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Cryogenic Separation Of Glauconite And Foraminifera From The Cretaceous/Paleogene Boundary Interval At Nasiłów, Poland, For Radiometric Dating And Stratigraphy

Cryogenic Separation Of Glauconite And Foraminifera From The Cretaceous/Paleogene Boundary... e ha e demonstrated that cryogenic separation o g rom the host roc allo s to preser e the integrity o e tracted specimens, assures minimal damage and causes no arti icial ractionation The K Ar dating o t o glauconite samples rom Cretaceous Paleogene boundary in the Nasi outcrop yields 2 0 and 3 Ma The discrepancy in these dates, much larger than e pected rom analytical precision, may result rom too lo K, hich as 5 91 and 5 73, respecti ely Keywords oramini era, glauconite, cryogenic separation, K-Ar dating 1. INTRODUCTION Mineral or specimen separation rom the host roc is a crucial part o the sample preparation process. Commonly used methods include acid etching and/or dissolution, mechanical grinding and subse uent use o hea y li uids as ell as magnetic separation. Success ul separation must be per ormed in a ay ensuring: (i) mechanical integrity o separated specimens, (ii) lac o contamination, (iii) minimal chemical damage, (i ) lac o eight or size-deri ed ractionation o the separate. By mechanical integrity one ould understand lac o crac s, brea s and ractures either on the sur ace or penetrating through the bul o separated specimens. Such mechanical damage is common, e.g. in calcite crystals separated by grinding the host roc . Also, a grain should be ell-separated in a sense o not being contaminated by other minerals. Chemical damage occurs hen acids are used to dissol e the host roc , e.g. in the case o specimen e traction rom limestone. eight or size­deri ed ractionation becomes a serious problem hen a gi en raction o the separate, e.g. the smallest grains or the largest shells, are more damaged than other ractions o the separate, or e en destroyed in the process. Cryogenic separation is a method that meets all the abo e re uirements. Series o reezing-tha ing cycles, ith each cycle lasting only tens o minutes, allo s ater to penetrate the grain boundaries e en in roc s as hard as granite. Belo 4oC ater e pands, and subse uently becomes ice belo 0oC. Ice crystals continue to e pand hen temperature drops, there ore increasing the distance bet een grains. The con enient des top apparatus o our construction as described in 1 , including schematic diagrams. It should be noted, that our design is based on the use o Peltier e ect, contains no mo able parts and it is en ironmentally riendly. or testing purposes e ha e chosen a ell- no n Cretaceous/Paleogene boundary section at Nasi . Up to 0.5 m thic layer o glauconitic sandstone is deposited directly on the uppermost Maastrichtian hard limestone (see ig. 1). Description o the pro ile and our pre ious stable isotope and radiogenic dating results ere published be ore in 2 . In ig. 2 a concentrate o glauconite grains is presented. igures 3 and 4 sho e amples o oramini er Both glauconites and oramini era ere separated rom the host roc (sandstone) by the use o appro imately 48 hours o repetiti e reezing-tha ing cycles in our cryogenic separation apparatus. FIG. 1. The Cretaceous/Paleogene boundary pro ile in the Nasi uarry. lauconitic sandstone o erlies an intensi ely burro ed hard limestone terminating the uppermost Maastrichtian siliceous limestone. FIG. 2. Cryogenic separate o glauconites rom the Nasi right. uarry, 1mm scale on the FIG. 3. Planoglobulina carseyae (Plummer). FIG. 4. Globoconusa daubjergensis (Br nnimann). 