Evaporites through time: Tectonic, climatic and eustatic controls in marine and nonmarine deposits

Warren, John K.

doi:10.1016/j.earscirev.2009.11.004

Cited by 484 publications

(303 citation statements)

References 133 publications

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“…We assume the pre--snowball salinity to be equal to modern, but there is significant evidence that it varied significantly and may have been as high as two times modern 43 ; see also some recent reviews of evaporites through time 44,45 . Salinity may have also increased during snowball events if oceans continued to receive a supply of salts through both subglacial runoff and subglacial sediment transport, while evaporite deposition would have been nonexistent.…”

Section: Salinity Uncertaintiesmentioning

confidence: 99%

Dynamics of a Snowball Earth ocean

Ashkenazy

Gildor

Lösch

et al. 2013

Nature

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Geological evidence suggests that marine ice extended to the equator at least twice during the Neoproterozoic (∼750-635 Myr ago) 1, 2 , inspiring the Snowball Earth hypothesis that the Earth was globally ice covered 3, 4 . In a possible Snowball Earth climate, ocean circulation and mixing processes would have determined the melting and freezing rates that determine ice thickness 5,6 , influenced the survival of photosynthetic life 4,5,7-9 , and may provide important constraints for the interpretation of geochemical and sedimentological observations 4,10 . Here we show that in a Snowball Earth, the ocean would have been well mixed and characterized by a dynamic circulation 11 , with vigorous equatorial meridional overturning circulation, zonal equatorial jets, a well-developed eddy field, strong coastal upwelling and convective mixing. This is in contrast to the sluggish ocean often expected in a snowball scenario 3 .As a result of vigorous convective mixing, the ocean temperature, salinity and density were either uniform in the vertical or weakly stratified in a few locations. Our results are based on a coupled ice flow-ocean circulation model driven by a weak geothermal heat flux under a global ∼1 km ice cover. Compared to the modern ocean, the snowball ocean had far larger vertical mixing rates, and comparable horizontal mixing by ocean eddies. The strong circulation and coastal upwelling resulted in melting rates near continents as much as ten times larger than previously estimated 6, 7 . While we cannot resolve the ongoing debate on the existence of a global snowball ice cover 10,12,13 , we discuss the implications to nutrient supply for photosynthetic activity and to banded iron formations. The new insights and constraints on ocean dynamics may help resolve the Snowball Earth controversy when combined with future geochemical and geological observations.The flow of thick ice over a Snowball ocean ("sea glaciers", characterized by very different dynamics from thinner sea ice 14 ), has received significant attention over the past few years [5][6][7]9,14,15 . Similarly, the role and dynamics of atmospheric circulation and heat transport, CO2 concentration, cloud feedbacks, and continental configuration have been studied [16][17][18] , as has the role of dust over the Snowball ice cover 17,19 . In contrast, despite its importance, the ocean circulation during Snowball events has received little attention. The few studies that used full ocean General Circulation Models (GCMs) concentrated mostly on the ocean role in Snowball initiation and aftermath 20,21 . None of these studied accounted for the combined effects of thick ice cover flow and driving by geothermal heating 11,13,22,23 , yet 11 simulated an ocean under a 200 m thick ice cover with no geothermal heat flux, and calculated a non steady--state solution with near--uniform temperature and salinity, and vanishing Eulerian circulation together with a strong parameterized eddy--induced high latitude circulation cells.To allow simulating the special circumstan...

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Section: Salinity Uncertaintiesmentioning

confidence: 99%

Dynamics of a Snowball Earth ocean

Ashkenazy

Gildor

Lösch

et al. 2013

Nature

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“…O1, V1, A1 and A2, also have high Mg 2+ /Ca 2+ and Cl − /Br − ratios (up to 4.4 and N 1000, respectively; Fig. 5) and HCO 3 − and SO 4 2− concentrations (up to 2900 and 7860 mg/L, respectively), these geochemical features commonly found in waters interacting with evaporitic deposits (Warren, 2010). This is also supported by the high concentrations of NH 4 + , Li + and B (Table 1), which are typically enriched in salt deposits (Helvaci and Alonso, 2000;Garrett, 2004).…”

Section: Processes Controlling the Chemistry Of Watersmentioning

confidence: 99%

Fluid geochemistry of a deep-seated geothermal resource in the Puna plateau (Jujuy Province, Argentina)

