holocene sediments from west part of black sea · Федоров (1982), Шопов (1993)...

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Трудове на Института по океанологияТ о м 3 . В а р н а , 2 0 0 1Българска академия на науките

МОРСКА ГЕОЛОГИЯ

Holocene sediments from West part of Black Sea

Ivan Genov, Veselin PeychevInstitute of Oceanology, Bulgarian Academy of Sciences, Varna, Bulgaria

Introduction: Historically the first datafor the stratigraphy of the Quaternarysediments in Black Sea are published byА н д р у с о в (1926);А р х а н г е л ь с к и й, С т р а х о в(1938) (Table 1). On the basis of detailedinvestigations Bivalvia formsН е в е с с к а я (1965), Н е в е с с к и й(1967) divide the Holocene in the Black Seainto four horizonts�Jemethinian, Kalamitian,Vityazian and Bugasian. Ш и м к у с,Е м е л ь я н о в (1974) propose a version ofstratigraphic scheme of the Upper Pleistoceneand the Holocene. R o s s, D e g e n s(1974), D e g e n s, P a l u s k a (1979),Ф е д о р о в (1982), Ш о п о в (1993)published classification of the Quaternary forBlack Sea region too (Table 1). TheBulgarian marine geologist confine to thescheme of Ш о п о в (1993).

Marine sediments are an association fromthe authochtonic components, fomed underspecific physico-chemical and biochemicalconditions of the sedimentation media and theallochtonic components, resulting from thesources of terrigenous material, which aretransformed under the influence of thepostsedimentical factors. The mainauthochtonic components in sediments aregases, solutions, biochemical solid substancesand organism remains of seaweeds,foraminiferes, moluscs, fishes and so on. Thebiogenic material, entering the middle andlower parts of the Bulgarian shelf is assessedto be 448 500 t/y, 90 % from which are

carbonates (М и х о в а, 1990). Allochtoniccomponents comprise the substances, whichare introduced into the basin by the solid riverflow, the marine erosion activity and the windtransportation. The solid flow of theBulgarian rivers, empting directly into theBlack Sea is 780 600 t/y (D i m i t r o v etal., 1997) and it is considerably lower thanthe solid flow of Danube river �68 000 000 t/y (П е ч и н о в, 1982). Themass erosion material of the Bulgarian BlackSea shore is assessed to be 575300t/y(Пейчев, 1998). Regular ivestigations of thewind transportation have not been carried out.According to data of Рождественски (1973)in the bay of Varna only the solid substancesfrom the winds ammount to 91.42g/m2 peryear � a quantity, comparable to the theirallochtonic components.

As a result of human activity an enormousquantity of pollution (heavy metals,pesticides, radionuklides, oil produkts) havebeen introduced into the Black Sea basinduring the last decades.

Materials and methods. With thepurpose of appaising the enviromentalconditions in the west part of the Black Seaduring 52 cruise of R/V �Prof. Vodianitsky�financed by International Atomic EnergyAgency (IAEA) and conducted from 10.09.till 22.09.1998 г., covering 18 station �insitu� samples were collected from the bottomholocene sediments (Fig. 1, Table 2).

The samples were collected by multicorer,type MARK II � 460 , with 4 plastic tubes of

Table 1. Holocene chronostratigraphic scheme in Black Sea region

StratigraphicScale

(series)

Андрусов

(1926)

Архангельский,Страхов(1938)

Невесская (1965)Невесский

(1967)

Шимкус,Емельянов

(1974)

Ross,Degens(1974)

Degens,Paluska(1979)

Федоров

(1982)

Шопов

(1993)

HOLOCENE

Recent

Recent0 � 2,5 Ky

Drevno �Chernomorian

2,5 � 5 Ky

Jemethinian0 � 1,5 Ky

Kalamitian1,5 � 3,8 Ky

Vityazian,Bugasian3,8 � 6 Ky

UpperHolocene0 � 3 Ky

MiddleHolocene3 � 7 Ky

LowerHolocene7 � 11 Ky

Chernomorian

Recent

Nymphian

Phanagorian

Neochernomorian

Drevne-chernomorian

Chernomorian

Nymphian

Phanagorian

Neochernomorian

Drevne-chernomorian

Chernomorian

Neochernomorian

Drevne-chernomorian

PLEISTOCENE

Caspian Neoeuxinian Neoeuxinian6 � 9 Ky

LateGlacial11 � 18 Ky

Iacoccolithic

ooze0 � 3 Ky

Ibsapropelic

mud3 � 7 Ky

Icband � clay7 � 25 Ky

Euxinian

Neoeuxinian

Epikarangatian

Neoeuxinian

Upper

Lower

Neoeuxinian

Upper

Lower

30

32Table 2. Sampling Station

Station,Current number

Date Depth of the sea,m

High of the core,cm

123456789

101112131415161718

11.09.9812.09.9812.09.9812.09.9813.09.9813.09.9814.09.9814.09.9817.09.9815.09.9815.09.9816.09.9817.09.9816.09.9816.09.9819.09.9820.09.9821.09.98