2. RESULTS AND DISCUSSION As it can be seen in ig. 2, glauconite grains are ery ell separated, ithout traces o etching or contamination. Results o potassium content determination are gi en in Table 1, hereas the K/Ar dating results are presented in Table 2. Sample D as ta en rom a burro illed ith glauconitic sandstone located 5 cm belo the hardground, hereas sample as ta en rom the glauconitic sandstone 11 cm abo e the Maastrichtian hard limestone sur ace. Cautious reader ill immediately note that age in Table 2 is apparently re ersed: sample D appears to be younger than sample . This result is not surprising i one considers the comple sedimentological history o the K/P boundary at Nasi as ell as the geochemistry o glauconite. aunal condensation and mi ing o Danian and Maastrichtian ossils in the glaucontic sandstone, o erlying the Maastrichtian hard limestone, are interpreted as being the result o the erosion o part o the section including the uppermost Maastrichtian and lo ermost Danian (e.g. 3- ). The unit itsel has been included either in Maastrichtian (e.g. 7 , 8 ) or in Danian (e.g. 3 , , 9, 10 ). During the deposition o the glauconitic sands the topmost sur ace o the Maastrichtian roc has been intensi ely burro ed and illed ith that sediment. E istence o multiple burro s penetrating the glauconitic sandstone and the Maastrichtian chal , together ith possible multiple bioturbation in the resh sediment, here the re or ed Maastrichtian material as also present, points to a ertical mi ing as one possible source o age re ersal in K/Ar dating. Another, perhaps e en more con incing e planation comes rom the geochemical point o ie . lauconite is a comple geochemical system, hich attains maturity o er an e tended period o burial time. Mature glauconite is closed to isotope e change ith its en ironment. One o the geochemical signatures o mature glauconite is the potassium content 11 . or lo potassium contents, the radiometric age o glauconite is arti icially increased. As it as sho n be ore 2 glauconite rom the Nasi section may be considered mature at potassium contents larger than .3 . Samples analyzed here re ealed potassium content belo and there ore are located on the slope o maturity cur e. Entire 4.3 Ma age di erence bet een our samples may there ore be considered as arti icial. At the present stage o in estigation, the conclusion is, that the 2Ma is an appro imate age o the oldest Paleocene sediments in this pro ile. More detailed study, in ol ing stable isotopes and grain size separates is needed in order to inally resol e the Nasi puzzle. Table Table 1. Results o potassium content determination o t o samples o glauconite. 39 K 41 K mi Sample K sample spi e Total eight mg A erage K Analysed eight mg Relati e standard error Nasi Nasi TABLE 2. Results o the radiometric dating o glauconite samples. Sample: eight mg Potassium content Nasi 48.55 5.91 71.21 0.5 1330 4 .5 77.8 2.0 Nasi 47.41 5.73 71.21 0.5 02 1457 70.9 79.7 .3 Ar dose pmol Ar/38Ar ratio Ar/3 Ar ratio Radiogenic 40Ar pmol/g o radiogenic Ar Radiometric age Ma Cryogenic method used in e tracting oramini ers rom the glauconitic sandstone or s as ell as or glauconites. Obtained rom that roc minute, thin-shelled and ragile Danian (and Maastrichtian) plan tonic oramini era are clean and ery ell preser ed (see igs 3 and 4). Plan tonic oramini era are the minor component o the oramini eral assemblage. Danian species are represented by Globoconusa daubjergensis (Br nnimann), Parasubbotina pseudobulloides (Plummer), Globanomalina sp., Chiloguembelina sp., Globotruncanella caravacaensis (Smit). e el ect ri cal propert i es o mi crocryst al l i ne CdSxSe1-x i l ms (0. 5 x 1. 0) manu act ured by t he impro ed R sput t eri ng t echnol ogy under i n l uence o hydrogen pl asma t reatment and ol l o i ng anneal i ng i n di erent regimes are descri bed. It as e hi bi t ed t hat i ncorporat i on o hydrogen rom pl asma produced drast i c changes hi ch occurred i n t he dar I­V charact eri sti cs and resi st i i t y o t he il ms. Dar conduct ance re eal ed i ncreasi ng under hydrogenat i on and a l ong-t i me rel a at i on (decrease) it h t i me or l o temperat ure hydrogenat i on. The nonmonot oni c i n l uence o t he i lm dimensi ons on dar conduct ance and I­V charact eri st i cs i s sho n, hi ch i s di erenti at ed or as-recei ed and hydrogenat ed i l ms and depends on regimes o hydrogen pl asma treat ment . Such beha i our i s associ at ed i t h