Itmurundy Accretionary Complex, Northern Balkhash Area: Geological Structure, Stratigraphy, and Tectonic Origin

Safonova, I.Yu.; Perfilova, A.A.; Obut, O.T.; Savinsky, I.A.; Chyornyi, R.I.; Petrenko, N.A.; Gurova, A.V.; Kotler, P.D.; Khromykh, S.V.; Krivonogov, S.K.; Maruyama, S.

doi:10.30911/0207-4028-2019-38-3-92-107

Cited by 4 publications

(24 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The thickness of the Tekturmas chert is estimated as at least 200 m (Figure ), that is, notably larger than that in other regions of central Kazakhstan (Gridina, ; Popov & Tolmacheva, ), but comparable with that of Itmurundy cherty formations outcropped in northern Balkhash (Safonova et al, ; Safonova, Savinskiy, Perfilova, Gurova, & Maruyama, ). Such a thickness, even if overestimated due to the coupling/thrusting of tectonic sheets, suggests a large oceanic realm as also was shown in the Itmurundy accretionary complex (Safonova et al, ).…”

Section: Discussionmentioning

confidence: 83%

“…In the section under the geological map (Figure ), we can clearly see that the rocks of all these formations form alternated tectonic sheets and lenses resembling thrust structures typical of accretionary complexes (e.g., Isozaki et al, ; Kemkin, Khanchuk, & Kemkina, ; Maruyama et al, ; Safonova et al, ; Wakita, ). Evidence for the accretionary nature of the Tekturmas belt comes from the presence of oceanic sediments and basalts formed in the deep ocean, because without accretion, those rocks would never remain on the surface but get subducted to the deep mantle (Hori, ; Isozaki et al, ; Maruyama et al, , ; Maruyama, Omori, Sensu, Kawai, & Windley, ; Safonova et al, , , ). The Tekturmas OPS (MORB/OIB, chert, and siliceous fine‐grained sediments) units were scraped off a subducting oceanic plate and then got incorporated into accretionary complex.…”

Section: Discussionmentioning

confidence: 99%

“…We suggest dividing the whole Tekturmas belt into three assemblages or units separated from each other by faults: “mantle” or ophiolitic assemblage (serpentinite mélange with plutonic mafic to felsic rocks), accretionary assemblage (OPS rocks, that is, basalt, chert, siliceous mudstone and siltstone, and sandstone), and “volcanic” assemblage (basaltic, andesitic, and dacitic lavas). Those lithologies, rocks assemblages, complicated structures, and high‐degree deformations are typical of numerous accretionary complexes in the western Pacific (e.g., Isozaki et al, ; Isozaki, Aoki, Nakama, & Yanai, ; Wakita and Metcalf, Wakita & Metcalfe, ; Safonova et al, ) and in the Central Asian Orogenic Belt (Safonova, ; Safonova et al, , ; Safonova & Santosh, ). The ages of the ophiolitic and OPS units span a wide interval from the late Cambrian to the early Silurian (e.g., Novikova et al, , Gerasimova et a. Gerasimova et al, , Degtyarev et al, ), suggesting a wide ocean evolving at least 50 m.y.…”

Section: Discussionmentioning

confidence: 99%

“…The concentrations of trace elements were measured by inductively coupled plasma mass spectrometry following a standard procedure (see method description in Safonova, Savinskiy, Perfilova et al, Safonova et al, ). In the MgO versus trace element plots (Figure ), the Karamurun high‐Ti samples plot certainly apart from the Bazarbai low‐Ti samples, in particular, in respect to La, Sm, Zr, and Nb (Figure c–f).…”

Section: Geochemical Datamentioning

confidence: 99%

“…Nevertheless, their ages and lithological composition of this or that formation overlap. The general succession of lithologies in this map, serpentinite mélange, pillow lavas, deep sea/pelagic chert (formerly called jaspers, phtanites, or simply silicilites), siliceous mudstone and siltstone, and sandstones match the succession or model of ocean plate stratigraphy (OPS), which has been reconstructed in numerous accretionary complexes worldwide, in particular, in Central and East Asia (e.g., Isozaki, Maruyama, Fukuoka, F., Isozaki, Maruyama, & Fukuoka, ; Wakita & Metcalfe, ; Maruyama, Kawai, & Windley, ; Kusky et al, ; Safonova & Santosh, ; Safonova et al, , ). A “classical” OPS succession includes basalt–pelagic chert–hemipelagic siliceous mudstone, siltstone and shale–trench/forearc sandstones.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

