The origin and maturation of lagoonal glauconites: a case study from the Oligocene Maniyara Fort Formation,western Kutch,India

An integrated study of the sedimentology, micropalaeontology, mineralogy and geochemistry of glauconites in the Oligocene Maniyara Fort Formation (western Kutch, India), has been undertaken. Authigenic glauconites, mostly of evolved type, formed within a back‐barrier lagoonal environment. Foraminifera help constrain the biostratigraphy and along with sedimentological evidence, provide information on the depositional conditions. Glauconite in the Maniyara Fort Formation occurs either as infillings within intra‐particle pores of larger foraminifers, or as an altered form of faecal pellets. X‐ray diffraction studies reveal the less mature nature of glauconite infillings compared to the glauconite pellets. Electron microprobe investigation confirms a relative enrichment of K₂O and total Fe₂O₃ in the latter. Both varieties of glauconite formed by initial authigenic precipitation of K‐poor glauconite and subsequently matured by addition of potassium in the interlayer sites and fixation of total iron in the octahedral sites; calcium, magnesium and aluminum were released from the glauconite structure concomitantly. Alkaline conditions during the entire process of glauconite formation did not allow dissolution of foraminiferal tests. Mineralogical and chemical characteristics of the Maniyara Fort Formation glauconites are more similar to deep marine glauconites than those reported from other shallow or marginal marine settings. A low negative cerium anomaly, as well as abundant pyrite, suggests formation of glauconite in sub‐oxic micro‐environments, created by decay of organic matter associated with foraminiferal chambers and faecal pellets. Sub‐oxic condition apparently prevailed relatively longer within the Maniyara Fort Formation lagoons. Copyright © 2011 John Wiley & Sons, Ltd.     

Diversity, distribution and prioritization of fodder species for conservation in Kullu District, Northwestern Himalaya, India

In the Indian Himalayan Region predominantly rural in character, livestock is one of the main sources of livelihood and integral part of the economy. Livestock mostly rely on fodder from wild. The diversity, distribution, utilization pattern, nativity, endemism, rarity, seasonality of availability, nutritive values, perceived economic values and pressure use index of livestock have not been studied. The present study attempts to enumerate 150 species of fodder representing trees (51 spp.), shrubs (54 spp.) and herbs (45 spp.). Poaceae (19 spp.) and Fabaceae (13 spp.) amongst families and Salix (6 spp.), Ficus, Clematis, and Desmodium (5 spp., each) amongst genera are rich in species. Maximum species were found in the 1801 ~ 2600 m zone, and the remaining two zones showed relatively low diversity. Out of the 150 species, 109 are used in summer, 5 winter and 36 throughout year. During rainy season, mostly grasses are used as fodder. Only 83 species are native to the Himalayan region, one species, Strobilanthus atropuroureus is endemic and 35 species are near endemic. The nutritive values of the fodder species were reviewed, and economic values and status of the species were also assessed. The pressure use index of the species was calculated on the basis of cumulative values of the utilization pattern, altitudinal distribution, availability, status, nativity and endemism. Amongst the species, Grewia oppositifoilia, Morus serrata, Indigofera heterantha, Quercus leucotrichphora, Ulmus villosa, U. wallichiana and Aesculus indica showed highest PUI indicating high preference and pressure. Season wise prioritization of the species for different altitudinal zones has been done. Appropriate strategy and action plan have been suggested for the conservation and management of fodder species.     

