Biosequence stratigraphical and palaeoenvironmental findings from the Cretaceous through Tertiary succession, Central Indus Basin, Pakistan

M I Wakefield,E Monteil

doi:10.1144/jm.21.2.115

M I Wakefield, E Monteil

Open Access

https://doi.org/10.1144/jm.21.2.115

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Abstract

Abstract. Integrated analysis of foraminiferal and palynological data from the Duljan-1 well, Central Indus Basin, Pakistan, is used to identify critical surfaces (candidate sequence boundaries (SB) and maximum flooding surfaces (MFS)) and construct a biosequence stratigraphical framework. Within the Barremian through Bartonian–Priabonian? succession 15 depositional sequences have been recognized, each with a candidate MFS. These biosequences are shown to equate with the local lithostratigraphy and tentatively with the ‘global’ large-scale depositional cycles of Haq et al. (1987). Detailed dating has enabled seven candidate MFS to be tentatively equated with MFS identified on the nearby Arabian plate (Sharland et al., 2001). A combination of detailed age dating and palaeobathymetric determinations indicates significant basin uplift and erosion at end Cretaceous and end Eocene times, the latter coinciding with closure of Neo-Tethys. Smaller-scale unconformities are also noted. Multi-disciplinary palaeoenvironmental interpretations enable recognition of detailed changes in water mass conditions. Palynological data suggest these changes result from variations in terrestrial/freshwater input, though evidence of periodically low oxygen bottom water conditions/shallowing of the oxygen minimum zone, possibly ‘Oceanic Anoxic Event-2’ (OAE-2; late Cenomanian–Turonian) is suggested as a further control.

Highlights

Integrated analysis of foraminiferal and palynological data from the Duljan-1 well, Central Indus Basin, Pakistan, is used to identify critical surfaces (candidate sequence boundaries (SB) and maximum flooding surfaces (MFS)) and construct a biosequence stratigraphical framework
LOCATION OF STUDY WELL This study is based on the investigation of foraminiferal, nannofossil and palynological data from the Duljan-1 well situated between the central and lower portions of the Indus Basin (Fig. 1)
Amorphous Organic Matter (AOM) is abundant in lowstand and transgressive times but is much reduced to absent above the candidate MFS (3091 m), while black and brown woods dominate the assemblage indicating a strong terrestrial influence (Fig. 5)

Summary

Introduction

Integrated analysis of foraminiferal and palynological data from the Duljan-1 well, Central Indus Basin, Pakistan, is used to identify critical surfaces (candidate sequence boundaries (SB) and maximum flooding surfaces (MFS)) and construct a biosequence stratigraphical framework. AOM is abundant in lowstand and transgressive times but is much reduced to absent above the candidate MFS (3091 m), while black and brown woods dominate the assemblage indicating a strong terrestrial influence (Fig. 5). This sequence was deposited at approximately middle neritic water depths, though there does appear to be a subtle deepening uphole that is more clearly emphasized by the increase of the P:B ratio and a general increase in marine palynological indicators (Figs 2 & 3).

Results

Conclusion