancing the carbonatitic nature of these dykes. Geochemically both dykes are ultrapotassic(K_2 O/Na_2 O: 3.0-9.4) with low CaO, Al_2 O_3 and Na_2 O content and high SiO_2(53.3-55.6 wt.%)and K_2 O/Al_2 O_3 ratio(0.51-0.89) characterizing them as high-silica lamproites. Inspite of these similarities, many other features indicate that both these dykes have evolved independently from two distinct magmas. In dyke 1, phlogopite composition has evolved towards the minette trend(Al-enrichment) from a differentiated parental magma having low MgO, Ni and Cr content; whereas in dyke 2, phlogopite composition shows an evolutionary affinity towards the lamproite trend(Al-depletion) and crystallized from a more primitive magma having high MgO, Ni and Cr content. Whole-rock trace-elements signatures like enriched LREE, LILE, negative Nb-Ta and positive Pb anomalies; high Rb/Sr, Th/La, Ba/Nb, and low Ba/Rb, Sm/La, Nb/U ratios in both dykes indicate that their pareintal magmas were sourced from a subduction modified garnet facies mantle containing phlogopite. From various evidences it is proposed that the petrogenesis of studied lamproitic dykes stand out to be an example for the lamproite magma which attained a carbonatitic character and undergone diverse chemical evolution in response to parental melt composition, storage at deep crustal level and autometasomatism.

Glimpses of the Lichen Flora of Achanakmar-Amarkantak Biosphere Reserve in Central India

The present paper enumerates an account of the lichen flora in Achanakmar-Amarkantak Biosphere Reserve located in Central India which comprises 78 species belonging to 25 genera under nine families. Of these, twenty two species have been reported for the first time from Central India. All the species are enumerated with their correct original citation, basionyms if any, their places of occurrence in the reserve area, distributional range and exsiccata have been provided.

Mineragraphic Study of Manganese Ore Deposits of Kandri, Mansar, Beldongri and Satak Mines, Nagpur District (Maharashtra) Central India

In Nagpur, M.P.-Maharashtra Manganese Belt is exposed which is part of Sausar Belt. In Nagpur, four manganese mines viz Mansar, Kandri, Beldongri and Satak are selected for the ore microscopic study. These mining areas are situated in that part of Central India which are highly deformed and metamorphosed and are characterised by high grade amphibolite facies to low grade greenschist facies. The Precambrian manganese ore deposits of Nagpur are formed by the metasediments of Sausar belt which is rich in manganese sediments. The manganese ores of the study area are co-folded with distinct rock types i.e. “gondites” and predominantly composed of a mixture of braunite, bixbyite, hausmannite, hollandite, jacobsite, vredenburgite, pyrolusite, cryptomelane and psilomelane. The dominant rocks are tirodi migmatitic gneiss, argillaceous and calcareous rock types. This paper discusses the mineralogy of the manganese ores of Kandri, Mansar, Satak and Beldongri. After the careful assessment of mineralogy, texture and paragenesis of the manganese ore of the study area, it has been concluded that the manganese ores of the study area are formed by the multiple processes i.e. metamorphism and supergene enrichment. These supergene enrichments are evidence of colloidal influx. Occurrence of free braunite, free hausmannite and free jacobsite indicates the high grade metamorphism. Pyrolusite, rhodonite, and psilomelane-cryptomelane are formed by supergene enrichment. The presence of lamellar twinning in braunite indicates about shear pressure. In this area the different manganese mineral assemblages and their textures suggest about the occurrence of different metamorphic activity and depositional environment. The texture and paragenesis of manganese ore of the study area are discussed here.

A New Species of Fossil <i>Mus</i>(Muridae, Mammalia) from the Late Quaternary Deposits of Narmada Valley, Central India

A new species of fossil Mus (Muridae, Rodentia) is described from the Pleistocene fluviatile deposits of the Narmada valley (Central India). The species, Mus narmadaensis sp. Nov., has a comparatively smaller lower molar which is characterized by a narrow molar with well connected cusps, small anterior expansion of lingual anteroconid, protoconid and metaconid, reduced posterior cingulum in addition to hypoconid and entoconid nearly at the same level. The large M3 has centrally placed bulbous hypoconid. Among the extant species, the present one is closest to M. shortridgei in having similarly placed protoconid and metaconid in M1 and a well developed hypoconid in M3.