Soil Carbon Sequestration in India

With a large land area and diverse ecoregions, there is a considerable potential of terrestrial/soil carbon sequestration in India. Of the total land area of 329 million hectares (Mha), 297 Mha is the land area comprising 162 Mha of arable land, 69 Mha of forest and woodland, 11 Mha of permanent pasture, 8 Mha of permanent crops and 58 Mha is other land uses. Thesoil organic carbon (SOC) pool is estimated at 21 Pg (petagram = Pg = 1 ×10¹⁵ g= billion ton) to 30-cm depth and 63 Pg to 150-cm depth. The soil inorganic carbon (SIC) pool is estimated at 196 Pg to 1-m depth. The SOC concentration in most cultivated soils is less than 5 g/kg compared with 15 to 20 g/kg in uncultivated soils. Low SOC concentration is attributed to plowing, removal of crop residue and other biosolids, and mining of soil fertility. Accelerated soil erosion by water leads to emission of 6 Tg C/y. Important strategies of soil C sequestration include restoration of degraded soils, and adoption of recommended management practices (RMPs) of agricultural and forestry soils. Potential of soil C sequestration in India is estimated at 7 to 10 Tg C/y for restoration of degraded soils and ecosystems, 5 to 7 Tg C/y for erosion control, 6 to 7 Tg C/y for adoption of RMPs on agricultural soils, and 22 to 26 Tg C/y for secondary carbonates. Thus, total potential of soil C sequestration is 39 to 49 (44± 5) Tg C/y.     

Coexisting chloritoid-staurolite from the Sillimanite (fibrolite) zone,Sini, district Singhbhum,India

Microprobe analyses of the minerals from an unusual chloritoid-staurolite-garnet (+ muscovite + quartz + ilmenite) assemblage from the sillimanite (fibrolite) zone of Sini, India are presented and the petrological significance of the paragenesis is discussed. The X Mg in the different minerals from the chloritoid-staurolite-bearing rock varies in the order, muscovite > chlorite > chloritoid > staurolite > garnet > ilmenite, and from the associated sillimanite-bearing schists: muscovite > biotite > staurolite > garnet rim > garnet core > ilmenite. A graphical representation of the mineral compositions in an AFM projection displays a consistent topology if the effects of non-AFM components such as Zn in the staurolite and Mn in the garnet are taken into account. Petrographic and mineralogical data are consistent with a prograde formation of the chloritoid-staurolite-garnet assemblage. It is suggested that the paragenesis has been formed at similar PT conditions to the associated sillimanite (fibrolite)-staurolite-garnet-mica schists. These conditions are estimated to be 600–625°C/6±0.5 Kb.     

黄土高原黄土和红粘土~(10)Be地球化学特征

充分认识元素和同位素在不同环境条件下的地球化学行为,是运用元素和同位素示踪环境变化的前提。对来自于黄土高原的黄土、古土壤和红粘土样品的宇宙成因核素10Be测量和化学成分分析,以及各种化学淋溶实验表明：10Be主要以吸附状态赋存于粉尘沉积物粘粒矿物的表面,部分已结合进自生的粘土矿物中;在粉尘沉积物风化过程中10BC与9Be和Al的活动性相似,基本没有发生迁移,其原因是连续沉积的粉尘含有大量的碱性物质,阻止了10Be的解吸附和淋滤;沉积和风化作用导致了10Be浓度与化学指标在黄土－古土壤和红粘土剖面中的协同变化。     

Tectonics induced switching of provenance during the Late Quaternary aggradation of the Indus River Valley,Ladakh, India

The Indus River flows through Ladakh, one of the driest and coldest places on earth, in a tectonically active domain. Fluvial, glaciofluvial, lacustrine and debris dominated sequences represent the Late Quaternary sedimentary record along the river course. Karakoram Fault, a major crustal scaled feature reported to be active during the Quaternary, is associated with the Indus River drainage. Linkages between a major, active fault and deposits formed during the activity period of the fault are explored using heavy mineral deduced provenance and Optically Stimulated Luminescence(OSL) chronology.Five deposits in a ~200 km long stretch of the Indus River have been examined for a ~80 ka period to decipher the climate linked aggradation history. Damming of the Indus River at ~79 ka and existence of the Spituk Lake for >30 ka is demonstrated. Using geology of the provenance in relation to the mineralogical attributes of the Quaternary deposits, the major drainage reorganization when the connection of the Tangtse Valley to the Indus was blocked, is inferred at ~73 ka. It is supported by the geologicalgeomorphological evidence. The study demonstrates the application of provenance linked mineralogy in terrestrial aggradation in a tectonically active region.     

