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European Journal of Applied Sciences – Vol. 11, No. 1

Publication Date: February 25, 2023

DOI:10.14738/aivp.111.13908.

Aliaj, S., & Mesonjesi, A. (2023). Scholar’s Viewpoints About Periadriatic Basin (Onshore Albania). European Journal of Applied

Sciences, Vol - 11(1). 383-407.

Services for Science and Education – United Kingdom

Scholar’s Viewpoints About Periadriatic Basin (Onshore Albania)

Shyqyri Aliaj

Retired from the Institute of Seismology, Academy of Sciences of Albania

Agim Mesonjesi

Faculty of Geology and Mining, Polytechnic University of Tirana

ABSTRACT

The Albanian and foreign scholar’s viewpoints about the structure formation of the

Periadriatic Foredeep Basin are summarized based on the data taken from the

following two investigated field studies: a) the geological & geophysical studies and

b) the seismotectonic studies for the November 26, 2019, Mw 6.4 Durres

earthquake. Based on the investigated geological and geophysical studies for the

formation of the Periadriatic Basin Structure the two different scholar’s opinions

are examined, as follows: (i) The first scholar’s group formed by Papa (1971), Velaj

et al. (1999), Skrami & Aliaj (1995), Skrami (2001), Melo (2002), Aliaj et al. (1995,

2018), Aliaj (1998, 2000, 2004, 2006, 2012, 2021) and Bega (1995) explained the

formation of the Periadriatic Basin structure through a rearranged (superimposed)

development, and (ii) the second scholar’s group formed by Roure et al. (2004),

Scrocca et al. (2008), Bega and Schleder (2017) and Bega (2020) explained the

Periadriatic Basin formation through an inherited development. Xhafa et al. (2002)

and Xhomo et al. (2002, 2005) explained the formation of the central part of the

Periadriatic Basin through inherited development, while its marginal parts through

the rearranged development. The Periadriatic Foredeep Basin is a Pull-apart Basin

installed in the Middle Miocene (Serravallian) between the South Adriatic Basin and

Tirana marginal basin, where it takes a graben shape delimited by the Durresi- Frakulla and PrezaRova-Bishqemi normal faults. The investigated seismotectonic

studies for 26 November 2019, M6.4 Durres earthquake reveal the architecture of

the Adria-Albanides collision that played the main role in the structural

rearrangement of the Periadriatic Basin due to the pre-Serravallian or ends

Langhian, intra-Messinian, Miocene-Pliocene boundary and early Pleistocene

compressional tectonic phases. Deformation of orogenic crust at the Albanides- Adria collision zone during Tertiary occurred and occurs into both levels: i) a basal

fold-and-thrust system in the Ionian Zone, that accommodated an increasing

amount of SW directed shortening, and ii) a structurally higher system of thrust

faulting affecting the overlying structure of the Periadriatic Depression, that

underwent a strong structural rearrangement.

Keywords: Periadriatic Basin, Albania. Structural formation through the rearranged or

inherited development.

INTRODUCTION

The Periadriatic Basin onshore Albania is the only Foredeep basin that is located in the frontal

part of the Albanides orogeny bordering eastward the Adriatic Foreland. It is formed as a

dextral pull-apart basin in Middle Miocene (Serravallian), subsequently to the main folding and

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thrusting of the Ionian Zone, through the strike-slip faulting mechanism. Two elements that

commonly develop the formation of the Periadriatic Foredeep Pull-apart Basin are the Drini

Bay-Lezha and Vlora- Bishqemi cross-basin strike-slip faults, and the Durresi-Frakulla and

Preza-Rova-Bishqemi basin sidewall oblique normal faults (Aliaj & Mesonjesi, 2022; see Fig. 1).

The Periadriatic Foredeep Basin is a Pull-apart Basin installed in the Middle Miocene

(Serravallian) between the South Adriatic Basin and Tirana marginal basin, where it takes a

graben shape delimited by the Durresi-Frakulla and Preza-Rova-Bishqemi normal faults (Aliaj

& Mesonjesi 2022).

Figure Tectonic Map of Albania shows in blue color two elements that commonly develop

formation of the Periadriatic Basin: (a) The Durresi Frakulla (DF) and Preza Rova- Bishqemi

(PRB) sidewall oblique normal faults, and (b) Drini Bay Lezha (DL) and Vlora- Bishqemi (VB)

cross-basin vertical strike slip faults, as well as the

The sedimentation in the Periadriatic Depression was controlled by intense syn-sedimentary

tectonics. The en-echelon basin margin normal fault system formed since the Middle Miocene

(Serravalian time) consists of the following two oblique normal faults:

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Aliaj, S., & Mesonjesi, A. (2023). Scholar’s Viewpoints About Periadriatic Basin (Onshore Albania). European Journal of Applied Sciences, Vol - 11(1).

