Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

S. K. Parcha ¹

Affiliations
1 Wadia Institute of Himalayan Geology, 33-Gen, Mahadeo Singh Road, Dehradun, 248 001, IN

Abstract

The Cambrian sequences exposed in the Kurgiakh Valley of the Zanskar area of Ladakh Himalaya contain a variety of trace fossils as in other Tethyan sequences of Himalayan region. The Ichnogenera identified from this sequence belongs mostly to the traces of trilobite origin, with other traces of arthropod and of unknown origin. These include the Ichnogeneras such as Rusophycus ; Cruziana; Monomorphichnus; Phycodes; Planolites; Skolithos; Meandering trails and trilobite scratch marks. The traces mostly belong to Early Cambrian to early Middle Cambrian in age and occur below the trilobite assemblage; few traces extend above the trilobite-bearing beds. The described species have been collected from the Kurgiakh Formation. The first appearance of species of Phycodes pedum has a special bearing on the identification of the beginning of Cambrian in the sequence. The present report of trace fossils from this Formation is the first report of trace fossils from this area of Ladakh Himalayan region.

Keywords

Palaeontology, Stratigraphy, Zanskar, Ichnogenera, Lower Cambrian, Ladakh Himalaya.

Full Text

     

S. K. Shah ¹, S. K. Parcha ², A. K. Raina ³

Affiliations
1 Post Graduate Department of Geology, University of Jammu, Jammu (Tawi), IN
2 Wadia Institute of Himalayan Geology, 33-General Mahadev Singh Road, Dehra Dun - 248001, IN
3 Western Coalfields Ltd., Coal Estate, Civil Lines, Nagpur 440001, IN

Abstract

A new agnostid genus Trilagnostus from Middle Cambrian of Kashmir is described in addition to Pagetia griesbachi and Pagetia sp. from the same level at the Solvan-Menevian boundary. Diplagnostus is also being reported and described in the same succession at the top of Menevian. This form helps in demarcating the Middle - Upper Cambrian boundary in the sequence.

Keywords

Trilobites, Middle Cambrian, Kashmir.

Full Text

     

S. K. Parcha ¹, S. V. Sabnis ², P. K. Saraswati ³

Affiliations
1 Wadia Institute of Himalayan Geology, Dehra Dun - 248 001, IN
2 Department of Mathematics, Indian Institute of Technology Bombay, Powai, Mumbai - 400 076, IN
3 Department of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai - 400 076, IN

Abstract

The morphological variables often have non-normal distribution The statistical analysis of such variables by imposing normal assumption invariably yields unreliable results Classification and Regression Trees (CART) and Random Forests (RF) are non parametric techniques that are alternative to conventional classification methods such as cluster analysis and linear discriminant analysis used in morphometric research This paper uses the aforementioned Non-Parametric techniques to the variables of the cramdial features of the trilobite genera Hundwarella and Iranoleesia. It is found that misclassification rates in CART and cluster analyses are comparable, whereas they are reduced substantially by the use of Random Forests.

Keywords

Taxonomy, Trilobites, Cambrian, Random Forests, Regression Tree, Morphometries.

Full Text

     

Nigel C. Hughes ¹, S. K. Parcha ²

Affiliations
1 Dept of Earth Sciences, University of California, Riverside, CA - 92521, US
2 Wadia Institute of Himalayan Geology, DehraDun - 248 001, IN

Abstract

No Abstract.

