Thermomagnetic Properties of Vivianite Nodules, Lake El'gygytgyn

Home , Pyrrhotite

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | to N; 0 1 − 30 cult to ◦ kg ffi 3 Climate m 6 of the Past − erent heating erent minerals ff 2 Discussions 10 ff × erent degree of oxida- ff , and K. J. Murdock ) and is higher than the susceptibility 2 1 − kg 3 m 6 4990 4989 − 10 , L. L. Brown × 1 1.05 = O, is an hydrated iron phosphate that has long been iden- 2 8H · (average 2 ) 1 4 − kg , T. V. Subbotnikova (PO 3 1 3 m 6 − E). Magnetic measurements, including weight low-field AC magnetic suscepti- 0 10 05 × ◦ This discussion paper is/has been under review for the journal Climate of the Past (CP). Please refer to the corresponding final paper in CP if available. North-East Interdisciplinary Scientific Research Institute of Far East Branch ofDepartment Russian of Geosciences, University of Massachusetts, Amherst, USA environments provide readily availableoxides, ferric and iron, inorganic usually phosphorous. It dissolution has products been of found iron as a secondary mineral in wide 1 Academy Science, Magadan, Russia 2 Received: 7 September 2012 – Accepted: 20Correspondence September to: 2012 P. S. – Minyuk Published: ([email protected]) 9 OctoberPublished 2012 by Copernicus Publications on behalf of the European Geosciences Union. selective vivianite and pyrite mixtures– produces magnetite, formation monoclinic of several pyrrhotite,interpret di the and thermomagnetic hexagonal curves. pyrrhotite, and make it di 1 Introduction Vivianite, Fe tified in variety of natural environments. This authigenic mineral forms when anoxic temperature dependence susceptibility oftion vivianite and indicate inclusions in di theto nodules. magnetite Vivianite and acts suppresses asvivianite the a and goethite-hematite reductant sulfur transition mixture and stimulate during reducesof the hematite heating. formation arsenic Heating of monoclinic inhibits pyrrhotite. the An additive formation of magnetite prior to its Curie temperature. Heating pendence of the saturation magnetization,media as provide well ample as information susceptibilitymicroscopy on in and vivianite. di energy Electron-microprobe dispersive analyses, spectroscopy electron erals. were Vivianite used to nodules identify are(oxic) diagnostic stages. abundant Magnetic min- susceptibility in of both1.72 the nodules sediments varies of from 0.78 of cold sediments (anoxic) from the and cold intervals.of warm Magnetic oxidation properties as of well vivianite are as due sediment to and product mineral inclusions. Three types of curves of high Vivianite, a hydrated ironlocated phosphate, in the is Anadyr abundant Mountains172 in of Central sediments Chukotka, of Northeasternbility, El’gygytgyn field Russia Lake, (67 dependent magnetic susceptibility, hysteresis parameters, temperature de- Abstract Thermomagnetic properties of vivianite nodules, Lake El’gygytgyn, Northeast Russia P. S. Minyuk Clim. Past Discuss., 8, 4989–5027, 2012 www.clim-past-discuss.net/8/4989/2012/ doi:10.5194/cpd-8-4989-2012 © Author(s) 2012. CC Attribution 3.0 License. 5 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | . The + 3 12 K (Mei- ∼ . In this paper we 1 E) (Fig. 1). The lake 0 − kg 05 3 ◦ m 6 − N; 172 10 0 ´ eel temperature of × 30 ◦ ´ eel temperature (Frederichs et al., 2003); becomes completely replaced by Fe 4992 4991 + 2 s, and basalt flows) of late Cretaceous age (Bely and ff ) is observed at the N 1 − kg 3 m 6 − 10 × Vivianite has been identified extensively in the earlier, shorter cores (Asikainen et al., 2007; Minyuk et al., 2007)terpreted using both as observational forming and laboratoryplentiful. under techniques, Fine-grained anoxic and dispersed in- conditions vivianite has whenmagnetic been phosphorus measurements recognized using and (Murdock low-temperature ironof et vivianite were al., as both 2012). bothet Due al. small (2007) to grains conclude and the itsnot formation larger influenced ubiquitous is by rounded occurrence large-scale controlled aggregates climate by conditions. diagenetic or microenvironments nodules, and Minyuk the lake (Melles et al.,leoclimate 2011), information providing (Melles et a al., vast 2012,the amount and entire of papers package material within has this to been issue). betuning established Chronology studied to using of for the paleomagnetic pa- marine time oxygen scale2012). isotope with record detailed and insolation variations (Nowaczyk et al., Belaya, 1998; Bely andinput Raikevich, to 1994; the Gurov lake etcrater; is output al., controlled from 2007; by the Layer, a lakeeast 2000). is series from only Sediment of the by some one crater stream, 50 tostudies the the small and Enmyvaam Bering inlet short River, flowing Sea streams cores south- (Nolanto draining collected and the the from Brigham-Grette, suitability the 2007). of lake Preliminary lakethis (Brigham-Grette High El’gygytgyn et Arctic sediments al., site. to 2007) Additional provideof deep attested a sediment drilling detailed was core climate done and in record 200 2008–2009, for m when of over 318 impact m breccia was extracted by ICDP at site 5011 in Vivianite was studied from sediments oftains El’gygytgyn of Lake, Central located Chukotka, in Northeastern the Russiais Anadyr (67 situated Moun- in a 3.6 Manimbrites, impact rhyolite crater to located andesite in tu a series of volcanic rocks (rhyodacite ig- 2 Geologic setting jer et al., 1967;(6.62 Frederichs et al., 2003).at Maximum room magnetic susceptibility temperature of theinvestigate vivianite susceptibility the magnetic is properties, closeite especially to nodules found those 1 in at thevivianite high sediments is paramagnetic temperature, of at Lake for room El’gygytgyn temperature, vivian- tigate in studies the of Northeast presence nodules Siberia. of or Although the absenceon material of the inves- magnetic magnetite properties grains within of lake the sediments vivianite, where and vivianite shed is light common. eventually altering to(Pratesi metavivianite et (kerchenite) al., (Rodgers, 2003), asmagnetic 1986) the properties or original of Fe santabarbaraite vivianiteis are paramagnetic in well-known natural (Meijerromagnetic environments et and at al., surface exceedingly temperature, 1967), low it and becomes temperature although antifer- with it a N quist, 1970) to Lago Maggiore, Italyvivianite (Nembrin in et lake al., sediments 1983). isdox The not formation conditions, of fully pH authigenic understood, values, but dissolvedimpurities appears elements, of to primarily Ca, be Fe Mn, influenced and andet by Mg, P, al., but re- organic 2006). often matter Vivianite including content, is6 and usually to a sedimentation 9 stable rate and mineral (Sapota low insmall Eh environments disaggerate values over of crystals the less pH to thanair range large 0.0 vivianite of (Nriagu nodules, readily and oxidizes, often Dell, turning several 1974). from centimeters Vivianite opaque in is or found diameter. white as In to vivid blue in a short time, ore veins, reducing soils andThe aquifers, presence and of lacustrine vivianite andsubject in marine of lake reduced detailed sediments sediments. studies isLake in well Baikal many (Fagel documented, lacustrine et and environments al.,Canadian it from 2005; prairie has large Sapota (Manning been lakes et et the such al., al., as 2006), 1991, to 1999) small to mesotropic Holocene lakes muds in the in Norway (Rosen- range of situations including weathering products of hydrothermal deposits, Fe-bearing 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ), s J cient ) was , MnO ffi T 5 - s O J 2 content cor- ), and rema- ,P c 3 3 is 0.55. Distri- H O O 5 2 2 O 2 ) of crushed nodules C and back to room and MnO, with some ◦ T - 5 k and P O 2 3 O is 35.18 %, with a range from 2 3 ), coercive force ( O 2 rs and MnO are synchronous in this J 5 O 2 4994 4993 and MnO is 0.55, between Fe ), saturation remanence ( appears to vary independent of P i 5 J 3 O displays values between 21.23–29.28 % (average 25.02 %) with 2 O . Temperature-dependent susceptibility ( 5 ) were measured by an automatic coercive spectrometer (Burov 2 1 cr − O 2 H and MnO. The average content of Fe min ◦ 5 O 2 . 