Antioxidant Potential Some Medicinal Plants of Central India

Cellular damage or oxidative injury arising from free radicals or reactive oxygen species (ROS) now appears the fun-damental mechanism underlying a number of human neurodegenerative disorder, diabetes, inflammation, viral infec-tions, autoimmune pathologies and digestive system disorders. Free radicals are generated through normal metabolism of drugs, environmental chemicals and other xenobiotics as well as endogenous chemicals, especially stress hormones (adrenalin and noradrenalin). Accumulated evidence suggests that ROS can be scavenged through chemoprevention utilizing natural antioxidant compounds present in foods and medicinal plants. In this review, research on the antioxi-dant potential of some medicinal plants of origin of Central India is considered.

Incidence of Sickle Cell Anaemia and Thalassaemia in Central India

Haemoglobinopathies are group of diseases characterized by abnormalities both quantitative and qualitative in the synthesis of haemoglobin. Haemoglobinopathies consist of sickle cell anaemia (SCA), thalassaemia (βT) and variant haemoglobins. In India, they are responsible for the largest number of genetic disorders and hence are of great public health hazardous. In India major concerned haemoglobinopathic disorders are sickle cell anaemia and β-thalassaemia. Of the several abnormal haemoglobin molecules, four which are widely prevalent in India include: HbS, HbβT, HbE and HbD. Examination of 6463 individuals showed high incidences for haemoglobin variants, HbS and HbβT in different ethnic groups, the frequency being varies from 0% - 20% and 0% - 9% respectively. The frequency of HbS in Brahmins is 4.17%, in Kalar 5.41%, in Rajput 2.04%, in Muslims 3.73% in Maratha 2.08% in Bania 9.09% while in Teli it is 3.65%. Among the Scheduled castes and Nomadic tribal groups HbS ranges from 1% - 12%;in backward caste categories it varies from 3% - 16%;while in Scheduled tribes it ranges from 0% - 20%. The high magnitude of sickle cell trait has been noticed in the Pardhan (20.31%) followed by the Marar (16.10%), the Dhiwar (11.90%), the Gond (11.89%), the Mahar (11.81%) and the Bania (9.90%). A considerable high frequency (9.27%) of β-thalassaemia has been observed among the Sindhi population. Sporadic occurrence of HbβT and HbD among other communities suggested the gradual spread of the genes into the region. The present findings in 11 communities with the thalassaemia syndrome suggest that the β-thalassaemia is accompanied by raised level of HbA2. Unusual greater mean RBC and WBC suggest the high concentration of hypochromic microcytosis in anaemia. The mean MCV and MCH in HbβT and HbD are much lower than the normal ranges compared to HbS. The mean MCHC is much lower in HbβT, HbDD and HbS than the normal range. The cumulative gene frequency of haemoglobinopathies in India is 4.2%. With a population of over 1 billion and a birth rate of 28 per 1000, there are over 42 million carriers and over 12,000 infants are born each year with a major and clinical significant haemoglobinopathy. Out of these, clinically significant sickle cell anaemia and β-thalassaemic disorders account for almost equal numbers.

Soft-sediment deformation structures in the Mesoproterozoic Kaimur Sandstone,Vindhyan Supergroup(Central India),and their seismotectonic implications

The unequivocal identification of soft-sediment deformation structures(SSDS)is a significant attribute to constrain the effect of transient geological events in the spatio-temporal evolution of ancient sedimentary basins.This paper reports and discusses,for the first time,the occurrence of several cm-to dm-scale SSDS within sandstone successions of the Mesoproterozoic Kaimur Group(Vindhyan Supergroup),exposed at the Hanumandhara Hill of Chitrakoot-Satna border region,Madhya Pradesh State,India.The SSDS are confined to a deformed interval comprising seven individual sedimentary units of variable composition and texture,which are sandwiched between nearly horizontally undeformed sandstone beds.The SSDS consist of load structures(load casts,flame structures,pseudonodules and ball-and-pillow structures),contorted lamination,convolute lamination,boudins and pinch-and-swell structures,deformed cross-stratification,slump structures,clastic injections,fluid escape structures,and syn-sedimentary fractures/faults.The pre-sent study suggests that the formation of these SSDS is essentially related to a combination of processes(gravitational instability,liquefaction,fluidization,and fluid escape)predominantly induced by seismic shocks.In addition,the restricted occurrence of fractures/faults in these deformed layers emphasizes the passage of seismically-induced Rayleigh waves.Considering the observed types of SSDS,their lateral homo-geneity and geographic distribution along with the geodynamic framework of the Vindhyan Basin,the whole area can be tentatively attributed to having experienced moderate-to high-magnitude(M≥5)seismicity.The present study combined with earlier reports of seismically-induced SSDS,from other regionally disposed formations belonging to the Lower(e.g.,Kajrahat Limestone,Chopan Porcellanite,Koldaha Shale,Rohtas Limestone,and Glauconitic Sandstone of the Semri Group)and Upper(e.g.,Bhander Limestone of the Bhander Group)Vindhyan Supergroup,respectively,provides evidence for the constant regional-scale seismo-tectonic activity within the Paleo-Mesoproterozoic Vindhyan Basin.Importantly,this observation further suggests that the intracratonic basins can be active tectonically contrary to the earlier propositions.

