Upper mantle rheology in a tectonic region: Evidence from New Guinea

Chappell, John

doi:10.1029/jb079i002p00390

Cited by 15 publications

(7 citation statements)

References 49 publications

(18 reference statements)

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“…Some features of the (undated) 8,. record can be reconciled with the sea level deviations from the present (Fig. 3 4 estimated from geological evidence at Barbados (Steinen et al 1973) and New Guinea (Veeh & Chappell 1970;Chappell 1974;Bloom et al 1974) Sea level estimates around 110 ka B.P. (stage 5d) are -60 to -70 m in the geological record, but -90 m in the S, record.…”

Section: Termination Of the Eemian Interglacialsupporting

confidence: 62%

The Eemian interglacial and its termination

Dansgaard¹,

Duplessy²

1981

Boreas

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The development and termination of the Eemian interglacial is important because it may serve as a model showing how the present warm period might end in the event of no anthropogenic impact. The most important methods for studying the Eemian are outlined and critically evaluated. In spite of interpretation and dating problems, the various proxy data seem consistent enough to allow the conclusion that some 120,000 years ago the warm Eemian climate deteriorated rapidly and drastically. The forest vegetation in West Europe was replaced by a tundra type vegetation, and within 5000 or 10,OOO years the volume of continental ice grew to at least double the present volume, corresponding to a sea level 65 m, perhaps 90 m, below that of today. There is considerable disagreement between sea level estimates deduced from geological evidence and from benthic foraminifera oxygen isotope records.

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Section: Termination Of the Eemian Interglacialsupporting

confidence: 62%

The Eemian interglacial and its termination

Dansgaard¹,

Duplessy²

1981

Boreas

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“…The viscosity of the material in the wedge above the slab was determined to be about 5 x lo1' poise from post-seismic rebound in Japan (Nur & Mavko 1974) and about 3 x 10" poise (apparently given incorrectly as stokes in the abstract) from deformed Pleistocene reefs in New Guinea (Chappell 1974). The former estimate directly provides a minimum estimate, as the long term viscosity cannot be lower than whatever mechanism caused the creep.…”

Section: Viscosity and Rheologymentioning

confidence: 95%

Stress and Flow beneath Island Arcs

Sleep

2007

Geophysical Journal of the Royal Astronomical Society

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The flow pattern, stress distribution, topography, and gravity anomalies were computed from numerical models having density and viscosity distributions resemblant to the Aleutian arc. The results were compatible with the hypothesis that the excess density of the slab drives its descent and that hydrodynamic forces are responsible for topographic and gravity highs over the outer rise seaward of the trench and the frontal arc and lows over the trench. In models with simple distributions of rheological parameters, the force from the slab was transmitted directly upward producing a negative gravity anomaly over the arc. Material with low resistance to flow was needed along the fault plane above the slab or within the crust of the frontal arc and within the wedge of asthenosphere above the slab to reduce that force and to allow the horizontal lithosphere to move with the slab. Models with the resistance to flow thus reduced had outer rises, deep trenches, horizontal tension seaward of the trench, horizontal compression under the trench, and downdip tension in the slab. Free air gravity anomalies, which are the sum of between deflections of the free surface due to hydrodynamic forces and direct attractions from the masses driving the flow, were not fit excellently by any of the models, in part because the coarse grid used prechded accurate representation of the fault zone above the slab and the frontal arc. An alternate to the hypothesis that about 5 kb of stress on the fault plane is needed to produce an outer rise is offered by these models. Shear stress between the slab and the island arc was always below 700 bars in the more successful models if the density distribution was scaled to match the topography of the trench. This is much less than the 2000 bars stresses needed if frictional heating causes island arc volcanism.

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“…Thus, the record of the stable areas is more difficult to resolve, but detailed work here will reward the geologist seeking paleosealevels by yielding better, more direct information on eustatic levels; whereas those eustatic sea level curves derived from tectonically active areas require assumptions regarding the nature of the uplift history (Broecker et al, 1968;Veeh and Chappell, 1970;Bloom et al, 1974;Chappell, 1974). It is also in the more stable areas that the question of major versus minor sea level events should best be resolved (Vacher, 1972).…”

Section: Correlation Of Coral Ages and Sea Level Featuresmentioning

confidence: 96%

Sea Level Events and Pleistocene Coral Ages in the Northern Bahamas

Neumann

Moore

1975

Quat. res.

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Emergent Pleistocene sea level indicators in the northern Bahamas include: a bioerosional notch at +5.3 to 5.9 m; sea caves, notches, and marine terraces at about +4.3 m; and lithified coral rubble and reef deposits between 0 and 3 m. Thorium 230 dates of the fossil corals, which were deposited as these features were being produced, span the age range from 100 to 145 thousand years BP with a majority falling between 115 and 130 thousand years BP. The notch at about +5.6 m is interpreted to be the product of a sea level stand 125 thousand years BP, while the features at +4.3 m are believed to be formed sometime later as sea level fell from the higher position. Part of the age span is inherent in the dating technique and possible sample alteration. Another cause of the spread may be mixing of corals of different ages into a single deposit.

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Upper mantle rheology in a tectonic region: Evidence from New Guinea

Cited by 15 publications

References 49 publications

The Eemian interglacial and its termination

The Eemian interglacial and its termination

Stress and Flow beneath Island Arcs

Sea Level Events and Pleistocene Coral Ages in the Northern Bahamas

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