Reply to the comment on "Orbitally forced climate and sea-level changes in the Paleoceanic Tethyan domain (marl–limestone alternations, Lower Kimmeridgian, SE France)" by S. Boulila, M. de Rafélis, L. A. Hinnov, S. Gardin, B

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Reply to the comment on "Orbitally forced climate and sea-level changes in the Paleoceanic Tethyan domain (marl–limestone alternations, Lower Kimmeridgian, SE France)" by S. Boulila, M. de Rafélis, L. A. Hinnov, S. Gardin, B. Galbrun, P.-Y.

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  Author's personal copy Reply to the comment on "Orbitally forced climate and sea-level changes in thePaleoceanic Tethyan domain (marl – limestone alternations, Lower Kimmeridgian, SEFrance)" by S. Boulila, M. de Rafélis, L. A. Hinnov, S. Gardin, B. Galbrun, P.-Y. Collin[ Palaeogeography Palaeoclimatology Palaeoecology 292  (2010) 57 – 70] Slah Boulila a,b , Silvia Gardin c , Marc de Rafélis a , Linda A. Hinnov d , Bruno Galbrun a, ⁎ , Pierre-Yves Collin a a Université Paris VI, CNRS   —  UMR 7193 ISTEP, Institut des Sciences de la Terre, Paris, case 117, 4 place Jussieu, 75252 Paris cedex 5, France b Observatoire de Paris, UMR 8028 IMCCE, 77 avenue Denfert-Rochereau, 75014 Paris, France c CNRS   —  UMR 7207 CR2P, Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, Université Paris VI, case 104, 4 place Jussieu, 75252 Paris cedex, France d Morton K. Blaustein Department of Earth and Planetary Sciences, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA a b s t r a c ta r t i c l e i n f o Available online 27 April 2011  In their comment on our paper (Boulila S. et al. 2010  —  Orbitally forced climate and sea-level changes in thePaleoceanic Tethyan domain, marl – limestone alternations, Lower Kimmeridgian, SE France,  Palaeogeog.Palaeoclim. Palaeoecol ., 292, 57 – 70), Mattioli and co-authors (E. Mattioli et al., Comment on "Orbitally forcedclimate and sea-level changes in the Paleoceanic Tethyan domain (marl – limestone alternations, LowerKimmeridgian, SE France) " by S. Boulila, M. de Rafélis, L. A. Hinnov, S. Gardin, B. Galbrun, P.-Y. Collin[Palaeogeography Palaeoclimatology Palaeoecology 292 (2010) 57 – 70], Palaeogeography PalaeoclimatologyPalaeoecology, this issue) criticize our depositional model of Lower Kimmeridgian marl-limestonealternations in the Vocontian Basin (SE France) and contest the nannofossil contribution to the build-up of micritic limestones. The model that we proposed links maxima of orbitally forced insolation with high sea-level, weaker continental erosion, and reduced detrital input, and insolation minima to low sea-level,increasing erosion of detrital materials and their transport to the basin. This involves a competition betweenmultiple variable  󿬂 uxes, and is supported by a multi-proxy study (magnetic susceptibility, weight percentcarbonate, manganese content coupled with cathodoluminescence analysis, oxygen and carbon stableisotopes, and calcareous nannofossil analysis) on a 8.5-m thick interval from a ~40 m-thick section atChâteauneuf-d'Oze (SE France). This differs substantially from previous models suggesting that detrital inputto this part of the Vocontian Basin constitutes  ‘ background noise ’ , and that the main mechanism inducing themarl – limestone rhythms was orbitally forced carbonate mud export from the Jura Platform.© 2011 Elsevier B.V. All rights reserved. 1. Introduction Mattioli and co-authors (E. Mattioli et al., 2011- this issue) disputeour depositional model of marl – limestone alternations of the LowerKimmeridgian Châteauneuf-d'Oze section in the Vocontian Basin (SEFrance), and instead support the depositional model of  Colombié(2002) for the same section, and that of  Pittet et al. (2000) for Oxfordian – Kimmeridgian Tethyan sections. Their comments focus oncalcareous nannofossil analysis in marls and limestones, detrital(clay) input vs. carbonate contribution in marl – limestone coupletformation,andinsitu(pelagic)carbonatevs.exportedcarbonatefromplatforms. We welcome this opportunity to reply to Mattioli and co-authors, and to advance the long-standing debate concerning thedeposition of marl – limestone alternations in Late Jurassic Tethys. 