Ghat Section Research Articles

Comparative analysis in GIS-based landslide hazard zonation—a case study in Bodi-Bodimettu Ghat section, Theni District, Tamil Nadu, India

The aim of this research article is to assess and compare the reliability of spatial-based different landslide hazard zonation mapping methods in the Bodi-Bodimettu Ghat section, Theni District as a case study. In favor of this intention, the three methods like the Bureau of Indian Standard (BIS), multi-criteria analysis (MCA), and frequency ratio (FR) model have been applied to find out three different landslide hazard zonation maps. The results of the three methods were compared using parameters such as landslide density, success rate curve, and spatially agreed area. Approximately the same variation is seen in the final results of BIS in comparison to the other methods, namely MCA and FR. But if we go actually into the detail, low hazard and moderate hazard seem to merge to indicate one single zone made as moderate hazard. Moreover, the nature of weightages used in different techniques may have the same influence on the outcome of the result.

Vegetation Changes along Altitudinal Gradients in Human Disturbed Forests of Uttara Kannada, Central Western Ghats

This study was carried out along the altitudinal gradients of Uttara Kannada district of Karnataka, representing different agro-climatic zones - coast, hilly and plains. 10 different sectors were selected for the study. Transect based survey resulted in documenting a total of 134 species of trees and 146 species of shrubs. It was found that the sectors 6, 7 and 8, lying in the Western Ghats section, were having semi-evergreen to evergreen forests and had the highest species diversity, percentage evergreen and percentage endemism. The sectors 9 and 10 in eastern plains harbour dry deciduous forests dominated by teak. The coastal sectors have more moist deciduous forests affected by human disturbances except for a patch of sacred grove in sector 1. However, the regeneration of evergreens, especially in the Ghat section areas, can be considered as a good sign for the return of evergreen forests and need to be austerely protected.

The Deccan Trap – Cretaceous–Paleogene boundary connection; new 40Ar/39Ar ages and critical assessment of existing argon data pertinent to this hypothesis

The Cretaceous–Paleogene boundary (KPgB) was dated by the 40Ar/39Ar method herein from the western interior of North America at 65.48±0.12Ma (1σ), in good agreement with other recent published estimates. For the Deccan Traps, India, new argon ages as well as others available in the literature, are assessed for reliability based on (a) statistical reliability of plateau/isochron sections and (b) freshness of material dated utilizing the alteration index method. From tholeiitic lavas from the Composite Western Ghats Section (CWGS), only six ages are found to be reliable estimates of the time of crystallization. These ages along with the magnetic polarity of the lavas agree with the geomagnetic polarity time scale (GPTS) at ∼67–64Ma. Alkaline rocks from the Anjar area of Kutch, provide three reliable ages that suggest a hiatus in lava extrusion around KPgB. For the Rajahmundry basalts, the upper flow’s age defines its formation during chron 29n; a single age from the lower reversed polarity flow appears somewhat dichotomous when plotted against the GPTS. The reliable lava ages indicate the most voluminous (reversed polarity) sections of the CWGS were extruded at a time statistically indistinguishable from that of the KPgB. The Deccan Trap – KPgB faunal extinction hypothesis remains plausible, but must compete with the latest report, favoring a very close temporal connection (∼0.03m.y.) between the Chixculub (Impact) Crater and the KPgB.

Technical Aspects of Variables Affecting Jatropha Methyl Ester Production — An Indian Case Study

Biodiesel obtained from vegetable oils as an alternative fuel for diesel engine is becoming increasingly important. The biodiesel quality and yield are affected by the properties of the oil used. The properties of the oil vary from region to region depending on the nature of the soil in which oil crops are cultivated, agricultural practices, rainfall etc. In this study the raw oil from Jatropha Curcas seeds grown in the western Ghat section of South India was tested for its physiochemical properties to determine its suitability for biodiesel production. A bench scale, compact biodiesel processor was developed locally by the authors and biodiesel was produced from raw Jatropha Curcas oil using alkali based transesterification process. The physiochemical properties of the biodiesel produced meet the ASTM standards but the yield was comparatively low (80%v/v) because of the high free fatty acid content (13.7 mg KOH/g of oil) in the raw Jatropha Curcas oil. The brake thermal efficiency of the biodiesel produced as a fuel in a four stroke single cylinder diesel engine coupled with an electric generator (34.19%) at maximum load conditions shows the possibility of utilization of biodiesel produced as a fuel in the diesel engine.