Vegetation succession and environmental changes in Central India during Early Cenozoic

In order to infer the climate and the floral changes during the early Cenozoic of central India, a critical analysis has been made of the generic composition of Deccan Intertrappean series of India, which is now known to a greater extent. Most of the information regarding Deccan Intertrappean flora is derived from the assemblages from Vidharbha-Chhindwara region and Mandla District in central India. The Vidharbha-Chhindwara region constituted by taxa representing all major groups of plant kingdom belonging to different habitats like(i) marine(3 genera of doubtful marine alga)(ii) estuarine(27 species of palms, Nypa and Viracorpon like Pandanaceous fruits, Sonneratia, Cocos like plants)(iii) fresh water(6 genera of fresh water algae, water ferns, Eichhornia, Nymphea like hydrophytic angiosperms)(iv) marshy(5 genera of bryophytes, water ferns, Selaginella and Equisetum like pteridophytes and many angiospermic plants showing aerenchymatous tissue and few parts infected by fungal spores) and(v) terrestrial(2 families of gymnosperms and 15 families of arborescent angiosperms). Mandla-Dindori District mainly comprise angiospermous flora. These constitute 15 species of palm woods and woods of 25 dicot families indicating terrestrial dry habitat. The fossil flora so far recovered from these beds indicate that the tropical evergreen to semi-evergreen type forests with some moist deciduous plants, similar to the present day forests of Western Ghats, and northeast India, were flourshing around Vidharbha, Chhindwara and Mandla area of Central India during Upper Cretaceous-Lower Tertiary period, in contrast to the present day dry deciduous to moist deciduous types of forest. This flora was well represented in India in the past but has become restricted to Burma and Andaman-Nicobar Islands due to change in the climatic conditions. The comparison of the temperature data from these fossiliferous localities and the comparable modern areas clearly indicates that the climate in Central India was much more uniform throughout the year.

Anthropogenic disturbances and status of forest and wildlife in the dry deciduous forests of Chhattisgarh state in India

The advent of modem forces and the changes in socio- economic patterns of forest dwellers have increased the pressures on the forests. In order to mitigate such pressures and also to protect the forests and wildlife the model of protected areas networks has shifted and en- hanced such pressures in the unprotected natural forests due to several reasons. Being a low profile category of protected status and continuous human settlements, the present study highlights the case of dry deciduous forests of Sarguja district of Chhattisgarh state of India. The major objec- tives of this study were to quantify the status of forests and wildlife and also to determine the extent of anthropogenic disturbances faced by the dry deciduous forests of central India. Transect and silent drive count methods were used for sampling wildlife and quadrat method was used for sampling vegetation. Besides, the local uses of various forest pro- duces were also studied in view of understanding the people dependency on forests. The forest vegetation, in the study area, was pre-dominated by Shorea robusta, which had Madhuca indica, Diospyrus melanoxylon and Buchnania lanzan as the major companion species. The forest had either the high girth class mature tree species or the saplings. The low vegeta- tion cover and density were due to the high anthropogenic pressures mainly in the form of heavy livestock grazing and collection of etlmo- botanically important species. The study though reveals that the area is not rich in wildlife and the forest is fragmented, the area still supports some important species, which include many rare and endangered plants and animals. The findings of this study have been discussed in view of the management and conservation of the forest and wildlife in the dry deciduous forests.

印度中亚政策的进展与局限

印度与中亚五国举行领导人线上峰会后,各方构建了多领域对话机制并进一步深化合作。随着阿富汗变局和乌克兰危机爆发,主要大国愈加关注中亚地区,印度为了平衡中国影响力并体现其大国角色也加快推进中亚外交,但是中亚地区风险、大国博弈态势、印度周边环境及其外交优先事项等因素又进一步限制了印度在中亚影响力的发挥。印度参与中亚事务增强了中亚国家与域外大国合作的灵活性,同时也使中亚地区一体化的进程更具不确定性,并可能弱化地区合作组织的部分功能。中国需要投入更多精力开展中亚外交,与中亚各国携手构建中国-中亚命运共同体。

