Uticaj paleosredine na raspodelu i obilnost zasićenih i aromatičnih ugljovodonika u sedimentima topličkog basena
The influence of paleoenvironmental conditions on the distribution and abundance of saturated and aromatic hydrocarbons in sediments of Toplica Basin
Докторанд
Burazer, Nikola M.Ментор
Jovančićević, BranimirЧланови комисије
Šajnović, AleksandraKašanin-Grubin, Milica
Stojanović, Ksenija
Vasić, Nebojša D.
Метаподаци
Приказ свих података о дисертацијиСажетак
Osnovni cilj ove doktorske disertacije bio je proučavanje uticaja paleosredine taloženja na
raspodelu i relativnu obilnost zasićenih i aromatičnih ugljovodonika u miocenskim jezerskim
sedimentima Topličkog basena. Rezultati ovog istraživanja omogućili su procenu porekla, naftno-
gasnog potencijala i zrelosti organske supstance u ispitivanim sedimentima. Takođe, ova disertacija
je razmatrala uticaje sedimentoloških procesa i tektonike na razvoj Topličkog basena i sastav
sedimenata. Toplički basen do sada nije bio predmet ovakve vrste naučnih istraživanja.
Ovo istraživanje je obuhvatalo interdisciplinarnu analizu i interpretaciju organskog i
neorganskog dela odabranih sedimenata iz četiri istražne bušotine: BL3, BL4, BL5 i BL7. Neorganski
deo je ispitivan primenom optičkih ispitivanja, rendgenske difraktometrije, rendgenske fluorescentne
spektroskopije, indukovane kuplovane plazme sa masenom spektrometrijom, skenirajuće elektronske
mikroskopije, kompleksometrijske analize sadrž...aja kalcijuma i magnezijuma. Organski deo
sedimenata je analiziran upotrebom petrografskih ispitivanja, Rok-Eval pirolize i
gasnohormatografsko-masenospektrometrijske metode.
Na osnovu sedimentoloških, litoloških i mineraloških rezultata, Toplički basen je podeljen na
zapadnu i istočnu subbasensku jedinicu. U dubljoj, zapadnoj subbasenskoj jedinici, ispitivani su
sedimenti bušotine BL7, dok su u plićoj, istočnoj subbasenskoj jedinici, ispitivani sedimenti bušotine
BL3 i BL5. Bušotina BL4 nalazi se blizu prelaza između dve subbasenske jedinice, preko kojeg je
omogućena potencijalna komunikacija zapadnog i istočnog dela basena. Postojanje dve nezavisne
subbasenske jedinice omogućila je proučavanje uticaja različitih procesa na taloženje sedimenata i
karakteristike organske supstance. Pored navedenog, na osnovu litoloških i mineraloških podataka,
miocenski sedimenti su raščlanjeni na nekoliko litofacijalnih jedinica koje su se međusobno
razlikovale po strukturnim i teksturnim osobenostima. U okviru ove disertacije detaljno su ispitivani
tufozni, analcimizirani i bituminozni finozrni klastiti Čučala i finozrni klastiti Prebreze, taloženi u
jezerskoj ili močvarnoj faciji. Sedimenti močvarne facije odlikuju samo bušotinu BL5.
Vulkanizam je pratio taloženje sedimenata u Topličkom basenu, što se odražavalo kroz
prisustvo vulkanoklastičnog materijala duž vertikalnih profila ispitivanih bušotina.
Vulkanski procesi su bili izraženiji u zapadnoj subbasenskoj jedinici, na šta je upućivao viši
sadržaj analcima u sedimentima bušotine BL7, kao i pojava tufogenog paketa, debljine 7 m. Značajna
količina vulkanoklastičnog materijala koja je transportovana sa zapadnog dela u basen, podstakla je
proliferaciju algalnih i planktonskih zajednica, istovremeno pospešujući primarnu bioproduktivnost,
što je uticalo na sadržaj organske supstance. Razvoj Topličkog basena praćen je tektonskim
istanjivanjem kore, što je dovelo do pojačanog termalnog fluksa iz litosfere, čime je prouzrokovano
pregrevanje organske supstance, koje je dalje podstaklo proizvodnju ugljovodonika i povećanje
njihovog ukupnog sadržaja. Organska supstanca sedimenata bušotine BL7 je nematurisana do rano
maturisana i izgrađena od kerogena tipa I ili II, koji imaju tendenciju ga generisanju tečnih
ugljovodonika. Akumulacija i očuvanje organske supstance u sedimentima BL7 je bilo omogućeno
zahvaljujući anoksičnim i mezo-slanim ili hiperslanim paleouslovima sredine, o kojima svedoči
predominacija fitana, prisustvo i-C30, β-karotana, perilena, gamacerana, δ-metiltrimetildecilhromana,
1,5- i 1,4-dimetilkarbazola.