1 − ,P 3 O 2 Cmin ◦ Major elements determination was performed on sediment samples from which vi- Electron-microprobe (EMP) analyses of polished nodules mounted in epoxy resin The chemical composition and major elements in the lake sediments minus the bution of phosphorous and manganesethese shows elements few levels – with depth higher intervals concentrations 8.71–9.21, of 11.51–12.19, 13.19–13.51, 18.39–18.85, of phosphorous to manganese in the vivianite samples rangevianite from 4.61 nodules to were 37.45. removed.along Figure the 3 shows depth the profile.section, distribution Distribution whereas of of Fe Fe bothintervals P showing strong correlations, butresponds other to regions the where phosphorous lowcorrelation Fe and between P manganese highs. For all samples the coe Electron-microprobe quantitative analyses of 10of selected Fe nodules reveal the presence 30.18 to 39.4 %. P MnO concentration varying from 0.67 to 6.34 % (average 2.06 %) (Table 1). The ratio Vivianite nodules range inoften size having up spherical to 3 morphology, cm.of sometimes nodules They crystal is are clusters darker composed then oron of inner flat crystal the parts, crusts. aggregates surface with Surface with aor striking oxidation. consist bluish Many to of spherical greenish visible nodules colornodules crystals appearing are are clusters; illustrated empty morphologies in in of Fig. the 2. inner central and outer parts 4.1 parts of typical Microprobe analyses – sediments and nodules Elemental compositions were determined(Borkhodoev, using 2002). the fundamental parameters method 4 Results SRM-25 (USSR) and S4 Pioneer X-ray fluorescence spectrometer (Bruker, Germany). nodules were analyzed using a multichannel X-ray fluorescence (XRF) spectrometer 12 were performed using “Camebax”.spot-size of Acceleration 4 voltage µm of wasenergy used. 25 kV dispersive Specimens and spectroscopy for scanning electron-beam and (EDS) electron carbon-coated. analyses microscopy The (SEM) were SEM-EDS and system analyses mounted including have scanning on been electron carried aluminum microscopy outspectroscopy (EVO-50) studs Quantax with using Espirit energy QEMSCAN dispersive (Bruker). X-ray measured on a Curieing express rate balance of 100 (Burov etwas al., measured 1986) continuously in fromtemperature field room using 500 mT temperature a with up kappabridgefurnace heat- to (AGICO MFK1-FA Ltd., equipped 700 Brno, with Czech Republic). a The CS-3 heating high-temperature and cooling rates were 10– momagnetic and mineralogical methodsResearch at Institute the of North-East Farfield East Interdisciplinary AC Branch magnetic Scientific susceptibility, of asmagnetic Russian well susceptibility Academy as were of field measured Science.Czech dependent on Republic). Weight kappabridge and Hysteresis low- frequency MFK1-FA (AGICO parameters, dependent induced Ltd., including magnetization Brno, the ( saturation magnetizationnence ( coercivity ( et al., 1986). The temperature dependence of the saturation magnetization ( Vivianite nodules and piecesICDP were site collected 5011) downnodules from continuous were 5 core retained to (Core forsieving, 28 1A, m study, using 1B with in a of the depth 250 nodules µm (Melles separated sieve. et from The al., lake nodules 2012). sediment were Both by analyzed sediment using and a range of ther- 3 Materials and method 5 5 25 20 15 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1 3 × × − O 2 kg 3 m ). 6 1 2.31–2.77 − − and 5.12 = 10 1 kg − 3 × ). These values erent forms and m kg 1 ff 6 3 − − 1 %. Although rare, m kg < 6 10 3 − × m 10 6 82.87–92.90 norm. wt %) , although the sediments − 1 × = − 583. From the high magnetic 10 kg = × 3 ), probably due to relatively high n 1 m − ), 6 1 1.05 − − = (average 0.95 374. As plotted in Fig. 5, there can be 10 54) shows values between 0.78 kg 1 3 = × − 35.62–33.26 norm. wt %, Ni = 100 Am m n = kg n 6 < 3 ), 21.93–28.54, Al and Si − 4996 4995 1 m ) susceptibility. − = (average 1 10 6 three of the samples show very little change in − − 1 kg × − 1 3 kg 10 − 3 m kg × 6 3 m − 6 m − 6 10 − 10 × to 5.12 10 × 1 × 29.31–34.86, O − (average 0.39 1.0 = 1 kg − < 3 kg – 4.02 %, MnO – 0.91 %. m 3 6 5 46.20–50.23 norm. wt %, S − m and 1.72 O (average 1.8 6 = 2 10 1 1 − − − × 10 kg kg × 3 3 m m 38.30–42.58, Ti 6 6 = − − MS of bulk sediments from low magnetic intervals ranges from 0.09 Magnetic susceptibility of nodules ( Four nodule samples, alltibility from zones in of a low rangescatter susceptibility, of were in the measured magnetic measurements for fields at suscep- measuring low from fields error 5 ( at to the 700magnetic mA very material. (Fig. low Above 6). fields 100 Theresusceptibility, Am (Hrouda less is et than considerable al., a few 2006)tent percent, susceptibility when whereas but dealing some one with 10 sample % para- (EV296) higher shows than a the original consis- value. nodules never yieldcan susceptibility have below much 0.8 lowersediment susceptibilities. with Over low half ( of the nodules measured4.4 come from Field variation of susceptibility 10 are much higher then those from the low MS intervalsto 1.73 in core sediments. intervals, the MS10 of bulk sedimentsobserved varies a between positive correlation 0.18 betweenthe the magnetic sediments susceptibility from of the which nodules they and were extracted. It should be noted that the vivianite Nodules were found in sediments withTable both 3). high In and general, low magnetic magnetic susceptibility susceptibilityfrom of (Fig. 0.09 the 3, sediment section studied here varies 4.3 Magnetic susceptibility of vivianite nodules tified (Fig. 4d) byFe the combined presencein of a iron few samples and Fe-richthe titanium, phases main with were constituent a and found, only with compositonfound a iron of to few (Fe % included P, minor Mn,images and minerals Si. these with All minerals high the look content nodulessizes. like investigated of dark were Si, patches Al, and and take Na. on On several the di electron attracted to magnet in handand sample. the A resulting few magnetic ofsulfides extract these of was “magnetic” Fe, nodules studied were presumably usingof crushed greigite, SEM iron and were and EDS. sulfur, foundsulfide In and (Fig. is a the 