the liguride complex of southern italy —a cretaceous to paleogene accretionary wedge
TRANSCRIPT
Tectonophysics, 142 (1987) 217-226
Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
217
The Liguride Complex of Southern Italy -a Cretaceous to Paleogene accretionary wedge
STEVEN D. KNOTT
Department of Earth Sciences, University of Oxford, Parks Road, Oxford OXI 3PR (Great Britain)
(Received March 25, 1986; revised version accepted January 1, 1987)
Abstract
Knott, SD., 1987. The Liguride Complex of Southern Italy-a Cretaceous to Paleogene accretionary wedge.
Tectonophysics, 142: 217-226.
The ophiolite-bearing allochthonous flysch (Liguride Complex) of the Southern Apennines, Italy, has traditionally
been divided into two tectonic units: the metamorphic Frido Unit and the unmetamorphosed Cilento Unit. The two
units have hitherto been considered to derive from two distinct paleogeographic domains; however, the identification of
Cilento Unit sediments within Frido Unit successions implies that the sediments of both units were coeval deposits
within the same sedimentary basin. Cilento Unit sediments also occur as the sedimentary cover of kilometre-scale
oceanic slices within the Liguride Complex indicating deposition on oceanic basement and not continental basement as
was previously considered. Thrust transport directions and sediment provenance indicate that during Late Jurassic time
this ocean basin lay to the east of the Calabrian terrain and to the west of Apulia, Calabria and Apulia representing the
European and African margins of Neotethys respectively. Northwestwards subduction of oceanic crust beneath the
Calabrian terrain from Late Cretaceous time onwards produced an accretionary wedge which was later emplaced onto
the Apulian margin during the Burdigalian collision of Calabria and Apulia. The Liguride Complex represents the
abducted remains of this accretionary wedge.
This interpretation contains three important implications for pre-Tertiary plate tectonic reconstructions of the
western Mediterranean region, these are:
(1) The Calabrian continental terrain formed part of the Iberian Plate on the north margin of Neotethys, this may
have implications for the former location and continuation of the North Pyrenean Fault.
(2) The existence of a continuation of the “Eo-Alpine” belt through Calabria and the Kabylies is placed in doubt
thus requiring only one, constant polarity (NW-dipping) subduction direction to explain the structures now seen in
these regions.
(3) The existence of a transform fault between the Europe-vergent structures of Corsica and the Africa-vergent
structures of Calabria. This transform must have been active from at least Late Cretaceous time in a position now
occupied by the Tyrrhenian Sea.
Introduction
The Calabrian Arc (Fig. l), Southern Italy, can
be divided into three major tectonic elements. The
lowest element consists of thrust sheets of
carbonate sediments, originally deposited upon
the continental margin of Apulia, and now for-
ming the Apennine mountain chain (Scandone,
1979). Tectonically overlying this element is an
ophiolite-bearing allochthonous flysch which, in
the Southern Apennines, is known as the Liguride
Complex (Ogniben, 1969). The upper-most
tectonic element consists of thrust slices of con-
tinental basement with or without a Mesozoic
sedimentary cover.
This sequence of tectonic elements is consid-
ered to be a remnant of the “Eo-Alpine” chain of
European vergence which was later thrust east-
0040-1951/87/$03.50 0 1987 Elsevier Science Publishers B.V.
STROVILLARI
Fig. I. Geologic map of Southern Italy and Sicily.
wards onto the Apennine domain in Late Tertiary time (Alvarez, 1976; Amodio-Morelli et al., 1976). In the most recent synthesis of Calabrian geology (Bonardi et al., 1982) the Liguride Complex was divided into the Frido Unit and the Cilento Unit each unit being derived from a different sedimen- tary basin, the former was situated upon Tethyan oceanic crust on which sedimentation commenced in Early Cretaceous time, the latter was situated upon the Apulian continental margin with deposi- tion commencing in Early Paleogene time.
The aim of this paper is to show that the Liguride Complex, including the Frido Unit and the Cilento Unit, represents the remains of a single ocean basin which originally lay between the Calabrian and Apulian terrains, was deformed by subduction-accretion processes and was finally emplaced onto the Apulian margin during the Neogene. The structure of the paper shall be to review the previous work on the Liguride Com- plex, present new structural and sedimentological data and finally to discuss the implications of this data and their interpretation to plate tectonic re- constructions of the western Mediterranean re- gion.
