Daund Lava Tube

Herbert Daniel Gebauer - 06/01/2018

What looks like the remnants of a lava tube report DURAISWAMI et al. (2005) from one western Deccan Volcanic Province, India and at a location near the railway bridge across Bhima river in the north-west of Daund (note 1). CAVE DESCRIPTION: The lava tube system is exposed as several exhumed outcrops and is composed of complex branching and discontinuous segments. The roof of the lava tube has collapsed but original lava tube walls and fragments of the tube roof are seen at numerous places along the tube. At some places the tube walls exhibit a single layer of lava lining, whereas, at other places it shows an additional layer characterised by smooth surface and polygonal cracks. The presence of a branching and meandering lava tube system in the Daund flow, which represents the terminal parts of Thakurwadi Formation, shows that the hummocky flow developed at a low local volumetric flow rate. This tube system developed in the thinner parts of the flow sequence and tumuli developed in ares where the tube clogged temporarily in the sluggish flow (DURAISWAMI et al. 2005: 819 abstract). The structure is curvilinear (figure 2: cave plan) and has undergone considerable erosion. It is preserved as a shallow empty, non-roofed depression flanked by tube walls. The roof of the tube appears to have collapsed/eroded. Segments that constitute the structure generally trend in the N60°–240° direction. The main segment of the tube can be traced for about 100 m in a single outcrop. However, the cumulative length of such segments from various outcrops is more than 300 m.The northern wall of the tube shows variable dips between 9° and 22°. This wall appears to show two distinct layers, each with different vesicle content, jointing pattern, and petrography. The inner layer displays large, circular vesicles, with a high vesicle density. This layer has a regular polygonal jointing pattern. In contrast, the outer layer is characterized by joints that are perpendicular to the trend of the tbe. This layer has smaller vesicles and has a low vesicle density. The average width of the tube floor varies from 5.53 m towards the western end to 1.70 m in the east. The Floor of the tube is almost horizontal. Towards the south-eastern wall of the main tube floor, a 0.30m wide and 0.40m deep structure is encountered.We term this depression as a -lava gutter-, which is filled partly by a fine-grained, leucocratic, clay-like material. The walls of the lava gutter exhibit variable dips. … A couple of branches of the tube system are also exposed on the northern bank of the Bhima river. The north-eastern branch is discontinuously exposed and only the fragments of the eastern wall are present. … The segments of the tube wall show high dips (30° to 60°). The surface of the tube wall is very smooth and appears glazed, with distinct cracks. The glaze is the result of sustained high temperature (L Keszthelyi, Pers. Comm., 2004). A segment of the north-western branch can also be traced for moe than 50 m and occurs as a sinuous depression (up to about 1.5 m wide). This depression is complete with lava walls and at places, fragments that could be part of the tube roof. Alternatively, these fragments may also represent tumulus crust, roofed over the tube (DURAISWAMI et al. 2005: 820-821).e than 50 m and occurs as a sinuous depression (up to about 1.5 m wide). This depression is complete with lava walls and at places, fragments that could be part of the tube roof. Alternatively, these fragments may also represent tumulus crust, roofed over the tube (DURAISWAMI et al. 2005: 820-821).