Late Miocene thrust tectonics of the Latin Valley: insights from seismic lines (Central Apennines, Italy)

2020 ◽  
Author(s):  
Giuseppe Vico ◽  
Giovanni Luca Cardello
Keyword(s):  
Late Miocene ◽  
Subduction Zones ◽  
Volcanic Field ◽  
Normal Faults ◽  
Past Century ◽  
Central Apennines ◽  
Kinematic Evolution ◽  
Geothermal Fluids ◽  
Thrust Tectonics ◽  
Thrust Sheets

<p>In west-directed subduction zones, as the compression moves towards the foreland, the accretionary prism progressively expands to follow the hinge migration towards the east. Although late Miocene foreland propagation implies the shift of the thrust front, in the central Apennines, the effects of the Messinian compression can be observed on a much broader area, implying out-of-sequence thrusting in the rear.</p><p>In order to understand the Messinian involvement of the previously formed Tortonian belt-foredeep system, a regional reinterpretation is here provided. The analysis of publicly available 2D seismic reflection lines across the upper and middle Latin Valley and 10 wells enables the identification of two main seismostratigraphic units: i) the Meso-Cenozoic neritic carbonates and ii) the upper Tortonian siliciclastic pelitic and arenaceous turbiditic associations of the Frosinone Formation.</p><p>The most evident reflectors are the upper Cretaceous and upper Serravallian top paraconformities, which, due to tectonic repetition can be followed at different depths. We find that minor reflectors can be attributed to the several thrusts affecting folded Meso-Cenozoic neritic carbonates. This observation allows us, together with field and well evidences, to trace several thrust sheets characterized by a general top-to-the NE sense of shear. In a few sections from the Latin Valley (e.g. Line FR-309-80), we recognized the Meso-Cenozoic neritic carbonates being thrusted together with the Tortonian Frosinone Formation, on top of a laterally variably thick siliciclastic succession. This further syn-orogenic unit could be related to the early Messinian sandstones of the Torrice Formation, implying that out-of-sequence thrusting took place in the Latin Valley during the wedge-top sedimentation. The thin-skinned fold-and-thrust fabric is defined by en-échelon distributed thrusts, NNE- and ENE striking tear faults and minor pop-up structures often determining ideal traps for hydrocarbon and geothermal fluids. Finally, conjugated NW-striking high-angle normal faults crosscut the orogenic heritage and sets a horst and graben structure associated with continental deposition and the Volsci Volcanic Field.</p><p>The limited oil exploitation over the past century has targeted only the shallower siliciclastic traps and some evidences in the shallower neritic carbornate thrust sheets. At the light of our new interpretation, the deeper carbonate units could be a new focus for hydrocarbon accumulation and may furnish targets for geothermal and/or hydrocarbon research in the area. Future work aims at quantify the Tortonian and Messinian amount of shortening by taking into consideration the adjoining Volsci Range. Finally, our findings bear implications on geodynamic reconstructions and may represent an example of the geometry and kinematic evolution of platform derived thrust sheets and similar belts worldwide associated with W-directed subduction zones.</p>

scholarly journals Constraining the Passive to Active Margin Tectonics of the Internal Central Apennines: Insights from Biostratigraphy, Structural, and Seismic Analysis

Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 160
Author(s):  
Giovanni Luca Cardello ◽  
Giuseppe Vico ◽  
Lorenzo Consorti ◽  
Monia Sabbatino ◽  
Eugenio Carminati ◽  
...  
Keyword(s):  
Seismic Analysis ◽  
Carbonate Platform ◽  
Structural Evolution ◽  
Normal Faults ◽  
Accretionary Wedge ◽  
Central Apennines ◽  
Active Margin ◽  
Kinematic Evolution ◽  
Regional Interest ◽  
Thrust Sheets

