604
characterized by strike-parallel and oblique chains of volcanic islands which produced large volumes of tephra and
indicate a transitional stage from continental rifting to oceanic backarc spreading.
Andaman Sea. One of the largest modem backarc basins is the Andarnan Sea in the northeastern Indian Ocean.
This basin is associated with the Sunda trench (cf. Fig.
12.23, Sect. 12.5.2). The center of this elongate basin is
floored by young oceanic crust, but its northern and southern extensions into Burma and Sumatra, respectively, Iie on
continental crust. Thus, moving from north to south, the
present-day depositional environment of the basin changes
from continental (Burma) to deltaic and oceanic (Andaman
Sea), and again resumes continental conditions in Sumatra
(Stoneley 1981). The overfilled part ofthe basin in Burma,
however, is overprinted by Plio-Pleistocene transpression
(Pivnik et al. 1998).
In summary, the modem baekare basins of the western Paeifie and the Andaman Sea displaya variety of
sediment types ineluding eoarse-grained mass flow
deposits, submarine fan turbidites and basinal
turbidites. Various types of tephra deposits play a
signifieant role (e.g. Klein 1985b), apart from
hemipelagie and pelagie silts and clays. Whereas volurne and nature of the silieiclastie material are eontrolled by are volcanism and the presence and relief
of nearby land sourees, the biogenie sediments (earSummary (Backare and Retroarc Basins)
- Baekare, retroare, and retro-foreland basins
evolve behind an aetive magmatie are. Baekare
basins form on pre-existing or newly aeereted
oeeanie ernst and retroare or retro-foreland basins on stretching eontinental ernst. Late-stage
eompressional deformation and overthrusting
on the side of the are are eommon - Small marginal oeean basins (e.g. in the present-day western Paeifie) develop by trapping of parts of a
major oeean basin or parts of a former baekare
basin by retreat of the former aetive are.
- The lifetimes of oeeanie baekare basins are limited; they tend to be closed by subduetion.
- The sediment fills of eontinental retroare basins
(often ealled foredeeps or foreland basins) re12.5.5 Preservation and Recognition of
Ancient Subduction-Related Basins
Aneient subduetion-related basins are normally identified by evaluating their temporal and spatial relationship with magmatie ares and suture zones, i.e.,
the boundaries between eollided plates. As a result of
eollision, late treneh fills, aeeretionary wedges, and
the sediments of foreare and oeeanie backare basins
are ineorporated into orogenie belts or subducted.
Chapter 12 Basin Evolution and Sediments
bonates and biosilieeous ooze) depend on oeean eireulation and surrace produetivity. Most of these sediments represent deep-water eonditions, either above
or below the CCD.
Black Sea and southern Caspian Sea. These deep basins,
floored by oceanic crust, are rernnants of a much larger,
3000 km long, 900 km wide, Mesozoic to early Tertiary
backarc basin. The area between the two basins was closed
by collision in front of the northward moving Arabian
prornontory. High rates of subsidence in conjunction with
the approaching thrust belts from the south (the western
and eastern Pontides, the Lesser Caucasus, and the Elburz
Mountains) enabled the accumulation of thick sediment
successions. Large rivers, partly draining high mountain
areas, including the Alps, delivered clastic material and
produced high sedimentation rates. The contribution of
volcaniclastics is of minor importance.
In the Black Sea, upper Cretaceous to Neogene sediments attain a maximum thickness of almost 15 km. The
oil-bearing middle Pliocene to Quaternary strata of the
southern Caspian Sea are 3-6 km thick and were deposited
at a rate in the order of 1000 mlMa. They are underlain in
the basin center by 8-10 km of older sediments. F or further
information see, e.g., Steininger and Rögl (1984),
Zonenshain and LePichon (1986) and Sects. 4.3.1 and
11.2.3.
fleet both the nearby magmatie are and the
more distal eratonie sediment sourees. Sometimes the latter souree predominates. Early deposition of eoarse clasties may be followed by
shallow-marine and then by thiek molasse-type
sediments.
Oeeanie backare basins are deeper and aeeumulate are-derived and intrabasinal pyroclastie flows, mass flow deposits, air-fall ash
and ash turbidites. Hemipelagie and pelagie
sediments, eontrolled by the oeeanie environment, play an inereasing role in the later stages
of basin evolution.
They are strongly deformed, disrnpted and partially
metamorphosed. In contrast, retroare or retro-foreland basins behind eontinental margins, i.e. basins on
eontinental ernst, have a better chance of being preserved. However, they may be strongly affeeted by
syn- and postdepositional folding and overthrusting.
The differentiation of aneient examples of treneh
fills and sequenees from foreare and backare regions
exposed in orogenie belts is diffieult. Trenehes are
always filled in deep water, but their sediments in-
characterized by strike-parallel and oblique chains of volcanic islands which produced large volumes of tephra and
indicate a transitional stage from continental rifting to oceanic backarc spreading.