Landslide vulnerability mapping using frequency ratio model: a geospatial approach in Bodi-Bodimettu Ghat section, Theni district, Tamil Nadu, India

This research paper assesses the vulnerability of landslide for the Bodi-Bodimettu Ghat section, Theni district, Tamil Nadu, India, using remotely sensed data and geographic information system (GIS). Landslide database was generated using IRS-1C satellite LISS III data and aerial photographs accompanied by field investigations using differential global positioning system to generate a landslide inventory map. Topographical, spatial, and field data were processed to construct the spatial thematic layers using image processing and GIS environment. Twelve landslide-inducing factors were used for landslide vulnerability analysis: elevation, slope, aspect, plan curvature, profile curvature, proximity to road, drainage and lineament, land use/land cover, geology, geomorphology, and run-off. The first five factors were derived from digital elevation model, and other thematic layers were prepared from spatial database. Frequency ratio of each factor was computed using the above thematic factors with past landslide locations. Landslide vulnerability map was produced using raster analysis. The landslide vulnerability map was classified into five zones: very low, low, moderate, high, and very high. The model is validated using the relative landslide density index (R-index method). The consistency of R-index indicates good performance of the vulnerability map.

Process Optimization for Biodiesel Synthesis From Jatropha Curcas Oil

Crude Jatropha Curcas Oil (CJCO) obtained from the seeds grownin the Western Ghat section of South India was investigated for biodie-sel production using one step alkali catalyzed transesterification. Thereactions were conducted at 400 rpm agitation rate for 1 hour. Differentmethanol to oil molar ratios (5.5:1, 6:1, 6.75:1, 7.5:1 and 8:1), catalyst tooil ratios (1.43, 1.68, 1.85, 2.1, 2.35 and 2.52 %w/w of oil) and reactiontemperatures (50°C to 70°C) were employed to investigate their effecton biodiesel yield. The maximum yield of 80.5% was obtained at theoptimum methanol to oil molar ratio of 7.5:1, catalyst to oil ratio of2.09%w/w of oil and reaction temperature 60°C. The physiochemicalproperties of the biodiesel produced meet the ASTM standards. Thereason for the low yield was observed as the high free fatty acid content(13.7 mg KOH/g of oil) in the Crude Jatropha Curcas oil. A biodieselfueled four-stroke diesel engine-generator set yielded an overall fuel-to-electricity efficiency of 24.38% at maximum load condition, thusshowing the possibility of utilization of CJCO derived fuel in dieselengines.

Process Optimization for Biodiesel Synthesis From Jatropha Curcas Oil

ABSTRACT Crude Jatropha Curcas Oil (CJCO) obtained from the seeds grown in the Western Ghat section of South India was investigated for biodiesel production using one step alkali catalyzed transesterification. The reactions were conducted at 400 rpm agitation rate for 1 hour. Different methanol to oil molar ratios (5.5:1, 6:1, 6.75:1, 7.5:1 and 8:1), catalyst to oil ratios (1.43, 1.68, 1.85, 2.1, 2.35 and 2.52 %w/w of oil) and reaction temperatures (50°C to 70°C) were employed to investigate their effect on biodiesel yield. The maximum yield of 80.5% was obtained at the optimum methanol to oil molar ratio of 7.5:1, catalyst to oil ratio of 2.09%w/w of oil and reaction temperature 60°C. The physiochemical properties of the biodiesel produced meet the ASTM standards. The reason for the low yield was observed as the high free fatty acid content (13.7 mg KOH/g of oil) in the Crude Jatropha Curcas oil. A biodiesel fueled four-stroke diesel engine-generator set yielded an overall fuel-to-electricity efficiency of 24.38% at maximum load condition, thus showing the possibility of utilization of CJCO derived fuel in diesel engines.

Macro Landslide Hazard Zonation Mapping - Case Study from Bodi – Bodimettu Ghats Section, Theni District, Tamil Nadu - India

Landslide is a common natural hazard that usually occurs in mountainous areas. Rapid urban development and high traffic intensity movements have been hampered to a great extent by phenomenon of landslides. In Ghat section, vertical cuttings and steep slopes are induced slope failures. An assessment of landslide hazards is therefore a prerequisite for sustainable development of the hilly region. In the present study, Macro Landslide Hazard Zonation was carried out in the Bodi – Bodimettu ghats section, Western Ghats, Theni district. The slope spreads over an area of about 10.09 sq km encompassing Puliuttu Ar. sub-watershed. The study was made with help of different types of data including Survey of India topographic map, geology map, important inherent factors like lithology, structure, slope morphometry, relative relief, land use/land cover and hydrogeological conditions using Bureau of Indian Standard (BSI 14496 (Part 2):1998) and related thematic maps. Based on the thematic layers, landslide hazard evaluation factor (LHEF) and total estimated hazard (TEHD) were calculated and the macro hazard zonation map was prepared. Landslide Hazard Zonation (LHZ) of the terrain shows that out of 17 facets, facets 1 to 5 and 8 falls under Moderate Hazard zone category and facets 6, 7 and 9 to 17 under the High Hazard zone category. The field study with further analysis for hazard concluded that about 68% of the total area falls in the high hazard zone.