trans ormat i on o pot ent i al rel i e o hydrogenat ed i lms. 1. INTRODUCTION CdSxSe1-x i l ms are bei ng st udi ed it h rene ed i nt erest o i ng t o t hei r use i n opt oel ect roni c de i ces and pot ent i al appl i cat i on i n sol ar cell st ruct ures 1 . Ho e er, t he reproduci bi l i t y o phot oel ect ri c and ot her propert i es o CdSxSe1-x t hi n i lms i s rat her sensi t i e t o t he t echnol ogy o t hei r manu act uri ng. Thi s i s due t o pol ycryst al l i ne st ruct ure, nat i e de ect s i n t he grai n bul and sur ace cont ami nat i on o t he i lms 2, 3 . To prepare CdSxSe1-x t hi n i l ms i t h t he desi red phot oel ect roni c prop ert i es, usual l y di erent dopi ng t echni ues are used 1, 2 . At t he same t ime, ne t echni ues such as pl asma hydrogenat i on and i on i mpl ant at i on o hydrogen, hi ch are appl i ed i n a l arge scal e i n semi conduct or de i ces t echnol ogy, ha e been l ess st udi ed i t h respect t o II­VI compounds, especi al l y CdSxSe1-x i l ms 4 . Among ot her act ors hi ch det ermi ne necessi t y o hydrogenat i on, t he pol ycryst al l i ne st ruct ure o t he i l ms i s o prime i mportance due t o t he i n l uence o e t ended de ect s (grai n boundari es, di sl ocat i ons, preci pi t at es, l uct uat i ons o composi t i on, et c. ) and nat i e de ect s i n t he grai n bul . Passi at i on o t hese de ect s and possi bl e dopi ng e ect s under hydrogen t reatment o CdSxSe1-x i l ms can si gni i cant l y change t hei r el ect ri c propert i es 4 . Ho e er, i or such semi conduct ors as si l i con and III­V compounds, t he processes proceedi ng under hydrogenat i on ha e been cl ari i ed t o a l arge degree 5, , or II­VI compounds t hey ha e not been ade uat el y i n est i gat ed. 3. CONCLUSIONS In this study e ha e demonstrated that cryogenic separation o g rom the host roc is a simple and con enient method. Use o cryogenic separation allo s to preser e the integrity o e tracted sample, assures minimal damage and no arti icial ractionation. Its applicability as sho n in the pre iously published paper 1 also or the granite- orming minerals and other host roc s li e tu as. RE ERENCES 1. No a J., Dura ie icz T., Ha as, S. (2002) Separation of single-mineral grains by means of cryogenic disintegrator and the LST heavy liquid for radiometric dating, Materials o the th Session on Dating o Minerals and Roc s , arsa , Poland, 2002, 40-47. Dura ie icz T., to icz , Bana M., Kalic a L., (1997) Isotopic composition of oxygen in Tertiary glauconites dated by K/Ar method, Materials o the 4th Session on Dating o Minerals and Roc s , 11-12 December 1997, Lublin, 27-40. Po arys a K. (19 5) Foraminifera and biostratigraphy of the Danian and Montian in Poland, Palaeontologia Polonica 14, 1-15 . Machals i M., alaszczy I. (1987) Faunal condensation and mixing in the uppermost Maastrichtian/Danian Greensand (Middle Vistula Valley, Central Poland), Acta eologica Polonica 37, 1-2, 75-91. Hansen H.J., Rasmussen K.L., d , R., Hansen, J.M., Rad a s i, (1989) The Cretaceous/Tertiary boundary in Central Poland, Acta eologica Polonica 39, 1-4, 1-12. Machals i M. (1998) Granica kreda, Przegl. eol. 46, 11, 1153-11 1. Po arys i . (1938) Stratygrafia senonu , Bull. eol. Sur . Poland 6, 1-94. Abdel- a ad . I. (198 ) Maastrichtian non-cephalopod mollusks (Scaphopoda, Gastropoda and Bivalvia) of the Middle Vistula Valley, Central Poland, Acta eologica Polonica 36, 1-3, 9-224. 9. Peryt D. (1988) Maastrichtian extinctions of planktonic Foraminifera in Central and Eastern Poland, Re ista Espa ola de Paleontologia 3, 105-114. 10. ars i M., Ja ubo s i ., a or-Biedo a E. (1998) The first Polish find of a Thoracosaurus Leidy, 1852: geological and palaeontological description, eological uarterly 42, 2, 121-130. 11. Odin .S., Dodson M.M., Zero isotopic age of glauconites, in: .S. Odin (ed.), Numerical Dating in Stratigraphy, iley (1982) 277-305. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Annales UMCS, Physica de Gruyter