383-407.

URL: http://dx.doi.org/10.14738/aivp.111.13908

(i) the NNW trending west dipping Preza-Rova-Bishqemi normal fault that has delimited

from the east the Periadriatic foredeep, nowadays observed as backthrust, and

(ii) the east-dipping Durresi-Frakulla (DF) normal fault, which is now represented by thrust

and backthrust faults shows the effect (consequence) of the Albanides orogen-Adria

collision in the surface of the Periadriatic Depression (see Fig. 2).

The Neotectonic Map of Albania in scale 1:1,000,000 shows in blue color the structural

elements that shape the Periadriatic Depression (PAD) with two depocenters, and Tirana

Depression (TD), as well as the active Albanides frontal thrust (see Fig. 2).

Figure 2 Neotectonic Map of Albania in scale 1:1000 000 shows in blue color structural element

that shape the Periadriatic depression (PAD) with two depocenters and Tirana depression

(TD)as well as the active Albanides frontal thrust (modified frontal Alia 1988. Main element of

Periadriatic basin are the DL-Drini Bay-Lezha and VB Vlora-Bshqemi Strieslip faults and the

DF-Durres-Fraulla and PRB-Preza-Rova-Bshqemi basin sidewall faults the active Albanides

frontal thrust is consisted of the following segments: DF-Durres-Frakulla, VB-Vlora-Bishqemi

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and OD-Othoni Island-Dhermi strikeslip faults. The LU-Lezha-Ulqini segment belongs to the

Dinarides. The north of sazani island transversal faults (NSI) marks the boundary between the

Apulian platform and the south Adriatic( after Aliaj & Mesonjesi,2022).

I. Regions subjected to uplifting tendency during the neotectonic period: 1. Regions subjected

to uplifting usually from the Middle Miocene, but more strongly after the beginning of the

Pliocene, with isolines of neotectonic deformations in m. 2. Oligocene to Lower Miocene

molasse basins which underwent uplifting from the Middle Miocene, with isolines of

neotectonic deformations in m.

II. Regions subjected to subsiding tendency during the neotectonic period: 3. Miocene (from

Middle Miocene) molasse basins subjected to uplifting in post-Miocene time (m), Miocene

(from Middle Miocene) to Pliocene molasse basins subjected to uplifting at the beginning of

the Quaternary (m2pq1). 4. Pliocene marine or lake basins (p) subjected to uplifting in

Quaternary; Pliocene to Lower Pleistocene Lake basins (pq1) subjected to uplifting from

Middle Pleistocene; Subsiding Pliocene to Quaternary depressions (pq). 5. Subsiding

Quaternary depressions (q). 6. Isolines of Pliocene floors in some depressions.

III. Structural elements and others: 7. Nappe boundaries deformed by normal faults during the

neotectonic period, 8.

Reverse faults-thrusts, 9. Normal faults, 10. Flexures and faults detected by seismic

exploration, 11. Strike-slips, 12. Active evaporite dome, 13. Inactive thrusts.

The Periadriatic Foredeep Basin is a Pull-apart Basin installed in the Middle Miocene

(Serravallian) between the South Adriatic Basin and Tirana marginal basin, where it takes a

graben shape delimited by the Durresi-Frakulla and Preza-Rova-Bishqemi normal faults (Aliaj

& Mesonjesi 2022).

There are two scholar groups that have explained the structure formation of the Periadriatic

Basin in different manners, as follows: i) one scholar’s group have explained through a

rearranged (superimposed) development, and ii) the other scholar’s group have explained

through an inherited development. That’s why we aim to review all Albanian and foreign

scholar’s studies about the structural formation of the Periadriatic Basin and based on their re- examination propose the possible manner of the structural formation of the Periadriatic Basin

using two investigation field studies: a) Geological & Geophysical Studies about Periadriatic

Basin, and b) Seismotectonic Studies for November 26, 2019, Mw 6.4 Durres Earthquake.

GEOLOGICAL SETTING

In Albania and Greece, along the southern convergent margin of the Eurasia Plate, a northern

segment of the margin belonging to the Adriatic continental collision, and a southern one

belonging to the Aegean (Hellenic) Arc related to active oceanic subduction could be

distinguished. The Adriatic-Eurasian collision happened along the western coast of former

Yugoslavia, Albania and central Greece. The boundary between the Aegean Arc and the Adriatic

collision is the Cephalonia transform fault (see Fig. 3).

The Albanides is divided into the external collision domain in compression characterized by

reverse faulting, and the internal domain in extension characterized by normal faulting. The

Albanides (frontal part of the Eurasian plate) collides with the Adria Microplate that is

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Aliaj, S., & Mesonjesi, A. (2023). Scholar’s Viewpoints About Periadriatic Basin (Onshore Albania). European Journal of Applied Sciences, Vol - 11(1).