5648471420233951

6007667

109470

1057131919801912485

363953391056203053353241575654484854

diameter 10 cm, and height 60 cm. The coreswere precisely sliced using an extruder,cutting plates and plastic rings with differentdimension (1, 2, 5 cm). Samples forcontamination history were obtainedcentimetre by centimetre. For radionuclidesand pesticides the uppermost part of the coreswere sliced at 0.5 cm.

The cores were stratigraphically describedwith the help of well known leading groupsor species of macrofauna (Н е в е с с к а я,1965). Marker horizons (coccolithic ooze andsapropelic mud) were used forlithostratigraphic division of deep seaHolocene sediments.

Results and discussion. On Fig. 2 arepresented the lithologic composition of thecores. Biostratigraphic analysis (moluscfauna) of the cores, sampled from station 1,10, 12 was done by Raina Christova (IO �BAS, Varna), (Table 3). In the cores from thestations 4, 14, 15, 18 molusc fauna was notrecorded.

Mixed thanatocoenose of the moluscfauna, formed by mechanical mode ischaracteristic of station 1. Frith forms withtypical marine forms and Mediterranianimmigrants exist together. The biocoenose

belong to Neochernomorian region substage(Jemethinian), but contain Vityazian �Bugasian and Neoeuxinian organisms too,and was formed as a result of hydrogeneouseffects, e. g. deep-water Dreissenarostriformis and shallow-water Dreissenapolimorpha were mixed together.

The molusc fauna in station 10 is presentedprincipally by Modiolus phaseolinus. Instation 12 the Holocene sediments containmainly Modiolus phaseolinus and Mytilusgalloprovincialis and in core high than 40 cmthe Neoeuxinian sediments with Dreissenarostriformis distincta, Monodacna andTurricaspia caspia were found.

For some cores density and water contentswere determined (Table 4) and was donegrain-size analysis, according to Bulgarianstandart (Table 5). It is possible to calculatethe rate of sediment accumulation in thestations, according preliminary data, givenfrom Kazimeras Shimkus (Table 6).

Complete sections of the Upper Holocenesediments (0 - 3 Ky) were revealed in mostcores recovered from the north-western shelfarea. Full sections of Middle Holocene arerepresented only two cores (station 11 and12). They are underlined by sediments with

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Fig. 2. Profiles and lithological composition

34

Fig. 2. Profiles and lithological composition (continuation)

35

Fig. 2. Profiles and lithological composition (continuation)

36Table 3. Biostratigraphy analysis

Core 1

1 - 2 cmBivalvia:Modiolus phaseolinus; Spisula subtruncata triangulata; Cardium papillosum; Cardium edule;Mytilus galloprovincialis - detritusGastropoda:Bittium reticulatum; Clessiniola variabilis

3 - 4 cmBivalvia:Modiolus phaseolinus - mainly; Dreissena polymorpha - 1 exemplar; Abra alba; Cardiumpapillosum; Cardium eduleGastropoda:Bittium reticulatum; Clessiniola variabilis; Nassarius reticulatus; Trophon muricatus

5 - 6 cmBivalvia:Modiolus phaseolinus; Dreissena rostriformis; Dreissena polymorpha - 1 exemplar;Monodacna caspia; Spisula subtruncata triangulata; Cardium eduleGastropoda:Trophon muricatus; Turricaspia caspia lincta

7 – 8 cmBivalvia:Modiolus phaseolinus; Spisula subtruncata triangulata; Abra alba pontica; Dreissenapolymorpha; Dreissena rostriformis; Cardium edule; Mytilus galloprovincialis - detritusGastropoda:Trophon muricatus breviatus; Calyptraea chinensis; Retusa truncatula; Turricaspia caspialincta; Bittium reticulatum; Clessiniola variabilis

9 - 10 cmBivalvia:Modiolus phaseolinus; Spisula subtruncata triangulata; Abra alba; Cardium papillosum;Paphia senescansGastropoda:Trophon muricatus; Bittium reticulatum

11 - 12 cmBivalvia:Mytilus galloprovincialis; Modiolus phaseolinus; Hypanis plicatus; Pitar rudis - 1 exemplar;Cardium papillosum; Spisula subtruncata; Abra alba

3713 - 14 cm

Bivalvia:Spisula subtruncata triangulata; Cardium edule; Dreissena polymorpha - 2 ex.Gastropoda:Bittium reticulatum - 1 ex.; Retusa truncatula - 1 ex.

