SSP
Stratigraphy, Sedimentology and Palaeontology
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Christian Zeeden

Christian Zeeden is a (cyclo)stratigrapher and geophysical sedimentologist at the Leibniz Institute for Applied Geophysics (LIAG, Hannover, Germany). His research includes sedimentology and stratigraphy of aeolian terrestrial deposits as palaeoclimate and geoarchaeological archives. He applies and advances cyclostratigraphy as part of an integrated stratigraphical approach. His research includes geological time series analysis and statistical programming, and focuses on terrestrial sediments and recorded climate cycles both as stratigraphical information as well as palaeoclimatic archive.

Investigating the climate history of Central Asia in Kashmir/India

As in most arid areas, dust storms are quite common in India. Repeatedly, the wind carries large quantities of dust from the Thar Desert in the south-west into the Asian country, sometimes across long distances. There have also been dust storms in India in the past, making geoarchives of aeolian dust a suitable recorder of the past local climate- and dust history. When the climate was rather warm and humid, thick soils would form in the dust deposits. However, if it was cold and dry, the dust would remain as a loose and grey/ochre sediment called loess. Such dust deposits can accumulate 10s to 100s of meters high, and represent valuable archives of past dust activity, soil formation and also other information on e.g. Earth’s magnetic field in the past.  Prominently, the loess occurring at the Chinese Loess Plateau has been extensively used for reconstructing past monsoon activity.

In the Indian subcontinent, such dust deposits have mainly been reported from northern Pakistan and northern India. From the Kashmir valley >20 m thick loess deposits including palaeosols have been reported, but little data is available. Yet, the age of these deposits is controversially discussed in the literature. Age-analyses derived from carbon isotope measurements (14C dating) suggest a rather young age (~40 ka for the outcrop in the image) and high deposition rates of ~26 cm/ka, while ages calculated via luminescence dating suggest deposits to be older (~120 ka for the outcrop in the image) and generally lower sedimentation rates. Such an inconsistency in dating results is uncommon, and the reason is unclear.

Recently, a field trip by Indian and German scientists visited several outcrops in Kashmir to investigate the spatial homogeneity of the reported dust deposits, and collected sediment samples for generating data for a better understanding of the past environment. We can confirm the statements on the occurrence of large dust deposits in the Kashmir valley of at least around 15 meters in height. In the dust deposits, several grey and brown soils are preserved. Therefore, these deposits indeed represent a valuable archive of the past environment. New dates and sedimentological data are expected to allow for a better understanding of the sediment itself and will place these deposits in a Eurasian perspective.

 

Exposure of dust sedimentation and soil formation in the Kashmir valley spanning the last ~40 or ~120 ka. The dark horizontal ‘layers’ represent soils, which have formed during humid phases in the dust deposits.

 

Selected further reading:

Bronger, A., Pant, R.K., Singhvi, A.K., 1987. Pleistocene climatic changes and landscape evolution in the Kashmir Basin, India: Paleopedologic and chronostratigraphic studies. Quat. Res. 27, 167–181.

Dodonov, A.E., Baiguzina, L.L., 1995. Loess stratigraphy of Central Asia: Palaeoclimatic and palaeoenvironmental aspects. Quat. Sci. Rev. 14, 707–720.

Pant, R.K., Dilli, K., 1986. Loess Deposits of Kashmir, Northwest Himalaya, India. Geol. Soc. India 28, 289-297–297.

 

DeepDust ICDP workshop in Norman, Oklahoma, USA discussed drilling the equatorial terrestrial Permian

From microbiology to geophysics – more than 50 international participants of the first DeepDust Workshop covered a wide range of topics. In Oklahoma researchers exchanged views on a possible international drilling project to study the continental geology of the Permian. During a change from the cold to a warm period, large ice masses melted. This may provide interesting insights into current and future climate developments.

After arriving from all around the globe and sharing a joyful ice breaker, the DeepDust workshop started with an introduction to the International Continental Drilling Program (ICDP) including its setup and possible support for projects. This was followed by an introduction to the Permian, highlighting the interest in Permian equatorial terrestrial geoarchives which may partly serve as Mars analogs. The need for a better understanding of this time period and setting was highlighted clearly. The first afternoon was spent with understanding the challenges of different possible drilling areas.

The second day was spent on an excursion where we saw Permian mudstones, including evaporites and siltstones in Oklahoma. The third day was mostly spent discussing key questions and how these may be answered. Discussions included practicalities such as obtaining site survey data and drill planning. The workshop ended with reviewing major objectives and how these may be achieved efficiently regarding, among others, drilling and funding.

Personally, I really enjoyed participating in such an international and focussed workshop. I learned a lot about the Permian, the Geology of Oklahoma and met many enthusiastic colleagues. I am looking forward to continuing pushing the DeepDust project forward.

The workshop participants in front of Permian mudstones in Oklahoma during the workshop field trip.