The polyphase structural evolution of a sector of the internal Central Apennines, where the significance of pelagic deposits atop neritic carbonate platform and active margin sediments has been long debated, is here documented. The results of a new geological survey in the Volsci Range, supported by new stratigraphic constraints from the syn-orogenic deposits, are integrated with the analysis of 2D seismic reflection lines and available wells in the adjacent Latin Valley. Late Cretaceous syn-sedimentary faults are documented and interpreted as steps linking a carbonate platform to the adjacent pelagic basin, located to the west. During Tortonian time, the pelagic deposits were squeezed off and juxtaposed as mélange units on top of the carbonate platform. Subsurface data highlighted stacked thrust sheets that were first involved into an initial in-sequence propagation with top-to-the-ENE, synchronous to late Tortonian foredeep to wedge-top sedimentation. We distinguish up to four groups of thrust faults that occurred during in-sequence (thrusts 1–3; about 55–60 km shortening) and backthrusting (thrust 4). During Pliocene to recent times, the area has been uplifted and subsequently extended by normal faults cross-cutting the accretionary wedge. Beside regional interest, our findings bear implications on the kinematic evolution of an orogenic wedge affected by far-traveled units.

Thrust tectonics on Brøggerhalvøya and their relationship to the Tertiary West Spitsbergen Fold-and-Thrust Belt

2002 ◽  
Vol 139 (1) ◽  
pp. 47-72 ◽  
Author(s):  
K. SAALMANN ◽  
F. THIEDIG
Keyword(s):  
Middle Eocene ◽  
Kinematic Model ◽  
Thrust Belt ◽  
Fold Belt ◽  
Kinematic Evolution ◽  
Fold And Thrust Belt ◽  
Thrust Tectonics ◽  
Tectonic Transport ◽  
Thrust Sheets ◽  
West Spitsbergen

The Tertiary fold-and-thrust belt on Brøggerhalvøya is characterized by a NE-vergent pile of nine thrust sheets. The sole thrust of the pile is located in Precambrian phyllites and climbs up-section to the northeast. Four lower thrust sheets consisting predominantly of Upper Palaeozoic sediments are overlain by two thrust sheets in the central part of the stack which contain a kilometre-scale syncline and anticline. The fold is cut by juxtaposed thrusts giving rise to the formation of three structurally higher basement-dominated thrust sheets. A multiple-stage kinematic model is proposed including (1) in-sequence foreland-propagating formation of the lower thrust sheets in response to N–S subhorizontal bedding-parallel movements, (2) a change in tectonic transport to ENE and out-of-sequence thrusting and formation of the kilometre-scale fold-structure followed by (3) truncation of the kilometre-scale fold and stacking of the highest basement-dominated thrust sheets by hind-ward-propagating out-of-sequence thrusting. The strain of the thrust sheets is predominantly compressive with the exception of the structurally highest thrust sheets, reflecting a temporal change to a more transpressive regime. Thrusting was followed by (4) N–S extension and (5) W–E extension. Comparison of the structural geometry and kinematic evolution of Brøggerhalvøya with the data reported for the fold belt further south allows us to assume a coeval evolution with the fold belt. A latest Paleocene/Early Eocene age for the main phase of thrusting is suggested for the West Spitsbergen Fold-and-Thrust Belt; the main phases therefore pre-date the separation of Svalbard and Greenland due to right-lateral movements along the Hornsund Fault Zone. The fold belt's temporal evolution followed by the formation of the Forlandsundet Graben can be linked with the plate-kinematic framework in the span between latest Paleocene and Middle Eocene times.

Comprehensive palaeomagnetic study of San Borja and Jaraguay monogenetic volcanic fields, Baja California (28–30° N): considerations on latitudinal corrections

2021 ◽  
Author(s):  
A N Mahgoub ◽  
B I García-Amador ◽  
L M Alva-Valdivia
Keyword(s):  
Dipole Moment ◽  
Late Miocene ◽  
Baja California ◽  
Temporal Distribution ◽  
Magnetic Minerals ◽  
Kinematic Evolution ◽  
Oxidation Reduction ◽  
Volcanic Fields ◽  
Spatio Temporal ◽  
Northwestern Mexico

