Geophysical records of dispersed weathering products on the Frasnian carbonate platform and early Famennian ramps in Moravia, Czech Republic: proxies for eustasy and palaeoclimate

Hladil, Jindřich

doi:10.1016/s0031-0182(01)00480-1

Cited by 45 publications

(64 citation statements)

References 59 publications

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“…As already proposed by different authors, the results presented here are pointing to a MS signal probably dominated by lithogenic inputs Ellwood et al, 2000;Hladil, 2002). The proportion of lithogenic inputs seems to be higher during low sea level, when important portion of continental area are emerged.…”

Section: Discussionsupporting

confidence: 84%

“…Ellwood et al (2000), suggested that within sedimentary rocks, paramagnetic and ferromagnetic minerals concentration depends on the lithogenic fraction (terrigenous contributions), which is markedly related to eustatism (provided there is no strong climatic or tectonic influence). During low stands of sea level, larger surface areas are subject to weathering, erosion (Hladil, 2002) and the detrital influx to the world's oceans are higher (Davies et al, 1977;Worsley and Davies, 1979). Thus, theoretically (Crick et al, 1997) the highest MS magnitudes represent maximum low stand in sea level and MS signal increases during a sea level fall.…”

Section: Methodsmentioning

confidence: 99%

“…MS has therefore been used as a proxy for sea level variations (Devleeschouwer, 1999;Boulvain, 2002, 2006;Racki et al, 2002;Hladil et al, 2003a,b). Atmospheric dust and eolian supplies were also identified as important mineral carriers (Hladil, 2002;Hladil et al 2005).…”

Section: Methodsmentioning

confidence: 99%

“…The Middle Frasnian (early Late Devonian) was a time of a globally warm (greenhouse) climate (for a recent review, see Streel et al, 2000;Joachimski et al, 2004;Hladil et al, 2005) and of high sea level (Vail et al, 1977;Johnson et al, 1985; and for a recent review, see Hladil, 2002). During the Devonian, the Earth's surface temperature reaches a peak during the Givetian and according to Streel et al (2000) those hot climates lasted until the Latest Frasnian.…”

Section: Geological Settingmentioning

confidence: 99%

“…During eustatic sea-level fall detrital supply increases and during low sea-level, average MS values are high (Crick et al, 1997;Ellwood et al, 2000). In addition to "classical" aquatic delivery, different authors considered that important amounts of magnetic minerals in carbonate rocks are related to supply from eolian suspension and atmospheric dust (Hladil, 2002;Hladil et al, 2005). This paper compares MS behaviour on carbonate attached platforms and carbonate detached platforms.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic susceptibility evolution and sedimentary environments on carbonate platform sediments and atolls, comparison of the Frasnian from Belgium and Alberta, Canada

Silva

Potma

Weissenberger³

et al. 2009

Sedimentary Geology

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a b s t r a c t a r t i c l e i n f oKeywords: Frasnian Magnetic susceptibility Correlations Platforms and atolls Magnetic susceptibility (MS) measurements on carbonate rocks are considered as a proxy for impurities delivered to the carbonate environments. In the absence of strong climatic or tectonic variations, bulk MS values have been linked to sea level variations, because sea-level fall increases clastic supply and therefore increases in magnetic mineral deposition. In this paper we explore the relationship between the average magnitude of bulk MS, with shallowing-up sequences and facies evolution in different Devonian carbonate complexes. Similarities and differences between these parameters have been scrutinized in carbonate attached platform and detached platforms (mounds and/or atolls) from Belgium and Canada. In the carbonate attached platforms from Belgium and Canada, the MS patterns are directly related to depositional environment. Mean MS values increase from the most distal towards the most proximal facies and towards the top of the majority of fourth-order shallowing-up sequences. These trends are in agreement with theoretical background (MS increases with regression). In the Belgian detached platform, the average MS pattern generally shows an opposite behaviour to that observed in the attached carbonate platforms. Average MS decreases towards the most proximal facies and towards the top of a majority of the fourth-order shallowing-up sequences. This behaviour can be explained by the influence of sedimentary rate and water agitation during deposition. A high sedimentary rate will dilute the magnetic minerals in the atoll facies and the high water agitation during deposition may be expected to have prevented the deposition of the magnetic grains. So, the combination of these two effects will result in the observed low values in the atoll crown and lagoonal facies. In the Canadian detached platform, MS is mainly negative. This means that the limestones are very pure. The technique does not appear to be appropriate in these rocks. The variations of average MS behaviour by platform type can imply difficulties in correlating carbonates from different settings. A comparison of time equivalent mound and platform deposits shows that after an important regressive surface, the MS values are increasing for the platform deposits and decreasing for the mound. So MS evolution can be in complete opposition (caused by highly different sedimentary rates) in different depositional settings. The MS signal preserved in carbonate rocks is probably mainly related to 1) varying clastic supplies; 2) varying carbonate accumulation rates (dilution of the magnetic minerals by high carbonate production) and 3) potentially diagenesis.