Liguride Complex
The Liguride Complex has been divided by Amodio-Morelli et al. (1976) into three tectonic units, the Frido Unit, the Cilento Unit and an
ophiolite unit (Fig. 2).
Frido Unit
The Frido Unit includes the Frido Formation of Vezzani (1969) and is roughly equivalent to the “ flysch ar~lloso-filladi~o” of Ippolito and Lucini (1957) the “flysch fillonitico” of Cotecchia (1958) the “ flysch a quartzites” of Caire et al (1960) and also the “argillitico-quartzoso-calcareo” flysch of Selli (1962). This unit is composed of weakly foliated shale, slate, talc-schist and quartz-arenite. In the Southern Apennines the Frido Unit is associated with kilometre-scale masses of con- tinental and oceanic crust. Figure 2 shows the extent of Frido Unit outcrops within the Southern Apennines. The age of the Frido Formation according to Vezzani (1969) is Neocomian to Ap- tian. However, Scandone (in Amodio-Morelli et al., 1976) identified Globotruncana sp. in Frido
Fig. 2. Geologic map of the Southern Apennines including the
region involved in this study. M-Timpa delle Murge,
P -Timpa Pietrasasso, T-Monte Tumbarino.
219
Formation shales from the Cilento area (Fig. 1)
suggesting a Late Cretaceous age.
Vezzani (1969) and Ogniben (1969) state that
the Frido Formation in the Southern Apennines
lies stratigraphically below the Crete Nere Forma-
tion (the oldest formation of the Cilento Unit).
Amodio-Morelli et al. (1976), however, state that
the two are separated tectonically by fragments of
an ophiolite unit and the Polia-Copanello base-
ment unit, and are therefore not in stratigraphic
contact. In the Calabrian Coastal Chain to the
west (Fig. 1) the Frido Unit is situated tectonically
beneath the ophiolitic Malvito, Diamante-Ter-
ranova and Gimigliano Units, and above Apen-
nine carbonate rocks of the Verbicaro and San
Donato Units (Amodio-Morelli et al., 1976).
The metamorphism of the Frido Unit within
the Southern Apennines is considered to be very
low, on the border between greenschist facies
metamorphism and diagenesis (Amodio-Morelli et
al., 1976). However, Lanzafame et al. (1979)
recognise high pressure/low temperature lawso-
nite-albite to incipient glaucophane schist facies
assemblages within this part of the Frido Forma-
tion. The latter authors and De Roever (1972)
distinguish true glaucophane schist facies assemb-
lages within outcrops of the Frido Unit in the
Calabrian Coastal Chain.
Cilento Unit
According to Amodio-Morelli et al. (1976) the
Cilento Unit belongs to a group of allochthonous
units of uncertain paleogeographic position and
lies tectonically above the Frido Unit.
The Cilento Unit comprises three sedimentary
formations. The oldest, the Crete Nere Formation
consists of black shale, quartz-arenite, calcarenite
and calcilutite, of Aptian to Albian age (Vezzani,
1968). The overlying Saraceno Formation consists
of calcarenite and calcilutite with occasional
volcaniclastic sediments of Middle to Late Eocene
age (De Blasio et al., 1978). Unconformably
overlying both these formations is the Albidona
Formation which comprises conglomerate and
quartz-arenite of Late Oligocene to Burdigalian
age (Zuppetta et al., 1984) and contains two
laterally continuous calcilutite beds occasionally
reaching 50 m in thickness. The conglomerates of
the Albidona Formation contain boulders which
have been derived from the Calabrian continental
terrain (Zuppetta et al., op. cit.).
“Ophiolites”
Various interpretations of the relationships be-
tween the tectonic units mentioned above and the
ophiolitic rocks have been suggested within the
literature. Dietrich and Scandone (1972) and
Amodio-Morelli et al. (1976) both consider that
the ophiolites belong to a tectonic unit distinct
from the Frido Formation, and that the latter is
the sedimentary cover to an oceanic basement not
yet recognised. Bousquet (1973) assigned the
ophiolite sedimentary cover to the “Timpa delle
Murge Formation” and stated that it is this for-
mation and not the Frido Formation which lies
stratigraphically beneath the Crete Nere Forma-
tion (cf. Vezzani, 1968), suggesting that the Cilento
Unit was deposited on the ophiolitic sequence.