Summary We report 24 palaeomagnetic directions and 10 high-quality Thellier-derived palaeointensity (PI) values, obtained from 27 sites located in Baja California Peninsula, northwestern Mexico. Sampling was done in four rock units (magnesian andesites, calc-alkaline lavas, ignimbrites, adakites) belonging to San Borja and Jaraguay monogenetic volcanic fields. These units have erupted between ∼ 15 and 2.6 Ma (previous K-Ar and 40Ar/39Ar data); hence results are presented in two consecutive periods: middle-late Miocene and Pliocene. The identified main magnetic minerals in the sampled sites are titanomagnetite, magnetite, and minor hematite, of variable grain size, present as intergrowths or surrounding grains, which reflect varying oxidation/reduction conditions during emplacement of high-temperature magmas. Based on previous geological and geophysical records, the kinematic evolution was carefully considered in the region, allowing for the independent restoration of the palaeoposition of each sampled site. Previous palaeodirections were also evaluated and corrected for tectonic motion in order to combine them with present data. Accordingly, a number of 15 and 36 directional data are used to calculate palaeopole position for Pliocene and middle-late Miocene periods, respectively, selected from a total of 74 data points. Pliocene (Plat = 87.8°, Plong = 147.5°, K = 41.06, A95 = 6.0°) and middle-late Miocene (Plat = 86.0°, Plong = 172.7°, K = 41.08, A95 = 3.8) palaeopole positions, calculated after tectonic corrections, are not statistically different from expected North American reference pole. Tectonic correction for Middle-late Miocene virtual geomagnetic poles plays an important role in reducing the resultant tilting from 2.7° to -0.8°. PI mean were calculated for Pliocene and middle-late Miocene periods at 29.2 ± 9.1 μT and 23.2 ± 6.3 μT, respectively. Compiling global filtered PI data, together with our results, indicates that the strength of the geomagnetic field during middle-late Miocene was weak (virtual dipole moment = 5.0 ± 2.2 × 1022 Am2) compared to Pliocene (6.4 ± 2.8 × 1022 Am2), and also relative to the present-day value (7.6 × 1022 Am2). This indicates the global nature of the low dipole moment during the middle-late Miocene period. However, issues related to the spatio-temporal distribution of PI data still present an obstacle to validating these suggestions; therefore, more reliable data are still needed.

The petrological and geochemical study of granitoid rocks from Mashhad area, Iran: Evidence for the Late Triassic Collisional Belt Northeast of Iran

2021 ◽  
Author(s):  
Banafsheh Vahdati ◽  
Seyed Ahmad Mazaheri
Keyword(s):  
Subduction Zones ◽  
Tectonic Setting ◽  
Crustal Contamination ◽  
Oceanic Lithosphere ◽  
Late Triassic ◽  
Common Belief ◽  
Thrust Tectonics ◽  
Wide Range ◽  
Lree Enrichment ◽  
Granitoid Rocks

<p>Mashhad granitoid complex is part of the northern slope of the Binalood Structural Zone (BSZ), Northeast of Iran, which is composed of granitoids and metamorphic rocks. This research presents new petrological and geochemical whole-rock major and trace elements analyses in order to determine the origin of granitoid rocks from Mashhad area. Field and petrographic observations indicate that these granitoid rocks have a wide range of lithological compositions and they are categorized into intermediate to felsic intrusive rocks (SiO<sub>2</sub>: 57.62-74.39 Wt.%). Qartzdiorite, tonalite, granodiorite and monzogranite are common granitoids with intrusive pegmatite and aplitic dikes and veins intruding them. Based on geochemical analyses, the granitoid rocks are calc-alkaline in nature and they are mostly peraluminous. On geochemical variation diagrams (major and minor oxides versus silica) Na<sub>2</sub>O and K<sub>2</sub>O show a positive correlation with silica while Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, CaO, Fe<sub>2</sub>O<sub>3</sub>, and MgO show a negative trend. Therefore fractional crystallization played a considerable role in the evolution of Mashhad granitoids. Based on the spider diagrams, there are enrichments in LILE and depletion in HFSE. Low degrees of melting or crustal contamination may be responsible for LILE enrichment. Elements such as Pb, Sm, Dy and Rb are enriched, while Ba, Sr, Nd, Zr, P, Ti and Yb (in monzogranites) are all depleted. LREE enrichment and HREE depletion are observed in all samples on the Chondrite-normalized REE diagram. Similar trends may be evidence for the granitoids to have the same origin. Besides, LREE enrichment relative to HREE in some samples can indicate the presence of garnet in their source rock. Negative anomalies of Eu and Yb are observed in monzogranites. Our results show that Mashhad granitoid rocks are orogenic related and tectonic discrimination diagrams mostly indicate its syn-to-post collisional tectonic setting. No negative Nb anomaly compared with MORB seems to be an indication of non-subduction zone related magma formation. According to the theory of thrust tectonics of the Binalood region, the oceanic lithosphere of the Palo-Tethys has subducted under the Turan microplate. Since the Mashhad granitoid outcrops are settled on the Iranian plate, this is far from common belief that these granitoid rocks are related to the subduction zones and the continental arcs. The western Mashhad granitoids show more mafic characteristics and are possibly crystallized from a magma with sedimentary and igneous origin. Thus, Western granitoid outcrops in Mashhad are probably hybrid type and other granitoid rocks, S and SE Mashhad are S-type. Evidences suggest that these continental collision granitoid rocks are associated with the late stages of the collision between the Iranian and the Turan microplates during the Paleo-Tethys Ocean closure which occurred in the Late Triassic.</p>