Cryogenic Separation Of Glauconite And Foraminifera From The Cretaceous/Paleogene Boundary Interval At Nasiłów, Poland, For Radiometric Dating And Stratigraphy

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Publisher
de Gruyter
Copyright
Copyright © 2015 by the
ISSN
2300-7559
eISSN
2300-7559
DOI
10.1515/physica-2015-0002
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Abstract

e ha e demonstrated that cryogenic separation o g rom the host roc allo s to preser e the integrity o e tracted specimens, assures minimal damage and causes no arti icial ractionation The K Ar dating o t o glauconite samples rom Cretaceous Paleogene boundary in the Nasi outcrop yields 2 0 and 3 Ma The discrepancy in these dates, much larger than e pected rom analytical precision, may result rom too lo K, hich as 5 91 and 5 73, respecti ely Keywords oramini era, glauconite, cryogenic separation, K-Ar dating 1. INTRODUCTION Mineral or specimen separation rom the host roc is a crucial part o the sample preparation process. Commonly used methods include acid etching and/or dissolution, mechanical grinding and subse uent use o hea y li uids as ell as magnetic separation. Success ul separation must be per ormed in a ay ensuring: (i) mechanical integrity o separated specimens, (ii) lac o contamination, (iii) minimal chemical damage, (i ) lac o eight or size-deri ed ractionation o the separate. By mechanical integrity one ould understand lac o crac s, brea s and ractures either on the sur ace or penetrating through the bul o separated specimens. Such mechanical damage is common, e.g. in calcite crystals separated by grinding the host roc . Also, a grain should be ell-separated in a sense o not being contaminated by other minerals. Chemical damage occurs hen acids are used to dissol e the host roc , e.g. in the case o specimen e traction rom limestone. eight or size­deri ed ractionation becomes a serious problem hen a gi en raction o the separate, e.g. the smallest grains or the largest shells, are more damaged than other ractions o the separate, or e en destroyed in the process. Cryogenic separation is a method that meets all the abo e re uirements. Series o reezing-tha ing cycles, ith each cycle lasting only tens o minutes, allo s ater to penetrate the grain boundaries e en in roc s as hard as granite. Belo 4oC ater e pands, and subse uently becomes ice belo 0oC. Ice crystals continue to e pand hen temperature drops, there ore increasing the distance bet een grains. The con enient des top apparatus o our construction as described in 1 , including schematic diagrams. It should be noted, that our design is based on the use o Peltier e ect, contains no mo able parts and it is en ironmentally riendly. or testing purposes e ha e chosen a ell- no n Cretaceous/Paleogene boundary section at Nasi . Up to 0.5 m thic layer o glauconitic sandstone is deposited directly on the uppermost Maastrichtian hard limestone (see ig. 1). Description o the pro ile and our pre ious stable isotope and radiogenic dating results ere published be ore in 2 . In ig. 2 a concentrate o glauconite grains is presented. igures 3 and 4 sho e amples o oramini er Both glauconites and oramini era ere separated rom the host roc (sandstone) by the use o appro imately 48 hours o repetiti e reezing-tha ing cycles in our cryogenic separation apparatus. FIG. 1. The Cretaceous/Paleogene boundary pro ile in the Nasi uarry. lauconitic sandstone o erlies an intensi ely burro ed hard limestone terminating the uppermost Maastrichtian siliceous limestone. FIG. 2. Cryogenic separate o glauconites rom the Nasi right. uarry, 1mm scale on the FIG. 3. Planoglobulina carseyae (Plummer). FIG. 4. Globoconusa daubjergensis (Br nnimann). 