Early Cenozoic global plate reorganization

Rona, Peter A.; Richardson, Evan S.

doi:10.1016/0012-821x(78)90069-9

Cited by 81 publications

(44 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This pattern is suggestive of pulsations in hydrothermal activity that have been recorded elsewhere and have been related to tectonic reorganization events (Owen and Rea, 1985;Lyle et al, 1987). Reconstruction of the tectonic histories of many locations and examination of the sediment composition of these locations have revealed a clear link between active rifting events and periods of increased deposition of hydrothermal materials (some at oregrade levels) that preceded and/or accompanied these events (Rona and Richardson, 1978;Rona et al, 1983;Lyle et al, 1987;Olivarez and Owen, 1989). For example, Lyle et al (1987) examined the Neogene history of hydrothermal deposition in association with tectonic reorganizations along the East Pacific Rise by modeling the deposition of hydrothermal Mn in ridge flank sediments as a function of distance from the ridge axis.…”

Section: Sediment Composition and Rifting Mechanismsmentioning

confidence: 61%

Geochemistry of Broken Ridge Sediments

Owen¹,

Zimmerman²

1991

Proceedings of the Ocean Drilling Program

View full text Add to dashboard Cite

The present study involves the analysis and interpretation of geochemical data from a suite of sediment samples recovered at ODP Hole 752A. The samples encompass the time period that includes the lithospheric extension and uplift of Broken Ridge, and they record deposition below and above the mid-Eocene angular unconformity that denotes this uplift. A Q-mode factor analysis of the geochemical data indicates that the sediments in this section are composed of a mixture of three geochemical end members that collectively account for 94.2% of the total variance in the data. An examination of interelement ratios for each of these end members suggests that they represent the following sedimentary components: (1) a biogenic component, (2) a volcanogenic component, and (3) a hydrothermal component. The flux of the biogenic component decreases almost thirtyfold across the Eocene unconformity. This drastic reduction in the deposition of biogenic materials corresponds to the almost complete disappearance of chert layers, diatoms, and siliceous microfossils and is coincident with the uplift of Broken Ridge. The volcanogenic component is similar in composition to Santonian ash recovered at Hole 755A on Broken Ridge and is the apparent source of the Fe-stained sediment that immediately overlies the angular unconformity. This finding suggests that significant amounts of Santonian ash were subaerially exposed, weathered, and redeposited and is consistent with data that suggest that the vertical uplift of Broken Ridge was both rapid and extensive. The greatest flux of hydrothermal materials is recorded in the sediments immediately below the angular unconformity. This implies that the uplift of Broken Ridge was preceded by a significant amount of rifting, during which faulting and fracturing of the lithosphere led to enhanced hydrothermal circulation. This time sequence of events is consistent with (but not necessarily diagnostic of) the passive model of lithospheric extension and uplift.

show abstract

Section: Sediment Composition and Rifting Mechanismsmentioning

confidence: 61%

Geochemistry of Broken Ridge Sediments

Owen¹,

Zimmerman²

1991

Proceedings of the Ocean Drilling Program

View full text Add to dashboard Cite

show abstract

“…Marine geologists have known for 20 years or more that the earlier portion of the Eocene was a time of plate boundary rearrangement (Hayes and Pitman, 1970;Rona and Richardson, 1978). More recent work on the timing of plate boundary realignments in the Pacific Basin (Rea and Dixon, 1983;Caress et al, 1988) has shown the early Eocene to be an important time of change in patterns of spreading centers and transform faults.…”

Section: Tectonic Events and Sea-floor Hydrothermal Activitymentioning

confidence: 99%

Global change at the Paleocene-Eocene boundary: climatic and evolutionary consequences of tectonic events

Rea

Zachos

Owen

et al. 1990

Palaeogeography, Palaeoclimatology, Palaeoecology

193

101

View full text Add to dashboard Cite

Rea, D. K., Zachos, J. C., Owen, R. M. and Gingerich, P. D., 1990. Global change at the Paleocene-Eocene boundary:climatic and evolutionary consequences of tectonic events. Palaeogeogr., Palaeoclimatol., Palaeoecol., 79: 117-128.Events of the Paleocene-Eocene boundary provide the clearest example to date of how a tectonic event may have global climatic consequences. Recent advances permit well-constrained stratigraphic determination of several events that occurred at that boundary, in chron C24R: a many-fold increase in sea-floor hydrothermal activity, a global warming, a reduction in the intensity of atmospheric circulation, a conversion to salinity-driven deep ocean circulation, a marked lightening of oceanic 313C values, extinction and evolution of both benthic foraminifera and land mammals, and important plate-boundary reorganizations including the outpouring of the east Greenland volcanics and the initiation of the oceanic rift between Norway and Greenland.We hypothesize that enhanced sea-floor hydrothermal activity occasioned by global tectonism resulted in a flooding of the atmosphere with COz, causing a reduced pole-to-equator temperature gradient and increased evaporation at low latitudes. Increased formation of warm, salty, probably low-nutrient waters coupled with the warm temperatures at high latitudes occasioned a salinity-driven, rather than temperature-driven, deep-water circulation. This newly-evolved ocean circulation pattern changed the apportionment of global heat transport from the atmosphere to the ocean, with concomitant changes in the circulation intensity of both. Reduced intensity of atmospheric circulation resulted in lower oceanic biological productivity and enhanced seasonality of climate on the continents. A major extinction event among benthic foraminifera was probably a response to the new low-nutrient and chemically changed bottom waters, and endemism following rapid evolution and dispersal of mammalian orders may have been in response to the new continental climate regime.