The potential for geothermal lithium in Italy

2021 ◽  
Author(s):  
Pierfranco Lattanzi ◽  
Andrea Dini ◽  
Giovanni Ruggieri ◽  
Eugenio Trumpy
Keyword(s):  
Rechargeable Batteries ◽  
Thermal Waters ◽  
Past Century ◽  
Geothermal Resources ◽  
High Enthalpy ◽  
The Past ◽  
Geothermal Fluids ◽  
Deep Reservoir ◽  
Increasing Demand ◽  
Made In

<p>Italy has never been a lithium (Li) producer, and the potential for “hard rock” deposits is moderate at best. On the other hand, the increasing demand for Li-based rechargeable batteries fostered new interest in this metal, and prompted the quest for alternative resources. The extraction of Li from geothermal brines (“geothermal lithium”) is currently considered in several countries, including, in Europe, France, Germany, and UK (EGEC, 2020).</p><p>Italy has vast geothermal resources, and there is a potential for “geothermal lithium” as well. A preliminary survey of literature data pointed out several occurrences of fluids with Li contents up to hundreds of mg/L. Among high-enthalpy fluids, we point out those of Cesano, Mofete, and Latera. At Cesano, geothermal fluids contain about 350 mg/L lithium (Calamai et al., 1976). Early studies conducted in the past century (Pauwels et al., 1990) suggested the feasibility of lithium recovery from these fluids. Even higher contents (480 mg/L) occur in the deep reservoir at Mofete (Guglielminetti, 1986), whereas fluids in the shallow and intermediate reservoir in the same field contain 28 to 56 mg/L. Geothermal fluids at Latera have somewhat lower contents (max 13.5 mg/L; Gianelli and Scandiffio, 1989). Several low-enthalpy thermal waters in Emilia-Romagna, Sardinia, Sicily and Tuscany also show significant (> 1 mg/L) Li contents (max 96 mg/L at Salsomaggiore; Boschetti et al., 2011). There are no published Li data for high-enthalpy fluids at Larderello; however, evidence of Li-rich fluids was found in fluid inclusions in hydrothermal minerals (Cathelineau et al., 1994). Moreover, the shallow (ca. 3.5 km) granitoid body underlying the field contains a Li-rich (about 1,000 ppm) biotite (A. Dini, unpublished data); it has been estimated that such rock may contain as much as 500 g Li per cubic meter.</p><p> </p><p>References</p><p>Boschetti T., et al. - Aquat Geochem (2011) 17:71–108</p><p>Calamai A., et al. <strong>- </strong>Proc. U.N. Symp. Development Use Geotherm. Energy, S. Francisco, USA (1976), 305-313</p><p>Cathelineau M., et al. – Geochim. Cosmochim. Acta (1994) 58: 1083-1099</p><p>EGEC (European Geothermal Council). https://www.egec.org/time-to-invest-in-clean-geothermal-lithium-made-in-europe/. Accessed December 2, 2020.</p><p>Gianelli G., Scandiffio G. - Geothermics (1989) 18: 447-463</p><p>Guglielminetti M. - Geothermics (1986) 15: 781-790</p><p>Pauwels H., et al. - Proc. 12th New Zealand Geothermal Workshop (1990), 117-123</p>

