DATING THE ROMANIAN PART OF THE EUROPEAN LOESS BELT USING
LUMINESCENCE METHODS
(DAROLUM)
Project leader
Scientific visibility and prestige
Main research results.
The project leader started her scientific activity in 2006 when she enrolled in a PhD
program, which she graduated in 2010 by submitting a thesis entitled “Retrospective luminescence
dosimetry: Applications in Archaeology, Geology and Environmental Studies”. The overriding
objective of the thesis was to implement luminescence dating at Babes-Bolyai University in Cluj
Napoca and apply state of the art dating technology to materials that are relevant to archaeology and
earth sciences. The work that has been accomplished though went far beyond mere implementation
and application and it was a fundamental contribution to the field of luminescence dating. The work
on dating Neolithic ceramics from Lumea Noua is one of the few studies available in international
literature that applied a single aliquot sate-of-the-art dating protocol technology to ceramics. The
dates provided the first direct and absolute age information for the cultural development at the site,
and in general, demonstrated the potential of modern SAR-IRSL and SAR-OSL techniques for
improving the chronological framework of archaeological sites. During the course of her PhD
(October 2006-June 2010) and up to the moment of writing this proposal the project leader carried
out fundamental and applied luminescence research on luminescence of quartz extracted from
Romanian loess. It is widely accepted that Romanian loess/palaeosol sequences represent important
and detailed archives of regional climate and environmental change during the Pleistocene.
However, prior to the studies of the applicant, very little absolute age information was available for
these deposits. The applicant applied a modern SAR-OSL technique to quartz grains extracted from
loess deposits at two “key sections” in SE Romania, Mircea Voda and Mostistea. At both localities,
the quartz-based SAR-OSL dates demonstrated that the uppermost loess/palaeosol unit represents
the Last Glacial/Interglacial cycle. These results urge that the old-established chronostratigraphical
framework must be revised, in that the S1 unit can no longer be considered a soil that developed
during a Last Glacial interstadial. By extrapolation, the same holds true for the underlying S2 unit.
For the section near Mircea Vodă the dates obtained also demonstrate that that the L1 unit did not
accumulate at a constant rate, with loess being deposited at a much lower rate during the past 70ka.
Loess is generally considered as an ideal material for testing and applying luminescence techniques;
however a comparison of SAR-OSL ages for silt and sand-sized quartz obtained by the current
proposal`s project leader convincingly demonstrated that loess may be one of the most difficult
materials to date. Her previous studies and on-going studies caution against blind application of
2
modern techniques to this type of material and challenge the luminescence dating community to
develop more robust luminescence dating procedures.
The accomplishments of the current proposal’s team leader can be summed up as follows:
(i) she contributed significantly to the set up of a modern luminescence dating laboratory in Cluj
and on the implementation of luminescence dating techniques in Romania; (ii) she demonstrated
that modern luminescence dating techniques hold considerable potential for dating heated
archaeological materials, especially if these can not be dated by other means; (iii) her work on
Romanian loess challenged the earth scientific community in their conventional interpretation of
these records and the luminescence dating community in their assumption that loess is an ideal and
non-problematic material for luminescence dating.
The visibility of the scientific contributions.
For part of her work on Romanian loess A. Timar-Gabor received the “Vagn Mejdahl for
her outstanding presentation at the “12th International Conference on Luminescence and Electron
Spin Resonance Dating (LED 2008)” which was held in Beijing 18–22 September 2008. This is a
very prestigious prize awarded at the most important scientific meeting for the luminescence dating
community. This is mentioned in the editorials of two highly ranked journals (for more information
please see Radiation Measurements 44 (2009) p. 415–416, Quaternary Geochronology 5 (2010)
p.83).
As a consequence to the contribution to LED 2008 A. Timar-Gabor was invited to give a
talk at Qinghai Institute of Salt Lakes (Chinese Academy of Sciences), Xinning, China- 24-25
September 2008 (http://www.isl.cas.cn/xwzx/xshd/200906/t20090607_573264.html).
In 2008 A. Timar-Gabor was offered a PhD position in Risø National Laboratory (the
forefront of luminescence dating research) under the supervision of Professor Dr. Andrew Murray.
The present applicant has chosen however to continue her activity in Romania. At the moment A.
Timar-Gabor has informal scientific collaborations through transfer of knowledge with other
researchers in the field of luminescence dating such as Dr. D. Vandenberghe (Ghent University) or
Dr. György Sipos (University of Szeged). Recently, A. Timar-Gabor started a collaboration with
one of the most prestigious researchers in luminescence dating -Professor Ann Grace Wintle
(Cambridge University and University of Wales Aberystwyth). This collaboration aims at
fundamental research into the luminescence of quartz and will result in a joint presentation at “12th
International Conference on Luminescence and Electron Spin Resonance Dating (LED 2011)”
which was held in Torun, Poland 10–15 July 2011.
