NOTES
OCCURRENCE OF PILLOW AND ROPY LAVA IN THE DECCAN TRAP
AT ASAMBIA, KACHCHH, GUJARAT
Deccan Trap Iava flows exposed more or less parallel to the coast line in south-central Kachchh
form a crescent shaped outcrop between the underlying Mesozoic sedimentary rocks and overlying
Tertiary deposits. We report here occurrence of pillow structure and ropy lava in theDeccan lava
of Asambia area (Fig. 1) and discuss its palaeoenvironmental significance.
Pillow structure (Fig. 2) in the Deccan lava can be seen on the Khojachora-Asambia road
section in anala cutting, occurring about 0.5 krn southeast of Khojachora village (lat. 23O1'30"N;
long. 69"27'00"E).The outcrop shows overlapping pillows in the form of flattened bulbous spheroid
bodies or spherical balloons of basaItic lava. The outcrop is however, highIy weathered and altered.
Ash or tuffaceous material underlies the pillow basalt. The pillow structures are
-20 cm to 70 cm in Iength, 10 to 30 cm in thickness and possess one cm thin glassy rim. Amygdales
and geodes are also seen. The pillow lava also shows wrinkled and twisted ropy structure (Fig. 3).
Turbulent flow of lava seems to have been responsible for development of ropy structure.Ghevariya
and Srikarni (1 990) have considered Kachchh lava flows as compound paltoehoe type. Towards
the western side of Nana Asambia village, basaltic flows are covered by laterite.
The pillow lavas point to subaqueous eruption most probably in a series of small ponds/lakes,
marshes and tidal lagoons similar to a coastal-tidal-estuarine complex. Bajpai et al. (1990) have
reported admixture of fresh water and brackish water marine biota from the Kachchh intertrappean
JOUR.GEOL.SOC.INDIA,
VOL.55, MARCH 2000
NOTES
l'ig.2. P~llowlava near Khojachora villagc, Kuchchh
Fig.3. Ropy luvrt near Anjar. Kachchh,
beds. Similar observations have been made by Bhattacharya et. al. (1990) for the Deccan Trap in
Mandln area, Madhya Pradesh.
Ackrtn~vledgernetrts:The authors are thankful to Prof. G.B. Pandya, former Head of Geology
Department, M.G. Science Institute, Ahmedabad, for offering valuable suggestions and for constant
encouragement.
References
RAJPAI,S.. S A ~ I NA,.
I . JOLLY,
A. and SRINIVASAN,
S,(1990). Kachchh lntertrappean biotas: Affinities and cornlation. In:
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RFIA-ITATIIARYA,
A.K., FULMARI,
M. and SEN,M,K. (1990). Patacoenvironrnental significance of the recent discovery of
foraminifera in the intertrappean beds and pillow lava in the Dcccan trap of Mandla area, M.P. I n : Serninar-cumWorkshop Volume, 1GCP Projects 216 and 245, Chandigarh, ( a s . ) A . Sahni and A . Jolly, p. 1 1 2.
RISWAS,
S.K.and Deshpande, S.V. (1970). Geological and Tectonic Map of Kutch. Bull. O.N.G.C., v.7, No.2, pp. 115123.
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JOUR,GEOL.SOC.INVIA.VOL.55, MARCH 2000