show abstract

“…In this paper (Fig.10), we attribute the timing to a ca. 45 Ma, mantle-wide rearrangement of convection (e.g., Courtillot et al, 2003), perhaps associated with the closing of the Tethys (Rona and Richardson, 1978;Patriat and Achache, 1984) or/and the sinking into the lower mantle of slabs that had accumulated near the 660 km transition zone (Fukao et al, 2001). The location of the BR may simply reflect a geochemically more fertile region of the upper mantle.…”

Section: What Produced Bermuda and The Bermuda Rise-why Then And Why mentioning

confidence: 99%

“…For example, Rona and Richardson (1978;see also Patriat and Achache, 1984) listed many Eocene events they attributed to the collision of India with Eurasia, i.e. the closing of the Tethys Ocean.…”

mentioning

confidence: 99%

Origin of the Bermuda volcanoes and the Bermuda Rise: History, observations, models, and puzzles

Vogt¹,

Jung²

2007

Special Paper 430: Plates, Plumes and Planetary Processes

View full text Add to dashboard Cite

Deep-sea drilling on DSDP Leg 43 and on Bermuda itself, together with geophysical data (anomalies in basement depth, geoid and heat flow) and modeling have long suggested the uplift forming the Bermuda Rise, as well as the initial igneous activity that produced the Bermuda volcanoes, began ca. 47-40 Ma, during the early to middle part of the Midde Eocene. Some authors attribute 65 Ma igneous activity in Mississippi and 115 Ma activity in Kansas to a putative "Bermuda hotspot" or plume fixed in the mantle below a moving North America plate. While this is more or less consistent with hotspot traces computed from 'absolute motion' models, the hotspot/plume must resemble a lava lamp, turning off for up to 25 million years at a time, and/or be heavily influenced by lithosphere structure. Moreover, Cretaceous igneous activity in Texas and Eocene intrusions in Virginia then require separate mantle "blobs".The pillow lavas forming the original Bermuda shield volcano have not been reliably dated, and the three associated smaller edifices have not been drilled or dated. A well-dated (ca. 33-34 Ma) episode of unusually titaniferous sheet intrusion in the Bermuda edifice was either triggered by plate-wide stress changes or reflects local volcanogenic events deep in the mantle source region. The high Ti and Fe of the Bermuda intrusive sheets probably relate to the very high amplitude magnetic anomalies discovered on the islands.Numerical models constrained by available geophysical data attribute the Bermuda Rise to some combination of lithospheric reheating and dynamic uplift. While the relative contributions of these two processes cannot yet be wholly separated, three features of the rise clearly distinguish it from the Hawaiian swell: 1) The Bermuda Rise is elongated at right angles to the direction of plate motion; 2) There has been little or no subsidence of the Rise and volcanic edifice since its formation-in fact, Rise uplift continued at the same site from the late Middle Eocene into the Miocene; and 3) The Bermuda Rise lacks a clear, age-progressive chain.We infer that the Bermuda Rise and other Atlantic midplate rises are supported by anomalous asthenosphere, upwelling or not, that penetrates the thermal boundary layer and travels with the overlying North America plate.The elongation, along crustal isochrons, of both the Bermuda volcanoes and the Rise and Rise development mostly within a belt of rougher, thinner crust and seismically "slower" upper mantle-implying retention of gabbroic melts at the ancient MAR axis-suggests the mantle lithosphere may have helped localize rise development-in contradiction to plume models. The Bermuda Rise area is seismically more active than its oceanic surroundings, preferentially along old transform traces and possibly reflecting a weaker upper mantle-lithosphere.We attribute the "Bermuda event" to a global plate kinematic reorganization, triggered by the closing of the Tethys and the associated gravitational collapse into the lower mantle of subducted slabs which had been ...

show abstract

Early Cenozoic global plate reorganization

Cited by 81 publications

References 54 publications

Geochemistry of Broken Ridge Sediments

Geochemistry of Broken Ridge Sediments

Global change at the Paleocene-Eocene boundary: climatic and evolutionary consequences of tectonic events

Origin of the Bermuda volcanoes and the Bermuda Rise: History, observations, models, and puzzles

Contact Info

Product

Resources

About