Arnold

Cabassi

Tassi

et al. 2017

Journal of Volcanology and Geothermal Research

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This study focused on the geochemical and isotopic features of thermal fluids discharged from five zones located in the high altitude Puna plateau (Jujuy Province between S 22°20′-23°20′ and W 66°-67°), i.e. Granada, Vilama, Pairique, Coranzulí and Olaroz. Partially mature waters with a Na + -Cl − composition were recognized in all the investigated zones, suggesting that a deep hydrothermal reservoir hosted within the Paleozoic crystalline basement represents the main hydrothermal fluid source. The hydrothermal reservoirs are mainly recharged by meteoric water, although based on the δ 18 O-H 2 O and δD-H 2 O values, some contribution of andesitic water cannot be completely ruled out. Regional S-oriented faulting systems, which generated a horst and graben tectonics, and NE-, NW-and WE-oriented transverse structures, likely act as preferentially uprising pathways for the deep-originated fluids, as also supported by the Rc/Ra values (up to 1.39) indicating the occurrence of significant amounts of mantle He (up to 16%). Carbon dioxide, the most abundant compound in the gas phase associated with the thermal waters, mostly originated from a crustal source, although the occurrence of CO 2 from a mantle source, contaminated by organic-rich material due to the subduction process, is also possible. Relatively small and cold Na + -HCO 3 − -type aquifers were produced by the interaction between meteoric water and Cretaceous, Palaeogene to Miocene sediments. Dissolution of evaporitic surficial deposits strongly affected the chemistry of the thermal springs in the peripheral zones of the study area. Geothermometry in the Na-K-Ca-Mg system suggested equilibrium temperatures up to 200°C for the deep aquifer, whereas lower temperatures (from 105 to 155°C) were inferred by applying the H 2 geothermometer, likely due to re-equilibrium processes during the thermal fluid uprising within relatively shallow Na-HCO 3 aquifers. The great depth of the geothermal resource (possibly N 5000 m b.g.l.) is likely preventing further studies aimed to evaluate possible exploitation, although the occurrence of Liand Ba-rich deposits associated may attract financial investments, giving a pulse for the development of this remote region.

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“…Both time periods are marked by extensive evaporite deposition and major global glacial events (Hitzman et al 2010;Warren 2010), which are thought to be important in ore formation. Such a link between large-scale SSC mineralization and the supercontinental cycle has also been suggested to apply to the late Paleoproterozoic (Hitzman et al 2010).…”

Section: Possible Link To the Columbia Supercontinentmentioning

confidence: 99%

Late Paleoproterozoic sedimentary rock-hosted stratiform copper deposits in South China: their possible link to the supercontinent cycle

Zhao

Zhou

et al. 2012

Miner Deposita

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Giant sedimentary rock-hosted stratiform copper (SSC) deposits commonly occur in rift environments, temporally coincident with the breakup of the Rodinia and Pangea supercontinents. However, whether or not such deposits have also formed during the breakup of the Paleoproterozoic Columbia supercontinent is not well known. A group of dolostone-hosted Cu deposits in late Paleoproterozoic rift-related sedimentary sequences of the Dongchuan Group, South China, form one of the largest SSC districts in the world. Being one of the largest SSC deposits in the region, the Yinmin deposit has stratiform Cu orebodies intruded by dolerite dykes. One dyke has a SIMS zircon U-Pb age of 1,701±28 Ma, slightly younger than the orehosting strata with a zircon U-Pb age of 1,742±13 Ma for a tuff unit. Six chalcopyrite and bornite separates from stratiform orebodies contain highly radiogenic Os and extremely low common Os and yield a weighted mean Re-Os model age of 1,666±82 Ma and a 187 Os-187 Re errorchron age of 1,585±100 Ma. The present zircon U-Pb and sulfide Re-Os ages thus constrain the timing of the mineralization at 1,700 Ma. The Yinmin deposit and, by inference, other SSC deposits in the region, arguably represent a large-scale SSC mineralization event during the late Paleoproterozoic. The formation of these deposits was coeval with the initial breakup/fragmentation of the Columbia supercontinent. This study highlights the temporal and likely genetic links between large-sized SSC deposits and the supercontinent cycle.

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Evaporites through time: Tectonic, climatic and eustatic controls in marine and nonmarine deposits

Cited by 484 publications

References 133 publications

Dynamics of a Snowball Earth ocean

Dynamics of a Snowball Earth ocean

Fluid geochemistry of a deep-seated geothermal resource in the Puna plateau (Jujuy Province, Argentina)

Late Paleoproterozoic sedimentary rock-hosted stratiform copper deposits in South China: their possible link to the supercontinent cycle

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