Geology, Geochemistry and U-Pb SHRIMP Age of the Tacloban Ophiolite Complex, Leyte Island (Central Philippines): Implications for the Existence and Extent of the Proto-Philippine Sea Plate
Leilanie Osano SuerteGraciano P. YumulRodolfo A. TamayoCarla B. DimalantaMei‐Fu ZhouRené C. MauryMireille PolvéCesar L. Balce
27
Citation
37
Reference
10
Related Paper
Citation Trend
Keywords:
Massif
Outcrop
Dike
Cite
Citations (29)
CONNECTION OF THE ŚLĘŻA OPHIOLITE WITH THE VARISCAN STRUCTURE OF THE SOWIE MEIAMORPHIC ROCKS
Summary
The structural analysis made in the area of about 100 sq km of the Sowie Mountains metamorphic segments (the Middle Sudety Mountains - the lower Silesia) shows that the main fold macrostructures developed in the second deformation phase (D2). The basic influence on geometry, size and orientation of microfolds (F2) had thrust sheets of basic rocks - mainly amphibolites. The most basic and ultrabasic rocks developed from segments of the former ocean crust (the Śleza ophiolite).
As a results of long standing tectonic processes (beginning in the Cadomian tectogenesis and lasted to lower Carboniferous) on the margins of the Bohemian Massif (in the Saxo-Turonian zone), mutual displacements of various segments of continental (Cadomides) and ocean crusts (e.g. the Śleza ophiolites) took place.
From the ocean crust undergoing subduction beneath the Bohemian Massif a large segment (the Śleza ophiolite) was tectonically detached. This ophiolite thrust sheet impressed in existing structural discontuities of the Cadomides.
Concomitance of subduction and obduction processes resulted in decreasing the rate of overthrust of this segment of the Bohemian Massif on the ocean crust. The rate of overthrust of the whole Bohemian Massif was not decreased.
Originated in that way the disagreement in displacement rates caused detachment and overthrust the Sowie Mountains sheets (northward) on the overthrusting (southward) the Śleza ophiolite. As the result of this process the thickness and weight increased in this marginal part of the Bohemian Massif. It caused submerging the whole zone (much more in the eastern part) and development among others migmatites and locally granitoids during the third deformation phase (D3). The Sowie Mountains structure is characterized by the tectonic macromelange pattern.
Thrust sheets, thrust slices, boundins, lens of ophiolite segments, numerous in the lower part of the Sowie Mountains slab characterize this type of pattern.
These macrostructural features originated in the Variscan tectogenesis (the Acadian phase?).
Massif
Obduction
Ultramafic rock
Island arc
Cite
Citations (4)
Massif
Outcrop
Section (typography)
Cite
Citations (35)
Massif
Petrochemistry
Cite
Citations (0)
<p>Figure S1: Discrimination diagrams for the granite dikes in the Monhhan ophiolite. Table S1: Major and trace element compositions of the Monhhan ophiolite and intruding granite. Table S2: LA-ICP-MS zircon U-Pb analytical data for the gabbro, intruding granite, and associated sandstone in the Monhhan ophiolite. Table S3: Lu–Hf data for zircons from the gabbro and intruding granite in the Monhhan ophiolite.</p>
Dike
Table (database)
Trace element
Cite
Citations (0)
Massif
Cite
Citations (11)
Massif
Ultramafic rock
Riphean
Cite
Citations (3)
The eastern Mediterranean region within the Tethyan realm shows a high concentration of ophiolites with contrasting times of formation and emplacement along the belt: In the Balkans, the ophiolites formed during the early to medial Jurassic, and were obducted during the late Jurassic, whereas in Turkey and farther east, structurally intact Jurassic ophiolites are rare and Jurassic ophiolite obduction is unknown. Here we report a structurally intact, large ophiolite body of early Jurassic age from NE Turkey, the Refahiye ophiolite, located close to the suture zone between the Eastern Pontides and the Menderes-Taurus block. The Refahiye ophiolite forms an outcrop belt, 175 km long and 20 km wide, and is tectonically bound by the late Cretaceous ophiolitic mélange to the south, and by the North Anatolian Transform Fault against the Triassic low-grade metamorphic rocks to the north. Early to medial Jurassic very low- to low-grade metamorphic rocks, interpreted as intraoceanic subduction-accretion complexes, occur either beneath the ophiolite or as thrust slices within it. The ophiolite body within the studied section is made up of mantle peridotite (clinopyroxene-bearing harzburgite and minor dunite) crosscut by up to 20 cm thick veins of clinopyroxenite and later dikes/pods/stocks of gabbro ranging in size from 2 m to several hundreds of meters. The gabbro is represented by two distinct types: (i) cumulate gabbro, and (ii) non-cumulate gabbro with locally well-developed igneous foliation. Within the non-cumulate gabbro or enclosing peridotite, there are up to 5 m and 50 cm-thick veins of trondhjemite and pegmatitic gabbro, respectively. LA-ICP-MS dating on zircons from two trondhjemite samples yielded weighted mean ages of ∼184 ± 4 Ma and 178 ± 4 Ma (2σ), respectively, suggesting formation during early Jurassic time. Formation in a suprasubduction-zone forearc setting is inferred from (i) wide-ranging pyroxene and spinel compositions in the peridotites as documented in most suprasubduction-zone ophiolites, (ii) arc tholeiitic signature of the non-cumulate gabbros, and (iii) association of the ophiolite with the coeval subduction-accretion complexes. Emplacement of a trapped forearc ophiolite above its own subduction-accretion complex as a backstop is proposed based on a series of field relationships such as (i) intimate association of the unsubducted suprasubduction-zone ophiolite with coeval accretionary complexes, (ii) absence of unambiguous relationship to the southern Atlantic-type continental margin, and (iii) absence of any stratigraphic indications for the ophiolite obduction in the southern Atlantic-type continental margin during Jurassic time. This is a clear difference from the Jurassic ophiolites in the Balkans that were obducted over the Atlantic-type continental margin. This difference in mode of emplacement is most probably related to the greater distance of the intra-oceanic subduction zone to the Atlantic-type continental margin than it was in the Balkans, which is commensurate with the greater width of the Tethys in the east during Jurassic time.
Obduction
Peridotite
Ultramafic rock
Cite
Citations (78)
<p>Figure S1: Discrimination diagrams for the granite dikes in the Monhhan ophiolite. Table S1: Major and trace element compositions of the Monhhan ophiolite and intruding granite. Table S2: LA-ICP-MS zircon U-Pb analytical data for the gabbro, intruding granite, and associated sandstone in the Monhhan ophiolite. Table S3: Lu–Hf data for zircons from the gabbro and intruding granite in the Monhhan ophiolite.</p>
Dike
Table (database)
Cite
Citations (0)