Taloženje sedimenata u istočnom delu Topličkog basena praćeno je intenzivnim aluvijalno-
jezerskim procesima, što se odrazilo kroz izraženo prisustvo peskovite i šljunkovite komponente duž
vertikalnog profila bušotine BL3, a u manjem obimu i u bušotini BL5. Peskovi i šljunkovi su
značajnije razblažili organsku supstancu ispitivanih sedimenata, koja je nematurisana i izgrađena od
kerogena tipa III ili mešovitog kerogena tipa II/III. Predominacija viših neparnih n-alkana (n-C27, n-
C29 i n-C31) i hopana u sedimentima bušotine BL3 i BL5, upućivali su na pojačano učešće viših
kopnenih biljaka i mikrobiološki prerađene organske supstance. Sredina sedimentacije je bila
generalno anoksična i veoma dinamična. Na dinamiku sedimentacije uticala je energija jezera i
Doktorska disertacija Nikola M. Burazer
aluvijalni sistem putem kojeg se transportovala velika količina klastičnog materijala različite veličine.
Klastični materijal je sa sobom dopremao organsku supstancu različitog porekla i stratigrafske
pripadnosti, time ukazujući na prisustvo resuspendovane organske supstance u istočnoj subbasenskoj
jedinici. Organska supstanca, istaložena pod ovakvim okolnostima, je odražavala kompleksne
informacije o paleosredini taloženja.
S obzirom da su više kopnene biljke dominantan prekursor u organskoj susptanci bušotina BL3
i BL5, postojala je mogućnost razmatranja uticaja paleoklimatskih uslova na raspodelu i obilnost
ugljovodonika. Paleoklimatski uslovi su odražavali pojavu određenih biljnih taksona u organskoj
supstanci ispitivanih sedimenata. Naime, visoke C-value i Rb/Sr, odnosno niske vrednosti Sr/Cu
odnosa, praćene obilnijim učešćem zasićenih i aromatičnih triterpenoida koji vode poreklo od
skrivenosemenica, odlikovali su veliku grupu ispitivanih sedimenata. Rezultati neorganskih
geohemijskih parametara i prisustvo skrivenosemenica odražavali su tople i semi-humidne/semi-
aridne do semi-humidne paleoklimatske uslove sredine. Dobijeni podaci su u skladu sa dosadašnjim
paleoklimatskim istraživanjima neogenih basena jugoistočnog dela Evrope.
S druge strane, tektonski procesi rastezanja kore i izdizanje (ekshumacija) Jastrebačkog
kompleksa su pratili razvoj Topličkog basena tokom neogena. Razlike u sedimentološkim, litološkim,
mineraloškim i organsko-geohemijskim osobenostima duž vertikalnog profila bušotine BL4, ukazale
su na pojavu cikličnosti u taloženju i četiri litočlana, A, B, C i D. U ovom slučaju cikličnost je
povezana sa tektonskim procesima. Naime, stvaranje prirodne „barijere“, u vidu ekshumiranog
Jastrebačkog kompleksa, kontrolisalo je prinos klastičnog materijala sa margina u zapadni i istočni
deo ispitivanog basena. Tokom inicijalne faze razvoja Topličkog basena, prirodna „barijera“ je
sprečila transport erodovanog materijala koji je odlikovao sedimente istočne subbasenske jedinice.