383-407.

URL: http://dx.doi.org/10.14738/aivp.111.13908

fragmented into two subplates: The Apulian platform from Sazani Island to the south, and the

Albanian basin (=South Adriatic basin) to the north of it (Aliaj 2006, Aliaj et al. 2018). The

Albanides orogenic frontal thrust is divided into the northwest-trending Lefkas-Corfu segment,

and the generally north-south trending Dhermi-Durres segment.

We concentrate our study on the structural formation of the Periadriatic Basin through the

rearranged or inherited development, using two investigation field studies: a) Geological &

Geophysical Studies about Periadriatic Basin, and b) Seismotectonic Studies for November 26,

2019, Mw 6.4 Durres Earthquake.

IS THE STRUCTURE OF THE PERIADRIATIC BASIN FORMED THROUGH

INHERITED OR REARRANGED (SUPERIMPOSED) DEVELOPMENT?

The Albanian and foreign scholar’s viewpoints about the structural formation of the

Periadriatic Foredeep Basin are collected below based on the data of two investigated field

studies: a) the geological & geophysical studies and b) the seismotectonic studies for the

November 26, 2019, Mw 6.4 Durres earthquake.

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Investigations of the Geological & Geophysical Studies for the Structural Formation of

The Periadriatic Basin

The Periadriatic Depression is first named by Mishunina (Mishunina and Ivanova, 1957) who

comprised into it the lowered hypsometrically onshore part of Albania, where the Pliocene and

Quaternary deposits are outcropped (see Figure 1). It has been considered a small

southeastern part of the so-called by her Periadriatic Zone developed within wide areas of the

Adriatic Sea up to the Italian borders. The small surfaces of the Middle-Upper Miocene

sediments are outcropped along the periphery of the Periadriatic Depression, as well as in

Tirana Depression and in Memaliaj and Dukat areas. The Periadriatic Basin originated at the

start of the Middle Miocene time as a foredeep basin; its deepest central part is located in Erzeni

river basin. So, Mishunina has distinguished both Periadriatic and Tirana depressions. The

Frakulla, Ardenica, Divjaka, Kryevidh and Lushnja Pliocene anticlines marked into the

Periadriatic Depression were shaped at the end of the Pliocene time. The Korabi, Albanian Alps,

Mirdita, Tomorri and Periadriatic zones are distinguished by Mishunina in tectonic zonation of

Albania (see Fig. 4).

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Aliaj, S., & Mesonjesi, A. (2023). Scholar’s Viewpoints About Periadriatic Basin (Onshore Albania). European Journal of Applied Sciences, Vol - 11(1).

383-407.

URL: http://dx.doi.org/10.14738/aivp.111.13908

Papa and Biçoku (1965) haven’t reflected the Periadriatic Depression on the Tectonic

Scheme of Albania, whereas in its place is shown the prolongation of the Ionian Zone towards

the north-northwest. Only in the description of the Scheme of Structural Stories separated in

the geological building of Albania, Papa and Biçoku (1965) underlined that the Upper

Helvetian-Upper Miocene molasse deposits overly transgressively and unconformably on the

older deposits of some peripheral parts of Periadriatic Depression and in Tirana Depression

too.

Papa (1971) pointed out that the Preadriatic Depression which is located in the northern part

of the Ionian Zone has been established after the folding of the Ionian zone, That part had not

emerged after the Ionian zone folding, the terrigenous sedimentation continued there since the

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Lower Helvetian and during all Miocene. Some structural chains are distinguished on

Preadriatic Depression which is considered a continuation of the anticlinal and synclinal chains

of the Ionian zone. Both the Periadriatic Depression and that of Tirana are superimposed

depressions, one over the Ionian zone and the other over the Kruja zone. They represent the

southeastern margin of the major Adriatic depression that takes place in the Adriatic offshore.

Velaj et al. (1999) show that the Durres basin is the major hydrocarbon-producing zone in

Albania, extending from the central southwest of Albania to the south and offshore into

western Greece, where it is known as the Periadriatic depression. It is filled with Neogene–

Quaternary sedimentary rocks. The basin lies unconformably on the folded and thrusted Ionian

zone to the southeast and the Kruja zone to the east. The Vlora-Elbasan Lineament, which is

shown in the Tectonic Map of Albania, is supposed to pass along the southern boundary of the

Periadriatic Depression.