2. Calcareous nannofossils in basinal marls and limestones Most of the criticism of Mattioli and co-authors focuses on thesubject of calcareous nannofossils in marls and limestones which inour work comprised a rather minor petrographic analysis to supportour interpretation. Their points are: (1) nannofossil contribution tothe marls and limestones (e.g. correlation between weight percentCaCO 3  and abundance of nannofossils), (2) fragmentation of nanno-fossils either due to diagenetic overprint or to breakage during pre-paration, (3) nannofossil contribution to micrite, and (4) srcin of micarbs. We discuss these points as follows. Palaeogeography, Palaeoclimatology, Palaeoecology 306 (2011) 252 – 257DOIs of srcinal article: 10.1016/j.palaeo.2010.12.028, 10.1016/j.palaeo.2010.03.026. ⁎  Corresponding author. E-mail address:  bruno.galbrun@upmc.fr (B. Galbrun). Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology  journal homepage: www.elsevier.com/locate/palaeo 0031-0182/$  –  see front matter © 2011 Elsevier B.V. All rights reserved.doi:10.1016/j.palaeo.2011.04.017  Author's personal copy  2.1. Nannofossil contribution to the marls and limestones Mattioli and co-authors write that our semi-quantitative analysis of calcareous nannofossilsreveals that  “ thecontribution of nannofossils ishigher in marls than in limestones ” . This difference (considered asdiagenetically controlled in our work) is suspected by Mattioli and co-authors to be exaggerated compared to the  “ poorly contrasted ”  (72 – 97%) CaCO 3  content of the analyzed samples. We object however thatwe didnotwrite that nannofossil  “ contribution ” ishigherin marlsthanin limestones, but wrote that nannofossil  “ abundance ”  is higher inmarlsthaninlimestonebeds(Boulilaetal.,2010,page64).Thispointiscrucial because it expresses the main divergence between ourinterpretation and that of Mattioli and co-authors. According to usabundance and contribution are two distinct concepts and the numberof counted coccoliths vs. CaCO 3  content is not suf  󿬁 cient to measurethe nannofossil contributiontocarbonateproduction (Erba,1994;Erbaand Tremolada, 2004), nor is it a linear function of CaCO 3  content. Inagreement with previous authors (Erba, 1991; Thierstein and Roth,1991; Bornemann et al., 2003), we think that diagenetic alteration of nannofossilsinsediments,e.g.,etching,overgrowthandfragmentation,goes along with higher CaCO 3  content and can lead to a biasedcalculation of nannofossil-derived CaCO 3  content (Bornemann et al.,2003).  2.2. Fragmentation of nannofossils Previous authors (Erba, 1991; Thierstein and Roth, 1991; Borne-mann et al., 2003) have reported that above a carbonate content of 60% differential changes in the preservation state of carbonate bedsare accompanied by an increasing proportion of nannofossil frag-ments and nannofossil-derived diagenetic microcarbonate. In partic-ular, Bornemann et al. (2003) showed that it is crucial to reconcileabsolute quantitative counts with SEM visual estimates when roughlycalculating the volumetric contribution of calcareous nannofossils tocarbonate sediments. Their analysis clearly demonstrated thatquanti 󿬁 cation of nannofossil produced carbonate  “ are biased byhigh amounts of unidenti 󿬁 able micrite and recrystallized or brokennannofossils which have not been quanti 󿬁 ed when studying theassemblage ” . Fragmentation of nannofossils can also occur duringmechanical breakage resulting in a further underestimation of nannofossil abundance in smear slides (Noel and Melguen, 1978;NoelandBusson,1991;Erba, 1994;ErbaandTremolada,2004).In ourpaper we refer to mechanical breakage (of hard lithologies) on page64 (Boulila et al., 2010); otherwise we have considered nannofossilfragmentation as the result of diagenetic imprint. We did not analyzea greater number of samples for nannofossil content because it wasnot the principal aim of the work; rather, we coupled our opticalmicroscope analysis