The Late Miocene-Early Pliocene out-of-sequence thrusting event: new insights into the tectonic evolution of the southern Apennines (Italy)

2021 ◽  
Author(s):  
Vitale Stefano ◽  
Prinzi Ernesto Paolo ◽  
Francesco D'Assisi Tramparulo ◽  
Sabatino Ciarcia
Keyword(s):  
Late Miocene ◽  
Hanging Wall ◽  
Early Pleistocene ◽  
Normal Faults ◽  
Southern Apennines ◽  
Campania Region ◽  
Early Pliocene ◽  
Upper Miocene ◽  
Thrust System ◽  
Tectonic Windows

<p>We present a structural study on late Miocene-early Pliocene out-of-sequence thrusts affecting the southern Apennine chain. The analyzed structures are exposed in the Campania region (southern Italy). Here, leading thrusts bound the N-NE side of the carbonate ridges that form the regional mountain backbone. In several outcrops, the Mesozoic carbonates are superposed onto the unconformable wedge-top basin deposits of the upper Miocene Castelvetere Group, providing constraints to the age of the activity of this thrusting event. We further analyzed the tectonic windows of Giffoni and Campagna, located on the rear of the leading thrust. We reconstructed the orogenic evolution of this part of the orogen. The first was related to the in-sequence thrusting with minor thrusts and folds, widespread both in the footwall and in the hanging wall. A subsequent extension has formed normal faults crosscutting the early thrusts and folds. All structures were subsequently affected by two shortening stages, which also deformed the upper Miocene wedge top basin deposits of the Castelvetere Group. We interpreted these late structures as related to an out-of-sequence thrust system defined by a main frontal E-verging thrust and lateral ramps characterized by N and S vergences. Associated with these thrusting events, LANFs were formed in the hanging wall of the major thrusts. Such out-of-sequence thrusts are observed in the whole southern Apennines and record a thrusting event that occurred in the late Messinian-early Pliocene. We related this tectonic episode to the positive inversion of inherited normal faults located in the Paleozoic basement. These envelopments thrust upward crosscut the allochthonous wedge, including, in the western zone of the chain, the upper Miocene wedge-top basin deposits. Finally, we suggest that the two tectonic windows are the result of the formation of an E-W trending regional antiform, associated with a late S-verging back-thrust, that has been eroded and crosscut by Early Pleistocene normal faults.</p>

scholarly journals Examining the tectono-stratigraphic architecture, structural geometry, and kinematic evolution of the Himalayan fold-thrust belt, Kumaun, northwest India

Lithosphere ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 414-435 ◽  
Author(s):  
Subhadip Mandal ◽  
Delores M. Robinson ◽  
Matthew J. Kohn ◽  
Subodha Khanal ◽  
Oindrila Das
Keyword(s):  
Cross Section ◽  
Structural Model ◽  
Kinematic Model ◽  
Thrust Belt ◽  
Main Central Thrust ◽  
Thrust Sheet ◽  
Balanced Cross Section ◽  
Kinematic Evolution ◽  
Thrust Sheets ◽  
Northwest India