4c), Fe few absence identified grains ofnorm. by phosphorous. wt %, the Semiquantitative and presence composition a few of percent of Mg, Al, K, and Si. In some nodules ilmenite was iden- 4.2 Scanning electron microscopy and energyIn dispersive most spectroscopy cases, theregular vivianite oxidized concretions patches as studied well are as discretestudied not mineral homogeneous, inclusions. by Ten but polish electron nodules contain were Backscatter ir- microscopy images with (SEM) accompanying and EDScan elemental energy be scans observed dispersive are in shown spectroscopyimages in Fig. have (EDS). Fig. 4a, higher 4. b, contents As the of lighter Fe and colored P. parts Some of of the the studied backscattered vivianite electron nodules were grained vivianite minerals are present atiments these in levels. Smear the slides indicated preparedpieces regions from of sed- reveal fine blue, concretions. greenish A– vivianite maximum 13.54 amount aggregates %, of and P the broken oxides in these zones are Fe 20.95–21.17, 24.31–24.73 m (Fig. 3, Table 2). Geochemical data suggest that fine- 5 5 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C C ◦ ◦ and c ratios C and warm- i H ◦ J T / - rs 20–74 mA k C, followed J ◦ = C in air, with ◦ c C, reaching its H ◦ and C. In the cooling ◦ c H C when there is in- / ◦ cr C and reaching a max- H ◦ C reaching a maximum ◦ C, with a cooling curve that is ◦ C and cycled back to 50 ◦ plot within the pseudo-single-domain field of C and a sharp drop at 615 4998 4997 ◦ c H 56–91 mA (corrected for paramagnetism) suggest- to erent. Susceptibility here includes up to 85 % due to = cr ff H cr H C, before a rapid decrease to room temperature. Heating ◦ and i J to C (Fig. 7a). The cooling curves are much higher than the heat- ◦ rs J at a value nearly double the initial susceptibility. Hysteresis behavior C, followed by a sharp decrease (Fig. 7e). Hysteresis behaviors after ◦ ff C (Fig. 7c). On continued cooling the susceptibility makes a sharp drop ◦ C. After the first heating cycle, the susceptibility shows an increase 1.4 times the C. Hysteresis data collected after each cycle is shown in Fig. 7b and tabulated in C. On initial heating low susceptibility is measured until 500 ◦ ◦ ◦ from the first heating run to the second run (Table 4). The cr after second heating suggest formation of multi-domain magnetic phase. slightly lower but not markedlya di paramagnetic component, producing anor noisy curve. hematite Curie are points clearly ofvery neither visible magnetite similar on to the the graph. firstcooling The cooling run, heating curve. curve But, with a for amaximum marked the at change strong second 270 is run increase observed is in inthe the first susceptibility and second observed second runs atH are 620 plotted in Fig. 7f. There are moderate increases in Day et al. (1977). 4.5.3 Nearly reversible curves In the samples shownversible. in There Fig. is a 7e decrease the in initial susceptibility heating up and to cooling 700 curves are almost re- 525 original. The heating curves ofan second increase run in are similar susceptibility aspath at for there 330–350 1st is type a curve marked increaseimum and in display at susceptibility 320 starting atbefore 615 leveling o after the first heatingTable 4. is Ratios shown of in Fig. 7d, along with hysteresis parameters listed in In these samples the heating anding cooling curves curves shows are a not gradual reversiblemarking decrease (Fig. in a 7c). susceptibility presence and of a magnetite.ceptibility sharp The at drop cooling the close curves Curie to display 580 temperature a of strong magnetite, increase with in a sus- small but steady increase after 4.5.2 Non reversible curves producing magnetite ing curves, with aat temperatures sharp of increase 280–330 inand cooling susceptibility curves from of third 630 curves runs are of almost second reversible and run650 have but same sharp shape as drop cooling ofTable 4. susceptibility on The heating samples isand shows coercivity not relatively of complete high remanence, until valuesing for the coercive formation force, a higher temperature magnetic phase. a strong increase infollowed susceptibility by a from continuous the decrease. After Curiemately the doubled, temperature first suggesting heating of the run formation magnetite theheating of to susceptibility magnetite curves approxi- within 500 of the second vivianite runa sample. The displays sharp an drop increase at in 630 susceptibility at 330–350 not reversible and producingcurves, phases but other producing only than magnetite, magnetite, and those curves that with are4.5.1 non-reversible nearly reversible. Non-reversible curves with other phasesIn than these magnetite samples the700 heating and coolingcrease curves of are susceptibility not with reversibleby during a a cycling marked sharp to peak drop at occurring the at Curie about point 560–570 of magnetite (Fig. 7a). The cooling curve displays Selected nodule samples were continuously measuredature for was susceptibility raised as from the room temper- repeated temperature to cycles 700 on thebroken down same into samples three general (Fig. classes: 7). those with The heating behavior and cooling of curves the that are nodules can be 4.5 High temperature dependence of magnetic susceptibility 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | s J C as ◦ C on the heating curves ◦ C. There is additionally a slight erences are noted. The visible ◦ ff C and cooling each time, shows ◦ non-reversible curves was heated C (Fig. 8). The initial heating curve ◦ T - k C. Cooling curves all show a consider- ◦ C, with continued increase to sharp peaks ◦ C producing marked Hopkinson peaks for ◦ 5000 4999 C. ◦ C and shows a steep increase to 450–500 ◦ C (Fig. 8). The second set of heating curves shows ◦ C for sample EV294 (Fig. 7a) is not observed on the ◦ C heating-cooling run. On all these runs the final sus- C and 580 ◦ ◦ ) with heating to 700 s at 580 J s C and cooled back to room temperature. J ◦ C and a decrease at 320–340 ◦ erent heating results when sulfur is added to goethite or hematite ff C (Fig. 9e). It appears that the arsenic suppresses the formation ◦ C, indicating the formation of magnetite. When heated with arsenic ◦ C and then decay as the temperature decrease for the plain vivianite and ◦ C but continues to increase up to room temperature. All samples finish with ◦ erence is seen in the heating and cooling curves for crushed vivianite samples ff CO), metallic powder of arsenic, and elemental sulfur, with the additives never 2 ) C after which the curves appear to flatten out. ◦ 2 heating curve (Fig. 8a); the hump visible on all the initial curves of magnetization There are very di Mixtures of vivianite and either hematite or goethite show vivianite to play the same There is a noticeable increase in susceptibility at 150–170 A vivianite sample representative of first type No di In comparing the high temperatures curves of magnetic susceptibility (Fig. 7a, c, e) s magnetite and hematite. The final magnetic susceptibility increases four-fold after the ceptibility increases but always less than a factor of 2. (Fig. 10b, e). Afterbetween heating 400 and hematite 610 andlarge times. goethite