15 - 16 cmBivalvia:Mytilus galloprovincialis - detritus; Cardium edule; Monodacna caspia; Dreissenapolymorpha

17-18 cmBivalvia:Mytilus galloprovincialis - detritus; Monodacna caspia; Dreissena polymorpha; CardiumeduleGastropoda:Lithoglyphus naticoides; Turricaspia caspia lincta; Clessiniola variabilis

19 - 20 cmBivalvia:Mytilus galloprovincialis - detritus; Monodacna caspia; Cardium edule; DreissenapolymorphaGastropoda:Turricaspia caspia; Clessiniola variabilis

21 - 22 cmBivalvia:Mytilus galloprovincialis - detritus; Cardium edule; Monodacna caspia; DreissenapolymorphaGastropoda:Turricaspia caspia

23 - 24 cmBivalvia:Mytilus galloprovincialis - detritus; Cardium edule; Monodacna caspia; DreissenapolymorphaGastropoda:Turricaspia caspia

25 - 27 cmBivalvia:Mytilus galloprovincialis - detritus;; Monodacna caspia; Cardium edule; DreissenapolymorphaGastropoda:Turricaspia caspia

3833 - 35 cm

Bivalvia:Mytilus galloprovincialis; Cardium edule; Monodacna caspia; Dreissena polymorpha;Dreissena rostriformis; Abra alba

Core 12

3 - 4 cmBivalvia:Modiolus phaseolinus

5 - 6 cmBivalvia:Modiolus phaseolinusGastropoda:Trophon muricatus; Bittium reticulatum


10 - 11 cmBivalvia:Modiolus phaseolinusGastropoda:Retusa truncatula; Bittium reticulatum

12 - 13 cmBivalvia:Modiolus phaseolinusGastropoda:Trophon muricatus

16 - 17 cmBivalvia:Modiolus phaseolinus; Mytilus galloprovincialisGastropoda:Bittium reticulatum

22 - 27 cmBivalvia:Mytilus galloprovincialis - detritus

27 - 32 cmBivalvia:Modiolus phaseolinus - detritus; Mytilus galloprovincialis - detritus

3934 - 35 cm

Bivalvia:Mytilus galloprovincialis; Dreissena rostriformis

39 - 40 cmNeuexinian

Bivalvia:Dreissena rostriformis distincta; Monodacna - fragmentGastropoda:Turricaspia caspia; Theodoxus pilidei lamelliferus

Core 10



4 - 6 cmBivalvia:Modiolus phaseolinusGastropoda:Trophon muricatus

6 - 8 cmBivalvia:Modiolus phaseolinusCardium sp.


10 - 12 cmBivalvia:Modiolus phaseolinusCardium

12 - 14 cmBivalvia:Modiolus phaseolinusSpisula subtruncata

40Table 4. Water contents and density

Core№

Interval,cm

Density;ρρρρn=M/V

g/cm3

Water contents;Wn=(Mw/Md).100%

1 2 - 313 - 1433 - 35

1.541.961.95

161012

12 0 - 0,50.5 - 11 - 22 - 33 - 44 - 55 - 66 -77 - 88 - 9

9 - 1010 - 1111 - 1212 - 1717 - 22

1.411.381.311.331.421.521.491.451.431.351.381.251.331.271.39

182124241917191923222320231420

14 4 - 66 - 88 -10

10 - 1212 - 1414 -1616 - 1818 - 20

1.962.111.551.211.211.271.241.23

10764314438333738

mixed brackish and marine fauna. Complete sections,Upper Holocene in age, were observed in deep-sea area.Middle Holocene sediments are presented as usually bynon-complete records, due to the insufficient length of thecores.

On the north-western Black Sea shelf it is not easy tofind areas with continuous and intensive sedimentation. Thelarge central part, for instance, is characterised by very lowrates of accumulation. Shelly sediments with smalladmixture of muddy material or without it are widespreadhere. The top sediments are usually shells covered withcarbonate and thin Fe-Mn crusts. It means that non-depositional conditions primary for terrgenous pelliticmaterial are prevailing here. Short bioturbated sedimentssections with some shelly horizons are chracteristic both forUpper and Middle Holocene sediments, showing presenceof non-depositional conditions and reduced sedimentationstages.

Apparently continous butbioturbated sediment sectionsare characteristic for someareas of Danube Pro-Delta, (st.3, 4) were terrigenous muds arewidespread. The same pictureis observed in the cores fromstation 6, opposite the Dnieprmouth.