Lanzafame et al. (1978) recognised a stratigraphic
continuity between the ophiolite sedimentary cover
and the overlying Crete Nere Formation and they
further suggested that this sedimentary cover lay
within a basin with an ophiolitic basement. In a
subsequent paper (Spadea et al. 1980) however,
the same authors stated that the relationship be-
tween the ophiolites and the sediments of the
Cilento Unit was still debated. (The “ophiolites”
of the Southern Apennines and Calabria are all
incomplete and dismembered and should really be
classed as disrupted oceanic slices following the
recommendation of the ophiolite Penrose Con-
ference (Conference Participants, 1972).
Present study
The present study was carried out within an
area situated in the region of Basilicata, Italy at
the northern extremity of the Calabrian Arc (Fig.
2).
Oceanic slices
Kilometre-scale oceanic slices crop out to the
east of Monte Pollino at Timpa delle Murge,
220
Timpa Pietrasasso and Monte Tumbarino (Fig. 2).
At each of these localities serpentinite (c. 15 m
thick), gabbro (c. 20 m), basalt dykes (rare), pillow
lavas (40 m) and sedimentary cover (10 m of
pelagic limestone and ribbon radiolarite) are ex-
posed. Detailed mapping around the base of Timpa
delle Murge and Timpa Pietrasasso (Fig. 3) was
carried out to determine the nature of the contact
between the slices and the underlying material.
At Timpa delle Murge a southward-dipping
shear zone (c. 200 m wide) lies beneath the slice,
separating it from underlying pelitic schists of
Early Cretaceous age. Within the shear zone a
number of diverse hthologies display moderate to
intense ductile deformation. The upper part of the
shear zone contains tectonised serpentinite derived
from the oceanic slice above. Beneath the
serpentinite sheet is a tectonic slice of granite
surrounded by a foliated granite envelope. Defor-
mation gradually increases away from the unde-
formed granite core with undeformed granite
augen becoming smaller and more diffuse until
eventually minor shear zones within the foliated
granite become so pervasive that the lithology is
entirely mylonitic displaying no original igneous
texture in thin-section. Beneath the granite and
serpentinite sheet lie pelitic schists and deformed
calcarenite and quartz-arenite. Well-bedded sedi-
CR ET E N E A E F 0 R hi A T I 0 N
m BASALT h GAEERO
m SHEAR ZONE
a APENNINIC IJNfT
- QEOLOGICAL BOUNDARY
- FAULT
- THRUST N tt-_
0.*.-O TRAVERSE 500m f
NORTH SOUTH
TIMPA OELLE MURGE
A S
Fig. 3. Geologic map and cross-section of the Timpa delle Murge and Timpa Pietrasasso oceanic slices.
221
ments belonging to the Crete Nere Formation occur below and outside the shear zone, and these appear to be the less deformed equivalents of the schists and metasediments found within the shear zone.
At Timpa Pietrasasso (Fig. 3) a similar south- ward-dipping shear zone occurs below an oceanic slice comprising ribbon radiolarite, basalt, gabbro and a serpentinite thrust sheet containing frag- ments of granite, amphibolite, talc-schist and basalt. The serpentinite sheet is superposed tecton- ically above calcarenite of Late Cretaceous age belonging to the Crete Nere Formation which contain abundant calcite veins. Immediately to the north of the serpentinite sheet the strike of adjac- ent Crete Nere Formation bedding becomes paral- lel to the shear zone margin. Figure 3 shows a schematic section displaying the geometry of these imbricate oceanic slices.
Fig. 4. Geologic map of the San Severino Lucano area showing
the extent of Cilento Unit sediments (i.e. Crete Nere and
Saraceno Formations) previously considered to belong to the
Frido Formation (Frido Unit).