increase The in with newly susceptibility formed sulfur at mineral susceptibility 580 is increases magnetite, indicated byreducing the role that sulfurthat does. during Heating heating a magnetite hematitesharply is and formed increases vivianite (Fig. at 10c). mixture both On (1 685 : cooling 1) the shows susceptibility curve of vivianite with added sulfurat (Fig. Curie 9g). temperature On of cooling, magnetitesulfur increases and in mixture monoclinic susceptibility to pyrrhotite. are Heating temperatures seen that the of all vivianite 200, heating and and 400 cooling andis curves 600 seen are irreversible only (Fig. after 9h). the The formation final of 600 pyrrhotite this increase is notature seen, around although 400 thereof a magnetite small prior increase to occurredsample the at does Curie form lower temperature. magnetite temper- Theseen at cooling in 580 the curve previous formation examples. the A can arsenic-added similar be result observedwith of in arsenic arsenic (Fig. the suppressing 9f). heating magnetite curves for- of plain chalcopyrite and chalcopyrite below 580 susceptibility 1.5 to 2 times greater than the initialwith value. arsenic. The initial vivianitetween run 500–600 (Fig. 9d) has a large increase in susceptibility be- the vivianite plus carbamide samples. The vivianite and sucrose sample also increases able increase in susceptibility starting ataround 580 500 various powders, as describednodules by Minyuk were et mixed al. with(NH (2011). sucrose Powder from (organic severalbeing carbon), vivianite more carbamide then 5 (nitrogen % ofroom compound the temperature total to material. 700 Samples were then heated continuously from without additive and those with sucrosecurves or show carbamide small added (Fig. but 9a–c). distinct All drops the near heating 580 (Fig. 7). 4.7 High temperature behavior of vivianiteTo further with investigate additive the material behavior of thein vivianite lake nodules with sediments, other common we materials studied high temperature susceptibility of vivianite mixed with hint of a minor increase in no hump, but continuous580 decay of the magnetization with increasedto temperature the to saturation magnetizationincrease (Fig. in 8a–c), susceptibility several at di J 500 with temperature (Fig. 8) are no where evident on initial heating curves of susceptibility Additional material from thebehavior three of samples magnetization discussed ( abovefor was each sample also shows studied a forat small temperature the but 180–200 distinctive “hump” marked by a slight increase in 4.6 Saturation magnetization versus temperature 5 5 25 20 10 15 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 5 C ◦ O 2 C on ◦ C and the ◦ 20 K). But, content pos- < 5 C and drop at ◦ cients between O C increases are ffi 2 ◦ erent results (Fig. 11e). On C and 360 ff ◦ C; the same increase is seen ◦ -transition from antiferro- to fer- λ 0.58) indicating fine grained vivianite is = r 5002 5001 erent growth conditions. Some nodules are empty ff C. On cooling both the 580 ◦ curve of pyrite (Fig. 11a) is very similar to the heating and T - k erent, with no sharp increase in susceptibility at monoclinic pyrrhotite Curie C (Fig. 11e). This may reflect the so-called ◦ ff curves of mixture 1 : 50 yield another set of very di and magnetic susceptibility in intervals 7.05–7.26 m and 9.13–9.33 m are 0.47 T 5 - O Magnetic behavior of vivianite particles and nodules is important to overall interpre- k Mixtures of pyrite and vivianite were also tested to further investigate changes in 2 and environmental change. magnetic properties of the bulkeral sediment. shows For low example, values magnetic in susceptibilitysusceptibility stage in 6 has gen- but increased at depths (Fig.and 7.05–7.26 MnO m 3). that and may Simultaneously, 9.13–9.33 m enhance thisP the magnetic depth formation of is vivianite. Correlation enrichedand coe in 0.68, respectively. In P stage 7.4itively at correlates depth with 11.59–12.19 increased m the MSalso high values P ( present. Large vivianite nodulescipitation are of absent vivianite in directly Fe-P-Mn from intervals lake suggesting water pre- that can be related to events of climate Nowaczyk et al., 2007, 2012).comes Vivianite antiferromagnetic is (weakly paramagnetic atsamples magnetic) room studied only temperature here at and be- showmany low of that temperatures the the lake ( sediments, nodulesthe and cold often have intervals. higher magnetic than In susceptibility the that susceptibility case similar of vivianite to sediments may from obscure the environmental signal of rock nodules are variable suggesting di or filled with crystals inface central towards parts center. indicating Other growthfragile nodules of crystals consist the suggesting of concretions that crystal from nodules the formed clusters sur- before with sediment randomly compaction. oriented tation of magnetic propertiesproxies. of In lacustrine the sediments studyrameter, that of and are is Lake used used El’gygytgyn, for as magnetic core environmental susceptibility descriptions, correlations is and an dating important (Melles et pa- al., 2012; In El’gygytgyn Lake sediment vivianite isother the iron-bearing more abundant minerals authigenic such mineralThe among as nodules pyrite, and greigite, concretionsfew siderite, of gram and vivianite per occur Fe-Mn sample that aggregates. (weight along of the sample core is profile 6 g amount in to average). Morphological features of 5 Discussion transfer to monoclinic pyrrhotite showing300–320 increase susceptibility atrimagnetic 220 behavior as described bycooling Dekkers curves (1989b) and of Kontny both et runsature al. is (2000). of no On monoclinic visible the pyrrhotite. increaseheating Sharp in and susceptibility cooling magnetite at curves Hopkinson the of peaks the Curie second are temper- runs. evident on the observed on all curves of second runs. cooling of the firston run, the susceptibility cooling increases curvenal at of pyrrhotite 280 second during run. cooling. During Such the increase second suggests heating a run formation the of hexagonal hexago- pyrrhotite oxide mineralogy. The cooling curves of aare 1 also : obtained 1 when mixture the of mixtureof is vivianite monoclinic 1 and pyrrhotite : are 5 pyrite (Fig. higher10 (Fig. 11c). then are 11b). In magnetite di this Very ones. case similar the Coolingtemperature curves Hopkinson curves obvious peaks of (Fig. mixture 11d). 1on Susceptibility : cooling, gradually but increases on fromCurie a 600 temperature second to of run 280 monoclinic heating pyrrhotite. Distinct curve Hopkinson there peaks is of a magnetite decrease are in susceptibility at pure goethite, but without visibleheating goethite-hematite curves transition (Fig. at temperature 10f). 360 expected There large is drop a small atnoted, increase 580 with in final susceptibility susceptibility at again 470 being four-fold larger than the initial. heating and cooling cycle. Goethite-vivianite mixture shows same cooling curves as for 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C C C ◦ ◦ ◦ (av- 1 C that C, and − ◦ ◦ kg 3 m 6 − O and beginning 10 2 × C followed by a sharp ◦ , as marked on DTA curve 3 spanning 65 to 315 C, and forms magnetite and O ◦ and 1.72 + 2 2 1 − kg 3 C to 250–300 m ◦ 6 − 10 × 5004 5003 erential thermal analysis DTA curve at temper- ´ an et al., 2002). ff and, occasionally, Fe during heating at temperatures from 180–200 3 s ) (e.g. Dekkers, 1989a). Magnetic susceptibility of nod- 3 J C. 1 ◦ curves (Fig. 7). The characteristic features of all vivianite − T ). Numerous nodules include grains of sulphides, ilmenite, kg - . The exothermic peak recorded on the DTA curve at 270 1 . 