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Section: Discussionsupporting

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic susceptibility evolution and sedimentary environments on carbonate platform sediments and atolls, comparison of the Frasnian from Belgium and Alberta, Canada

Silva

Potma

Weissenberger³

et al. 2009

Sedimentary Geology

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Early Pragian conodont‐based correlations between the Barrandian area and the Spanish Central Pyrenees

et al. 2007

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Occurrences and distribution of extremely scarce eognathodontids do not facilitate reliable correlation across the European regions. The correlation of the traditional early Pragian of the Prague Synform (a part of the classical Barrandian area) and the Spanish Central Pyrenees (section Segre 1) is based on conodont taxa of the Icriodus steinachensis and the Pelekysgnathus serratus stocks. This correlation has the potential to be extended to other peri-Gondwanan regions where this scarcity of eognathodontid faunas exists as well. Application of the morphotype subdivision in I. steinachensis enables approximation of the beginning of the Pragian in the Pyrenees. It is based on the entry of I. steinachensis beta morphotype; it enters together with early eognathodontid taxa in the Barrandian sections. These correlations show that routine application of certain zonal concepts can lead to misleading conclusions.

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A pragmatic test of the early origin and fixation of gamma-ray spectrometric (U, Th) and magneto-susceptibility (Fe) patterns related to sedimentary cycle boundaries in pure platform limestones

Hladil

Bosák

Slavík

et al. 2003

Carbonates Evaporites

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In a pragmatictest conductedon vertical stratigraphicsectionsin Quaternaryplatform limestonesof San SalvadorIsland, The Bahamas,gamma-rayspectrometric(GRS)andmagnetosusceptibility (K) dataconfirmedthatcharacteristic geophysicalpatternsarecoupledwith depositionalcycleboundaries. These geophysicalpatternsappearto developintheearlystagesof diagenesisandare long lasting,becausesimilar patternsarefoundbothintheveryyoungBahamianlimestones andinveryoldDevonian(Givetian-Frasnian)platformlimestones ofMoravia,Czech Republic. Becausethe Devonianlimestonesretaingammaray and magneticsignaturessimilarto thoseseenin theBahamianrocks,thesesignals are apparentlyresistantto changes that occur in later diageneticalteration,includingdeep-burialdiagenesisand 380 million years of rock-fluid interactions. Each sedimentarycycle on the Bahamiancarbonateplatform is markedby a terra rossa paleosolhorizonthat representsa lowstand emergentsurface. Thepaleosolis typicallycharacterizedby a GRS-spikerelatedto increasedTh concentration. Thereis only a subtledownward infiltrationofthat GRSsignal,but theTh signalmay diffuseupwardvia sedimentrecycling. TwoV-relatedGRSmaximaareregularlydeveloped within shortdistancesbelow and above the cycleboundary. The loweranomalyreflectsV enrichmentin the sub-soilcementationzone,whereas the upper anomalyis related to increasedV -contentin the floodingbeds of the next cycle. Such a combinationof one Th-spikebetweentwoVanomaliesformsa distinctivetripartiteGRS pattern.Thex-anomaliesforma bimodalsignalthatconsistsof a narrowbut extraordinarily strongpositiveK-anomalythatiscoincidentwiththeTh-spike, andanotherspikethatisdevelopedinthe sub-soil cementationzone. Incaseswhereaburiedcycleboundaryformsthetruncatedfloorofa horizontal cave that is filledwith carbonatesediment,bothV and Th GRS peaks arebroadened. The K -curvesalso displayelevatedbut stronglyoscillating values acrossthe cave fill. The spikesare arrangedasymmetricallydownwardand the strongestspike correspondsto infiltration/cementation of the cave floor. The evidencefromthe Quaternarylimestonessuggeststhatthesetwopatterns(the tripartiteTh andV patternof the standardcycle boundary,andthebroadenedpatternrelatedto filledcaves)havean earlyorigin.In spiteoflarge inhomogeneities on cycle-boundarysurfaces,the abovegeophysicalpatternsappearto bedistinctive, differfromthenormalGRS-andx-backgroundsofplatformcarbonates,andappearstabileover the long term. This test indicatesthat these two patternsmay be useful for recognitionof exposuresurfaces/cycleboundariesvia routinepattern searches in GR, GRS and K well-logsfrom platform limestonesequencesof a wide range of ages and paleoenvironments.

show abstract

Geophysical records of dispersed weathering products on the Frasnian carbonate platform and early Famennian ramps in Moravia, Czech Republic: proxies for eustasy and palaeoclimate

Cited by 45 publications

References 59 publications

Magnetic susceptibility evolution and sedimentary environments on carbonate platform sediments and atolls, comparison of the Frasnian from Belgium and Alberta, Canada

Magnetic susceptibility evolution and sedimentary environments on carbonate platform sediments and atolls, comparison of the Frasnian from Belgium and Alberta, Canada

Early Pragian conodont‐based correlations between the Barrandian area and the Spanish Central Pyrenees

A pragmatic test of the early origin and fixation of gamma-ray spectrometric (U, Th) and magneto-susceptibility (Fe) patterns related to sedimentary cycle boundaries in pure platform limestones

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