2. RESULTS AND DISCUSSION As it can be seen in ig. 2, glauconite grains are ery ell separated, ithout traces o etching or contamination. Results o potassium content determination are gi en in Table 1, hereas the K/Ar dating results are presented in Table 2. Sample D as ta en rom a burro illed ith glauconitic sandstone located 5 cm belo the hardground, hereas sample as ta en rom the glauconitic sandstone 11 cm abo e the Maastrichtian hard limestone sur ace. Cautious reader ill immediately note that age in Table 2 is apparently re ersed: sample D appears to be younger than sample . This result is not surprising i one considers the comple sedimentological history o the K/P boundary at Nasi as ell as the geochemistry o glauconite. aunal condensation and mi ing o Danian and Maastrichtian ossils in the glaucontic sandstone, o erlying the Maastrichtian hard limestone, are interpreted as being the result o the erosion o part o the section including the uppermost Maastrichtian and lo ermost Danian (e.g. 3- ). The unit itsel has been included either in Maastrichtian (e.g. 7 , 8 ) or in Danian (e.g. 3 , , 9, 10 ). During the deposition o the glauconitic sands the topmost sur ace o the Maastrichtian roc has been intensi ely burro ed and illed ith that sediment. E istence o multiple burro s penetrating the glauconitic sandstone and the Maastrichtian chal , together ith possible multiple bioturbation in the resh sediment, here the re or ed Maastrichtian material as also present, points to a ertical mi ing as one possible source o age re ersal in K/Ar dating. Another, perhaps e en more con incing e planation comes rom the geochemical point o ie . lauconite is a comple geochemical system, hich attains maturity o er an e tended period o burial time. Mature glauconite is closed to isotope e change ith its en ironment. One o the geochemical signatures o mature glauconite is the potassium content 11 . or lo potassium contents, the radiometric age o glauconite is arti icially increased. As it as sho n be ore 2 glauconite rom the Nasi section may be considered mature at potassium contents larger than .3 . Samples analyzed here re ealed potassium content belo and there ore are located on the slope o maturity cur e. Entire 4.3 Ma age di erence bet een our samples may there ore be considered as arti icial. At the present stage o in estigation, the conclusion is, that the 2Ma is an appro imate age o the oldest Paleocene sediments in this pro ile. More detailed study, in ol ing stable isotopes and grain size separates is needed in order to inally resol e the Nasi puzzle. Table Table 1. Results o potassium content determination o t o samples o glauconite. 39 K 41 K mi Sample K sample spi e Total eight mg A erage K Analysed eight mg Relati e standard error Nasi Nasi TABLE 2. Results o the radiometric dating o glauconite samples. Sample: eight mg Potassium content Nasi 48.55 5.91 71.21 0.5 1330 4 .5 77.8 2.0 Nasi 47.41 5.73 71.21 0.5 02 1457 70.9 79.7 .3 Ar dose pmol Ar/38Ar ratio Ar/3 Ar ratio Radiogenic 40Ar pmol/g o radiogenic Ar Radiometric age Ma Cryogenic method used in e tracting oramini ers rom the glauconitic sandstone or s as ell as or glauconites. Obtained rom that roc minute, thin-shelled and ragile Danian (and Maastrichtian) plan tonic oramini era are clean and ery ell preser ed (see igs 3 and 4). Plan tonic oramini era are the minor component o the oramini eral assemblage. Danian species are represented by Globoconusa daubjergensis (Br nnimann), Parasubbotina pseudobulloides (Plummer), Globanomalina sp., Chiloguembelina sp., Globotruncanella caravacaensis (Smit). e el ect ri cal propert i es o mi crocryst al l i ne CdSxSe1-x i l ms (0. 5 x 1. 0) manu act ured by t he impro ed R sput t eri ng t echnol ogy under i n l uence o hydrogen pl asma t reatment and ol l o i ng anneal i ng i n di erent regimes are descri bed. It as e hi bi t ed t hat i ncorporat i on o hydrogen rom pl asma produced drast i c changes hi ch occurred i n t he dar I­V charact eri sti cs and resi st i i t y o t he il ms. Dar conduct ance re eal ed i ncreasi ng under hydrogenat i on and a l ong-t i me rel a at i on (decrease) it h t i me or l o temperat ure hydrogenat i on. The nonmonot oni c i n l uence o t he i lm dimensi ons on dar conduct ance and I­V charact eri st i cs i s sho n, hi ch i s di erenti at ed or as-recei ed and hydrogenat ed i l ms and depends on regimes o hydrogen pl asma treat ment . Such beha i our