3 k + − + , Fe(PO 3 m 2 4 kg 6 (e.g. Hirt et al., 2002), goethite is antiferromagnetic with sus- C marks a major loss of structurally bound H − 3 ◦ 1 − m to Fe 10 6 curves there are no visible signs of dehydration of vivianite at these + kg × − 2 3 T - 10 m k 8 × − C and 205 ◦ 54) exhibit values between 0.78 10 1.05 C. On curves show increased × = curves of first type show increased susceptibility on heating at temperature ◦ = n T C (Fig. 7a). The hump on heating curves is possible attributed to the transfor- T - ◦ - s k A plausible explanation can be obtained with goethite as an oxidation product of Natural vivianite shows weight loss steps at 105, 138, 203, 272 and 437 There are three types of J Investigations of behavior of vivianite upon cyclic heating and cooling reveal the min- However, the products of oxidation appear to have little influence onLepidocrocite the is magnetic paramagnetic at room temperature with a low field susceptibility In most cases, the vivianite concretions are not homogeneous, but contain irregu- a mixture of vivianite and goethite(Fig. a similar 10f). increase in susceptibility is seen after 500 mation of sulfides fromduring heating pyrite usually begins to at magnetite temperaturesmonoclinic of pyrrhotite during 420–450 (e.g. heating. Wang et Butstudy al., pyrite of 2008; vivianite transformation Tanikawa et and al., pyriteproduce 2008). mixtures monoclinic Thermomagnetic show or that hexagonal depending pyrrhotite(high (Fig. on pyrite 11). the content) In mixture or our composition hexagonal case pyrite monoclinic (low pyrrhotite pyrite content) dovivianite. not Goethite form. shows no such hump on heating curves (Fig. 10d) but on heating the formation of a-FePO at 660 temperatures indicating that this process does not influence magnetic500 susceptibility. the ensuing oxidation Fe are attributed to dehydrationendothermic (Frost peaks et recorded al., on 2003). theature Marincea di 183 et al. (1997)of point oxidation out of that Fe corresponds to another phase ofloss oxidation. of Rodgers structural and water combined Henderson with (1986) the report oxidation the of Fe nodules are observed inshow an the increase cooling in curves susceptibilitydrop. from of 620–650 second and third runs. These(Fig. curves 8). The hump on the curves possibly reflects the dehydration of vivianite and edly heated and cooled to 700 the attraction of nodules totive a correlation magnet between and, magnetic thus, susceptibilityof increase of magnetic sediment nodules susceptibility. and Posi- suggest magnetic that susceptibility But during this growth included the materialthe nodules susceptibility is of capture a the grains secondary nodulesintervals. from is source higher sediments. of than magnetic that of susceptibility the because sediment fromeralogical low changes that magnetic can occur inpredominantly this magnetite system. The and/or formation hematite, of occurs new mineral when phases, vivianite samples are repeat- of 57.8 ceptibility 0.5–1.5 ules ( erage iron, titanomagnetite, and/or clay minerals. Some magnetic inclusions could increase the product of vivianiteet auto-oxidation on al. cleaved (2006) surfacesyellow-brown is indicate iron ferric that oxides, hydroxide. likely Sapota some goethite.to Baikal In poorly crystalline a vivianite lepidocrocite calcareous microconcretions (Rold medium vivianite are is covered oxidized with properties of vivianite dueproducts. to the weak magnetic susceptibility of any of the oxidation lar oxidized patches. In backscatteredcolor electron and images record the higher oxidizedlocated parts along Fe cracks have and and lighter in Pvivianite outer content or parts santabarbaraite. (Fig. of Some nodule 4a, oxidationby grains, spots b). Fagel and are et possibly The depleted al. consist in (2005) oxidized of Mn for parts meta- as Baikal was vivianite. are reported On often the other hand, Pratt (1997) indicates that 5 5 25 15 20 10 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C to ◦ 1 − kg 3 , and an i m J erent from / ff 6 rs − J 10 ratios the single erent media was × c ff H / cr H C. If this is indicative of ◦ and i curves after heating to 200 J / T - rs k J ) and is higher than the susceptibility 1 − C for this transition. According to Li and C are reversed from this. Our data indi- kg ◦ ◦ 3 m 6 5006 5005 − C, are formed. Such behavior is di ◦ 10 × C), it is lower then hematite and closer to maghemite C, monoclinic pyrrhotite, marked by Hopkinson peak ◦ ◦ 1.05 = C). But, magnetite that formed at higher temperature is the ◦ (average indicate the formation of lower coercivity minerals and larger domain 1 C. On the third run it has increased to 650 − c ◦ H after few cycles of heating and cooling, a decrease in / kg -transition from antiferro- to ferrimagnetic behavior of pyrrhotite. Kontny 3 cr cr 620 λ C exhibit irreversible thermomagnetic behaviors (Fig. 9h). After heating the H m H ◦ ∼ 6 − and 10 C. Interpretation of this hump is highly ambiguous. Such increase in susceptibility × c ◦ H Magnetic properties of vivianite are due to product of oxidation as well as sediment Thermomagnetic data are widely used to diagnostic magnetic minerals but heat- Thermomagnetic data shows that quantities of magnetic minerals are not generated The behavior of the susceptibility of vivianite upon heating in di Continued cycling of samples from the first type shows in the second run a phase ¨ Ozdemir, 1990; Gehring et al., 2009). According to and mineral inclusions. 6 Conclusions Vivianite nodules arestages. abundant Magnetic in susceptibility both of1.72 sediments vivianite nodules of varies cold fromof (anoxic) 0.78 sediments and from warm thethe (oxic) cold environmental intervals. signal determined This from susceptibility rock of magnetic vivianite properties. can then obscure Heating-cooling of a pyrite/vivianite mixturepyrrhotite. (1 This : pyrrhotite 50) is exhibits unstable the duringble formation of a monoclinic hexagonal second pyrrhotite heating and andrun. transforms magnetite, to as unsta- seen on the cooling curve of the second that vivianite acts as aing reductant and heating stimulates of formation of goethite-vivianitehematite magnetite transition mixture (Fig. but 10c). (1 stimulates Dur- : formation 1) ofand magnetite the vivianite (Fig. vivianite mixture 10f). Behavior suppresses during ofThermomagnetic the a heating curves pyrite goethite- depends for on mixtureilar with the to vivianite specific those content pyrite/vivianite for upof content. pyrite to magnetite (Fig. 80 and % 11a–c). monoclinic are Pyrite/vivianiteson nearly pyrrhotite mixing peak sim- during ratio of 1 heating pyrrhotite : but 10 on show lacking cooling. formation the A sharp second Hopkin- heating run produces more magnetite. tion of magnetite in large amounts (Fig. 10b, e). ing media and thepretation of presence the of results. otherhematite, The goethite minerals influence and in pyrite of was vivianite the investigated. Hematite-vivianite on samples mixture the (1 can thermomagnetic : complicate 1) behavior shows inter- of thermomagnetic curves of hematite and goethite mixtures with sulfur showing forma- 170 may reflect at al. (2000) reportFranzen temperatures of (1996) 160–210 thermomagnetic heating-coolingthe curves temperature for range between acates 20 peak-type that the and pyrrhotite mineral 400 phase in formedand here to is unstable. 