Equilibrium Structures of Differentially Rotating Primary Components of Binary Stars

In this paper a method is proposed for computing the equilibrium structures and various other observable physical parameters of the primary components of stars in binary systems assuming that the primary is more massive than the secondary and is rotating differentially about its axis. Kippenhahn and Thomas averaging approach (1970) is used in a manner earlier used by Mohan, Saxena and Agarwal (1990) to incorporate the rotational and tidal effects in the equations of stellar structure. Explicit expressions for the distortional terms appearing in the stellar structure equations have been obtained by assuming a general law of differential rotation of the typeω² = b ₀+b ₁ s ²+b ₂ s ⁴, where ω is the angular velocity of rotation of a fluid element in the star at a distance s from the axis of rotation, and b ₀, b ₁, b ₂ are suitably chosen numerical constants. The expressions incorporate the effects of differential rotation and tidal distortions up to second order terms. The use of the proposed method has been illustrated by applying it to obtain the structures and observable parameters of certain differentially rotating primary components of the binary stars assuming the primary components to have polytropic structures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cosmic ray produced isotopes in terrestrial systems

Continuing improvements in the sensitivity of measurement of cosmic ray produced isotopes in environmental samples have progressively broadened the scope of their applications to characterise and quantify a wide variety of processes in earth and planetary sciences. In this article, I will concentrate on the new developments in the field of nuclear geophysics, based on isotopic changes produced by cosmic rays in the terrestrial systems. This field, which is best described as cosmic ray geophysics, caught roots with the discovery of cosmogenic¹⁴C on the Earth by Willard Libby in 1948, and grew rapidly at first, but slowed down during the ’60s and ’70s. In the ’80s, there was arenaissance in cosmic ray produced isotope studies, thanks mainly to the developments of the accelerator mass spectrometry technique capable of measuring minute amounts of radioactivity in terrestrial samples. This technological advance has considerably enhanced the applications of cosmic ray produced isotopes and today we find them being used to address diverse problems in earth and planetary sciences I discuss the present scope of the field of cosmic ray geophysics with an emphasis ongeomorphology. I must stress here that this is the decade in which this field, which has been studied passionately by geographers, geomorphologists and geochemists for more than five decades, has at its service nuclear methods to introduce numeric time controls in the range of centuries to millions of years.     

Decay and preservation of stone in modern environments

Stone objects decay in all environments, but the modes of decay vary from one region to another. In the modern industrial countries acid deposition has accelerated the decay of stone. Many objects that survived centuries of weathering without serious damage have, in the present century, decomposed beyond recognition. The black crusts seen on stone structures mostly contain gypsum formed by SO₂ reactions with calcareous minerals. These crusts exfoliate, destroying the sculptural form. Because of the absence of proven technology to treat and restore these objects, the caryatids at the Acropolis had to be moved indoors to save them from further disfiguration.In arid climates, the salts in stone and the meteorologic conditions combine to disrupt stone structures. The Great Sphinx at Giza is a prominent example of this mode of stone decay. In humid, tropical regions, such as in southern India, hydrolysis disrupts the mineral structure, causing rapid damage even to such durable stone as granite.The human effort to save the deteriorating structures has often aggravated the problem. The sandstone at the Legislative Building in Olympia, Washington has, because of the protective acrylic coating, suffered greater damage than the similar but unprotected sandstone at a nearby school building.It appears that proper management can greatly help to reduce the decay of the stone. A scientifically designed cleaning can inhibit the formation of crusts and the accumulation of efflorescences. The absence of the crusts and efflorescence and application of appropriate impregnants, which consolidate yet maintain the "breathability" of stone, may prolong the life of historic structures.