Abstract Existing structural models of the Himalayan fold-thrust belt in Kumaun, northwest India, are based on a tectono-stratigraphy that assigns different stratigraphy to the Ramgarh, Berinag, Askot, and Munsiari thrusts and treats the thrusts as separate structures. We reassess the tectono-stratigraphy of Kumaun, based on new and existing U-Pb zircon ages and whole-rock Nd isotopic values, and present a new structural model and deformation history through kinematic analysis using a balanced cross section. This study reveals that the rocks that currently crop out as the Ramgarh, Berinag, Askot, and Munsiari thrust sheets were part of the same, once laterally continuous stratigraphic unit, consisting of Lesser Himalayan Paleoproterozoic granitoids (ca. 1850 Ma) and metasedimentary rocks. These Paleoproterozoic rocks were shortened and duplexed into the Ramgarh-Munsiari thrust sheet and other Paleoproterozoic thrust sheets during Himalayan orogenesis. Our structural model contains a hinterland-dipping duplex that accommodates ∼541–575 km or 79%–80% of minimum shortening between the Main Frontal thrust and South Tibetan Detachment system. By adding in minimum shortening from the Tethyan Himalaya, we estimate a total minimum shortening of ∼674–751 km in the Himalayan fold-thrust belt. The Ramgarh-Munsiari thrust sheet and the Lesser Himalayan duplex are breached by erosion, separating the Paleoproterozoic Lesser Himalayan rocks of the Ramgarh-Munsiari thrust into the isolated, synclinal Almora, Askot, and Chiplakot klippen, where folding of the Ramgarh-Munsiari thrust sheet by the Lesser Himalayan duplex controls preservation of these klippen. The Ramgarh-Munsiari thrust carries the Paleoproterozoic Lesser Himalayan rocks ∼120 km southward from the footwall of the Main Central thrust and exposed them in the hanging wall of the Main Boundary thrust. Our kinematic model demonstrates that propagation of the thrust belt occurred from north to south with minor out-of-sequence thrusting and is consistent with a critical taper model for growth of the Himalayan thrust belt, following emplacement of midcrustal Greater Himalayan rocks. Our revised stratigraphy-based balanced cross section contains ∼120–200 km greater shortening than previously estimated through the Greater, Lesser, and Subhimalayan rocks.

scholarly journals Repeated surveys reveal nontectonic exposure of supposedly active normal faults in the central Apennines, Italy

2017 ◽  
Vol 122 (1) ◽  
pp. 114-129 ◽  
Author(s):  
Vanja Kastelic ◽  
Pierfrancesco Burrato ◽  
Michele M. C. Carafa ◽  
Roberto Basili
Keyword(s):  
Normal Faults ◽  
Central Apennines

Neogene and active brittle deformation on Amorgos Island (Greece)

2020 ◽  
Author(s):  
Jan Behrmann ◽  
Jakob Schneider ◽  
Benjamin Zitzow
Keyword(s):  
Moment Tensor ◽  
Spatial Relationship ◽  
Shear Zones ◽  
Fault System ◽  
Normal Faults ◽  
Small Scale ◽  
Past Century ◽  
Fault Plane Solutions ◽  
Moment Tensor Solution ◽  
Late Neogene

<p>Amorgos is the south-eastern outpost of the Cyclades Islands in the Aegean Sea, which forms part of the Neogene-Quaternary zone of crustal and lithospheric N-S upper plate extension northward of the Hellenic subduction zone and deep sea trench. Apart from subduction-related earthquakes further south, the southern Aegean is affected by frequent earthquakes sourced in the upper plate. The twin earthquakes of 9 July 1956, followed by a strong tsunami, were the strongest events of this kind in the past Century. Hypocenters are related to a NE-SW oriented normal fault bounding the Amorgos-Santorini Graben System. There are questions in the literature regarding the seismic source and fault plane solutions, especially the contribution of a transcurrent faulting component.</p><p>We have analyzed the kinematics of brittle faults exposed on Amorgos Island itself that could be related to Neogene and active extensional and/or transcurrent deformation. Seismic slip often occurs on previously existing faults. Thus, their orientations and kinematics may help shed light on the structure of seismic sources at depth. We present evidence for a complex history of faulting. Early normal detachment faults and shear zones overprint older (rare) reverse faults, and are themselves overprinted by several sets of dominantly dextral NE and SE trending strike slip faults. Youngest is a conjugate set of NE trending high-angle normal faults. These are especially frequent along the SE coast of the island, suggesting a clear spatial relationship with the 1956 rupture. They can be fitted to a moment tensor solution similar to the published solutions for the 1956 Amorgos earthquake. The kinematic solution for the population of early normal faults suggests that the whole of Amorgos Island may have experienced a 15° NNW tilt during later extension, which lets us suspect that the island could be a tilted block of a much larger fault system. Regarding long-term late Neogene to Quaternary kinematics, dextrally transtensive fault slip is required to fit the regional pattern of extensional deformation in the Aegean, and this is reflected by small-scale brittle faulting on Amorgos.</p>

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