印度中部某三级眼科护理中心的角膜屈光手术实践

目的:研究印度中部患者的特征和角膜屈光手术(KRS)实践。方法:回顾性研究2017-06/2022-04在印度中部某三级眼科护理中心行KRS的患者410例。记录患者的人口统计学资料,如年龄、性别、居住地(城市或农村)、屈光不正、手术原因、最佳矫正视力、手术类型、术后随访和并发症。结果:410例患者中,324例接受KRS(79.0%)。其中,200例(61.7%)行激光辅助原位角膜磨镶术(LASIK),124例(38.3%)行屈光性角膜切除术(PRK)。研究组最终由179名女性和145名男性组成。患者平均年龄为(25±3.5)岁。大多数患者来自城市地区(n=250,77.2%)。右眼和左眼的平均术前显性屈光度分别为-4.5±2.1和-4.9±2.0。LASIK患者双眼平均手术时间为(15±2)min,PRK患者双眼平均手术时间为(17±3)min。未出现上皮内向生长、皮瓣愈合并发症或感染,且无患者需行增强手术。角膜厚度不理想(n=28,32.6%)是排斥手术最常见的原因。随访1a,3名接受LASIK手术的患者出现回退(-0.5D±1D),屈光度校正分别为-6.75D,-8.5D,-7.0D。结论:LASIK是印度中部人群矫正屈光不正的主要手术。虽然PRK手术的数量很少,但LASIK和PRK都具有良好的视力预后。高度近视选择LASIK时应考虑近视消退。

极北的地理位置演变考略

极北(Hyperborea)在古代希腊罗马文献中是个“北风之外”的“乐土”,它在中西交通史和西方的中国形象研究中始终是个无法绕过去的话题且有着重要的意义。无论是古希腊罗马的文献史料,还是近现代的学者的先行研究,对极北及极北人的认知存在着诸多的争议和谜团,其中之一就是极北人的地理位置和种族的问题。目前对于极北的地理方位大致有三种看法:极北在欧洲、在印度和在中亚。本文将对极北人与中国人的二者的关联进行梳理考辨。

中印度洋洋盆GC11岩心富稀土深海沉积的元素地球化学特征

对中印度洋洋盆的沉积GC11岩心开展了主量元素、微量元素和稀土元素分析研究,根据主微量元素相关性特征、稀土元素富集程度以及澳大利亚后太古代平均页岩归一化模式特征,初步探讨了GC11岩心的沉积地球化学特征,以及影响稀土元素富集的可能因素。研究表明,GC11岩心稀土元素总量在400.64×10^?6~742.74×10^?6,平均值为658.41×10^?6,略低于邻近海域的GC02岩心,与沃顿海盆DSDP213岩心中含沸石型深海粘土层位中的稀土元素含量相当。δCe负异常明显,(La/Yb)N为0.42,显示重稀土相对富集的特点。稀土元素与P2O5呈显著正相关性,CaO/P2O5的平均值为2.3,表明生物钙磷灰石可能是稀土元素的主要载体矿物,而铁锰水合物可能对富集稀土元素有一定的促进作用,但影响不大;GC11岩心中δCe负异常程度远低于GC02岩心,略低于DSDP213岩心,中稀土富集特征与GC02和DSDP213岩心基本一致。不同程度陆源物质的混入可能是导致以上不同岩心中稀土元素富集程度和分馏特征的主要原因。

Standardization of harvesting age of bamboo shoots with respect to nutritional and anti-nutritional components

Bamboo shoots can be harvested at different ages but the data on the changes in nutritional composition with age are scanty. We standardized harvesting age of bamboo shoots in central India to obtain best quality produce with respect to nutritional composition. The shoots harvested on different days （2–20 days after emergence from ground） were analyzed for their nutritional （dietary fibres, carbohydrates, proteins, total phenols, ascorbic acid, sodium, potassium, phosphorus, calcium, magnesium and phenolic acids） and anti nutritional （cyanogen） constituents. A significant variation （at p ≤ 0.5） was observed in the nutritional composition of shoots of Dendrocalamus asper, D. strictus and Bambusa tulda harvested at different days. An overall decrease was observed in proteins and total phenols while dietary fibres and carbohydrates increased with ages. Significant variation （at p ≤ 0.5） was also observed in phenolic acids while minerals did not vary significantly. Results revealed that the optimum harvesting age for D. asper, D. strictus and B. tulda was on 10–14 days, 6–10 days and 10–16 days （after emergence from the ground） respectively. These results can be used to obtain quality bamboo shoots.

弥勒菩萨与观音菩萨——图像的创立与演变

以弥勒菩萨、观音菩萨像的发展演变为例,探寻其在印度、中亚、东亚的信仰演变情况,对二菩萨信仰在印度与东亚的异同及其理由、背景进行考察。