The Earth's sedimentary shell (quantitative patterns of its structure, compositions, and evolution)

Ronov, A. B.

doi:10.1080/00206818209451075

Cited by 82 publications

(46 citation statements)

References 23 publications

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“…[32] Fluctuations in the carbonate deposition flux over Earth's history have already been noticed [Wilkinson and Algeo, 1989] and are generally thought to be linked to changes in degassing rate (and thus to the global silicate weathering rate) [Ronov, 1982]. Here, we explore the effect of the paleogeography on the carbonate weathering rate, which can influence the carbonate deposition rate as well.…”

Section: Consequences Of the Pangea Breakup On The Oceanic Carbonate mentioning

confidence: 99%

A GEOCLIM simulation of climatic and biogeochemical consequences of Pangea breakup

Donnadieu¹,

Goddéris

Pierrehumbert

et al. 2006

Geochem Geophys Geosyst

128

127

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[1] Large fluctuations in continental configuration occur throughout the Mesozoic. While it has long been recognized that paleogeography may potentially influence atmospheric CO 2 via the continental silicate weathering feedback, no numerical simulations have been done, because of the lack of a spatially resolved climate-carbon model. GEOCLIM, a coupled numerical model of the climate and global biogeochemical cycles, is used to investigate the consequences of the Pangea breakup. The climate module of the GEOCLIM model is the FOAM atmospheric general circulation model, allowing the calculation of the consumption of atmospheric CO 2 through continental silicate weathering with a spatial resolution of 7.5°long Â 4.5°lat. Seven time slices have been simulated. We show that the breakup of the Pangea supercontinent triggers an increase in continental runoff, resulting in enhanced atmospheric CO 2 consumption through silicate weathering. As a result, atmospheric CO 2 falls from values above 3000 ppmv during the Triassic down to rather low levels during the Cretaceous (around 400 ppmv), resulting in a decrease in global mean annual continental temperatures from about 20°C to 10°C. Silicate weathering feedback and paleogeography both act to force the Earth system toward a dry and hot world reaching its optimum over the last 260 Myr during the Middle-Late Triassic. In the super continent case, given the persistent aridity, the model generates high CO 2 values to produce very warm continental temperatures. Conversely, in the fragmented case, the runoff becomes the most important contributor to the silicate weathering rate, hence producing a CO 2 drawdown and a fall in continental temperatures. Finally, another unexpected outcome is the pronounced fluctuation in carbonate accumulation simulated by the model in response to the Pangea breakup. These fluctuations are driven by changes in continental carbonate weathering flux. Accounting for the fluctuations in area available for carbonate platforms, the simulated G 3

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Section: Consequences Of the Pangea Breakup On The Oceanic Carbonate mentioning

confidence: 99%

A GEOCLIM simulation of climatic and biogeochemical consequences of Pangea breakup

Donnadieu¹,

Goddéris

Pierrehumbert

et al. 2006

Geochem Geophys Geosyst

128

127

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“…This rise in strontium isotope values through the Tonian is stalled by short term falls coincident with the emplacement of unradiogenic LIPs (Halverson et al 2010). On average, basalt contains~3 times as much phosphorus as granite (Ronov 1982;Halverson et al 2014;Cox et al unpublished) and the low latitude weathering of extensive LIPs between 820 and 720 Ma may have led to an additional increase in phosphorous delivery to the oceans. Fe speciation studies through Tonian and Cryogenian strata have found predominantly anoxic and ferruginous subsurface conditions (Poulton and Canfield 2011) with oxic shallow water (Sperling et al 2013) and local euxinia through organic carbon loading (Johnston et al 2010).…”

