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 The Bengal Fan, also known as the Ganges Fan, is the largest submarine fan on Earth. Geography It is located in Eurasia, being about long, wide with a maximum thickness of . The fan resulted from the uplift and erosion of the Himalayas and the ...

between India,

Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mo ...

and the

Andaman Islands The Andaman Islands () are an archipelago 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 maritime boundary between t ...

. 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 ( ar, اَلْبَحرْ ٱلْعَرَبِيُّ, Al-Bahr al-ˁArabī) is a region of the northern Indian Ocean bounded on the north by Pakistan, Iran and the Gulf of Oman, on the west by the Gulf of Aden, Guardafui Channe ...

. 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 Kashmir region spanning the borders of Pakistan, China, and India, with the northwest extremity of the range extending to Afghanistan and Tajikistan. Most of the Karakoram mountain range falls under the ...

and the

Western Himalaya The Western Himalayas refers to the western half of the Himalayas, in northern Pakistan and northwestern India. It is also known as the Punjab Himalayas. Four of the five tributaries of the Indus River in Punjab (Beas, Chenab, Jhelum, and Ravi) ...

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

Miocene The Miocene ( ) is the first 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 means "less recen ...

, 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 atmospheric circulation and precipitation associated with annual latitudinal oscil ...

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: lithostra ...

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

References

{{Reflist River deltas of Asia