Enhanced Cenozoic chemical weathering and the subduction of pelagic carbonate

  title={Enhanced Cenozoic chemical weathering and the subduction of pelagic carbonate},
  author={Ken Caldeira},
  • K. Caldeira
  • Published 1 June 1992
  • Environmental Science, Geology
  • Nature
THE observed trend of increasing oceanic 87Sr/86Sr ratios during the late Cenozoic led Raymo et al.1 to propose that chemical weathering rates increased at this time as a result of enhanced weatherability of silicate rocks. They suggested that this was due in turn to continential uplift, primarily in the Himalayas and the Andes. Because weathering involves the reaction of silicates with atmospheric carbon dioxide, considerations of changes in weathering rates must take into account the need to… 

Global Chemical Erosion during the Cenozoic: Weatherability Balances the Budgets

The question addressed here is whether global chemical weathering and erosion rates have increased over Cenozoic time in response to uplift of the Himalayas.1–2 Chemical weathering of the continents

Balancing the Cenozoic carbon and alkalinity cycles: Constraints from isotopic records

A simple model of the carbon, alkalinity and strontium cycles is built up and used to interpret the carbon and strontium isotopic evolution of seawater over the Cenozoic as recorded in marine

The Himalayas, organic carbon burial, and climate in the Miocene

  • M. Raymo
  • Environmental Science, Geography
  • 1994
Cooling ages of rock in the Himalayas imply that rapid exhumation between the Main Central thrust system and the South Tibetan detachment system occurred between 21 and 17 Ma. The generation of

Neogene continental denudation and the beryllium conundrum

A beryllium cycle model is presented whose results show that variations in the 9Be weathering flux are counterbalanced by near-coastal scavenging while the cosmogenic 10Be flux from the upper atmosphere stays constant, and predicted seawater 10Be/9Be ratios remain nearly constant even when global denudation and Be weathering rates increase by three orders of magnitude.

Geochemical consequences of increased Late Cenozoic weathering rates and the global CO2 balance since 100 Ma

Large imbalances in the relative net CO2 flux over the last 100 m.y. are obtained from independently derived estimates of CO2 uptake by weathering and organic carbon burial and of CO2 outgassing

Synchronous changes in seawater strontium isotope composition and global climate

THE 87Sr/86Sr ratio of sea water has increased gradually over the past 40 Myr, suggesting a concomitant increase in global chemical weathering rates1–6. Recently, Dia et al.7 analysed a 250-kyr

Modulation of Late Cretaceous and Cenozoic climate by variable drawdown of atmospheric pCO 2 from weathering of basaltic provinces on continents drifting through the equatorial humid belt

Abstract. The small reservoir of carbon dioxide in the atmosphere (pCO2) that modulates climate through the greenhouse effect reflects a delicate balance between large fluxes of sources and sinks.

The early Paleozoic carbon cycle




Influence of late Cenozoic mountain building on ocean geochemical cycles

In a steady-state ocean, input fluxes of dissolved salts to the sea must be balanced in mass and isotopic value by output fluxes. For the elements strontium, calcium, and carbon, rivers provide the

Modelling the Phanerozoic carbon cycle and climate: constraints from the 87Sr/86Sr isotopic ratio of seawater.

A history of atmospheric carbon dioxide and climate during Phanerozoic time, consistent with the strontium isotopic data, is reconstructed and is shown to be compatible with paleoclimatic indicators, such as the timing of glaciation and the estimates of Cretaceous paleotemperatures.

Tertiary paleoceanic chemical variability: Unintended consequences of simple geochemical models

Five lines of concrete, quantitative evidence about oceanic chemical composition during the past 65 m.y. can provide insights into the controlling processes and their temporal variations, but the

Rise of angiosperms as a factor in long-term climatic cooling

  • T. Volk
  • Environmental Science, Geology
  • 1989
By Late Cretaceous or early Tertiary time, the diversification and proliferation of angiosperm-deciduous ecosystems resulted in higher rates of mineral weathering. This increase in the global average

The carbonate-silicate geochemical cycle and its effect on atmospheric carbon dioxide over the past 100 million years

A computer model has been constructed that considers the effects on the CO/sub 2/ level of the atmosphere, and the Ca, Mg, and HCO/sub 3/ levels of the ocean, of the following processes: weathering

Continental-pelagic carbonate partitioning and the global carbonate-silicate cycle.

Model results suggest that carbonate deposition patterns established during the Cenozoic may be pushing the Earth system from the continental to the pelagic mode on a time scale of 10(8) yr, with a possible consequent order-of-magnitude increase in the metamorphic CO2 flux to the atmosphere.

Variation of seawater 87Sr/86Sr throughout Phanerozoic time

Precise measurements of 786 marine carbonate, evaporite, and phosphate samples of known age provide a curve of seawater 87Sr/86Sr versus geologic time through the Phanerozoic. Many episodes of

Late Cenozoic Ge/Si record of marine biogenic opal: Implications for variations of riverine fluxes to the ocean

We have determined germanium/silicon ratios in purified diatoms and radiolarians from siliceous sediments in Holocene core tops, one late Pleistocene piston core, and four high-latitude Southern