| Abstract |
- This multidisciplinary study integrates remote sensing, stratigraphy, siliciclastic and carbonate sedimentology, tectonics, and petrography of the Nisai, Khojak and Sharankar Formations to reveal the Paleogene depositional, diagenetic and deformational history of the Katawaz Basin.
Study of Landsat Thematic Mapper (TM) digital data shows that maximum discrimination of different rocks is achieved in bands 5, 4, and 2 in red, green and blue, respectively. Maximum spectral contrast of Nisai limestone lithofacies uses band ratios 7/5(R), 4/3(G)and 3/2(B). Laboratory spectral measurements suggest Nisai lithofacies are best discriminated in lower wavelength regions (TM
bands 1, 2, 3, and 4).
Late Paleocene to early Oligocene Nisai Formation records
carbonate platform, slope and basinal deposition. Newly formed structural highs and lows, due to emplacement of ophiolites on the western passive margin of Indo-Pakistan subcontinent, controlled deposition and thickness of Nisai lithofacies. Revised age of the ophiolite emplacement, based on benthic forams, is early Paleocene.
Siliciclastic Khojak Formation includes newly identified upper continental slope, prodelta, delta front, lower and upper delta plains lithofacies. These lithofacies represent prograding fluvial-dominated, wave-modified Katawaz delta that axially fed Khojak submarine-fan turbidites to the southwest. Sandstone detrital modes and paleocurrent analysis suggest derivation from the early Himalayan orogen and longitudinal dispersal down the basin axis. Decrease in quartz, and increase in total lithics from bottom to top reflect gradual uplift and unroofing of the early Himalaya. Diagenetic relationships suggest complex paragenetic sequence of chlorite-quartz-calcite cementation.
Himalaya-derived molasse, delta, and turbidite fan sediments are related in time and space. Molasse sedimentation began in late Paleocene, when early Himalayan orogenic highlands formed. However, sedimentation on the modern Indus delta-fan began in the early Miocene. This age-range discrepancy implies that a major portion of the Himalayan marine record is missing. Khojak strata are that missing record.
The Katawaz remnant ocean closed, scissors fashion, by the end of early Miocene and the Katawaz-Khojak complex was incorporated to the Indo-Pakistan subcontinent. The Himalaya-Katawaz system is a Paleogene analogue to the Carboniferous Appalachian-Black Warrior-Ouachita system.
|
|---|