400 sulfur-vivianite mixture toon 600 cooling curve at temperature 320 presses the generation ofture magnetite of at this mineral temperaturessame (578 lower amount as than that the formedcific Curie after thermomagnetic heating tempera- vivianite curves withAll are sucrose and first produced carbamide. heating for Spe- curves vivianite show mixed a with small elemental hump sulfur. in susceptibility at temperatures of 150– increase in state particles (Table 4, sample EV294). during heating and cooling.twofold after Magnetic heating. susceptibility does not increase bymonitored. more Vivianite than mixedshows with similar thermomagnetic sucrose curves (organic as carbon) vivianite without or the carbamide additive. (nitrogen) Arsenic sup- formed at a Curie temperature (630–650 ( domain particles were formed duringof the first heating (Day et al., 1977). The decrease 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | cult to , 2002. ffi erent minerals ff 10.1029/2001JB000242 5008 5007 Drilling operations were funded by the ICDP, the NSF, the German Fed- erent degrees of oxidation and inclusions in nodules. ff properties of lepidocrocite, J. Geophys. Res., 107, 2011, doi: and natural vivianite, Thermochim. Acta, 401, 121–130, 2003. of natural maghemite:1371, a 2009. magnetic and spectroscopic study, Geophys. J.tectonics, and Int., morphology, Meteorit. 179, Planet. 1361– Sci., 42, 307–319, 2007. a tool for magnetic mineralogy of rocks, Phys. Earth Planet. Int., 154, 323–336, 2006. siderite, rhodochrosite, and vivianite inties, sediments Phys. by Chem. their Earth, low-temperature magnetic 28, proper- 669–679, 2003. J., 97, 323–340, 1989a. ior of Jrs and TRM as function of grainVivianite size, Phys. formation Earth and Planet. Int., distribution315–336, 57, 2005. in 266–283, Lake 1989b. Baikal sediments, Global Planet. Change, 46, composition dependence, Phys. Earth Planet. Int., 13, 260–267, 1977. and high-field related rockmagnetic parameters measured at room temperature, Geophys. 1986 (in Russian). a 250 ka paleoclimate record1–16, from 2007. El’gygytgyn Crater Lake, NE Russia, J. Paleolimnol., 37, ysis of rocks, X-Ray Spectrom., 31, 209–218, 2002. River), NEISRI FEB RAS Press, Magadan, 1998 (in Russian). ture, Impactites, Problems ofPress, Investigation Magadan, and 1994 (in Preservation Russian). of Nature), NEISRI FEB RAS grain-size as indicators of 65ern ka Siberia, of J. climate Paleolimnol., 37, change 105–122, from 2007. El’gygytgyn Crater lake,The Northeast- astronomical theory of climate andEarth the Planet. age Sc. of Lett, the Brunhes-Matuyama 126, magnetic 91–108, reversal, 1994. There are three types of curves of high temperature versus susceptibilityVivianite for act vivianite as a reductant and reduces hematite toAdding magnetite, sulfur while to also inhibiting vivianite stimulates formation of monoclinicHeating pyrrhotite, whereas selective vivianite the and pyrite mixtures shows formation of di Hirt, A. M., Lanci, L., Dobson, J., Weidler, P., and Gehring, A. U.: Low-temperature magnetic Gurov, E. P., Koerbel, C., and Yamnichenko, A.: El’gygytgyn impact crater, Russia: structure, Gehring, A. U., Fischer, H., Louvel, M., Kunze, K., and Weidler, P. G.: High temperature stability Hrouda, F., Chlupacova, M., and Mrazova, S.: Low-field variation of magnetic susceptibility as Frost, R. L., Weier, M. L., Martens, W., Kloprogge, J. T., and Ding, Z.: Dehydration of synthetic Frederichs, T., von Dobeneck, T., Bleil, U., and Dekkers, M. J.: Towards the identification of Dekkers, M. J.: Magnetic properties of natural pyrrhotite – II.Fagel, High- N., and low-temperature Alleman, behav- L. Y., Granina, L., Hatert, F., Thamo-Bozso, E., Cloots, R., and Andre, L.: Dekkers, M. J.: Magnetic properties of natural goethite – I. Grain-size dependence of some low- Day, R., Fuller, M., and Schmidt, V. A.: Hysteresis properties of titanomagnetites: grain size and Burov, B. V., Nourgaliev, D. K., and P.G.: Yasonov, Paleomagnetic Analysis, KGU Press, Kazan, Brigham-Grette, J., Melles, M., Minyuk, P., and Scientific Party: Overview and significance of Borkhodoev, V. Y.: Accuracy of the fundamental parameter method for X-ray fluorescence anal- Bely, V. F. and Belaya, B. V.: Late Stage of the OCVB Development (UpstreamBely, of V. F. and the Raikevich, Enmyvaam M. I.: The El’gygytgyn Lake Basin (Geological Structure, Morphostruc- Bassinot, F. C., Labeyrie, L. D., Vincent, E., Quidelleur, X., Shackleton, N. J., and Lancelot, Y.: Asikainen, C. A., Francus, P., and Brigham-Grette, J.: Sedimentology, clay mineralogy and erated by DOSECC. FundingDevelopment of Foundation sample analyses (grant was RUG1-2987-MA-10),(12-II-SB-08-024; provided 12-III-A-08-191; RFBR by 12-III-V-08-191). (grant the 12-05-00286), Civilian Research FEB and RAS References – magnetite, monoclinicinterpret pyrrhotite, the and thermomagnetic hexagonal curves. pyrrhotite thatAcknowledgements. make iteral di Ministry of Education andtre Research (BMBF), Potsdam Alfred (GFZ), Wegener Institute FarRussian and Foundation East Helmholtz for Cen- Branch Basic Research ofand (RFBR), the Research. and The Russian the Austrian Russian Academy Federal Global of Ministry Lake of Sciences Drilling Science (FEB 800 RAS), drilling the system was developed and op- indicating di the goethite-hematite transition during heating. addition of arsenic suppresses the formation of magnetite below its Curie temperature. 5 5 30 25 20 15 10 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 2012. ¨ ossbauer and chemical doi:10.5194/cpd-8-4565-2012 5010 5009 raction and thermomagnetic study, J. 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T.: Formation of vivianite in Holocene clay sediments, Lithos, 3, 327–334, 1970. Rold Rodgers, K. A. and Henderson, G. S.: The thermochemistry of some iron phosphate miner- Rodgers, K. A.: Metavivianite and kerchenite: a review, Mineral. Mag., 50, 687–691, 1986. Pratt, A. R.: Vivianite auto-oxidation, Phys. Chem. Mineral., 25, 24–27, 1997 Pratesi, G., Cipriani, C., Guili, G., and Birch, W. D.: Santabarbaraite: a new amorphous phos- Nowaczyk, N. R., Haltia-Hovi, E. M., Ulbricht, D.,Nriagu, Wennrich, J. O. V., and Kukkonen, Dell, M., C. I.: Rosen, Diagenetic formation P., Ozdemir, of iron phosphates in recent lake sediments, Minyuk, P. S., Subbotnikova, T. V., and Plyashkevich, A. A.: Measurements of thermal magnetic Nowaczyk, N. R., Melles, M., and Minyuk, P.: A revised age model for core PG1351 from Lake Minyuk, P. S., Brigham-Grette, J., Melles, M., Borkhodoev, V. Y., and Glushkova, O. 