Litočlanovi A i B odražavali su tip organske supstance i paleouslove slične kao u sedimentima
zapadnog dela Topličkog basena (bušotina BL7). Mirna, anoksična i mezoslana sredina sedimentacije,
pohranjena makro- i mikro- nutrijentima oslobođenih tokom vulkanskih procesa, odlikovala je
organsku supstancu litočlanova A i B. O ovome svedoče znatne količine analcima, predominacija
fitana, značajnije koncentracije i-C25 i i-C30, kao i izraženo prisustvo β-karotana. Organska supstanca
bila je pretežno obogaćena algalnim prekursorima.
Sedimentacija se nastavila formiranjem litočlanova C i D. U tom trenutku, prirodna „barijera“ je
sprečavala transport erodovanog materijala sa zapadne subbasenske jedinice. U ovom slučaju,
organska supstanca odražavala je tip i paleouslove slične kao u sedimentima istočnog dela Topličkog
basena (bušotine BL3 i BL5). Organska susptanca bila je mešovitog porekla, istaložena u anoskično-
disoksičnim i slatkovodnim uslovima sredine. U prilog iznešenom, potvrdu je predstavljalo i
izraženije prisustvo peskovite komponente dopremljene aluvijalnim sistemom, promenljive vrednosti
Pr/Ph odnosa, smanjene relativne koncentracije i-C25 i i-C30, kao i odsustvo β-karotana.
Sedimentacija u Topličkom basenu se okončala prinošenjem grubozrnih i srednjozrnih klastita
sa svih margina, čime se polagano završila sedimentacija i nagovestilo gašenje neogenog jezerskog
basena.
The main goal of this doctoral dissertation was to study the influence of the paleoenvironmental
conditions on the distribution and relative abundance of saturated and aromatic hydrocarbons in the
Miocene lake sediments of the Toplica basin. The results of this research enabled the assessment of
the origin, oil and gas potential and maturity of the organic matter in the investigated sediments. Also,
this dissertation considered the influence of sedimentological processes and tectonics on the
development of the Toplica basin and composition of sediments. The Toplica basin has not been the
subject of previous scientific investigations.
The research included an interdisciplinary analysis and interpretation of the organic and
inorganic parts of selected sediments from four boreholes: BL3, BL4, BL5 and BL7. Examination of
the inorganic part of the sediments was made possible by applying optical examinations, X-ray
diffractometry, X-ray fluorescence spectroscopy, Inductively couple...d plasma mass spectrometry,
scanning electron microscopy, and complexometric analysis of calcium and magnesium content. The
organic part of the sediments was analyzed using petrographic tests, Rock-Eval pyrolysis and gas
chromatography-mass spectrometry methods.
Based on sedimentological, lithological and mineralogical results, the Toplica basin was
divided into western and eastern sub-basin units. In the deeper, western subbasin unit, the sediments
of borehole BL7 were investigated, while in the shallower, eastern subbasin unit, the sediments of
boreholes BL3 and BL5 were examined. The BL4 borehole was located near the transition between
these sub-basin units, through which the potential communication of the western and eastern parts of
the basin was probable. The existence of two independent sub-basin units opened the possibility of
studying the influence of different processes on the deposition of sediments and the characteristics of
organic matter. In addition to the above, lithological and mineralogical data allowed the
categorization of Miocene sediments into several lithofacies, which were different in terms of
structural and textural properties. Within the framework of this dissertation, the tuffaceous,
analcimized and bituminous fine-grained clastites of Čučale and fine-grained clastites of Prebreza
deposited in lake or swamp lithofacies were examined. Swamp sediments were only detected within
the borehole BL5.
Volcanism characterized the deposition of sediments in the Toplica basin, which was reflected
in the presence of volcaniclastic material along the vertical profiles of the examined boreholes.
Volcanic processes were more pronounced in the western subbasin unit, which was indicated
by the higher content of analcime in the sediments of borehole BL7, as well as the appearance of a 7
m thick package of tuffs. Significant proportions of volcaniclastic material transported from the
western part into the basin enhanced the proliferation of algal and planktonic communities,
simultaneously increasing primary productivity, which affected organic matter content. The
development of the Toplica Basin was accompanied by crustal thinning that led to an increased
thermal flux from the lithosphere, which caused overheating of the organic matter and further
stimulated the production of hydrocarbons and an increase in their total content. The organic matter
in sediments of the borehole BL7 was immature to early mature and composed of type I or II kerogens,
which tend to generate liquid hydrocarbons. The accumulation and preservation of organic matter in
BL7 sediments were attributed to the anoxic and meso-saline or hypersaline paleoenvironmental
conditions, which is evidenced by the predominance of phytane, presence of i-C30, β-carotane,
perylene, gammacerane, δ-methyltrimethyltridecyl chroman, 1,5- and 1,4-dimethyl carbazoles.
