Geomorphic control on the formation of mixed layer clays by progressive degradation of biotite: A case study from Jutulsessen Gjelsvikfjella, East Antarctica

Verma, Kamlesh; Bhattacharya, Siddhartha; Ansari, A. M. Asim; Srivastava, Prakash Kumar; Dharwadkar, Amit

doi:10.1007/s12594-014-0080-8

Cited by 1 publication

(2 citation statements)

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“…5). Biotite and muscovite occur as clay-size fraction of soil (Fordham, 1990;Moore and Reynolds, 1997;Verma et al, 2014). Biotite is found in clay fractions of the pyroclastic deposits of Mount St. Helen (Pevear et al, 1982).…”

Section: Clay Fraction Investigationmentioning

confidence: 99%

“…lllite may form by (i) weathering of silicates (primarily feldspar), (ii) alteration of other clay minerals (Lynch et al, 1997), and (iii) degradation (Deer et al, 1992) or weathering of muscovite in soils (Fanning et al, 1989). Illite is reported to form from weathering of biotite in soils in United States (Nettleton et al, 1973), and in sandstone from Antarctica (Verma et al, 2014). Smectite may convert to illite at deep burial (Boles and Franks, 1979;McKinley et al, 2003).…”

Section: Clay Fraction Investigationmentioning

confidence: 99%

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Occurrence of a Likely Tuff Bed between the Middle and Upper Siwaliks, Taunsa area, Dera Ghazi Khan, Eastern Sulaiman Range, Pakistan

Ullah

Fengjuin

Zhang

et al. 2020

IJEEG

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A likely tuff bed lies along the gradational contact of the Middle and Upper Siwaliks in eastern Sulaiman Range, Taunsa area of Dera Ghazi Khan district, Pakistan. This tuffaceous unit is 0.5–3 m thick and extends for 10 km along the north-south strike in the eastern limb of the Zindapir anticline. It is greyish white to white on fresh surface, fine-grained to silty at the bottom and clayey at the top and thus shows a fining upward grain-size grading. The lower part of the ash bed shows a prominent lamination defined by megascopically visible abundant biotite, while the central and upper parts are so fine-grained that the individual minerals cannot be seen in hand sample. Unlike the lower well-laminated part, the central and upper parts are crudely laminated to apparently massive. The bulk samples analysed with X-ray diffraction consist of quartz, feldspar (plagioclase), biotite, clays, calcite and some ore mineral likely spinel, while the clay-size fractions contain illite, chlorite, biotite and probably their mixed-layered varieties. The colour, texture, presence of abundant biotite and stratigraphic position of the Taunsa tuff correlate with those reported from Potwar plateau and from Kashmir basin. However, the apparent absence of smectite from the XRD pattern makes the Taunsa ash bed different from both Potwar and Kashmir tuffs. The present stratigraphic position of the tuff bed corresponds to shallow diagenetic zone, while the absence of smectite in the tuff and crystallinity of illite suggest that the tuff is probably derived upon reworking from a deeper diagenetic zone belonging to a lower stratigraphic level. The Eocene or other older pre-Siwalik units in Pakistan may have or had some primary ashfall deposits as reported in the northwestern Himalayas of India. This older volcanic ash may have been reworked to its present site of occurrence along the gradational contact of the Middle and the Upper Siwaliks in Taunsa area of Dera Ghazi Khan. However, the primary source of the Taunsa tuff may belong more likely to Chagai arc in Pakistan than to Dacht-e-Nawar volcanic complex in Afghanistan.

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Section: Clay Fraction Investigationmentioning

confidence: 99%