Skrami & Aliaj (1995) and Skrami (2001) underlined that Periadriatic Basin formed after

the main folding and thrusting of the Ionian zone. It is filled with Middle Miocene-Pliocene

molasse formation which is transgressively placed over the Ionian and Kruja zones along its

eastern and southern borders. The geological structure of the Periadriatic Depression is well

known from the seismic explorations carried out by foreign companies there and westwards

it, in the Adriatic offshore. The Periadriatic Depression is built by some linear relatively narrow

anticlines and wide synclines. The positive structures of the western coastal part are well

expressed on the relief: the anticlines are represented by hills while the synclines are buried

under Holocene plains between them. The structure of the Periadriatic Basin finally is shaped

by the Early Pleistocene compressional phase. The Quaternary deposits horizontally and with

unconformity overly the folded Mio-Pliocene structures of Periadriatic Depression. There are

marked the Periadriatic and Tirana depressions on the Tectonic Map of Albania. The Durresi,

Kryevidhi, Ardenica and Preza backthrusts are shown through seismic lines.

Melo (2002) has considered the Periadriatic Depression as a foredeep basin located at the

Albanian orogen front, that borders to the west with the Adriatic plate. It is filled by the Middle- Upper Miocene and Pliocene molasses. The Miocene (Serravalian-Tortonian-Messinian)

molasse is with unconformity placing over the Burdigalian-Langhian deposits and Oligocene- Aquitanian flysch one or the limestones of Sazani, Ionian and Kruja zones. Such important

discordance is more accentuated in the margins of the Periadriatic Depression, while

westwards it is not clearly observed. The Pliocene molasse transgressively and with

unconformity overlies the Miocene molasses. The Pliocene and Quaternary are overlying with

unconformity at the western margin up to the limestones of the Apulian platform. The

Periadriatic structure is represented by some anticline and syncline ranges that are well

expressed on the relief. The following structural lines are distinguished from its eastern margin

westwards: Tirana syncline, Preza monocline, Erzeni i poshtem syncline and Lushnja-Kavaja- Golemi-Shkoza anticline, Myzeqe syncline and ArdenicaKyevidhi anticlinal line.

Xhafa et al. (2002) pointed out that Adriatic Depression represents a foredeep basin overlying

the Sazani, Ionian, and Kruja zones as well as the South Adriatic Basin. The Adriatic Depression

is characterized by the Middle-Upper Miocene-Pliocene terrigenous sediments that overly with

unconformity on the eastern marginal part (Tirana-Ishmi Depression and east of Ardenica

anticline), whereas they are successively overlying on the central part of Adriatic Depression

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383-407.

URL: http://dx.doi.org/10.14738/aivp.111.13908

into which are included the onshore parts from GolemKavaja anticlinal line westwards to

Ardenica-Durresi anticlinal line, as well as on the offshore part generally not deformed.

Xhomo et al. (2002, 2005) underlined the viewpoint of the inherited development of

Periadriatic Depression that is well marked in the geological profiles III-III, IV-IV, V-V, VI-VI

and VII-VII of the Geological Map of Albania in scale 1: 200,000 and in its Explanatory Text (see

Xhafa et al. 2002).

Roure et al. (2004) show both the Periadriatic and Tirana depressions, and the Vlora-Elbasan

Transfer Zone on the Structural map of the Outer Albanides. The Vlora-Elbasan major

lineament is likely to be connected with a deeply buried basement fault. They pointed out the

following: “The Periadriatic Depression is characterized by a thick terrigenous synflexural

(Oligocene flysch) and synkinematic (Neogene molasse) series, which is presently detached

from its former Mesozoic carbonate substratum. The total thickness of the Cenozoic siliciclastic

series imaged on seismic profiles frequently exceeds 7 km. Although the pre-Oligocene

substratum has never been reached by drilling, it is assumed to be basinal in type, likely

resembling the Ionian Basin farther to the south or the Adriatic offshore in the west. There are

used seismic profiles for the construction of two transects: (1) the northern transect from

Durresi to Kruja zone, and (2) the southern transect from Ardenica to Ionian Zone. The

northern part of the Outer Albanides comprises two distinct domains: (1) the Peri-Adriatic

Depression in the west, where only the Neogene molasse of the foredeep crops out at the

surface; and (2) the Kruja Zone or Platform, which comprises thrust anticlines of Mesozoic

platform carbonates. The Oligocene flysch and pelitic interbeds of the Neogene molasse

constitute major decoupling horizons in the Peri-Adriatic Depression. We assumed the western

part of the platform domain was again involved in the Pliocene-Quaternary deformations, thus

accounting for a progressive wedging of the terrigenous sequences of the Peri-Adriatic

Depression, which became progressively thrust backward and eastward on top of the Kruja

duplexes” (see Fig. 5).

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Scrocca et al., 2008 underlined that the external portion of this orogen (i.e., the Outer

Albanides) shows some remarkable peculiarities, as for instance the presence in its central and

northern sectors of a deep basin, the so-called Periadriatic Depression. This basin, filled with

Neogene-Quaternary siliciclastic and terrigenous deposits more than 6 km thick, developed in

Miocene times when the Albanian off-shore and the frontal zone of the outer Albanides

accretionary prism (deformed in Late Oligocene-Middle Miocene) were affected by unexpected

strong subsidence. Although the Peri-Adriatic Depression is generally interpreted as the

Albanides foredeep basin, its offshore depocenter is characterized by a thinned continental

crust (<24 km), an anomalously high heat flow (>80 mW/m2), and a still persisting

physiographic depression.