During her scientific activity (2006-2011) A. Timar-Gabor participated in 13 international
conferences with 7 oral presentations and 6 poster presentations.
3
Project description
Scientific context and motivation.
A better comprehension of past and current climate variability requires the integration of
multiple data sources, either empirical or mathematically modeled. Therefore, a wealth of
paleoclimatic information has been obtained in the past decades by the investigation at
unprecedented details of a variety of proxies and archives worldwide. Nevertheless, compared with
other parts of Europe, limited paleoclimate information is currently available from South-Eastern
Europe, and especially from Romania, even though this region could be of particular interest for
understanding past climatic dynamics at both regional and continental scales. Loess originated
mainly from silty material blown out of sparsely vegetated areas during the dry and cold periods of
the Pleistocene while during interglacials and most interstadials, the loess sedimentation areas were
covered by newly formed soils. Thus, the alternation of cold and warm periods throughout the
Quaternary led to the formation of interbeded loess- palaeosol sequences (LPSS), some of the most
detailed terrestrial archives of climate and environmental change. Marine records and ice core
records primarily record global climate signals, whereas loess/paleaeosol additionally reflect
regional and climate and environmental conditions (Frechen, 2011). However, because significant
lateral variation in both physical and chronological parameters may occur over large distance, their
significance can only be fully and securely understood if an absolute chronology is developed for
each investigated profile (Frechen et al., 2003, Roberts, 2008). Application of newly developed
absolute dating methods fit for loess research and notably the luminescence dating method
produced convincing evidence that loess deposits could be affected by varying accumulation rates
and erosive hiatuses (see for example Stevens 2007, Buylaert 2008). These new findings call for a
re-evaluation of some of the previously established facts concerning the nature, formation and
significance of loess records, and question the utility of simple stratigraphic correlation of several
palaeosols as stratigraphic markers, especially in the absence of any chronological constrains.
Consequently, absolute dates in loess-related research are essential to determine (i) the timing of
climatic events that are registered in the loess, (ii) the rate of processes such as sedimentation and
pedogenesis and (iii) the correlation between different loess sequences.
Loess deposits cover significant areas in Europe, extending from NW-France and Belgium
through to Central Europe, the Ukraine and Western Russia (Hasse et al., 2007, Zoeller, 2010). The
LPSS of the Carpathian Basin-Lower Danube region (Romania, Serbia, Bulgaria) are thought to
represent the most continuous and high resolution archives of regional climate and environmental
change during the Late and Middle Pleistocene, in this part of Europe and a link between similar
deposits in central Europe and Eurasia.
4
In comparison to other loess sequences elsewhere in Western, Central and Eastern Europe,
the deposits in Romania have been much less extensively studied (Frechen et al., 2003). A
chronostratigraphical framework for the Romanian loess deposits has previously been established
through geomorphological, lithological and pedostratigraphical analyses (Conea, 1969, 1970) while
more recent studies of the magnetic properties of the LPSS have demonstrated the potential of
magnetic susceptibility as a climatic proxy (see e.g. Panaiotu et al., 2001; Buggle et al., 2009).