The cores obtained from theanoxic upper zone of the north-western continental slope(stations 13, 14, 15) consistmainly of biogenic sediments,accumulated slowly (< 10cm/ky). Coccolithic carbonatedmuds (50-70 % CaCO3), rich inorganic matter, form the UpperHolocene unit. Sapropelic, lowcarbonated (< 10 % CaCO3)muds are characteristic forMiddle Holocene.

Studied cores have novisual signals of sedimentationinterruption or post-depositional disturbances andbioturbations. Thus, they aregood for radiometric dating andstudies of man-maderadionuclides as well, butrequire very precise slicing ofsediment cores in theuppermost part of sections,down to 3-5 cm (less than0.1 cm for each sample).

On the basis of preliminarylito-bio-stratigraphical division,the aver age rates ofaccumulation were calculatedin the most studied areas forthe Upper Holocene and onlyin some places for MiddleHolocene.

The most intensiveterrigenous sedimentation (>13-18 cm/Ky) in UpperHolocene is observed on theDanub Pro-Delta (stations 2, 3,4) and Odessa Bay (station 6).Biogenic sedimentation showshigher values on the upper zoneof the north-western slope(station 13, 14), and on thesouthern continental rise(station 17).

41

Тable 5. Grain-size analysisFRACTION, %

CORE

N

Interval

cm

gravel>2.0mm

sand2.0 - 0.1

mm

silt0.1 - 0.005

mm

clay<0.005

mm

Mediand50,mm

U=d60/d10

1 1 - 3 12.1 20.6 57.5 9.8 0.19 751 13 - 14 9.4 76.6 13.0 0.0 0.16 31 33 - 35 11.0 64.2 20.2 4.6 0.17 124 25 - 30 0.0 6.0 80.0 14.0 0.013 4

10 13 - 15 11.3 28.7 45.5 14.5 0.025 2512 0 - 5 3.1 22.7 52.9 21.3 0.016 1512 12 - 17 10.1 28.0 45.9 16.0 0.030 3312 17 - 20 6.3 34.9 40.3 18.5 0.045 4214 22 - 24 0.0 3.3 54.9 41.8 0.010 1015 21 - 23 0.0 1.4 56.8 41.8 0.007 1015 49 - 51 0.0 1.8 73.0 25.2 0.019 1218 55 - 60 0.0 2.2 86.4 11.4 0.015 6

Psephitic (>2.0 mm) and psammitic (0.1 - 2.0 mm) fractions of cores 1,10, 12 consist shellsmainly.

Table 6. Rates of sediment accumulationHolocene Rate of sedimentation, mm/yStation

№ Upper, Hl3cm

Middle, Hl2cm

Lower, Hl1cm

Hl3 Hl2

12346789

101112131415161718

0 � 120 -> 390 -> 530 -> 390 -> 560 -> 200 � 120 � 460 � 190 � 150 � 170 � 360 � 380 � 280 � 270 -> 480 -> 54

12 -> 36-----

12 -> 3046 -> 5319 -> 3515 � 3017 � 3836 -> 5738 -> 5628 -> 5427 ->48

--

---------

30 -> 3238 -> 41

------

0.04> 0.13> 0.18> 0.13> 0.19> 0.070.040.150.060.050.060.120.130.090.09

> 0.16> 0.18

> 0.06-----

> 0.05> 0.04> 0.040.040.05

> 0.05> 0.05> 0.07> 0.05

--

The lowermost values (4-6 cm/Ky) weredetermined in the middle and outer zones ofthe north-western shelf (stations 1, 8, 11, 12).

It is to bed noted the momentarysedimentation rates may be higher incomparison with the average ones.

Aknowledgements. The authors areindebted to Mrs. Iolanda Osvath (IAEA) fororganisation of the cruise, to Mr. KazimerasShimkus (S.B. of IO-RAS) for givenpreliminary data of rate of sedimentation andto Mrs. Raina Christova (IO-BAS) for donebiostratigraphic analysis.

42

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Холоценски седименти от западната част на Черно мореИван Д. Генов, Веселин Д. Пейчев

(Резюме)Извършено е изследване на холоценски седименти от 18 станции от западната част на

Черно море, опробвани с мултикорер по време на 52-рия рейс на НИК �Проф.Водяницки�, проведен през месец септември 1998 г. Определен е литоложкият състав напробите, скоростта на седиментация и е извършен биостратиграфски анализ. На част отпробите е определен зърнометричният състав, плътността и водното съдържание.Холоценските седименти са разгледани като асоциация от автохтонни компоненти,формирани при специфични физикохимични и биохимични условия и алохтонникомпоненти, постъпили от източници на теригенен материал и трансформирани подвъздействието на постседиментни фактори.

Постъпила на 01.03.2000 г.

holocene sediments from west part of black sea · Федоров (1982), Шопов (1993)...

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