Sedimentary cover
At Timpa delle Murge a traverse (Fig. 3) was carried out to determine the relationship between the sedimentary cover of the oceanic slice and the surrounding sediments. The traverse commenced at the conformable stratigraphic contact between the Crete Nere and Saraceno Formations and terminated at the base of the sedimentary cover exposed on top of Timpa delle Murge. The sedi- ments throughout the entire traverse were found to be in stratigraphic continuity from the basal contact of the Saraceno Formation, down succes- sion through the Crete Nere Formation to the pelagic limestone and ribbon radiolarite deposited above the pillow lavas. The sedimentary cover at Timpa delle Murge is lithologically identical to exposures already attributed to the Crete Nere Formation (e.g., Crete Nere Formation at Serra Scorzillo located on the border between Calabria and Basilicata, Foglio 221 I NO Terranova di Pollino). This suggests that the entire succession above the pillow lavas up to the base of the Saraceno Formation, should be assigned to the Crete Nere Formation.
Significance of the Frido Formation and the Frido
Unit
A re-evaluation of the Frido Formation type- area (Fig. 4) showed that all members of this formation were in fact moderately or intensely deformed rocks of the Crete Nere Formation or Saraceno Formation. The less deformed portions were lithologically and petrographically similar to Crete Nere Formation and Saraceno Formation sediments found within the eastern part of the area (i.e. Cilento Unit). Figure 5 shows the similar- ity between the sedimentary petrography of the Frido Formation (Frido Unit) and the Crete Nere and Saraceno Formations (Cilento Unit). Within the “calcareo-scistoso” member of the “Frido
Formation” it was possible to recognise Saraceno Formation lithic arenites, the base of the beds containing the characteristic schist, limestone and quartz clasts commonly found in Saraceno Forma- tion sediments in the eastern part of the area (see Fig. 32; Vezzani, 1968a). The identification of
222
IRF Q mQn
MRF ’ F L
C
0 FRIDO FORMATION QUARTZ-ARENITE 0 FRIDO FORMATION LITH-ARENITE l CRETE NERE FORMATION QUARTZ-ARENITE l SARACENO FORMATION LITH-ARENITE
Fig. 5. Petrography of the Frido Formation (Frido Unit) and the Crete Nere and Saraceno Formations (Cilento Unit). IRF-igneous
rock fragments; SRF-sedimentary rock fragments: MRF-metamorphic rock fragments; Q-total quartz; F-total feldspars; L
-total lithic fragments; m&r-non-undulose monocrystalhne quartz; mQu--undulose monocrystalline quartz; C-stable lithic
fragments.
~u~~u~if~s from the detrital clasts of these iithic arenites by the present author and P. Scandone (pers. commun., 1985) indicates an Eocene age which makes them correlatable with the Saraceno Formation. The type-area also contains numerous major and minor isoclinal folds and thrusts (Fig. 6). The type-area was re-mapped replacing the Frido Formation with the Saraceno and Crete Nere Formations where applicable (Fig. 4).
A
SSE
Fig. 6. Schematic cross-sections of fold and thrust structures
near San Severino Lucano, see Fig. 4 for locations.
St~ctura~ data
Structural analysis of the Liguride Complex shows a polyphase history involving internal de- formation within thrust sheets at deeper structural levels with an early pressure-solution cleavage de- formed by later thrusts and recumbent isoclines
r
Fig. 7. Thrust transport directions within the Liguride Com-
plex derived from stretching lineations, shear bands and thrust
plane mineral fibre lineations coupled with fold vergence, the
area shown is roughly the same as that in Fig. 2.
223
which are themselves folded by minor upright
folds. At higher structural levels kilometre-scale
recumbent folds are affected by later minor thrusts
and upright folds, and pressure-solution is less
intense but dilation veins filled with calcite are
common. Serpentinite often occurs along the basal
decollement to large thrust sheets of both oceanic
and continental basement. Kinematic data derived
from extension lineations, shear bands, and minor
thrust geometries combined with fold vergence
indicate thrust transport towards present-day
northeast. These data are summarised in Fig. 7.
Discussion
The equivalence of the sedimentary successions
of the Frido Unit and the Cilento Unit and their
deposition upon oceanic crust is supported by the
following lines of evidence:
(1) Similarities in lithology, petrology and
facies.
(2) Equivalence in age range, i.e. Late Jurassic
to Eocene (based on the identification of Late
Cretaceous and Eocene faunas in Frido Forma-
tion localities).
(3) Stratigraphic continuity from condensed
pelagic cover sequences belonging to oceanic slices
passing upwards to younger levels of the Crete
Nere Formation (Middle Eocene; M. Russo, pers.
commun., 1985).