The deposition of sediments in the eastern part of the Toplica basin was characterized by intense
alluvial-lacustrine processes, which were reflected in the pronounced presence of sand and gravel
components throughout the borehole BL3 and, to a lesser extent, in well BL5. Sand and gravel
components significantly diluted the organic matter of the investigated sediments, which was
immature and consisted of type III kerogen or mixed type II/III kerogen. The predominance of odd
Doktorska disertacija Nikola M. Burazer
long-chain n-alkanes (n-C27, n-C29 and n-C31) and hopane in investigated sediments indicated an
increased participation of higher plants or microbiologically reworked organic matter. The
paleoenvironmental conditions were generally anoxic and very dynamic. The sedimentation
dynamics were influenced by the energy of the lake and the alluvial system through which a large
amount of clastic material of different sizes was transported. The clastic material transported organic
matter of mixed origins and stratigraphy, indicating resuspended organic matter in the eastern
subbasin unit. The organic matter deposited under these circumstances reflected complex information
about paleoenvironmental conditions.
Given that higher terrestrial plants were the dominant precursor in the organic matter of
boreholes BL3 and BL5, the possibility of considering the influence of paleoclimatic conditions on
the distribution and relative abundance of hydrocarbons opened up. Paleoclimatic conditions reflected
the occurrence of specific plant taxa in the organic matter of the investigated sediments. Namely, high
C-value and Rb/Sr ratios, low Sr/Cu ratio values, followed by greater participation of saturated and
aromatic triterpenoids originating from angiosperms, characterized a large group of investigated
sediments. The results of inorganic geochemical parameters and the presence of angiosperms
suggested warm and semi-humid/semi-arid to semi-humid paleoclimate conditions. The obtained data
were in accordance with the previous paleoclimatic research of Neogene basins of the southeastern
part of Europe.
On the other hand, tectonic processes of crustal extension and uplift (exhumation) of the
Jastrebac complex followed the development of the Toplica basin during the Neogene. Differences
in sedimentological, lithological, mineralogical and organic-geochemical characteristics along the
vertical profile of the BL4 borehole indicated the occurrence of cyclicity in deposition and
lithomembers A, B, C and D. In this case, cyclicity is associated with tectonic processes. The
formation of a natural "barrier" (exhumed Jastrebac complex) controlled the flow of clastic material
from the margins to the western and eastern parts of the studied basin. During the initial phase of the
development of the Toplica basin, a natural "barrier" prevented the transport of eroded material that
characterized the sediments of the eastern sub-basin unit. Therefore, lithomembers A and B reflected
the type of organic matter and paleoenvironmental conditions similar to those in the sediments of the
western part of the Toplica basin (borehole BL7). A calm, anoxic and mesosaline paleoenvironment,
stored with macro- and micro-nutrients released during volcanic processes, characterized the
formation of lithomembers A and B. This was evidenced by significant amounts of analcime, the
predominance of phytane, significant concentrations of i-C25 and i-C30, and the pronounced presence
of β-carotene. The organic matter was predominantly enriched in algal precursors.
Sedimentation continued with the formation of lithomembers C and D. At that point, a natural
"barrier" prevented the transport of eroded material from the western subbasin unit. Therefore, the
organic matter reflected the type and paleoenvironmental conditions similar to those in the sediments
of the eastern part of the Toplica basin (boreholes BL3 and BL5). The organic matter was of mixed
origin, deposited under anoxic-dysoxic and freshwater environmental conditions. In support of this,
a more pronounced presence of the sandy fraction supplied by the alluvial system, fluctuating values
of the Pr/Ph ratio, reduced concentrations of i-C25 and i-C30, as well as the absence of β-carotene
characterized these lithomembers.
Sedimentation in the Toplička basin ended with the deposition of coarse-grained and medium-
grained clastites from all margins, which slowly ended the sedimentation and indicated the extinction
of the Neogene lake basin.