Geochemical signatures for the grain size variation in the siliciclastics of Kaimur Group, Vindhyan Supergroup from Markundi ghat, Sonbhadra district, (U.P.), India

The chemical composition of siliciclastics from Mesoproterozoic Kaimur Group, Vindhyan Supergroup have been investigated to determine and appraise the influence of the weathering, hydraulic sorting and recycling processes upon source rock signature. The studies pertaining to the relationship between major, trace and REE and the grain size variation were carried out along Markundi ghat section, Sonbhadra district, Son valley. Upper Kaimur Group has been divided into three principal formations-the uppermost-Dhandraul quartzites, Scarp sandstone and Bijaigarh shales. Petrographically, they range from quartz arenite, sublitharenite, subfeldspathic arenite to pyritiferous shale. The elemental enrichment, except for SiO2, is in the following order-Bijaigarh Shale > Scarp Sandstone ≫ Dhandraul Sandstone.

Strong myotoxic activity of Trimeresurus malabaricus venom: Role of metalloproteases

Trimeresurus malabaricus is an endemic snake found in the Southern region of Western Ghats section of India along with the more widely distributed species like Naja naja and Daboia russelii. T. malabaricus venom is not lethal when injected (i.p.) up to 20 mg/kg body weight in mice, but causes extensive local tissue degeneration. N. naja and D. russelii are highly toxic (i.p.) with minimum local tissue damage in experimental mice. In this study a comparative analysis of local tissue damage of T. malabaricus venom is made with N. naja and D. russelii snake venoms of the Southern regions of Western Ghats. T. malabaricus venom exhibits caseinolytic activity 16 and 24 times more than N. naja and D. russelii venom. Inhibition studies with specific protease inhibitors reveal that the major proteases belong to metalloproteases. T. malabaricus venom hydrolyses gelatin and induces strong hemorrhagic activity in mice. Both N. naja and D. russelii fail to hydrolyze gelatin even at very high concentration and did not induce any hemorrhagic activity. With D. russelii venom small hemorrhagic spot was observed at the site of injection. The hemorrhagic activity of T. malabaricus venom is completely neutralized by metalloprotease inhibitors and not by serine protease inhibitor. The i.m. injection of T. malabaricus venom causes extensive degradation of muscle tissue within 24 h. The light microscopic observation of muscle tissue showed congestion of blood vessels and hemorrhage at the early stage followed by extensive necrosis of muscle fibers. The elevated levels of serum CK and LDH activity further supported the muscle degeneration. Such pathological symptoms were not seen with N. naja and D. russelii snake venom. The hemorrhagic and the muscle necrosis was completely neutralized by metalloprotease inhibitors and not by serine protease inhibitor strongly suggests that the major toxin component in the T. malabaricus venom is metalloprotease and its activity can be easily neutralized using chelating agents and its use in the first aid as chelation therapy is beneficial.

Geochemical stratigraphy of Deccan flood basalts of the Bijasan Ghat section, Satpura Range, India

The ∼240-m-thick Bijasan Ghat section exposes Deccan basalt flows and dykes that have major and trace element compositions suggestive of variable amounts of contamination by continental material. Most flows and a dyke are chemically similar to lavas of the Poladpur Formation in the southwestern Deccan. One flow and one dyke are similar to lavas of the Bushe Formation in the southwest, and one dyke is similar to lavas of the Mahabaleshwar Formation in the southwest. The type-sections of these formations are located ∼350 km to the south of Bijasan Ghat, but many Poladpur-type lavas, a few Mahabaleshwar-like lavas and dykes, and a few broadly Bushe-like lavas and dykes have recently been identified in the Satpura region. Lavas resembling the thick Ambenali Fm. of the southwest are absent from Bijasan Ghat and nearby areas. Our data further extend the known outcrop area of Poladpur-like flows (estimated at ≥3×10 5 km 2), one of the most widespread Deccan magma types. Seven ‘giant plagioclase basalt’ flows encountered in seven different sections in this region cannot unambiguously be correlated at present, either physically or chemically, and therefore are of little use in deciphering the complicated stratigraphic and structural make-up of the regional lava pile.