Evidence for a subduction related origin for the
Liguride Complex include:
(1) A detached northwestward-dipping litho-
spheric slab beneath the Tyrrhenian Sea (Caputo
et al., 1972).
(2) A talk-alkaline volcanic arc in Sardinia
(Cohen, 1980).
(3) HP/LT metamorphic assemblages in Cala-
bria (De Roever, 1972).
The oceanic slices within the Liguride Complex
represent fragments of oceanic crust and upper
mantle accreted to the inner slope of a trench.
Similar features have been recognised in the
accreted terrains of the Tonga and Mariana arcs
(Evans and Hawkins, 1979). The condensed pelagic
sequences of Late Jurassic age deposited above the
pillow lavas probably represent sedimentation
upon seamounts which stood proud of the ocean
floor and were accreted to the inner slope. The
abundance of serpentinite along thrust contacts
and as individual thrust sheets suggests that sub-
duction may have initiated along an oceanic frac-
ture zone where large volumes of mantle material
would be involved in the first imbricate slices. The
terrigenous detritus deposited on the pillow lavas
at Timpa delle Murge and the tectonic inclusions
of continental basement at the base of the oceanic
slices suggest that the site of subduction initiation
was near the southeast margin of the Calabrian
continental terrain (Knott and Turco, in press).
The presence of HP/LT mineral assemblages in
parts of the “Frido Unit” is probably due to
underplating of material during subduction.
Zuppeta et al. (1984) have shown that sedi-
ments of the Albidona Formation were derived
from the Longobucco Unit (Fig. l), i.e. Calabrian
continental terrain. Provenance studies by the pre-
sent author show a clear correlation between the
detrital evolution of the Liguride Complex, from
Eocene time onwards, and the progressive denuda-
tion of the Calabrian terrain (Longobucco Unit)
(Fig. 8). Are&es at the base of the Saraceno
Formation contain detrital clasts of mainly
carbonate material which were probably derived
from either Apulian carbonates or the predomi-
nantly carbonate-rich cover sediments of the
Longobucco Unit. Towards the upper part of the
Saraceno Formation abundant detritral clasts of
lithic rock fragments occur suggesting provenance
from the pelitic and granitic basement of the
emergent Calabrian terrain. Conglomerates from
the overlying Albidona formation contain boulders
which are readily identifiable as elements of the
Calabrian continental terrain.
It follows from the discussion above that the
Calabrian continental terrain lay on the northern
(European) margin of Neotethys in Late Creta-
ceous time. This is in contrast to the interpreta-
tions of Alvarez (1976) and Amodio-Morelli et al.
(1976) who both placed Calabria on the southern
margin at this time. This would suggest that the
so-called “Alpine” units from the rest of the
Calabria-Peloritani arc will contain structures in-
dicating transport directions towards Africa/Apu-
lia. Dietrich (in press) has in fact shown, from
microstructural evidence, that the upper-most units
224
LONGOBUCCO UNIT Early Cretaceous
l”OOm
CARBONATE TURBIDITES
SHELF CARBONATES LlaS
CONTINENTAL ARENITES PELlTtC SCHIST
GRANITE BASEMENT
>A T
CA CALCARENITE LA’- LlTHlC ARENITE I SRF S PREDOMINATE) LA2-LlTHiC ARENlTE ( IRF’S PREDOMINATE1 C -CONGLOMERATE WliH BOULDERS OF 10NGOB”CCO WIT AND SARACENO FORMATION
LA’ T c
QA
1 1
LIGURIOE COMPLEX
Fig. 8. Petrographic evolution of the Liguride Complex showing the derivation of litho-types from the progressive denudation of the
Calabrian continental terrain (~ngobucco Unit).
of the “Alpine” nappes in north Calabria were
transported from west to east. However, more
detailed work is required around the Calabrian arc
and within the Kabylies to determine the age of
such structures and the nature of the tectonic
contacts (?thrust/back-thrust or extensional fault)
before a comparison can be drawn with the struc-
tures described in this paper.
Bouillin (1984) also proposed that the Calabrian
continental terrain originally lay on the northern
margin of Neotethys based, essentially, on a com-
parison between the structure of Calabria and the
Maghrebides with very little new data. The data
presented here provides more conclusive evidence
for the former position of the Calabrian terrain
and contains important implications for pre-Ter-
tiary plate tectonic reconstructions of the western
Mediterranean region as follows.