Aliaj (1998, 2000, 2012, 2021), Aliaj et al. (2018); Meço & Aliaj (2000) pointed out that

the Periadriatic Depression comprising the hilly and plain terrains of the western Lowland of

Albania originated in Middle Miocene, since the Serravallian, subsequently to the main folding

and thrusting of the Ionian Zone. It is located in the frontal orogenic part, between the Lezha

and Mali i Kanalit Block-Dumre diapir transfer fault zones (Aliaj 2021). The Mali i Kanalit

Block-Dumre diapir dextral transfer zone delineates the northern boundary of Çika,

Kurveleshi, and Berati anticlinal belts of the Ionian zone, and forms also the southern boundary

of the Periadriatic Depression (Aliaj, 2021; see Fig. 6).

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383-407.

URL: http://dx.doi.org/10.14738/aivp.111.13908

The Mali i Kanalit Block-Dumre diapir transfer fault zone consists of two dextral strike-slip

faults: i) the northern one, named the Vlora-Bishqemi strike-slip fault, that forms the southern

boundary of Periadriatic Depression, starts at Gjiri i Ariut-Dukat i Ri sinistral strike-slip and

follows towards NNE in Vlora City, near Patosi town, west border of Dumre diapir up to

Bishqemi village north of Dumre diapir, dislocating (cutting) from the south the Panaja and

Frakulla anticlines, and anticlinal line of Lushnja-Kavaja-GolemiShkoza, and ii) the southern

one, named as the Othoni Island-Dhermi strike-slip fault follows towards NNE in the west of

Shkoza village, near to Berati town up to the offset of Devolli river to the east of Dumre diapir,

separating the north-west trending Lefkas-Corfu segment from the generally north-south

trending Dhermi-Durres segment of the Albanides orogenic frontal thrust.

The Periadriatic Depression is considered as a foredeep basin installed over the folded and

thrusted Ionian zone and has a different structural plan. The geological structure of the

Periadriatic Depression is well known from the seismic explorations carried out by foreign

companies there and westwards it in the Adriatic offshore. The Early Pleistocene

compressional phase caused the folding and thrusting of the Periadriatic Depression. The Mio- Pliocene anticlines are superimposed over thrust or backthrust faults, s some of them "flower"

structures of "palm tree" type. The thrust and backthrust faults originated from the inversion

Figure 6 : Tectonic Map of the Mali i Kanalit

Block - Dumre diapir dextral strike -slip fault

zone NNE trending in transpression that crosses

the Albanides Collision Zone in NE-SW

compression (after Aliaj, 2021). Map based on

Tectonic Map of Albania in scale 1:200,000

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of syn-sedimentary normal faults due to the post-Pliocene regional compression. The seismic

and geological cross sections passing through the Ardenica and Durresi hills show that thick

Oligocene to Quaternary clastic sediments of the South Adriatic Basin (=Albanian Basin) was

detached from their carbonate substratum through a detachment fault maybe at the base of

Oligocene clastics. The clastic sediments were largely back-thrusted onto the Ionian Zone

frontal structures, which are deeply buried underneath the Middle Miocene-Pliocene molasses

of the Periadriatic Foredeep Basin (Aliaj, 2020). The so-called Durresi anticline shows the

major contact between the Eurasia Plate (frontal part of Albanides Fold-and-Thrust Belt) and

Adria Microplate. It is built by the high-angel west dipping backthrust of the Upper Miocene

sediments of the Adria Microplate that overlies the western flank of the Durresi narrow

syncline (see Fig. 11). The Durresi and Ardenica backthrusts are not part of Periadriatic

Depression; they are formed during the Adria Microplate - Albanides Collision and haven’t been

synsedimentary faults, as the Preza backthrust is.