Luminescence dating allows the direct determination of depositional ages for sediments
from a wide variety of depositional environments, and especially aeolian sediments (Murray and
Olley, 2002). However, the dating of loess deposits in Romania by luminescence methods is just at
the beginning. In the exploratory study by Balescu et al. (2003), four IRLS ages were obtained for a
section near Tuzla (Dobrogea, SE Romania). Despite the limited dataset, they could demonstrate
that the uppermost palaeosol in the section was formed during MIS5 and that the first three loess
layers accumulated during the last three glacial periods (MIS 4, MIS 6, respectively MIS 8). So far,
the current proposal’s research group have intensively investigated two “key sections” in SE
Romania. The first section (~26 m thick) is located near Mircea Vodă (Timar et al. 2010, TimarGabor et al. 2010) and it comprises six well developed palaeosols (stratigraphic nomenclature: S0S5, with S0 representing the Holocene soil) and intercalated loess layers (L1-L6), with no apparent
evidence for large hiatuses. The L1 unit also contains a weakly-developed palaeosol. The second
section is located on the border of Mostiştea lake (Vasiliniuc et al. 2011). It is ~21 m thick and
consists of four loess-palaeosol units and the Holocene topsoil. Our research design and strategy
consisted of sampling the sections at a high vertical resolution (preferably ~20-30cm). The
chronometric investigations focussed on the L1/S1/L2 sequence and involved the SAR protocol and
OSL signals from quartz. At both localities, the quartz-based SAR-OSL dates demonstrate that the
uppermost loess/palaeosol unit represents the Last Glacial/Interglacial cycle. These results support
the conclusions of Balescu et al. (2003, 2010) and urge that the old-established
chronostratigraphical framework (Conea 1969, 1970) must be revised, in that the S1 unit can no
longer be regarded as a soil that developed during a Last Glacial interstadial. By extrapolation, the
same holds for the underlying S2 unit. For the section near Mircea Vodă, the dataset indicates that
the L1 unit did not accumulate at a constant rate, with loess being deposited at a much lower rate
during the past 70ka. So far, we did not observe any hiatuses in the record (within the limits on the
time-resolution that can be achieved using quartz-based SAR-OSL dating), but it does appear that
the rate of loess deposition during MIS5 differs between the two localities. As tight independent age
control is lacking, the optical ages are probably the best chronological data currently available for
these sites. Our studies demonstrates that quartz-based SAR-OSL dating is a powerful tool to
spatially and temporally correlate Romanian loess-palaeosol sequences, and to assess the validity of
5
proxy-based methods for timing and reconstructing climatic and environmental change. This
proposal aims at deepening and extending the preceding work both in terms of the study areas
covered as well as and the dating methodology.
C2. Objectives.
The main objective of this project is to establish an accurate and precise chronology for
some of the most important loess sequences in Romania. This approach is essential for (i) securely
linking loess records from Romania in a chronologically reliable regional framework (including
information from the better investigated and well-known Danube loess sites in Serbia and Bulgaria),
and to extend this information to other sites from central and eastern European loess belt, in order to
understand past paleoenvironmental dynamics at both regional and continental scales. To achieve
these goals, the sediments will be dated using luminescence methods for establishing a reliable and
detailed chronology for sediments that have been deposited during the last Glacial/Interglacial cycle
(i.e. last ~130ka, MIS2-5), and if possible, for earlier cycles as well. Additionally, high-resolution
sedimentological, geochemical and rock- and paleomagnetic measurements will be carried out for
the investigated sections. Luminescence dates will be compared with the sedimentological data and
the magnetic susceptibility based time depth model an initiative which should allow producing a
detailed multi-approach age model, with immediate application in interregional correlations and on
the reconstruction of climate and environmental gradients using a common temporal framework.
Method and approach.
Field work and sampling strategy
Potential sampling sites will be surveyed and selected in collaboration with field specialists.
These key sections (see figure) represent the most complete and/or detailed palaeoclimatic and
palaeoenvironmental records for S Romania and cover several glacial/interglacial cycles. The
youngest loess (L1) will be sampled at a high vertical resolution (e.g. every 20-30cm); the older
loess deposits will be sampled with a larger vertical spacing.
Costinesti section: Consisting of five palaeosoil layers and interbedded loess, the loess-palaeosoil
section from Costineşti is located on the Black Sea shore (43, 97 oN 28,65 oE), north of Costineşti
village. L1 has a thickness of approx. 1.20 m and L2 approx. 2.15 m. High resolution sampling (10 20 cm) has been already performed for the first two loess layers (L1 and L2) and from S1.
Turnu Magurele area: The sections are located north of Turnu Magurele between Slobozia Mandra
and Lunca localities. The sections comprise of 30-35m of aeolian deposits (loess, sands) with 6-7
6
interbedded paleosoils and several volcanic-ash layers. The area will be sampled in spring-summerautumn 2012.
Map of loess distribution in Europe (Haase et al., 2007) (right). The locations which will be
investigated are depicted with red ovals. Map of Romania (left-side) depicting (in gray) the loess
and loess like deposits. The previously studied sections (Mostistea and Mircea Voda are
represented as open circles. The profiles that will be the subject of the current proposal are
depicted as stars.
Focsani area: In the area between the riverbeds of Putna, Ramnicu Sarat and the left bank of Siret
River there are several deposits with thickness of 10-20m. These deposits are of major importance
because of the peculiarity of the loess which is coarser than in the typical deposits of Danube Plainprobably due to the proximity of one of the source areas (the Carpathians). Due to the tectonic
movement in the area at several locations gravel beds are intercalated. We envisage that dating of
these deposits will contribute in improving the modeling tectonic movement as well. The area will
be sampled in spring-summer-autumn 2012.