with detailed SEM observations in order to havemore reliable information on the composition of micritic limestonebeds.Inourvisualstudiesofthemicriticlimestones(SEMimages)theoccurrence of coccolith debris as a fabric component is clear.To demonstrate that mechanical breakage cannot produce ourobserved variations in nannofossil abundance, Mattioli and co-authorsprovide two optical microscope images from two samples fromChateauneuf-d'Oze, one of a marly sample, where coccoliths seemmore abundant and show both small and big sizes, and a more cal-careous sample in which only a large-size coccolith is present. Theyconcluded that,  “ since larger sizes are found in the more calcareoussample, none or little mechanical fragmentation occurred duringpowdering ” . We object however, that we did not write that theobserved variations in nannofossil abundance were due to mechanicalbreakage only, but rather, they are more dependent on the diageneticimprint of the rock, which can result in fragmentation of nannofossils(see above).The preferentialdestructionoflarge-size coccolithsduringsmear-slide preparation suggested by Mattioli and co-authors is thusnot relevant. Rather, it ismore dependent oncoccolith/nannolith ultra-structure (Noel and Melguen, 1978; Erba, 1994; Erba and Tremolada,2004; Young et al., 2005). We suggest that these images are, instead,further evidence of the worse nannofossil preservation in limestonebeds and concur with our analysis ( “ coccolith abundance and diversityare greater in marls than in limestones ” , Boulila et al., 2010, pag. 64).Individualcoccolithsoccurinlowernumberbecausediageneticimprintis stronger and small coccoliths are likely more easily obliterated asdemonstrated by Roth (1973) and Adelseck et al. (1973).Preservation of nannofossils can be enhanced by the presence of clay that, to some extent, exerts a protective function and allowseasier isolation of individual coccoliths in smear-slide preparation(Noel and Busson, 1991; Noel et al., 1993; Breheret, 1994). This pro-tective function of clay is routinely acknowledged by planktonicforaminifer specialists for washing residue preparation. Mattioli andco-authors report examples of nannofossil  “ optimal preservation ”  inlithologieswith40to55%carbonatebyweight(Erba,1991;Thiersteinand Roth, 1991), which are values far below those of the samplesanalyzed at Chateauneuf-d'Oze. The preservation of calcareousnannofossils reported by Erba (1991, page 462) is moderate to poor,not optimal, and this does not contradict our observations since wenever suggested that our samples show optimal preservation. We dobelieve that preservation is usually better in marly lithologies such asthose of the aforementioned literature, although those cases refer tolaminated, organic rich sediments of Albian age.  2.3. Nannofossil contribution to micrite Mattioli and co-authorsargue that our interpretation of the natureof micarbs is based on only a few studies, namely that of  Cook andEgbert (1983) and they defer recognizing in our photos the smallestfragments of coccoliths as nannofossil derived micarbs. In reply, weinvite them to examine our photos more closely and to consultreference literature on this subject (Noel, 1968, 1969; Busson andNoel, 1991; Noel and Busson, 1991; Busson et al., 1997; Bornemannet al., 2003). In not recognizing the nannofossil-derived micarbs inphotos 5 and 6 (Plate 1 in Boulila et al., 2010), they conclude thatcoccoliths do not constitute the bulk carbonate and infer a primary(e.g. not diagenetic) correlation between wt.% CaCO 3  and number of coccoliths. At the same time, they do not offer any evidence that thiscorrelation is not diagenetic. In our work we showed that pervasive,small grains regarded as micarbs are derived from coccoliths. Also,coccoliths are occasionally present as molds,further supportingthat aportion of the micrite was produced by in situ dissolution and re-crystallization of coccoliths. This evidence combined with chemicalandphysicaldata(seenextsection),leadsustobelievethatcoccolithswere the main autochthonous component of limestone micrite atChâteauneuf-d'Oze (Boulila et al., 2010, page 65). At the same time,we do not reject that the carbonate micrite might have had, at least inpart, a different srcin than a biological one. This is stated on page 67(Boulila et al., 2010) where we conclude that  “ marine carbonateproductionwasmostlikelyinsitu,andmainlycomposed ofcoccolithsand debris of coccoliths ” .  