Bega (1995) pointed out the thrust and backthrust tectonics in external Albanides using the

results of geological and seismic investigations carried out. He distinguished the following

structural lines of the Periadriatic Depression: 1) the backthrust of Preza Monocline, 2) the

Tikas-Karbunare-Mlik-Golem

Kavaje-Shkoze anticlinal line having a thrust and backthrust system (backthrust of Rrogozhine,

Mlik, Kavaje), 3) Ardenice-Divjake-Kryevidh-Durres-Palla anticlinal line that has the thrust of

Divjaka and backthrusts of Ardenica and Kryevidh-Durres-Bisht Palla, and 4) thrust of Panaja- Frakull anticlinal line. The Durres-Palla backthrust north-south trending is well evidenced in

the seismic profile RO-132 north of Bisht Palla (see Fig. 1). The Upper Miocene deposits outcrop

only along the Durres-Palla backthrust that belong to the Adria Microplate, while eastwards in

the Periadriatic Depression are outcropped the Pliocene sediments. Bega (1995) arrived at the

following conclusions: (1) the continuation to the north of Vlore(Lushnje)-Elbasan transversal

fault of the Ionian zone orogeny beneath the Middle Miocene (since Serravalian)-Pliocene

molasses of Periadriatic Depression, (2) the Pliocene and post-Pliocene compressional phases

led to the final shaping of Periadriatic depression folding structure dislocated with thrust and

backthrust faulting.

Bega and Schleder (2017) suggested that Montenegro and NW Albania share the same

Mesozoic platform plays. The basis for this model is the vast geological and geophysical data

gathered during the mid-90's and early 2000. This data set can be interpreted so that it allows

for the presence of another hydrocarbon province yet to be found in the NW Albania–

Montenegro region. This new play consists of deep-seated contractional structures made up of

Mesozoic platform units that are buried underneath the frontal zones of the thin-skinned

Kruja-Dalmatian thrust belt. The shallow, thin-skinned thrust belt has a westward vergence

with the structures implying a shortening of about 50 kilometres. The main detachment

horizon is the Oligocene shales for this level. Seismic and gravity data suggest that this thin- skinned belt was subsequently folded by a deeper system of thrusts. These deep thrust slices

are interpreted to detach on the Triassic salt level and accommodate a shortening of about 10

km. At shallower levels, both shortening are accommodated by regional back thrusts (Durres- Palla and Ishem-Preza-Rodoni). They suggested that the most important play type in this area

is this structurally inverted platform carbonates. These deeply buried platform carbonate

antiforms resemble those in the Southern Apennines of Italy. A deep SE-NW trending

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URL: http://dx.doi.org/10.14738/aivp.111.13908

anticlinorium with platform carbonate units is interpreted in the onshore Albania–Montenegro

region. The anticlinorium, which is stretched for about 140 km towards onshore Montenegro

comprises a cluster of several structural closures. The structural inversion is relatively young

and it is related to post-Miocene deformations.

Bega (2020) reviewed the Mesozoic carbonate architecture and its role in overall Neogene

deformations in Durres-Buna Region. The author paid much attention to Neogene backthrusts

and Mesozoic carbonate settings in two examples: a) Offshore Montenegro and b) Offshore- Onshore NW Albania using seismic and key well data. In the Offshore-Onshore NW Albania

region, through some geological-seismic sections, three regions with different carbonate

architecture are identified from west to east as follows: 1) South Adriatic Basin (SAB) in the

west, 2) thick-skinned carbonates in the centre, and 3) Kruja imbricates in the east. Very

important results are taken from the following two geological-seismic sections: a) RO-91-134

+ 95ASB104 and b) RO-91-150 + 15-88 (see Figs 7, 8).

Figure 7: Off-Onshore Albania Seismic Example Ro-91-134 + 95ASB104– South of Rodoni Area (after

Bega, 2020).

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The obtained from both geological-seismic sections main conclusions are: 1) The features of

the SAB offshore and thick-skinned in onshore are well marked, 2) deep-seated not deformed

carbonates of SAB reach a depth of 14 km ( ~ 7 sec TWT) along the basin axis, 3) thick-skinned

carbonates generally are inverted/thrusted with thin Oligocene cover on top, while the top

Mesozoic carbonates are depicted at around 4.5-5.0 sec TWT depth, 4) the uplifted structures

in form of anticlines are observed in thick-skinned carbonates deeply buried beneath the

molasses of Periadriatic Depression, 5) the Rodoni and Shkoza structural highs are marked on

the tectonic schematic map, 6) Kruja thrust likes a mega-thrust ramp, 7) Preza backthrust

follows to the west the molasse base of Periadriatic Depression and is finally connected with

the Durres-Palla backthrust, whereas it is connected also with the Shkoza thrust. Such a

backthrust network is mainly due to the Kruja wedge drifting westward. 8) the Neogene setting

shows that the eastern backthtrusts (Krraba, Preza and Adriatic ones) follow the Kruja front,

while the eastern backthrusts (Mliku, Durres-Palla, and Rodoni ones) follow the thick-skinned

Mesozoic margin, 9) two major backthrusts (Durres-Palla and Preza ones) are due to the post- Pliocene thrusting, 10) the such a Neogene setting of backthrusts has been caused by a

combination of Kruja wedge and deep-seated Mesozoic carbonates.