Semlac: The profile at Semlac (thickness of 15 m) will be studied as it has major importance for
correlating the deposits in SE Romania (previously studied and described in this proposal) to the
very intensively studied deposits in Central Europe (see e.g. Ujvari et al. 2010, Stevens et al. 2011,
Markovic et al. 2011). The area will be sampled in spring-summer-autumn 2012.
Other locations that are of interest will be also sampled occasionally to test for their records. As an
example we indicate the sites of Daneasa (Olt river) and Caciulatesti (Jiu river) where tephra layers
have been identified intercalated between loess and loess-like deposits.
7
Dating methodology
Our high resolution dating studies and multi proxy approach is intended to overcome limitations of
the paleoclimatic and dating methods. As far as the luminescence dating methodology is concerned,
it seems appropriate to start where previous work has ended. Therefore, the investigations will
begin by documenting the OSL characteristics of silt (4-11µm) and sand-sized (63-90µm) quartz
grains extracted from the samples. Research efforts will concentrate on the applicability and
performance of the single-aliquot regenerative-dose (SAR) OSL technique (Murray and Wintle
2000, 2003, Wintle and Murray 2006); this technique uses a minimum amount of pure quartz (i.e. a
few mg on a single aliquot) and blue light as the signal stimulation source. In a following phase, an
in-depth study of the luminescence characteristics of polymineral fine-grains and coarse feldspar
grains will be performed, including investigations on whether or not it is possible to minimize
anomalous fading. Finally, innovative and very new luminescence techniques such as TT-OSL
(Wang 2007) and isothermal decay (Vandenberghe 2009) will be applied. Luminescence dates/
respectively mass accumulation rates derived from determined absolute ages will be compared to
the grain size distributions and a novel magnetic susceptibility time depth model.
Impact, relevance, applications.
The strength of the project lies both in its interdisciplinary and multidisciplinary approach as well as
on the foreseen broad scientific impact. The study proposed here should establish a final and
reliable absolute chronological framework for some of the most important loess sequences in
Romania. As such, it will contribute significantly to improving the understanding of stratigraphic
and chronological relations between local and regional geological sequences, a necessary preamble
for securely linking the Lower Danube loess deposits with comparable sequences elsewhere in
Europe and Eurasia. The age results will also yield precise information on loess accumulation rates
and through complementary analyses, could lead to better understanding of the importance of past
atmospheric circulation patterns and related dust fluxes as both records and a potential agents of
climate change. The proposed project will also capitalize important contributions to the efforts
made by the international community to improve both the protocols of the luminescence method
and to extend its temporal range. A luminescence dating method yielding reliable ages over an
extended time-span will undoubtedly mark a completely new chapter in the study of earth surface
processes, human evolution and terrestrial climate change. This project will also produce crucial
new developments concerning the charge storage, movement and recombination in non-conducting
crystalline solids, and the use of these phenomena in the measurement of absorbed radiation dose.
Last but not least, it is hoped that the implementation of the current project proposal will lead to the
8
development of a multi and interdisciplinary team of young specialists in paleoclimate research
based on absolute numerical investigation techniques in Romania.
References:
Balescu S, Lamothe M, Mercier N, Huot S, Balteanu D, Billard A and Hus J, 2003. Luminescence
chronology of Pleistocene loess deposits from Romania: testing methods of age correction for
anomalous fading in alkali feldspars. Quaternary Science Reviews 22 (10-13), 967-973.
Balescu, S., Lamothe, M., Panaiotu, C., Panaiotu, C., 2010. La chronologie IRSL des séquences
loessiques de l’Est de La Roumanie. Quaternaire, 21 (2), 115-126.
Buggle, B., Hambach, U., Glaser, B., Gerasimenko, N., Marković, S., Glaser, I., Zöller, L., 2009.
Stratigraphy and spatial and temporal paleoclimatic trends in Southeastern/Eastern European loess–
paleosol sequences. Quaternary International, 196 (1-2), 86-106.
Buylaert, J.P., Murray, A.S., Vandenberghe, D., Vriend, M., De Corte, F., Van den haute, P., 2008.
Optical dating of Chinese loess using sand-sized quartz: Establishing a time frame for Late
Pleistocene climate changes in the western part of the Chinese Loess Plateau. Quaternary
Geochronology 3, 99-113.
Conea A, 1969. Profils de loess en Roumanie. La stratigraphy des loess d’Europe. In: Fink, J. (Ed.),
Bulletin de l’Association Française pour l’étude du Quaternaire. Suppl. INQUA, pp. 127-134.
Conea, A., 1970. FormaŃiuni Cuaternare în Dobrogea (loessuri şi paleosoluri) (Quaternary units in
Dobrogea) Editura Academiei RSR, Bucureşti : 234 pp (in Romanian).