Giant Plagioclase Basalts, eruption rate versus time

I welcome Sheth’s comments on a more intrigu-ing aspect of my paper, namely, the calculation ofage of the Deccan lava pile in the Western Ghats(type section) using sizes of the “giant” plagioclasecrystals in “Giant Plagioclase Basalt (GPB)” lavaflows. I found the GPB lavas to be very interest-ing because in some cases they clearly mark theboundary between Formations (Hooper et al 1988;Subbarao et al 1988; Khadri et al 1988). They alsoseem to have erupted over bole beds, each of whichpossiblyrepresentsahiatusbetweeneruptiveactiv-ities (Sen 2001). In my view, the latter aspect stillneeds to be proven with solid field work.Sheth correctly points out that typically erup-tion rate is expressed in terms of some sort ofunit volume as a function of time. I did not dothis because I am not sure that we know thevolumes of individual lava flows all that well. Itis clearly something that we need to know bymapping out individual flows in the field. Thatis why I chose to estimate a “one dimensionaleruption rate,” a practice that is not uncommonin experimental and modeling studies. I was ini-tially encouraged by Sheth’s new (and correct)eruption rate calculations based on my approach,suggesting that the Western Ghats section spana time of 4.4m.y. He notes that this range coin-cides very well with the

Generation of Deccan Trap magmas

Deccan Trap magmas may have erupted through multiple centers, the most prominent of which may have been a shield volcano-like structure in the Western Ghats area. The lavas are predominantly tholeiitic; alkalic mafic lavas and carbonatites are rare. Radioisotope dating, magnetic chronology, and age constraints from paleontology indicate that although the eruption started some 68 Ma, the bulk of lavas erupted at around 65–66 Ma. Paleomagnetic constraints indicate an uncertainty of ± 500,000 years for peak volcanic activity at 65 m.y. in the type section of the Western Ghats. Maximum magma residence times were calculated in this study based on growth rates of “giant plagioclase” crystals in lavas that marked the end phase of volcanic activity of different magma chambers. These calculations suggest that the > 1.7 km thick Western Ghats section might have erupted within a much shorter time interval of ∼ 55,000 years, implying phenomenal eruption rates that are orders of magnitude larger than any present-day eruption rate from any tectonic environment. Other significant observations/conclusions are as follows: (1) Deccan lavas can be grouped into stratigraphic subdivisions based on their geochemistry; (2) While some formations are relatively uncontaminated others are strongly contaminated by the continental crust; (3) Deccan magmas were produced by 15–30% melting of a Fe-rich lherzolitic source at ∼ 3–2 GPa; (4) Parent magmas of the relatively uncontaminated Ambenali formation had a primitive composition with 16%MgO, 47%SiO2; (5) Deccan magmas were generated much deeper and by significantly more melting than other continental flood basalt provinces; (6) The erupted Deccan tholeiitic lavas underwent fractionation and magma mixing at ∼ 0.2 GPa. The composition and origin of the crust and crust/mantle boundary beneath the Deccan are discussed with respect to the influence of Deccan magmatic episode.

Geochronological studies on whole-rock basalts, Deccan Traps, India: evaluation of the timing of volcanism relative to the K-T boundary

KAr and 40 Ar 39 Ar incremental heating studies have been carried out on whole-rock basalts spanning different sections of the Deccan Traps. KAr dates typically fall in the range ∼ 55–65 Ma and, for an individual section, are commonly out of stratigraphic order; indicating post-crystallization loss of 40Ar ∗ from some samples. Specimens from six lava flows spanning a composite Western Ghats section and another six from sections in the southern, western, and northern areas of the Deccan, were selected for 40 Ar 39 Ar step-heating studies. Many of these specimens yield low temperature steps with apparent ages < 60 Ma, indicating post-crystallization loss of 40Ar ∗. The following (low-intermediate temperature) steps commonly yield apparent ages (> 70 Ma) older than crystallization values. Such spectra are characteristic of fine-grained basalts exhibiting 39Ar recoil loss and could involve: (1) 39Ar internal redistribution, out of K-rich sites into K-poor phases, and/or (2) 39Ar recoil loss out of the sample. Comparison of total gas ages with KAr dates permitted constraints to be placed on these two mechanisms. For some rocks, plateau ages were recovered from the intermediate-high temperature steps in the range 64–66 Ma, with 1σ errors of 0.5–1.0 m.y. A dyke specimen from the western Deccan, with a KAr date of ∼ 97 Ma, shows a descending staircase type of age spectrum and its estimated crystallization age is ∼ 65 Ma. Two lava flows from the central Deccan with low KAr dates ( ∼ 50–55 Ma) yield crystallization ages of ∼ 65 Ma; KAr dates deviating significantly from ∼ 65 Ma, do not reflect crystallization ages. Integration of the age data with the magnetic polarity of the different sections of lavas suggests the main reversed polarity epoch trapped in the Deccan volcanic province is chron 29R, which includes the Cretaceous-Tertiary boundary (estimated age 64.5 Ma). The plateau ages presented herein tend to be slightly older ( ∼ 1%) than the age of chron 29R; this probably results from minute amounts of 39Ar recoil loss out of the sites degassed in the intermediate-high temperature range. The Western Ghats section of the Deccan Traps, representing > 80% of the exposed material, was extruded in ∼ m.y.