Unlike trenches, oceanic troughs probably owe their origins to a wide variety of geologic mechanisms.
Maximal depths of oceanic troughs range between 2,300 m (7,500 feet) in the Papuan Trough and 7,440 m in the Banda Trough.
Near the continental masses some of the oceanic material sinks into the mantle in zones of subduction, which are associated with oceanic troughs, deep-focus earthquakes, and volcanic activity.
Oceanic troughs continued to receive clastic facies, particularly turbidites (sedimentary rock formed by a turbidity current), and pulses of mountain-building began to markedly affect the depositional sequences and their thicknesses.
New Guinea and its adjacent islands, possibly including the island of Halmahera, sit on the Sahul Shelf, which is a northwestern extension of the Australian continental mass; the shelf is bounded to the northeast by a series of oceanic troughs and to the northwest by troughs, a chain of coral reefs, and a series of submarine ridges.
Island arcs, mountain chains, volcanism, deep ocean troughs, and oceanic ridges are often features of seismic belts.
A series of deep ocean troughs frame the belt on the oceanic side, and continental landmasses lie behind.
The subtropical jet stream rounding the base of the mid-oceanic upper trough is thought to be one of the reasons most of the Hawaiian Islands have been resistant to the long list of Hawaii hurricanes that have approached.
The youngest oceanic basin, the Mariana Trough, which is ∼1000 km long and ∼200 km wide, has opened behind the Mariana Arc since ∼6 8 Ma (Hussong and Uyeda 1981; Fryer 1995; Stern et al. 2003; Kato et al. 2003).
Consequently, the northern Okinawa Trough is considered an oceanic area where EASM-related variability in SSS can be seen (Chang and Isobe 2003).
