Evidence of polyphase deformation in gneissic rocks around Devgadh Bariya: implications for evolution of Godhra Granite in the Southern Aravalli Region (India)

In this paper, field evidence documenting the polydeformed nature of banded gneiss that comprises a part of the Godhra Granite and Gneiss in the southern portion of Aravalli Mountain Belt (AMB), India, is presented. The structural geometry involving an episode of recumbent-reclined folding in the gneiss lying in the vicinity of Devgadh Bariya town is worked out. The banded gneiss occurs as enclaves in the granite. Therefore, it is suggested that the banded gneiss of the region is older than Godhra Granite. Microstructures preserved in the granitic rocks are documented and it is suggested that the granitic rocks underwent deformation and strain during their evolutionary history. Variation in the mesoscopic scale fabric of the gneiss and granite along a south-to-north traverse within the study area is documented, and different possibilities for evolution of Godhra Granite are discussed

Structural geology of Kusma-Sirkang section of the Kali Gandaki valley and its bearing on the tectonic framework of Nepal Himalaya

The rocks of the Kali Gandaki valley along the Kusma Sirkang section of Central West Nepal fall into two tectonic units having a marked difference in the grade of metamorphism. The units are demarcated by the NW-SE extending Phalebas Thrust which has been considered equivalent to the Chail Thrust of the Kumaon Himalaya by earlier workers. The Kusma Reverse Fault to the north parallels the Phalebas Thrust, both being related to Late Orogenic movements. The fold pattern shows at least four episodes, and it is believed that two of them existed prior to the main Himalayan orogeny of Tertiary time

Lead in soils and plants: its relationship to traffic volume and proximity to highway (Lalbag, Baroda city)

The accumulation of lead from motor-vehicle exhausts on soils and trees growing along a busy thoroughfare in the Lalbag area of Baroda city has been investigated. The analysis of soils and tree samples showed that the distribution of emitted lead was influenced by the direction of the prevailing wind. The plants and soils near the roadside have a higher lead concentration than at a distance of 4-6 m

Calcretes in semi-arid alluvial systems: formative pathways and sinks

Late Quaternary deposits in Gujarat, western India show an abundant development of calcretes. Three major sinks of carbonate in the alluvial deposits are recognized: (1) groundwater calcretes, (2) pedogenic calcretes, and (3) calcrete conglomerates. Groundwater calcretes originate from carbonate-saturated waters travelling preferentially along stratification planes. Pedogenic calcretes form through soil-forming processes typically in extra-channel areas. Calcrete conglomerates occur as ribbons, sheets and lenses due to the reworking of both pedogenic as well as groundwater calcretes. As a result a pathway of calcretization develops that has the route: groundwater calcrete to pedogenic calcrete to calcrete-conglomerate. The formation of pedogenic calcretes over sediments containing groundwater calcretes demonstrates that (1) apart from aeolian dust, river waters are also a major source of carbonate, and (2) pedogenic carbonates may attain large sizes at accelerated rates due to the presence of pre-existing groundwater calcretes. Consequently, the maturity of a soil may be overestimated if determined by following established morphogenetic sequences

A rapid method of microgram analysis of titanium from rocks

A new spectrophotometric method for the microgram determination of Ti from rock samples in the presence of commonly occurring metal ions has been developed. Ti is extracted from a 1-hexanol solution of benzohydroxamic acid (BHA) at pH < 2. The yellow extract has the maximum absorbance at 370 nm. The extraction was quantitative and obeys Beer's law at 370 nm over the range of 5-20 ppm Ti and the molar absorptivity is 2.4×103 l mol-1 cm-1