2.4. Origin of micarbs Mattioli and co-authors argue that micarbs might have a differentsrcin than a biological one and propose various examples from theliterature. We do not exclude that micarbs in general might have anon-biological or bio-induced srcin, but we object to the examplesthat were raised that are not pertinent to our work, being speci 󿬁 c toother time intervals, other sedimentary basins, or other contexts. Theeuhedral micarbs shown in Bour et al. (2007), one of the examplesgivenbyMattioliandco-authors,havenothingto do withthe micarbsof our photos which, although impacted by diagenesis, are stillrecognizable as nannofossil-derived micarbs by SEM analysis. This 253 S. Boulila et al. / Palaeogeography, Palaeoclimat ology, P alaeoecology 306 (2011) 252 –  257   Author's personal copy was shown srcinally by Busson et al. (1997) for the Chateauneuf-d'Oze section.The nannofossil contribution to carbonate micrite is not a trivialproblem and requires detailed SEM analysis (Noel, 1968, 1969;Scholle, 1971a,b; Noel and Melguen, 1978; Flugel and Keupp, 1979;Erba and Quadrio, 1987; Thierstein and Roth, 1991; Erba, 1994; Noelet al., 1994; and many others). It cannot be evaluated just by thenumber of coccoliths correlated to a CaCO 3  curve. This is a majortopicof discussion that deserves to be addressed in another debate. 3. Clay input and carbonate production: antagonist cyclicprocesses vs. only cyclic carbonate input The main components of the Late Jurassic Vocontian Basin marl – limestone alternations are detrital clay from terrestrial sources, andmarine carbonate from biological/non-biological sources. To formstrong alternations of clay-rich marl and carbonate-rich limestonerequires cyclical delivery of one over the other sediment componentto the basin. The challenge is to identify the basic driver and theconditions that favored deposition of one component over the other.There is compelling evidence that depositional conditions werecontrolled by astronomically forced insolation (e.g., Strasser, 2007);theforcingsignalhasbeenrecoveredfromtheChâteauneuf-d'OzeandLa Méouge sections using high-resolution MS data and time-frequency analysis (Boulila et al., 2008a,b). The other part of thechallenge is to identify the physical conditions involved in the cyclicsedimentation of clay vs. carbonate. It is on this point that inter-pretations diverge, and that Mattioli and co-authors object to in ourpaper. This point is important, because it has implications for thesequence stratigraphy that has been developed for the KimmeridgianVocontianBasin,anditsapplicationasacorrelationtooltootherareasaround Europe.Colombié (2002) considered that carbonate mud export fromSwiss Jura platform into the Vocotian Basin (SE France) was the onlycyclic process in the Lower Kimmeridgian marl – limestone alterna-tions at Châteauneuf-d'Oze and La Méouge sections (SE France). Sheused thickness variations of the limestone beds to explain thecontribution of carbonate and clay inputs to the cyclic pattern of thecouplets. Colombié (2002) applied this thickness method to the LaMéouge section to exclude a cyclic detrital input (her Fig. 10.1). Thismethod was subsequently used for sequence stratigraphic interpre-tation of three basinal sections and their correlation (Fig. 5.3 of Colombié, 2002). The correlations were made considering thethicknesses of couplets with only limestone bed members, and ledColombiétoconcludethatclayinputconstitutesa “ backgroundnoise ” in the marl – limestone alternations (Colombié, 2002, her Fig. 10.1).She did not take into account the importance of limestone vs. marlthickness within total couplet thickness, which greatly in 󿬂 uences hermethod. For example, couplet