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F.: Ordering, incommensuration, and phase transitions in pyrrhotite. Part Layer, P.: Argon-40/argon-39 age of the El’gygytgyn impact event, Chukotka, Russia, Meteorit. Kontny, A., De Wall, H., Sharp, T. G., and Posfai, M.: Mineralogy and magnetic behavior of 5 5 30 25 20 15 10 30 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 5012 5011 MnO P Fe Mn P Fe Mn P/Mn 3 O 2 Fe 5 O % % % % % % normalised wt % wt/wt 2 234 21.236 27.80 34.017 25.37 37.64 2.228 37.57 2.01 9.27 25.07 1.33 12.1412 26.36 22.07 39.24 11.08 29.18 1.72 25.78 37.18 0.67 1.56 29.1214 37.29 35.96 1.02 1.03 41.58 10.9515 29.28 58.81 1.46 39.84 55.42 30.4216 34.03 9.64 3.90 0.52 58.07 3.01 11.26 27.91 6.34 9.562 28.82 38.95 2.09 13.81 27.8818 23.08 36.18 0.79 12.79 1.13 60.01 19.06 19 25.49 31.74 1.31 36.97 26.38 41.16 1.0420 36.88 2.15 61.32 4.91 12.19 56.51 37.45 25.64 1.93 1.71 42.36 28.05 10.08 2.3322 26.93 38.16 21.62 1.02 48.46 11.13 24.60 17.67 23 25.76 36.44 1.38 43.05 1.67 9.18 28.5924 35.44 1.11 1.50 54.93 40.87 11.20 4.61 25.27 1.88 40.00 2.02 55.32 11.76 29.5826 24.72 35.43 1.07 56.97 21.31 3.81 11.25 28.2527 26.41 35.48 1.84 0.86 39.70 3.03 10.73 27.4728 33.83 2.07 1.46 42.14 58.16 13.20 11.03 25.99 4.36 41.20 56.13 2.14 10.79 27.4730 23.48 34.15 1.43 55.79 1.74 18.55 11.53 27.5031 24.85 34.61 1.35 1.60 40.77 3.01 24.22 26.2232 34.14 2.20 3.38 40.05 56.26 13.69 11.35 22.83 2.21 41.22 56.59 2.97 26.47 10.2534 22.60 34.13 1.05 51.97 3.36 13.73 10.85 26.8335 22.16 30.18 1.23 42.64 1.71 6.81 11.92 26.4736 32.10 1.36 1.71 55.15 39.30 9.969 6.05 25.54 2.55 40.96 2.22 57.02 9.869 26.4638 23.26 35.07 0.95 55.39 19.21 3.68 9.677 23.4039 25.98 34.33 1.72 1.05 39.60 3.65 10.68 24.88 34.59 2.71 1.98 42.11 58.27 11.22 11.15 25.52 1.89 39.35 55.35 2.13 10.16 27.19 25.22 34.28 1.33 56.12 2.54 18.59 11.34 26.61 35.52 1.58 2.10 41.34 4.53 16.58 26.81 2.45 1.47 38.92 55.88 11.14 8.69 41.96 56.54 2.79 11.01 26.57 1.22 54.99 4.54 14.82 27.53 1.90 41.94 3.05 8.57 40.26 55.46 13.76 55.82 2.60 3.91 16.13 10.30 Nodule Analyze P 10 19 27.61 5 39.48 1.857 12.06 26.39 30.54 9 37.37 1.43 1.22 40.46 136 56.83 11.52 25.95 28.97 2.71 33.99 0.95 14.93 26.46 4.31 40.98 17 36.115 57.12 11.33 1.92 26.35 1.90 11.55 3.34 21.57 22.7 27.99 40.72 21 1.49 34.614 52.51 41.39 1.62 6.77 55.60 26.21 6.01 9.91 3.00 25 36.43 26.83 13.80 3 2.22 1.26 38.88 11.45 25.58 58.35 28.24 29 36.00 2.78 1.722 3.61 13.99 40.77 55.78 11.17 22.52 27.91 3.45 33 32.41 2.80 11.82 1 1.67 39.58 54.83 9.834 22.43 25.12 5.59 37 32.87 1.29 7.08 2.15 40.15 56.87 9.795 24.79 25.48 2.98 34.34 1.67 13.47 1.32 39.39 56.83 10.83 26.62 3.78 1.02 10.42 41.38 56.42 2.20 18.81 Electron-microprobe analyses of selected vivianite nodules from El’gygytgyn Lake. Sci. China. Ser. D, 5, 1144–1153, 2008. produced by thermal decompositionEarth Planet. of Sc. core Lett., 272, samples 372–381, from 2008. the Chelungpu fault in Taiwan, Table 1. Wang, L., Pan, Y., Li, J., and Qin, H.: Magnetic properties related to thermal treatment of pyrite, Tanikawa, W., Mishima, T., Hirono, T., Soh, W., and Song, S. R.: High magnetic susceptibility 5 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1 − kg 3 m 6 − 10 1 − kg 3 , % MnO, % P/Mn Fe/P m 5 6 O − 5014 5013 2 Nodules vivianite sediment interval ,%P 3 m mg 10 O 2 (average) (average) (average) Sample Depth Weight,2425 MS,2643 6.1344 6.1567 6.17 332 MS,68 6.51 65173 6.53 108 Magnetic 74 6.99 113 1.12159 7.01 180 0.940163 7.01 118 0.866287 7.12 457 0.993 9.35296 170 0.993 0.567 9.53297 0.607 136 0.945 12.35 112303 0.260 0.886 12.53 156361 0.252 247 0.810 12.55369 0.248 L 200 0.839 12.67 L 370 0.453 1.43 330 13.97 L 0.919385 0.213 416 14.13 1.54 L 387 0.388 417 14.15 1.288 L 388 0.191 419 14.57 1.274 L 389 0.207 551 15.21 0.971 0.453 L 438 104 15.23 2.129 1.72 L 439 2.655 176 15.25 1.01 L 445 1.956 303 16.23 1.12 L 484 0.548 L 113 16.25 1.23485 H 181 16.37 2.110 1.11 H 488 254 17.27 1.689 1.03 H 597 437 17.29 1.606 1.04 L 2363 17.35 1.867 1.15 1082 H 19.59 2.472 1.08 2854 H 0.888 2.559 0.960 H 598 2.667 0.844 H 2.302 0.787 H 1.781 0.165 H 0.868 1.410 H 0.311 H 0.171 H L 0.405 H L L L Magnetic susceptibility of vivianite nodules. Chemical composition of P-Mn rich sediments intervals. Depth, m8.71–9.2111.51–12.19 Fe 6.33–8.9713.19–13.51 5.61–8.99 (7.58) (7.03)18.39–18.85 6.03–7.74 0.20–0.88 (6.72) 0.12–1.94 (0.44) (0.39)20.95–21.17 2.54–5.99 (3.57) 0.09–1.18 0.08–0.45 (0.46) 0.07–0.55 (0.19) (0.20)24.31–24.73 4.48–7.74 (5.67) 0.06–2.32 (0.52) 0.07–0.12 (0.09) 0.58 0.59 3.96–6.77 (5.17) 0.06–1.92 (0.53) 0.05–0.36 (0.12) 0.98 0.72 0.66 0.07–0.88 (0.21) 0.05–0.22 (0.10) 0.93 0.87 0.05–0.13 (0.07) 0.99 0.92 0.90 0.96 0.42 Table 3. Table 2. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | c H / cr H i J / rs J 1 − kg rs 3 J m 6 − 10 i J 1 − kg 3 m cr 6 H − 5016 5015 c H Nodules vivianite sediment interval m mg 10 m (corrected) (corrected) (corrected) (corrected) Sample Depth Weight,620621 MS,622 20.05632 20.07644 214 20.09683 MS, 109 20.41687 1127 20.65715 360 21.58 1.34 Magnetic 716 247 21.66 1.09717 0.914 202 22.33725 382 22.35 0.878733 122 22.37 0.775 1.533754 495 22.59 0.851 0.378 1.53816 275 22.75 1.13819 0.296 127 23.17 1.06822 0.692 H 124 24.59 0.908823 H L 273 24.65 0.815 1.754844 167 24.71 0.846 1.858 L 845 170 24.73 0.145 1.15 L 846 0.164 354 25.34 0.870853 0.190 1198 H 25.36 1.28854 0.131 H 145 25.38 1.07855 L 155 25.52 0.880 2.105 L 877 0.915 0.987 117 25.54 L 878 165 25.56 2.967 1.44 L 901 623 26.00 1.360 1.20937 0.330 H 404 26.02 0.472 1.28 H 198 26.55 0.927 H 213 27.37 0.865 1.937 H 124 0.881 2.253 L L 207 2.192 1.03 0.222 1.43 0.215 H 0.782 0.400 H 1.08 H 3.141 L 2.252 L 0.163 L 1.199 H H L H AS S S S 0 N + + + + + + L (H) – Low (high) susceptibility intervals. Hysteresis parameters of vivianite nodules. Continued. SampleEV294EV294 Depth, 1st heatingEV294 2nd 12.49 heatingEV294 3rd heating 36.53 (74.07)EV-297EV297 91.361st heating 41.15 0.35 (50.32) (0.02)EV297 12.552nd 0.03 91.72 20.02 heating (22.71)EV297 0.09 0.79 (1.11) (0.37) 62.721st heating 18.07 26.34 2.50 (20.03) (77.25) (1.23) 0.16EV297 1.05 (0.56) 56.89 0.201st 90.81 (0.44) heating 0.17EV297 0.97 2.22 0.37 23.56 (0.50) (1.82) (0.02) (34.84) 0.16 (0.30)2nd heating 0.14 0.02 3.13EV-622-1 75.79 23.34 (2.76) (31.24) 0.15 0.051st (0.29) (1.18) heating 0.57 (0.17) 97.78EV-622-1 3.14 3.44 (2.83) 35.22 (1.17) (49.77) 0.052nd 0.77 20.09 heating (0.28) 0.10EV687 93.60 (0.32) 46.48 0.10 (72.68)EV687 3.21 0.65 (2.17) (0.21) 0.13 149.30 (0.36)1st 22.92 heating (25.53) 0.09 0.55 4.18EVSM (0.20) (3.13) 59.45 0.14EVSM 21.66 (0.44) 0.08 3.331st 1.16 (4.40) 2.65 heating (0.69) (1.88) 0.14 (0.40) 17.27–17.35EVSM 12.79 (21.44) 0.20 11.12 3.21 (25.77) (2.05) 68.011st heating 107.24 7.3 0.17 (27.46) (0.29)EVSM 0.36 63.75 (0.02) 0.39 (0.07) 2.591st (2.32) heating 14.67 0.002 0.36 (23.30) (0.04) 67.24 0.01 0.01 (0.10) 0.01 73.64 0.33 0.02 (0.02) (0.15) 72.24 0.02 0.52 (130.71) (0.29) 8.38 (0.14) 0.01 (5.00) 168.87 – 5.72 (2.47) 0.03 0.01 (0.27) 13.30 0.50 (23.59) (0.11) 0.06 9.16 (0.23) (2.44) 0.10 67.73 5.01 36.81 (3.15) (51.65) 0.19 (0.84) 0.46 (0.09) 102.98 2.33 (1.29) 0.02 0.65 (0.22) 0.04 (0.25) 0.09 5.09 (2.87) 0.14 (0.40) 2.79 (1.99) In brackets – parameters corrected for paramagnetism. Table 4. Table 3. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