Bega and Schleder (2017) and Bega (2020) were inspired by Roure et al. (2004) geological

model of an inherited development of Periadriatic Depression. They suggested that the

present-day geological structure of Periadriatic Depression was formed by the post-Pliocene

compressional phase due to the common mechanism of Durres-Palla and Preza backthrusts

that detached from its former Mesozoic carbonate substratum the Neogene molasse deposits

of it.

Seismotectonic Investigation Studies for November 26, 2019, Mw 6.4 Durres Earthquake

Reveals The Architecture of the Active Frontal Thrust of the Adria-Albanides Collision

that Leads to the Structural Formation Of The Periadriatic Basin

Aliaj (2020) paid special attention to the present-day tectonics of the Adria-Albanides

collision zone and the geometry of the main Albanides thrust that was quantified based on the

fault plane solutions for November 26, 2019, Mw 6.4 Durres earthquake and other earthquakes

events in Albanides collision zone. Here, the inferred geological and geophysical (seismic and

gravimetric) data for the Albanides, and separately for the Periadriatic Foredeep Basin were

also used. The Albanides collision zone is situated in an area lying between the Adria-Albanides

Figure 8: Off-Onshore NW Albania Seismic Example from South Adriatic Basin to Kruja Thrust Front

(after Bega, 2020).

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383-407.

URL: http://dx.doi.org/10.14738/aivp.111.13908

collision thrust and Kruja nappe front. In the seismic and geological cross sections passing

through Ardenica and Durresi hills two structural stories could be distinguished: an upper

story or ‘superstructure’ which shows the tête à tête Adria-Albanides collision, and a lower

story or ‘infrastructure’ that shows deep Earth crust part of the Adriatic block. Both the fault

plane solutions determined by various agencies for the November 26, 2019 earthquake and

the focal plane solutions determined by GFZ for main shock and two aftershocks of magnitude

greater than 5 of the November 26, 2019 earthquake show that they occurred on the NNW-SSE

striking frontal blind thrust of low-angle dipping towards the east, locating on the main basal

thrust separating the Adria microplate underthrusting beneath the Albanides that is called the

main Albanides thrust (MAT), as follows: a) The fault plane solutions determined by various

agencies identify that the November 26, 2019 Mw 6.4 Durres earthquake was generated by an

NNW-SSE striking (337o) blind thrust fault low-angle (21o) dipping towards the east (97o) that

locates within the frontal area of the main basal thrust of the Albanides, and b) the focal plane

solutions for the main shock and the two aftershocks of magnitude greater than 5 of the

November 26, 2019 earthquake determined by GFZ show that they occurred on the NNW-SSE

striking (335o) frontal blind thrust of low-angle (22o) dipping towards the east (97o) locating

on the main basal thrust.

The seismic and geological cross sections passing through the Ardenica and Durresi hills show

that thick Oligocene to Quaternary clastic sediments of the South Adriatic Basin (=Albanian

Basin) was detached from their carbonate substratum through a detachment fault maybe at

the base of Oligocene clastics. The clastic sediments were largely backthrusted onto the Ionian

Zone frontal structures, which are deeply buried underneath the Middle Miocene-Pliocene

molasses of Periadriatic Foredeep Basin (Figs. 9, 10).

An excellent seismic section passing through the Ardenica hill (north of Fieri) reveals the gently

eastdipping Cretaceous-Eocene carbonate substratum of the South Adriatic Basin (Adria

Microplate) beneath the buried Ionian structures overlain by the Middle Miocene-Pliocene

molasses of Periadriatic basin. Here the eastwards backthrust of the clastic sediments of the

Albanian Basin for about 50 km onto the PatosVerbasi carbonate structures is identified

(Figure 9).

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Seismic section through Adriatic offshore, 15 km north of Durres city, shows that the clastic

sediments of the Albanian Basin were largely backthrusted onto the frontal margin of buried

Ionian zone forming a triangular zone at the depth, the same as at the Ardenica hill (Figure 10).

Here, the backthrust of Oligocene to Quaternary clastic sediments has cut and displaced the

marine Quaternary sediments. It identifies here the present-day activity of the Adria-Albanides

collision.

The Periadriatic Depression structure is built by NNW trending narrow anticline and wide

syncline lines. From southwest to northeast are distinguished: Frakulla-Ardenica-Durresi

anticlinal line, Myzeqe syncline, Lushnja-Golem Kavaja anticlinal line, Erzeni i poshtem

syncline, and Preza monocline (see Fig. 11). The positive structures are well expressed on the

topography except the Povelça-Semani anticline, which is buried under Quaternary deposits;

so, the anticlines build hills, while the synclines are buried under Holocene plains.

Figure 9: Seismic section from Adriatic coastline eastwards, passing slightly north of Fieri town, shows

the large backthrust of deformed clastic sediments of Albanian Basin over the Ionian Zone blind thrust -

bounded imbricates. Beneath them is evidenced the gently east dipping Cretaceous-Eocene carbonate

substratum of South Adriatic Basin (after Aliaj 2006).