thicknesses comprise 63% limestonethickness vs. only 37% marl thickness in the most marly interval at LaMeouge (Fig. 1). This implies that limestones are almost twice asimportant in this distal pelagic section, which overwhelminglydominates couplet cyclicity to the detriment of marls. Additionally,marly interbeds are always more strongly compactedthan limestones(e.g. Ricken, 1987; Munnecke and Samtleben, 1996; Westphal, 2006).Thisdifferentialcompactionfurtherin 󿬂 uencesmarl-coupletthicknesscorrelation (Fig. 10.1 of  Colombié, 2002), and so should not be takenas factor in primary deposition.In the sequence stratigraphic interpretation of  Colombié (2002)and Colombié and Strasser (2003), thicker limestone beds areattributed to lowstand deposits, and thicker marly interbeds tomaximum  󿬂 ooding deposits. This interpretation was based on theassumption that the main source of carbonate is from shallowcarbonate platforms: when sea level is high, carbonate producedwithin the platform remains on the platform; when sea level is low,the carbonate factory moves offshore and delivers more carbonate tothe basin (Colombié and Strasser, 2003, their Fig. 6). This approachcoupled with a rough estimate ( 󿬁 eld) of clay content variations wereused to interpret basinal sequences. The use of clay content evolutionis useful in sequence stratigraphic interpretations, being a powerfulindicator of climatic change, but it does not necessarily depend onstratigraphic thickness. Thickness variations can be affected factorsother than climate (differential compaction, subsidence, volume of detrital supply, etc.). Colombié (2002) however, based her interpre-tation on marl – limestone thickness analysis.Colombié and Strasser (2003) concluded that  “ thicknesses of marl – limestonealternationsfrom onesection to another are the mostappropriate way to correlate the small-scale sequences ”  (p. 679).However, in a high-resolution correlation of the La Méouge andChâteauneuf-d'Oze sections, Boulila et al. (2008a, their Fig. 2), withthe assistance of spectral analysis and  󿬁 ltering, found differentnumbers of couplets within correlative small-scale (100 kyr) bundles,and that not only couplets but also couplet bundles (100 kyr) areaffected by hiatuses. These collective observations point to thevulnerability of a simple couplet thickness method in interpretingand correlating basinalsections.Moreover, Colombié (2002) assumedan à priori de 󿬁 ned sequence stratigraphic model (from Strasser et al.,1999) to interpret these basinal sections.Instead of using bed thicknesses, we relied on clay content in oursequence stratigraphic interpretation, and a cyclic (orbitally forced)detrital input (Boulila et al., 2010). Through cyclostratigraphicanalysis of the two aforementioned basinal sections, using magneticsusceptibility (MS) as the paleoclimatic proxy, Boulila et al. (2008a,b)found that clay 󿬂 ux also played an important role in the cyclic patternofthestudiedsections.Forinstance,ifextractingMSmaximafromthemarls to seek for lower-frequency cyclicity (i.e., couplet bundles),eccentricitycyclesare well preserved in theclay content(e.g.,Fig. 8 of Boulila et al., 2010). If detrital input constituteda backgroundnoise inthe rhythmic marl – limestone alternations as postulated by Colombié(2002), then one would not see lower frequency orbital modulation(i.e., eccentricity modulates precession) in the clay content (MSintensity).The more complete La Méouge section, about 30-km fromChâteauneuf-d'Oze, offers an exceptional example of Jurassic recordof orbital forcing: the high-resolution MS measurements clearly showthe precession/eccentricity modulation highlighted in the MS signal(e.g., Figs. 2 and 3 of  Boulila et al., 2008b, and the spectrumin Fig. 5B).Compared to our high-resolution MS analysis, and to the closeresemblance of the La Meouge MS signal to astronomical theory(Fig.1), Colombié'sinterpretation (2002) is notreliable, at least in thecase of these basinal sections. To demonstrate this, we have providedin Fig. 1 the stratigraphically most complete and regular interval( ∼ 24 m thick) of the La Méouge section that shows two 405 kyreccentricity cycles. These two cycles modulate the precession indexcycles in a similar astronomical fashion. This  󿬁 gure clearly shows theimportant role that played detrital (clay) input in the cyclicity of marl – limestone couplets. 