i s associ at ed i t h trans ormat i on o pot ent i al rel i e o hydrogenat ed i lms. 1. INTRODUCTION CdSxSe1-x i l ms are bei ng st udi ed it h rene ed i nt erest o i ng t o t hei r use i n opt oel ect roni c de i ces and pot ent i al appl i cat i on i n sol ar cell st ruct ures 1 . Ho e er, t he reproduci bi l i t y o phot oel ect ri c and ot her propert i es o CdSxSe1-x t hi n i lms i s rat her sensi t i e t o t he t echnol ogy o t hei r manu act uri ng. Thi s i s due t o pol ycryst al l i ne st ruct ure, nat i e de ect s i n t he grai n bul and sur ace cont ami nat i on o t he i lms 2, 3 . To prepare CdSxSe1-x t hi n i l ms i t h t he desi red phot oel ect roni c prop ert i es, usual l y di erent dopi ng t echni ues are used 1, 2 . At t he same t ime, ne t echni ues such as pl asma hydrogenat i on and i on i mpl ant at i on o hydrogen, hi ch are appl i ed i n a l arge scal e i n semi conduct or de i ces t echnol ogy, ha e been l ess st udi ed i t h respect t o II­VI compounds, especi al l y CdSxSe1-x i l ms 4 . Among ot her act ors hi ch det ermi ne necessi t y o hydrogenat i on, t he pol ycryst al l i ne st ruct ure o t he i l ms i s o prime i mportance due t o t he i n l uence o e t ended de ect s (grai n boundari es, di sl ocat i ons, preci pi t at es, l uct uat i ons o composi t i on, et c. ) and nat i e de ect s i n t he grai n bul . Passi at i on o t hese de ect s and possi bl e dopi ng e ect s under hydrogen t reatment o CdSxSe1-x i l ms can si gni i cant l y change t hei r el ect ri c propert i es 4 . Ho e er, i or such semi conduct ors as si l i con and III­V compounds, t he processes proceedi ng under hydrogenat i on ha e been cl ari i ed t o a l arge degree 5, , or II­VI compounds t hey ha e not been ade uat el y i n est i gat ed. 3. CONCLUSIONS In this study e ha e demonstrated that cryogenic separation o g rom the host roc is a simple and con enient method. Use o cryogenic separation allo s to preser e the integrity o e tracted sample, assures minimal damage and no arti icial ractionation. Its applicability as sho n in the pre iously published paper 1 also or the granite- orming minerals and other host roc s li e tu as. RE ERENCES 1. No a J., Dura ie icz T., Ha as, S. (2002) Separation of single-mineral grains by means of cryogenic disintegrator and the LST heavy liquid for radiometric dating, Materials o the th Session on Dating o Minerals and Roc s , arsa , Poland, 2002, 40-47. Dura ie icz T., to icz , Bana M., Kalic a L., (1997) Isotopic composition of oxygen in Tertiary glauconites dated by K/Ar method, Materials o the 4th Session on Dating o Minerals and Roc s , 11-12 December 1997, Lublin, 27-40. Po arys a K. (19 5) Foraminifera and biostratigraphy of the Danian and Montian in Poland, Palaeontologia Polonica 14, 1-15 . Machals i M., alaszczy I. (1987) Faunal condensation and mixing in the uppermost Maastrichtian/Danian Greensand (Middle Vistula Valley, Central Poland), Acta eologica Polonica 37, 1-2, 75-91. Hansen H.J., Rasmussen K.L., d , R., Hansen, J.M., Rad a s i, (1989) The Cretaceous/Tertiary boundary in Central Poland, Acta eologica Polonica 39, 1-4, 1-12. Machals i M. (1998) Granica kreda, Przegl. eol. 46, 11, 1153-11 1. Po arys i . (1938) Stratygrafia senonu , Bull. eol. Sur . Poland 6, 1-94. Abdel- a ad . I. (198 ) Maastrichtian non-cephalopod mollusks (Scaphopoda, Gastropoda and Bivalvia) of the Middle Vistula Valley, Central Poland, Acta eologica Polonica 36, 1-3, 9-224. 9. Peryt D. (1988) Maastrichtian extinctions of planktonic Foraminifera in Central and Eastern Poland, Re ista Espa ola de Paleontologia 3, 105-114. 10. ars i M., Ja ubo s i ., a or-Biedo a E. (1998) The first Polish find of a Thoracosaurus Leidy, 1852: geological and palaeontological description, eological uarterly 42, 2, 121-130. 11. Odin .S., Dodson M.M., Zero isotopic age of glauconites, in: .S. Odin (ed.), Numerical Dating in Stratigraphy, iley (1982) 277-305.

Journal

Annales UMCS, Physicade Gruyter

Published: Mar 1, 2015

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