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Aliaj, S., & Mesonjesi, A. (2023). Scholar’s Viewpoints About Periadriatic Basin (Onshore Albania). European Journal of Applied Sciences, Vol - 11(1).

383-407.

URL: http://dx.doi.org/10.14738/aivp.111.13908

Deformation of orogenic crust at Albanides-Adria collision zone during Tertiary occurred and

occurs into both levels: i) a basal fold-and-thrust system in the Ionian Zone, that accommodated

an increasing amount of SW directed shortening, and ii) a structurally higher system of thrust

faulting affecting the overlying structure of the Periadriatic Depression, that underwent a

strong structural rearrangement (see Fig. 11).

Ganas et al., (2020) using the GNSS/INSAR Deformation caused by the M6.4 Durres (Albania)

Nov. 26, 2019 Earthquake, reveal that the earthquake occurred deep in the crust on a low-angle

fault (23o) dipping towards east with a centroid at 16.5 km depth. The best-fitting length and

width of the fault are 22 and 13 km, and the reverse slip, 0.55 m. This geometry is compatible

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with a blind thrust fault that may root on the main basal thrust, i.e., along the thrust front that

separates Adria–Apulia from Eurasia.

Handy et al. (2020) identified the main source of the M 6.4 Albanian earthquake of Nov. 26,

2019 that rocked north-central Albania on November 26, 2019 to be located within the frontal

area of the basal thrust of the Dinaric-Hellenic orogen. This earthquake was easily felt some

400 km away and was the strongest to affect the eastern Adriatic coast since the M7.1 event

that struck Montenegro in 1979. Already two months earlier on Sept 21-22, several M5

earthquakes hit the same area. According to the USGS and EMSC/CSEM, all 2019 events

occurred within a c. 40 km wide epicentral area extending along strike of the front of the

northernmost Hellenides between the city of Durres to offshore of the town of Lezhë. A depth

interval of 10-20 km was poorly constrained for these events, with hypocenters located below

the Periadriatic Foredeep Basin made up of deformed and poorly consolidated Neogene and

Pleisto-Holocene sediments. For the M6.4 event, InSAR images from the Sentinal-1 satellite

indicate up to 7 cm of epicentral uplift and a centroid depth of c. 17 km for the M6.4 event. By

combining own onshore geologic mapping with previously published subsurface imaging of

the top of the pre-Neogene carbonates across the convergent margin, we have identified

structures associated with a large ENE-dipping blind thrust forming the base of the Neogene- to-Present accretionary wedge at the front of the northernmost Hellenides belt. The centroid

depth for the M6.4 event is interpreted to lie within this basal thrust; the shallower Sep 21 M5.6

event is inferred to lie at the western end of this same thrust, which does not appear to break

the surface in offshore sections. Taken together, these events point to seismic slip on a thrust

plane dipping some 30° ENE.

Teloni et al. (2021) underlined that the Outer Albanides fold–thrust belt is subdivided into

two distinct structural provinces by the NE-trending Vlora–Elbasan lineament. The southern

structural province is characterized by extensive outcrops of folded and faulted Mesozoic

carbonates of the Ionian basin, detached along Triassic evaporites. The northern structural

province is dominated by the thick Oligocene-PlioQuaternary clastic succession of the Peri- Adriatic Depression. The Vlora-Elbasan lineament is commonly interpreted as a Cenozoic

major transfer zone, controlled by an inherited deep-seated basement fault. They underline as

follows: “This study provides a comprehensive picture of the structural architecture of the

northern sector of the outer Albanides. In particular, a critical reassessment of published

geological sections and subsurface data, integrated with the new seismological datasets made

available by the 2019–20 seismic sequence, allowed us to unravel the basement-involved

thrusting style characterizing the frontal portion of the fold–thrust belt at the latitude of Durrës

(c. 41° 20’ N). The offshore thrust front in this sector of the fold–thrust belt is defined by a

seismogenic upper crustal blind fault that we term here the Northern Albanide Frontal Thrust

(NAFT). The seismological evidence provided by the 2019–20 earthquakes, analyzed in this

study by stress inversion performed on the focal mechanisms available from the RCMT

catalogue (Pondrelli 2002), is consistent with the roughly horizontal, ENE–WSW-trending

active maximum compression characterizing the region. The integrated analyses of the

epicentre distribution, hypocentre depth and fault plane solutions suggest that co-seismic slip

associated with the Mw 6.4 November 2019 Albania earthquake occurred along a NNW–SSE- striking, ENE-dipping thrust fault. The hypocentre distribution indicates that most of the

earthquakes, including the Mw 6.4 main shock, nucleated within the basement, with only some

of the shallow aftershocks tending to cluster around the deeper portion of previously identified