The Indus Fan is one of the most significant depositional feature of the offshore Indus basin. It is the second largest fan system in the world after the Bengal Fan between India,

Bangladesh Bangladesh, officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world and among the List of countries and dependencies by ...

and the

Andaman Islands The Andaman Islands () are an archipelago, made up of 200 islands, in the northeastern Indian Ocean about southwest off the coasts of Myanmar's Ayeyarwady Region. Together with the Nicobar Islands to their south, the Andamans serve as a mari ...

. The Indus fan was deposited in an unconfined setting on the continental slope, rise and basin floor, covering much of the

Arabian Sea The Arabian Sea () is a region of sea in the northern Indian Ocean, bounded on the west by the Arabian Peninsula, Gulf of Aden and Guardafui Channel, on the northwest by Gulf of Oman and Iran, on the north by Pakistan, on the east by India, and ...

. The entire fan extends over an area of 110,000 square kilometers with greater than 9 km of sediment accumulating near the toe-of-slope.

History

The Indus Basin was created through the erosion of

Karakoram The Karakoram () is a mountain range in the Kashmir region spanning the border of Pakistan, China, and India, with the northwestern extremity of the range extending to Afghanistan and Tajikistan. Most of the Karakoram mountain range is withi ...

and the

Western Himalaya The Western Himalayas are the western half of the Himalayas, in Northwestern India, northwestern India and northern Pakistan. Four of the five tributaries of the Indus River in Punjab (Beas River, Beas, Chenab River, Chenab, Jhelum River, Jhelum ...

s. Fan sedimentation is estimated to have begun at the end of the Oligocene or beginning of the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

, during a period of faster Himalayan exhumation, possibly linked to

Monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in Atmosphere of Earth, atmospheric circulation and precipitation associated with annu ...

intensification. The fan rapidly gained sediment during the middle Miocene. The upper Indus Fan, both ancient and recent, consists some of the largest channel-levee systems (CLS). These channel-levee systems act as conduits for carrying and depositing sediments into the deeper part of the basin. The coarser grained sediments are deposited in the channel belts whereas the finer grained silts and clays are deposited along the levees. This arrangement of sediments is ideal for

stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithost ...

plays and is why these channel-levee systems are important to the petroleum industry.

References

{{Reflist River deltas of Asia