Full Text

   

S. K. Parcha ¹

Affiliations
1 Wadia Institute of Himalayan Geology, Gen. Mahadeo Singh Road, Dehra Dun - 248 001, IN

Abstract

The Middle Cambrian successions of Himalaya are well exposed in the Pohru Valley of northwestern Kashmir Himalaya. The fossiliferous successions are exposed in the Kandi, Nutunus, Takiwadopura, Zachaldor, Khanpura, Neilipora and in the Magam areas of the Kupwara district of northwestern Kashmir. This is one of the highly fossiliferous parts of the Cambrian successions of northwestern Kashmir. The fauna is characteristic of the early Middle Cambrian Maochuangian stage to the late Middle Cambrian representing Maochuangian, Hsuchuangi an stages of the Middle Cambrian. The lower part of the Middle Cambrian Maochuangian is poorly fossiliferous, but the Middle Hsuchuangian and upper parts of Changhian of the successions are profusely fossiliferous. Several faunal assemblages have been recorded which includes some revised as well as new faunal elements. The fauna mainly includes polymerid and agnostid trilobites and few inarticulate brachiopods. In the light of the present biostratigraphic studies attempts have been made to correlate these Middle Cambrian faunal assemblages of Kashmir with the known analogous Middle Cambrian successions of the Tethys Himalaya and preliminarily with other corresponding successions of the Middle Cambrian, on the basis of polymerid and agnostid trilobite fauna.

Keywords

Middle Cambrian, Tethyan Successions, Agnostid, Polymerid Trilobites, Biostratigraphy, NW-Kashmir Himalaya.

Full Text

     

S. K. Parcha ¹, Birendra P. Singh ¹

Affiliations
1 Wadia Institute of Himalayan Geology, 33 General Mahadeo Singh Road, Dehra Dun - 2480 01, IN

Abstract

The Cambrian succession in the Zanskar Basin of Tethys Himalaya contains an abundant ichnofossils like in the other Tethyan Himalayan successions. The ichnofossils are stratigraphically important as they occur below the trilobite body fossils and are useful to define the basal part of the Cambrian. The ichnofossil assemblage reported from the Zanskar Basin of Ladakh Himalaya is significant to demarcate the Early Cambrian age due to lack of other faunal elements so far. The body fossils of trilobites recorded from the overlying beds indicates the earliest part of the Middle Cambrian age. Sixteen ichnogenera identified include: Bifungites, Cruziana, Diplichnites, Dimorphichnus, Isopodichnus, Lockeia, Merostomichnites; Monomorphichnus, Psammichnites, Palaeophycus, Planolites, Rhizocorallium, Skolithos, Taphrhelminthopsis, Teichichnus, Trepitichnus and trilobite scratch marks etc. The ichnogenera reported so far from this part of the Tethyan Himalayan region belongs mostly to the traces of arthropod origin. The ichnofauna ranges in age from Lower Cambrian to late part of the Middle Cambrian. The ichnofaunal assemblage can be assigned to repichnial, cubichinial, pascichnial, to fodinichnial behaviour. The distribution of ichnofossils in the studied sections shows that the ichnofossils are predominately less in occurrence in the sections were trilobites dominates and higher in the successions the abundance of ichnofossils decreases.

Keywords

Ichnofossils, Cambrian, Zanskar, Ladakh Himalaya.

Full Text

     

S. K. Parcha ¹, Shivani Pandey ¹

Affiliations
1 Wadia Institute of Himalayan Geology, 33 General Mahadeo Singh Road, Dehradun - 248 001, IN

Abstract

The Muth Formation is one of the most characteristic marker horizon traced throughout the northwestern Himalaya. The present studies were carried out in the Farakah Muth (Pin Valley) section of Spiti Basin. The formation uniformly consists of quartzarenite with a high textural and compositional maturity. The development of carbonate beds in the upper part of the Muth Formation separates it conformably from the overlying Lipak Formation. A variety of traces were observed throughout the succession, includes: Metaichna, Planolites, Skolithos, vertical and horizontal burrows. The presence of ichnofossils in the Muth Formation of the Farakah section indicates subtidal settings having soft sandy substrate, whereas, the gradual maturity of the quartz grains from base to top indicates deposition under high energy condition.

Keywords

Ichnofossils, Depositional Environment, Muth Formation, Pin Valley, Spiti Himalaya.

Full Text