Frechen, M., Oches, E.A., Kohfeld, K.E., 2003. Loess in Europe – mass accumulation rates during
the Last Glacial Period. Quaternary Science Reviews 22, 1835-1857.
Frechen M., 2011. Loess in Eurasia, Guest Editorial, Quaternary International 234, 1-3.
Haase, D. Fink, J., Haase, G., Ruske, R., Pecsi, M., Richter, H., Altermann, M., Jager, K., D., 2007.
Loess in Europe-its spatial distribution based on a European Loess Map, scale 1:2,500,000.
Quaternary Science Reviews 26, 1301-1312.
Markovic S. B., Hambach U., Stevens, T., Kukla G.J., Heller, F., McCoy W.D., Oches E.A.,
Buggle, B., Zoeller L., 2011. The last million years recorded at the Stari Slankamen (northern
Serbia) loess-palaeosol sequence: revised cronostratigraphy and long term environmental trends.
Quaternary Science Reviews, xxx (2011) 1-13, doi: 10.1016/j. quascirev.2011.02.004.
Murray, A.S., Wintle, A.G., 2000. Luminescence dating of quartz using an improved single-aliquot
regenerative-dose protocol. Radiation Measurements 32, 57-73.
Murray A.S., Olley J.M., 2002. Precision and accuracy in the optically stimulated luminescence
dating of sedimentary quartz: a status review. Geochronometria 21, 1-16
Murray, A.S., Wintle, A.G., 2003. The single aliquot regenerative dose protocol: potentials for
improvement in reliability. Radiation Measurements 37, 377-381.
9
Panaiotu CG, Panaiotu EC, Grama A and Necula C, 2001. Paleoclimatic record from loess-paleosol
profile in Southeastern Romania. Physics and Chemistry of the Earth A (11-12): 893-898.
Roberts, H.M., 2008. The development and application of luminescence dating to loess deposits: a
perspective on the past, present and future. Boreas 37, 483–507.
Stevens, T., Armitage, S.J., Lu, H., Thomas, D.S.G., 2007. Examining the potential of high
sampling resolution OSL dating of Chinese loess. Quaternary Geochronology 2, 15-22.
Stevens, T., Marcovic, S., Zech M., Hambach, U., Sumegi, P., 2011. Dust deposition and climate in
the Carpathian Basin over an independently dated last glacial-interglacial cycle. Quaternary Science
Reviews, 662-681.
Thomsen, K. J., Bøtter-Jensen, L., Denby, P., Moska, P., Murray, A.S., 2006. Developments in
luminescence measurement techniques. Radiation Measurements 41, 768-773.
Timar, A., Vandenberghe, D., Panaiotu, E.C., Panaiotu, C.G., Necula, C., Cosma, C. and Van den
haute, P., 2010. Optical dating of Romanian loess using fine-grained quartz. Quaternary
Geochronology, 5, 143-148 .
Timar Gabor, A., Vandenberghe, D.A.G., Vasiliniuc, S., Panaoitu, C. E., Panaiotu, C. G., Dimofte,
D., Cosma, C., 2010. Optical dating of Romanian Loess a comparison between silt-sized and sandsized quartz. Quaternary International, xxx - 2010, 1-9, available online: DOI:
10.1016/j.quatint.2010.10.007.
Ujvari G., Kovacs, J., Varga G., Raucsik, B., Markovic, S., 2010. Dust flux estimates for the Last
Glacial Period in East Central Europe based on terrestrial records of loess deposits: a review.
Quaternary Science Reviews, 29, 3157-3166.
Vandenberghe, D. A. G., Jain M., Murray A.S., 2009. Equivalent dose determination using a quartz
isothermal TL signal. Radiation Measurements 44, 439-444.
Vasiliniuc, S., Timar-Gabor, A., Vandenberghe, D.A.G., Panaiotu, C.G., Begy, R. Cs., Cosma, C.,
2011. A high resolution optical dating study of the Mostiştea loess-palaeosol sequence (SE
Romania) using sand-sized quartz, Geochronometria, 38(1), 34-41, DOI: 10.2478/s13386-011-0078.
Wang, X.L., Wintle, A.G., Lu, Y.C., 2007. Testing a single aliquot protocol for recuperated OSL
dating, Radiation Measurements, 42, 380-391.
Wintle, A.G. and Murray A.S., 2006. A review of quartz optically stimulated luminescence
characteristics and their relevance in single-aliquot regeneration dating protocols. Radiation
Measurements 41: 369-391.
Zoeller, L., 2010. New approaches to European loess: a stratigraphic and methodical review of the
past decades. Central European Journal of geosciences 2(1), 19-31.
10