A paleomagnetic pole and estimated age for Lo-En Guyot, Republic of the Marshall Islands

Bryan, Phillip; Shoberg, Thomas G.; Gordon, Richard G.; Petronotis, K. E.; Bergersen, D. D.

doi:10.1029/gm077p0387

Cited by 4 publications

(3 citation statements)

References 19 publications

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“…The paleolatitude determined from drilling samples from Lo-En Guyot is significantly different from the paleolatitude of 14°S determined by Bryan et al (1993) using magnetic-seamount-anomaly modeling. If the hotspots within the South Pacific Superswell are fixed, then the 14°S latitude may correspond to the Tahiti hotspot or the edge of influence of the Rarotonga hotspot (Fig.…”

Section: Lo-en Guyotcontrasting

confidence: 72%

Comparison of the Origin and Evolution of Northwest Pacific Guyots Drilled during Leg 144

Haggerty¹,

Silva²

1995

Proceedings of the Ocean Drilling Program, 144 Scientific Results

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Five northwest Pacific guyots were drilled during Leg 144. Drilling results indicate that carbonate platforms grew atop volcanic edifices produced by two pulses of volcanism associated with hotspots. The first pulse of volcanism, during Barremian-Albian time, constructed the MIT and Takuyo-Daisan edifices and the pedestals of Lo-En and Wodejebato guyots, and was widespread at abyssal locations. A second pulse of volcanism, mainly across the Santonian/Campanian boundary, created emergent islands in the northern Marshall Islands and Line Islands. Eruptions during the younger portion of this second episode formed some of the southern Marshall Islands chain, including Limalok Guyot.Independent of their age of formation, most of the volcanic islands developed weathering profiles (including soils) and forests. Two to seven million years after an island formed, its edifice was flooded and a carbonate platform began. These carbonate platforms responded to a complex function of sea-level fluctuations and environmental changes.Shallow-water sedimentation on Leg 144 platforms terminated either in Albian, late Maastrichtian, or middle Eocene time. Their termination was not a simple mid-Cretaceous drowning event. When the northward motion of the Pacific Plate brought the platforms into the zone of equatorial upwelling, this apparently inhibited carbonate production, enhanced bioerosion, and the platforms died.Modern Pacific atolls are an inadequate analog for these ancient Pacific platforms. The Cretaceous and Eocene carbonate platforms resembled modern carbonate banks, rather than modern atolls that have a coral-algal reef framework surrounding a lagoon. These Cretaceous and Eocene platforms produced vast quantities of loose carbonate sediment in large shoal deposits. Cretaceous rudist-algal-coral boundstones formed relatively thin bioherms associated with shoals; this association built periplatform ridges near the summit margins.

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Section: Lo-en Guyotcontrasting

confidence: 72%

Comparison of the Origin and Evolution of Northwest Pacific Guyots Drilled during Leg 144

Haggerty¹,

Silva²

1995

Proceedings of the Ocean Drilling Program, 144 Scientific Results

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“…Indeed, the observed inclinations for Lo-En, MIT, and Takuyo-Daisan guyots (Table 6) differ from those inferred from the magnetic anomaly data in the sense expected from a viscous or induced magnetization contribution. The normal-polarity Southern Hemisphere inclination of Lo-En (^-9.8°) and Takuyo-Daisan (-19.2°) guyots are significantly more negative than the average model inclinations (Lo-En, -26.5°, Bryan et al, 1993;Takuyo-Daisan, 4.9°, Sager et al, 1993), although the discrepancy for Takuyo-Daisan may be somewhat reduced after correction for the -10° deviation of Hole 879 A from vertical (Premoli Silva, Haggerty, Rack, et al, 1993). Similarly, the inclination (22°) of reversed polarity lavas at MIT Guyot is shallower than the 52.2°i nclination derived from the sea-surface anomaly data (Sager et al, 1993).…”

Section: Discussionmentioning

confidence: 84%

Magnetic Petrology and Magnetic Properties of Western Pacific Guyots: Implications for Seamount Paleopoles

