Deciphering condensed sequences

A case study from the Oxfordian (Upper Jurassic) Dhosa Oolite member of the Kachchh Basin, western India

Matthias Alberti, Franz T. Fürsich, Dhirendra K. Pandey

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

In large parts of the Kachchh Basin, a Mesozoic rift basin situated in western India, the Oxfordian succession is characterized by strong condensation and several depositional gaps. The top layer of the Early to Middle Oxfordian Dhosa Oolite member, for which the term 'Dhosa Conglomerate Bed' is proposed, is an excellent marker horizon. Despite being mostly less than 1m thick, this unit can be followed for more than 100km throughout the Kachchh Mainland. A detailed sedimentological analysis has led to a complex model for its formation. Signs of subaerial weathering, including palaeokarst features, suggest at least two phases of emersion of the area. Metre-sized concretionary slabs floating in a fine-grained matrix, together with signs of synsedimentary tectonics, point to a highly active fault system causing recurrent earthquakes in the basin. The model takes into account information from outcrops outside the Kachchh Mainland and thereby considerably refines the current understanding of the basin history during the Late Jurassic. Large fault systems and possibly the so-called Median High uplift separated the basin into several sub-basins. The main reason for condensation in the Oxfordian succession is an inversion that affected large parts of the basin by cutting them off from the sediment supply. The Dhosa Conglomerate Bed is an excellent example, demonstrating the potential of condensed units in reconstructing depositional environments and events that took place during phases of non-deposition. Although condensed sequences occur frequently throughout the sedimentary record, they are particularly common around the Callovian to Oxfordian transition. A series of models has been proposed to explain these almost worldwide occurrences, ranging from eustatic sea-level highstands to glacial phases connected with regressions. The succession of the Kachchh Basin shows almost stable conditions across this boundary with only a slight fall in relative sea-level, reaching its minimum not before the late Early Oxfordian.

Original languageEnglish
Pages (from-to)574-598
Number of pages25
JournalSedimentology
Volume60
Issue number2
DOIs
Publication statusPublished - 02-2013

Fingerprint

oolite
Oxfordian
Jurassic
basin
conglomerate
condensation
sea level
synsedimentary tectonics
paleokarst
emersion
Callovian
highstand
active fault
depositional environment
slab
outcrop
weathering
uplift
earthquake
matrix

All Science Journal Classification (ASJC) codes

  • Geology
  • Stratigraphy

Cite this

Alberti, Matthias ; Fürsich, Franz T. ; Pandey, Dhirendra K. / Deciphering condensed sequences : A case study from the Oxfordian (Upper Jurassic) Dhosa Oolite member of the Kachchh Basin, western India. In: Sedimentology. 2013 ; Vol. 60, No. 2. pp. 574-598.
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Deciphering condensed sequences : A case study from the Oxfordian (Upper Jurassic) Dhosa Oolite member of the Kachchh Basin, western India. / Alberti, Matthias; Fürsich, Franz T.; Pandey, Dhirendra K.

In: Sedimentology, Vol. 60, No. 2, 02.2013, p. 574-598.

Research output: Contribution to journalArticle

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