Firstly the Calabrian continental terrain would
have formed the eastern promontory of the Iberian
Plate (Fig. 9) and may therefore have experienced
Pyrenean deformation. This may help constrain
the former location and continuation of the North
Pyrenean Fault (NPF). Secondly the European
vergence in Calabria and the Kabylies proposed
by Alvarez (1976) and Amodio-Morelli et al. (1976)
implies the existence of an early southward dip-
ping subduction zone. This would then be fol-
lowed by subduction with opposite polarity giving
rise to the structures of African vergence. How-
ever, if the evidence for the European vergence is
rejected or at least considered to be due to back-
thrusting, as is suggested here, then the structures
in Calabria and the Maghrebides can be explained
by subduction with a single polarity (i.e. north-
1
Fig. 9. Early Cretaceous plate tectonic configuration of the
western Medit~rr~ean with the Calabrian continental terrain
forming the eastern promontory of the Iberian Plate.
NPF-North Pyrenean Fault, stippled-oceanic crust (after
Knott and Turco, in press. and Dewey et al., 1973).
225
westward) commencing in approximately Late
Cretaceous time. Finally the opposed vergence of
structures in Corsica (towards Europe) and
Calabria (towards Africa) requires the existence of
a transform fault between the two regions active
from at least Late Cretaceous time in a position
now occupied by the Tyrrhenian Sea (cf. Bouillin
1984 who places a transform zone along the length
of the Apennines).
Conclusions
It is proposed that the sediments of both the
Frido Formation and the Frido Unit are in fact
deformed and metamorphosed Crete Nere Forma-
tion and Saraceno Formation sediments. This im-
plies that prior to ?Late Cretaceous subduction
the sediments of both the Frido Unit and the
Cilento Unit were lateral equivalents within the
same sedimentary basin lying for the most part
upon an oceanic basement. Thrust transport direc-
tions towards present-day northeast (i.e. towards
Apulia) and sediment provenance from Calabria
indicate that this ocean basin originally lay be-
tween the Calabrian and Apulian terrains. This
Late Cretaceous paleogeography is in agreement
with Ogniben (1969) and Boullin (1984) with the
Calabrian terrain on the European (i.e. NW)
margin of the Neotethys ocean (Fig. 10).
The structures described above are related to
subduction-accretion during Late Cretaceous to
Early Oligocene time prior to the Burdigalian con-
tinent-continent collision of Calabria and Apulia.
The subsequent deformation history involving em-
placement of the Liguride Complex onto the
Apulian margin, the formation of the Apennine
LATE EOCENE I
Fig. 10. Schematic cross-section of the Late Eocene configura-
tion of the Liguride Complex, Calabrian terrain and Apulia.
European margin of the Neotethys is on the left; stipple-oce-
anic crust; crosses-continental crust.
mountain chain and the opening of the Tyr-
rhenian Sea has greatly disrupted the original
large-scale geometries of the accretionary wedge.
The interpretation presented here places in
doubt the validity of the Frido Formation type-
section proposed by Vezzani (1969). Furthermore
the usefulness of the terms “Frido Unit” and
“Cilento Unit” is brought into question. It is
suggested that the latter two terms be abandoned
and the stratigraphy of the Liguride Complex be
revised.
On a more regional scale this interpretation
places three main constraints on the pre-Tertiary
plate tectonic evolution of the western Mediter-
ranean (see also Knott and Turco, in press), they
are:
(1) Calabria formed part of the Iberian Plate
and may show Pyrenean deformation and thus
help constrain the former location of the NPF.
(2) Only one polarity of subduction (i.e. north-
westward-dipping) from Late Cretaceous time on-
wards is required to explain the structures in
Calabria and the Kabylies.
(3) A transform fault occurred between the
Europe-vergent structures of Corsica and the
Africa-vergent structures of Calabria. The trans-
form was active from at least Late Cretaceous
time and was located in a position now occupied
by the Tyrrhenian Sea.
Acknowledgements
I would like to thank Professor E. Turco for
providing stimulating discussion on the implica-
tions of this work on western Mediterranean geol-
ogy. I thank Drs. J.P. Platt and W.S. McKerrow
for their criticism of an early draft of the
manuscript. A N.E.R.C. Studentship Award is
gratefully acknowledged.
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