Shatsky Rise: Seismic Stratigraphy and Sedimentary Record of Pacific Paleoceanography since the Early Cretaceous

Sliter, William V.; Brown, Glenn R.

doi:10.2973/odp.proc.sr.132.302.1993

Cited by 22 publications

(31 citation statements)

References 17 publications

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“…several times thicker (Den et al, 1969;Gettrust et al, 1980). Furthermore, seismic profiling showed that the tops of the rise edifices hold thick piles of pelagic sediments (up to 1.2 km), whereas sediments on the rise flanks are thin or occasionally absent (Ewing et al, 1966;Ludwig and Houtz, 1979;Neprohnov et al, 1984;Sliter and Brown, 1993).…”

Section: Prior Research On Shatsky Risementioning

confidence: 94%

What built Shatsky Rise, a mantle plume or ridge tectonics?

Sager¹

2005

Plates, Plumes and Paradigms

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Shatsky Rise is an oceanic plateau that formed at the Pacific-Farallon-Izanagi triple junction during the Late Jurassic to Early Cretaceous. Its origin is unclear, but volcanism from a mantle plume or plume head is accepted as an explanation because many observations from the plateau are consistent with the plume head model. Initial eruptions were massive and rapid, with emplacement rates estimated at 1.2-4.6 km 3 /yr, similar to continental flood basalts. The plateau exhibits an age progression, with igneous output waning over time, possibly representing the transition from plume head to plume tail. Shallow water fossils imply that the rise top was subaerial and that thermal and dynamic uplift was significant. Furthermore, the age progression and trends of Shatsky and Hess rises are mimicked by the Mid-Pacific Mountains, to be expected if these features formed by the drift of the plate over mantle plumes. In contrast, several observations do not fit the plume head model. The initial eruption was coincident with a reorientation of the Pacific-Izanagi ridge and an 800-km jump of the triple junction, a low probability occurrence if plume heads behave independently of plate motions. Moreover, this same type of event may have occurred repeatedly, as other western Pacific plateaus occur near the trace of this triple junction (Hess Rise) and the Pacific-Farallon-Phoenix triple junction (Magellan Rise, Manihiki Plateau, MidPacific Mountains). If these other plateaus formed from plumes, either there were many plumes or the plumes defining the triple junction paths exhibited large relative motion. Moreover, rocks recovered from the main Shatsky Rise edifices have midocean ridge basalt (MORB) geochemistry and isotopic signatures, whereas most plume head models imply that lower mantle material, with a different signature, will be carried to the surface. A simpler hypothesis is that Shatsky Rise and other neartriple-junction plateaus were formed as a result of ridge tectonics. One possibility is that decompression melting occurred near the triple junctions during the Mesozoic because the northwest Pacific was located over a region of anomalous asthenosphere that was susceptible to melting given only small perturbations in lithospheric stress. A pitfall for this argument is that changes in the thin, fast-spreading Pacific lithosphere must result in massive volcanism. Although both plume and ridge tectonics hypotheses explain some observations from Shatsky Rise, uncertainties make it premature to conclude which, if either, is correct. Resolution awaits future investigations, which must reveal missing pieces to this puzzle.

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Section: Prior Research On Shatsky Risementioning

confidence: 94%

What built Shatsky Rise, a mantle plume or ridge tectonics?

Sager¹

2005

Plates, Plumes and Paradigms

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“…In contrast, option A would require quite variable sedimentation rates and periods of condensation, which would suggest that the Permanente Quarry record of OAE1a is incomplete. Condensation and hiatuses at about the Barremian-Aptian boundary have been identifi ed at other Pacifi c sites (Sliter, 1989(Sliter, , 1992Sliter and Brown, 1993), but it is not clear if these horizons can be correlated on a basinal scale. On the southern high of Shatsky Rise, the most signifi cant hiatus appears to occur near the Barremian-Aptian boundary, but it is likely below the interval of OAE1a (see Figure 7 in Sliter and Brown, 1993).…”

Section: Implications For Early Aptian Paleoceanographymentioning

confidence: 99%

Mid-Cretaceous oceanic anoxic events in the Pacific Ocean revealed by carbon-isotope stratigraphy of the Calera Limestone, California, USA