Gee¹,

Nakanishi²

1995

Proceedings of the Ocean Drilling Program, 144 Scientific Results

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Despite the importance of seamount paleopoles in reconstructing past tectonic motions of the Pacific Plate, few data exist on the magnetic properties and processes of remanence acquisition in seamounts. We present a basic magnetic characterization and a detailed petrographic and microprobe study of the oxide minerals in mildly to strongly alkalic lavas recovered from five western Pacific guyots sampled during Ocean Drilling Program Leg 144. The Ti-rich chrome spinel compositions and Al-and Mg-enrichment in titanomagnetites reflect the alkalic nature of the lavas. The alteration history of these samples is diverse, ranging from low-temperature oxidation to highly oxidizing conditions resulting in an assemblage of magnesioferrite + titanohematite. The natural remanent magnetization (NRM) intensities for all five guyots are quite similar, yielding a combined arithmetic mean NRM intensity of 3.53 A/m, similar to previously reported values from dredged and drilled seamount material. The mean Königsberger ratio (9.8) implies an approximate 10% contribution of induced magnetization. Systematic discrepancies between the observed inclinations and inclinations derived from the magnetic anomaly data for Lo-En, MIT, and Takuyo-Daisan guyots are compatible with a significant bias from viscous and induced magnetization in these Cretaceous guyots.

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“…Seamount paleopoles are available for three of the guyots drilled during Leg 144. Bryan et al (1993) reported a paleolatitude of 14°S for Lo-En Guyot based on least-squares modeling of their preferred subset of bathymetry and magnetic data. Sager et al (1993) determined paleolatitudes for MIT and Takuyo-Daisan guyots of 32.8°S and 2.5°N, respectively.…”

Section: Comparison To Seamount Magnetic Anomaly Modelingmentioning

confidence: 99%

Paleomagnetic Investigations of Volcanic Rocks: Paleolatitudes of the Northwestern Pacific Guyots

Nakanishi¹,

Gee²

1995

Proceedings of the Ocean Drilling Program, 144 Scientific Results

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Paleomagnetic properties of 340 minicore samples from 5 guyots in the northwestern Pacific Ocean were measured on board the JOIDES Resolution and in the paleomagnetic laboratories of the Ocean Research Institute, University of Tokyo, and of Lamont-Doherty Earth Observatory. Stepwise thermal and alternating-field (AF) demagnetizations typically isolate the same characteristic magnetization direction. The shipboard and shore-based paleomagnetic measurements suggest a paleolatitude of 10°S for Limalok, Wodejebato, MIT, and Takuyo-Daisan guyots. Lo-En Guyot apparently was constructed at a latitude of 31°S. According to the radiometric age of volcanic rocks from MIT Guyot, the reversed polarity of the volcanic basement of MIT Guyot corresponds to Chron M1 or older. A reversed polarity remanence of Wodejebato Guyot was acquired during Chron C33R because radiometric age determinations for Wodejebato Guyot range from 79 to 85 Ma. Our paleolatitude estimates for Lo-En, MIT, and Takuyo-Daisan guyots differ from those derived from previous seamount magnetic anomaly modeling. The sense and magnitude of this paleolatitude discrepancy are consistent with a significant contribution from viscous and induced magnetizations. We estimated the paleolatitudes of the guyots from the age data and from a previously published absolute-motion model for the Pacific Plate. Differences between these paleolatitude estimates and those derived from paleomagnetic measurements except for Wodejebato Guyot are smaller than 6°.

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A paleomagnetic pole and estimated age for Lo-En Guyot, Republic of the Marshall Islands

Cited by 4 publications

References 19 publications

Comparison of the Origin and Evolution of Northwest Pacific Guyots Drilled during Leg 144

Comparison of the Origin and Evolution of Northwest Pacific Guyots Drilled during Leg 144

Magnetic Petrology and Magnetic Properties of Western Pacific Guyots: Implications for Seamount Paleopoles

Paleomagnetic Investigations of Volcanic Rocks: Paleolatitudes of the Northwestern Pacific Guyots

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