Andaman Sea. One of the largest modem backarc basins is the Andarnan Sea in the northeastern Indian Ocean.
This basin is associated with the Sunda trench (cf. Fig.
12.23, Sect. 12.5.2). The center of this elongate basin is
floored by young oceanic crust, but its northern and southern extensions into Burma and Sumatra, respectively, Iie on
continental crust. Thus, moving from north to south, the
present-day depositional environment of the basin changes
from continental (Burma) to deltaic and oceanic (Andaman
Sea), and again resumes continental conditions in Sumatra
(Stoneley 1981). The overfilled part ofthe basin in Burma,
however, is overprinted by Plio-Pleistocene transpression
(Pivnik et al. 1998).
In summary, the modem baekare basins of the western Paeifie and the Andaman Sea displaya variety of
sediment types ineluding eoarse-grained mass flow
deposits, submarine fan turbidites and basinal
turbidites. Various types of tephra deposits play a
signifieant role (e.g. Klein 1985b), apart from
hemipelagie and pelagie silts and clays. Whereas volurne and nature of the silieiclastie material are eontrolled by are volcanism and the presence and relief
of nearby land sourees, the biogenie sediments (earSummary (Backare and Retroarc Basins)
- Baekare, retroare, and retro-foreland basins
evolve behind an aetive magmatie are. Baekare
basins form on pre-existing or newly aeereted
oeeanie ernst and retroare or retro-foreland basins on stretching eontinental ernst. Late-stage
eompressional deformation and overthrusting
on the side of the are are eommon - Small marginal oeean basins (e.g. in the present-day western Paeifie) develop by trapping of parts of a
major oeean basin or parts of a former baekare
basin by retreat of the former aetive are.
- The lifetimes of oeeanie baekare basins are limited; they tend to be closed by subduetion.
- The sediment fills of eontinental retroare basins
(often ealled foredeeps or foreland basins) re12.5.5 Preservation and Recognition of
Ancient Subduction-Related Basins
Aneient subduetion-related basins are normally identified by evaluating their temporal and spatial relationship with magmatie ares and suture zones, i.e.,
the boundaries between eollided plates. As a result of
eollision, late treneh fills, aeeretionary wedges, and
the sediments of foreare and oeeanie backare basins
are ineorporated into orogenie belts or subducted.
Chapter 12 Basin Evolution and Sediments
bonates and biosilieeous ooze) depend on oeean eireulation and surrace produetivity. Most of these sediments represent deep-water eonditions, either above
or below the CCD.
Black Sea and southern Caspian Sea. These deep basins,
floored by oceanic crust, are rernnants of a much larger,
3000 km long, 900 km wide, Mesozoic to early Tertiary
backarc basin. The area between the two basins was closed
by collision in front of the northward moving Arabian
prornontory. High rates of subsidence in conjunction with
the approaching thrust belts from the south (the western
and eastern Pontides, the Lesser Caucasus, and the Elburz
Mountains) enabled the accumulation of thick sediment
successions. Large rivers, partly draining high mountain
areas, including the Alps, delivered clastic material and
produced high sedimentation rates. The contribution of
volcaniclastics is of minor importance.
In the Black Sea, upper Cretaceous to Neogene sediments attain a maximum thickness of almost 15 km. The
oil-bearing middle Pliocene to Quaternary strata of the
southern Caspian Sea are 3-6 km thick and were deposited
at a rate in the order of 1000 mlMa. They are underlain in
the basin center by 8-10 km of older sediments. F or further
information see, e.g., Steininger and Rögl (1984),
Zonenshain and LePichon (1986) and Sects. 4.3.1 and
11.2.3.
fleet both the nearby magmatie are and the
more distal eratonie sediment sourees. Sometimes the latter souree predominates. Early deposition of eoarse clasties may be followed by
shallow-marine and then by thiek molasse-type
sediments.
Oeeanie backare basins are deeper and aeeumulate are-derived and intrabasinal pyroclastie flows, mass flow deposits, air-fall ash
and ash turbidites. Hemipelagie and pelagie
sediments, eontrolled by the oeeanie environment, play an inereasing role in the later stages
of basin evolution.
They are strongly deformed, disrnpted and partially
metamorphosed. In contrast, retroare or retro-foreland basins behind eontinental margins, i.e. basins on
eontinental ernst, have a better chance of being preserved. However, they may be strongly affeeted by
syn- and postdepositional folding and overthrusting.
The differentiation of aneient examples of treneh
fills and sequenees from foreare and backare regions
exposed in orogenie belts is diffieult. Trenehes are
always filled in deep water, but their sediments in-