4. The in situ carbonate production vs. mud export from adjacentplatforms: constraints from multi-proxy study and nannofossilanalysis The studied interval at Châteauneuf-d'Oze section exhibits astrong expression of precession cycles (couplets) modulated by two~100 kyr eccentricity cycles (couplet bundles). These ~100 kyreccentricity cycles is also recognized by Colombié (2002) as a typicalexample of her interpreted couplet bundles (Fig. 2 of  Colombié andStrasser, 2003). In our MS and %CaCO 3  signals, the same cycle isrecorded in both marls and limestones, i.e. extrema in MS and %CaCO 3 values. Colombié (2002) considered this cycle as regional in srcin(Vocotian Basin and Swiss Jura platform) via her correlation. Also,Boulila et al. (2008a) correlated this cycle to its equivalent in the La 254  S. Boulila et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 306 (2011) 252 –  257   Author's personal copy ABC 12 17 22 27 3201234 F i  l   t   er  e d  pr  e c  e s  s i   oni  n d  ex F i  l   t   er  e d M S M a gn e t  i   c  s  u s  c  e p t  i   b i  l  i   t   y  (  1  0 -  8  m  3   /  k  g )   Lower Kimmeridgian 0 100 200 300 400 500 600 700 800-0.8-0.400.40.81.20 100 200 300 400 500 600 700 800-0.06-0.0200.020.06 1243 56789101112 1314151617181920 123456789 10 11121314151617181910 15 20 25 30 Meters kiloyearsKiloyears ago Fig. 1.  ~24 m thick interval extracted from the La Méouge section (from Boulila et al., 2008b their Fig. 5) showing a strong amplitude modulation (AM) analogy between high-resolution (~7 cm) magnetic susceptibility (MS) variations and astronomical model. Note that clay content is modulated by the lower orbital f requency (i.e., eccentricity) cycles, indicatingthatclayinputiscyclicandnotabackgroundnoiseaspostulated byColombié(2002).(A)RawMSvariations,thenumbersshowprecessionindexcyclesexpressedinboth lithology and MS. In addition, MS detects very well lower frequency (405 kyr eccentricity) cycles, which are strongly expressed in MS maxima of the marls, so in clay content (seealso Boulila et al., 2008a their Figs. 2 and 5B). Each 405 kyr eccentricity cycle contains almost 20 marl – limestone couplets (see Boulila et al., 2008a,b for time-series analysis). (B) MS 󿬁 ltered to precession  ‘ P1 ’  band and the extracted envelopes by Hilbert transform. (C) Precession index in the La2004 astronomical model (Laskar et al., 2004)  󿬁 ltered to  ‘ P1 ’ component and the extracted envelopes by Hilbert transform. Note that the analogy between (B) and (C), i.e., geology/astronomy, is exceptional: the precession index  ‘ P1 ’  ismodulated bythe405 kyreccentricity cycles.Weexplainthestrongexpressionofthe405 kyrAMcyclesbythefactthattheprecessioncomponent  ‘ P1 ’ ,whichrepresents thehighestamplitude in the total climatic precession (e.g., Laskar et al., 2004), is well documented in the stratigraphic signal, and thus the modulation comes mainly from it.255 S. Boulila et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 306 (2011) 252 –  257   Author's personal copy Méouge section. This motivated us to undertake a multi-proxy studyto delineate a depositional model that links insolation, climate, andsea level changes.The proxies show signi 󿬁 cant variations in the lithologies, allowingus to develop a consistentmodel of the couplets and coupletbundlingas follows (Fig. 5 of  Boulila et al., 2010): insolation maxima inducedwarmer conditions, higher sea level and the formation of thelimestones; insolation minima induced colder conditions, lower sea level and the formation of the marls. Our model is also supported bygeochemical proxies, e.g. bulk oxygen isotopes (Fig. 5 of  Boulila et al.,2010). This result concurs with that of  Pross et al. (2006), who used palynofacies and bulk rock oxygen isotopes in their interpretation of the German Kimmeridgian (deep ramp carbonates). The in situ vs.allochtonous carbonate srcin hypothesis between our model andColombié's model, respectively, led to this opposing interpretation.ThemainargumentofMattioliandco-authorsfortheallochtonous(platform)carbonate srcinhypothesis in the Vocotianbasin relies on1) their rejection of cyclic behavior of detrital input process due toapparent non-correlation of limestone and clay thicknesses withincouplets (Colombié, 2002) and 2) the supposed minor contribution of coccoliths in limestone beds than in marls, having recognized none ina previous SEM study (Colombié, 2002). This undoubtedly fueled theplatform carbonate hypothesis proposed by Colombié and Strasser(2003). Our high-resolution cyclostratigraphic analysis instead sug-gests a cyclic behavior of detrital input (see above), and evidence forthe in situ (pelagic) origin of carbonate fraction by testing thecontribution of nannofossils to carbonate beds with a detailed SEManalysis. Busson and Noel (1991) and Boulila et al. (2010) have unequivocally shown an omnipresence of coccoliths and coccolithdebris in both marls and limestones at Châteauneuf-d'Oze furthersupporting a pelagic carbonate srcin for limestone beds that likelycan be applied throughout the Vocontian Basin. 5. Concluding remarks In sum, our study used physical and chemical proxies to develop adepositional model for the Vocontian Basin marl – limestones thatlinks insolation, climate, and sea level changes.The work of  Boulila et al. (2010) focused on the genesis of theKimmeridgian marl – limestone alternations found in the VocontianBasin, SE France. The work led to signi 󿬁 cant adjustments to previouswork on the problem, and new insights into the conditions leading tobasinalmarl – limestonedepositionoftheseremarkableepicontinentalsedimentary formations. In this reply, we have attempted to answerto criticisms in the comment to our work by Mattioli and co-authors,who are experienced students of the Vocontian Basin and Swiss Jura.Their points express long-standing issues that face all researchers of LateJurassicTethyansedimentologyandstratigraphy.Mainpointsareas follows: •  Nannofossil contribution to marls and limestones: nannofossilabundance is higher in the marls than in the limestones becausealteration of nannofossils e.g., etching, overgrowth and fragmenta-tion, is more prevalent in the limestones, and can lead to a biasedcalculation of nannofossil-derived CaCO 3  content. •  Nannofossil fragmentation: mechanical breakage during slidepreparation of hard lithologies can fragment nannofossils. HoweverSEM analysis indicates that in our study most of the nannofossilfragmentation in the limestones was the result of diagenesis. •  Origin of micarbs: the micarbs examined in our SEM analysis arenannofossil-derived, although this does not rule out non-biologicalsrcins for micarbs from other geologic ages. •  Statistical analysis of high-resolution magnetic susceptibility vari-ations highlights the cyclic behavior of clay content. These resultsrule out the hypothesis of   ‘ background noise ’  in clay input process. •  Chemical proxies, in particular oxygen isotopes data, reveal thatlimestones were deposited under higher sea level and warmerconditions,whilemarlsunderlower sea level andcolder conditions.This concurs with previous studies using oxygen isotope approach. •  Sequence stratigraphy of the Vocontian Basin  —  present-day con-ceptual models of sequence stratigraphy do not agree with newoxygen isotope evidence, which require a change to opposite phase. •  Correlating cyclic basinal sequences  —  simple correlation of bedthicknesses between sections without any high-resolution cyclos-tratigraphic analysis can result in gross inaccuracies. •  In situ (pelagic) carbonate srcin  —  the omnipresence of coccolithsand coccolith debris in the marls and limestones at Châteauneuf-d'Oze rather points to an in situ pelagic carbonate srcin for Vocon-tian Basin limestones.  Acknowledgments We thank Axel Munnecke for his very interesting comments. 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