Section: Diversity Patterns In Relation To Tectonic and Geochemical Fmentioning

confidence: 99%

The Proterozoic Record of Eukaryotes

2015

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Abstract.-Proterozoic strata host evidence of global "Snowball Earth" glaciations, large perturbations to the carbon cycle, proposed changes in the redox state of oceans, the diversification of microscopic eukaryotes, and the rise of metazoans. Over the past half century, the number of fossils described from Proterozoic rocks has increased exponentially. These discoveries have occurred alongside an increased understanding of the Proterozoic Earth system and the geological context of fossil occurrences, including improved age constraints. However, the evaluation of relationships between Proterozoic environmental change and fossil diversity has been hampered by several factors, particularly lithological and taphonomic biases. Here we compile and analyze the current record of eukaryotic fossils in Proterozoic strata to assess the effect of biases and better constrain diversity through time. Our results show that mean within assemblage diversity increases through the Proterozoic Eon due to an increase in high diversity assemblages, and that this trend is robust to various external factors including lithology and paleogeographic location. In addition, assemblage composition changes dramatically through time. Most notably, robust recalcitrant taxa appear in the early Neoproterozoic Era, only to disappear by the beginning of the Ediacaran Period. Within assemblage diversity is significantly lower in the Cryogenian Period than in the preceding and following intervals, but the short duration of the nonglacial interlude and unusual depositional conditions may present additional biases. In general, large scale patterns of diversity are robust while smaller scale patterns are difficult to discern through the lens of lithological, taphonomic, and geographic variability.

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“…First, continents differ in land area and exposed sedimentary rock. Globally, sedimentary rocks cover approximately 65%-67% of all land surface (Blatt and Jones 1975;Ronov 1982;Amiotte Suchet et al 2003). Overall, there is less exposed sedimentary rock in the continents of the Southern Hemisphere (Africa, Antarctica, Oceania, South America) than in the Northern Hemisphere (Asia, Europe, North America; table 1).…”

Section: Tests Of Sampling Biasesmentioning

confidence: 99%

Testing the Biases in the Rich Cenozoic Angiosperm Macrofossil Record

Xing

Gandolfo

Onstein

et al. 2016

International Journal of Plant Sciences

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Premise of research: The Cenozoic fossil record is crucial for understanding the evolution of the remarkably high diversity of angiosperms. However, the quality and biases of the angiosperm fossil record remain unclear mainly due to the lack of a global database. Methodology: We introduce a new global occurrence-based database for Cenozoic angiosperm macrofossils, the Cenozoic Angiosperm Database. We test the temporal, spatial, and phylogenetic biases of the Cenozoic angiosperm macrofossil record and explore their causes. Pivotal results: The data presented here include 2478 assemblages from all Cenozoic epochs and 1961 sites from all continents, as well as representatives of 221 families (of 445 recognized) and 1859 genera, and show that the Cenozoic angiosperm macrofossil record is extraordinarily rich. However, this rich record is temporally, spatially, and phylogenetically biased: the Miocene is much better sampled than the rest of Cenozoic, the Northern Hemisphere is better sampled than the Southern Hemisphere, and the rosids are better sampled than the rest of the angiosperms. The sampling bias might be caused by collecting effort, geological history, or diverse features of the families, such as growth form and distribution. Conclusions: The Cenozoic macrofossil record of angiosperms is remarkably rich, especially of woody families found in the Northern Hemisphere. Even if there are numerous biases in these data, a judicious use of the database should be highly informative. Editor: Maria von BalthazarPremise of research. The Cenozoic fossil record is crucial for understanding the evolution of the remarkably high diversity of angiosperms. However, the quality and biases of the angiosperm fossil record remain unclear mainly due to the lack of a global database.Methodology. We introduce a new global occurrence-based database for Cenozoic angiosperm macrofossils, the Cenozoic Angiosperm Database. We test the temporal, spatial, and phylogenetic biases of the Cenozoic angiosperm macrofossil record and explore their causes.Pivotal results. The data presented here include 2478 assemblages from all Cenozoic epochs and 1961 sites from all continents, as well as representatives of 221 families (of 445 recognized) and 1859 genera, and show that the Cenozoic angiosperm macrofossil record is extraordinarily rich. However, this rich record is temporally, spatially, and phylogenetically biased: the Miocene is much better sampled than the rest of Cenozoic, the Northern Hemisphere is better sampled than the Southern Hemisphere, and the rosids are better sampled than the rest of the angiosperms. The sampling bias might be caused by collecting effort, geological history, or diverse features of the families, such as growth form and distribution.Conclusions. The Cenozoic macrofossil record of angiosperms is remarkably rich, especially of woody families found in the Northern Hemisphere. Even if there are numerous biases in these data, a judicious use of the database should be highly informative.

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The Earth's sedimentary shell (quantitative patterns of its structure, compositions, and evolution)

Cited by 82 publications

References 23 publications

A GEOCLIM simulation of climatic and biogeochemical consequences of Pangea breakup

A GEOCLIM simulation of climatic and biogeochemical consequences of Pangea breakup

The Proterozoic Record of Eukaryotes

Testing the Biases in the Rich Cenozoic Angiosperm Macrofossil Record

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