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- 1 spot Clim. Past, 2012, submitted Clim.2012, Past, Science, Science, 315 0°E A 15 °E Location of Lake El’gygytgyn in easternmost Russia. 60°N 75°N 135 Backscattered electron images of polished sections of vivianite microconcretions: P. Minyuk S. Page 22 5, line Change “ Page 3: 20,“ line Party Scientific “ line 24: 21, Page Party Scientific line 2 21, Page “ Change line 3: 22, Page “ Change Page 30. 2 figureChange Figure into below Thermomagnetic properties of vivianite nodules, Lake El’gygytgyn, Northeast Russia outer surface of a concretion, Fig. 2. (A) (white line) is 20 µm. map of the Lake El’gygytgynFormation: adapted from 1 Bely – and Pykarvaam Raikevichdeluvian; (1994); ( 6 Bely – and terrace Belaya deposits; (1998). 7 – ﬂood plain deposits; 8 – core site. Fig. 1. (A)

32 , and MnO, and oc- 5 O 2 ,P 3 O 2

5020 5019 Figure Figure 4 Figure Figure 3

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Backscattered electron images of polished sections of vivianite nodules and energy Distribution of magnetic susceptibility (MS), percent Fe

3 1 2 Fig. 4. dispersive spectroscopy. V – vivianite, S – sulﬁdes, Il – ilmenite, Si – siliclastic. Fig. 3. currence of vivianite nodules, inrine grams, isotope in stages sediments (MIS) samples adapted(warm) over from stages. 28 Bassinot m et of al. core (1994). material. Blue Ma- (yellow) bars indicate cold Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

34 33

5022 5021 Figure Figure 6 Figure Figure 5 Magnetic susceptibility of sediments versus magnetic susceptibility of vivianite nodules. The representative curves for four samples of susceptibility vs. ﬁeld variation of vivianite. Fig. 6. Fig. 5.

35 of representative vivianite (a, c, e)

Figure Figure 7 5024 5023 Figure Figure 8 .

1 2 3 (b, d, f) Susceptibility versus temperature (in air) curves

Saturated magnetization versus temperature curves of representative vivianite samples.

1 2 3 Fig. 8. Cursive number shows the heating runs. Fig. 7. samples (the arrows indicate the heatingand and cooling cooling runs) curves, cursive and number typicalvivianite shows examples the of heating hysteresis loops (uncorrected for paramagnetism) of Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (g, – with

As);

38 + (c) 37 – with sucrose; (b) – in air;

(a, d) 5026 5025 Figure Figure 9 Figure Figure 10 chalcopyrite heating in air (ch) and with arsenic (ch (f) – with arsenic; (e) Susceptibility versus temperature curves of hematite and goethite mixed with sulfur

Susceptibility versus temperature curves:

1 2 1 2 with sulfur. The arrows indicate the heating and cooling runs. Fig. 10. and with vivianite (1runs. : 1). The arrows and cursive numbers indicates the heating and cooling h) Fig. 9. carbamide; Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

5027 Figure Figure 11 Susceptibility versus temperature curves of pyrite and vivianite mixtures. The arrows

1 2 3 Fig. 11. and cursive numbers indicate the heating and cooling runs. PY – pyrite, EVSM – vivianite.