Robinson

Clarke

Nederbragt

et al. 2008

Geological Society of America Bulletin

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The paleoceanographic history of the Pacifi c Ocean during the mid-Cretaceous is poorly constrained due to the loss of much of the contemporaneous Pacifi c seafl oor to subduction and diffi culties in recovering chert-rich sediments by ocean drilling. Pelagic sediments that were originally deposited in the Pacifi c Ocean but that have been subsequently accreted during subduction potentially provide an alternative paleoceanographic archive. This study presents micropaleontological and carbon-isotope data from the Calera Limestone, part of the classic Franciscan Complex exposed in Permanente Quarry, central California, USA. In the three stratigraphic sections studied, pelagic limestones with low organic-carbon contents are the dominant lithology. However, two stratigraphic intervals are recognized that contain organic carbon, and these date to the early Aptian and late Albian-early Cenomanian. These time intervals correspond to two mid-Cretaceous oceanic anoxic events (OAEs): early Aptian OAE1a (equivalent to the "Selli level") and late Albian OAE1d (equivalent to the "Breistroffer event"). It is well established that both of these events were associated with signifi cant carbon-isotope excursions, which are also shown to exist in the Calera Limestone. The record of OAE1a from the Calera Limestone complements ocean drilling records by providing further evidence for variability in the sedimentary and stratigraphic record of this event. The carbon-isotope data from the late Albianearly Cenomanian provide the fi rst detailed chemobiostratigraphic record of this period for the Pacifi c Ocean, confi rming that environmental change occurred at this time in the Pacifi c, possibly related to OAE1d.

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“…Second, the spreading of the ridges adjacent to Shatsky Rise was relatively rapid, and the rise volcanism was spread laterally, rather than stacked vertically, so that the history of the rise is more easily interpreted. Third, sediments on Shatsky Rise flanks are generally thin [ Ewing et al , 1966; Ludwig and Houtz , 1979; Sliter and Brown , 1993], so the morphology of the rise, which can be measured by bathymetry, is a direct reflection of its structure and evolution. Finally, the rapidly spreading triple junction indicates the formation of Shatsky Rise on thin lithosphere, which should have had minimal influence on melt generation and migration.…”

Section: Introductionmentioning

confidence: 99%

Seismic tomography of Shatsky Rise by adaptive importance sampling

2012

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We present results from a wide‐angle seismic refraction survey over Shatsky Rise, a large oceanic plateau in the northwestern Pacific. A new Monte Carlo sampling scheme is developed to explore comprehensively the model space of crustal velocity structure by joint refraction and reflection seismic tomography. The new scheme, which is founded on the notion of adaptive importance sampling, is made possible by the combination of several independent developments, including the introduction of effective model parameters, the implementation of automated model regularization, and a polynomial expansion of the probability density function. From 21 ocean‐bottom instruments deployed along a 420‐km‐long refraction transect, we collect 16446 Pg and 4735 PmP travel times, which are inverted to construct a two‐dimensional compressional velocity model across the major axis of Shatsky Rise. The convergence of Monte Carlo sampling is tested by running parallel sampling chains, and the effective dimensions of the model space are estimated to be ∼10 by principal component analysis. The thickness of the rise crust varies from ∼9 km to ∼30 km, and the average velocity of the lower crust ranges from ∼7.0 km s−1 to ∼7.2 km s−1. One standard deviation uncertainty for whole‐crustal thickness and average lower‐crustal velocity is <1 km and ∼0.05 km s−1, respectively, for most of the model domain. Shatsky Rise crustal structure exhibits a negative correlation between crustal thickness and velocity, which implies that a chemically anomalous mantle may have been responsible for the formation of the rise.

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Shatsky Rise: Seismic Stratigraphy and Sedimentary Record of Pacific Paleoceanography since the Early Cretaceous

Cited by 22 publications

References 17 publications

What built Shatsky Rise, a mantle plume or ridge tectonics?

What built Shatsky Rise, a mantle plume or ridge tectonics?

Mid-Cretaceous oceanic anoxic events in the Pacific Ocean revealed by carbon-isotope stratigraphy of the Calera Limestone, California, USA

Seismic tomography of Shatsky Rise by adaptive importance sampling

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