The Tekturmas ophiolite belt of central Kazakhstan: Geology, magmatism, and tectonics

et al. 2020

View full text Add to dashboard Cite

The Tekturmas ophiolite belt of central Kazakhstan is located in the western Central Asian Orogenic Belt. It consists of three structural‐formational zones: Tekturmas (centre), Bazarbai (north), and Sarysui (south). The Tekturmas zone includes igneous and sedimentary rocks of Karamurun, Tekturmas, and Sarytau formations, which are dominated by volcanogenic, deep sea, and clastic deposits, respectively. The Bazarbai zone consists of Kuzek and Basarbai formations dominated, respectively, by basaltic and sedimentary rocks. The Sarysui zone includes terrigenous Airtau and olistostromic Ermek formations. The age of sedimentary rocks was constrained by microfossils. The igneous rocks of the Karamurun and Bazarbai formations are alkaline and subalkaline basalt/dolerite, andesibasalt, and andesite. There are three main groups of rocks: high‐Ti, mid‐Ti, and low‐Ti. The high‐Ti Karamurun volcanics and low‐Ti Bazarbai are variably enriched in light rare earth element (LREE) showing LREE enriched (high‐Ti) and LREE flat (low‐Ti) REE patterns. The high‐Ti group shows enrichment in Nb, Th, Zr, and Sm compared with the low‐Ti group. The low‐Ti group is special for the Nb troughs in primitive mantle‐normalized multi‐element diagrams, which are typical of supra‐subduction settings. Both groups yielded positive εNd values, although the averages are 4.6 and 7.5 for the high‐ and low‐Ti rocks, respectively. The geochemical features suggest formation of the igneous rocks in oceanic and supra‐subduction (intra‐oceanic arc) settings. The geological and geochemical features of the Tekturmas ophiolite belt accord well with the tectonic emplacement of ophiolites and formation of accretionary complex at a Pacific‐type convergent margin similar to those of the western Pacific.

show abstract

Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Geochemical Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Tekturmas ophiolite belt of central Kazakhstan: Geology, magmatism, and tectonics

et al. 2020

View full text Add to dashboard Cite

show abstract

Evolution of Late Paleozoic Magmatic Arc in the Yili Block, NW China: Implications for Oroclinal Bending in the Western Central Asian Orogenic Belt

et al. 2020

View full text Add to dashboard Cite

Subduction transformation (advancing vs. retreating) may be manifested by compositional variations of arc magmas and may result in oroclinal bending. Identifying relevant chemical and physical processes is crucial for understanding accretionary orogenesis and continental crustal evolution. The Northern Yili Block (NYB) was situated on an active margin associated with subduction of the Junggar Ocean (part of the Paleo-Asian Ocean) and underwent perplexing accretionary orogenesis in late Paleozoic. Two episodes of subduction-related granitoid magmatism have been identified, the first in the Late Devonian (374-369 Ma) and the second in the Late Carboniferous (ca. 304 Ma). These two episodes of granitoid magmatism exhibit contrasting features; for example, the first episode shows low ε Nd (t) (−6 to −2) and ε Hf (t) (−12 to +3) values, while the second episode displays relatively higher values (−2 to +7 and 0 to +20, respectively), suggesting increase contribution of juvenile components in the magma sources. The calculated zircon saturation temperatures are mostly <800°C for the first episode but increased to >800°C for the second episode. The (La/Yb) N ratios of the two-episode granitoids vary from 2-17 to 1-9, indicative of the NYB crustal thinning in the Late Carboniferous. In addition, the migrations of the magmatic arc and trench in the NYB took place coevally in the Late Carboniferous and were accompanied by development of an accretionary complex and an immature back-arc basin. We interpret that the arc magmatic variations and migrations reflect geodynamic transition from the Late Devonian advancing subduction to the Late Carboniferous retreating subduction. The retreating subduction of the Junggar oceanic plate possibly resulted in prominent oroclinal bending of the southern Kazakhstan collage system in the Late Carboniferous.

show abstract

Survived and disappeared intra-oceanic arcs of the Paleo-Asian Ocean: evidence from Kazakhstan

Safonova

Perfilova

2022

National Science Review

View full text Add to dashboard Cite

The paper reviews published and presents new data on U-Pb detrital zircon ages, petrographic, geochemical and isotope (Sm-Nd, Lu-Hf) compositions obtained from greywacke sandstones of Kazakhstan in order to reconstruct fossil intra-oceanic arcs once existed at Pacific-type convergent margins of the Paleo-Asian Ocean (PAO) in Paleozoic time. We focused on orogenic belts of central Kazakhstan (Itmurundy and Tekturmas) and eastern Kazakhstan (Zharma and Char) in the western Central Asian Orogenic belt (CAOB). These orogenic belts host accretionary complexes with greywacke sandstones of early Paleozoic (central Kazakhstan) and middle-late Paleozoic (eastern Kazakhstan) ages. First, we evaluate general perspectives for studying sandstones to reconstruct survived and disappeared magmatic arcs taking into account episodes of subduction erosion. Then we discuss the analytical data from sandstones to conclude about the ages and settings of formation of their igneous protoliths and define maximum deposition ages. Finally, we discuss the role of serpentinite mélange in tectonic reconstructions. We argue that sandstones hosted by accretionary complexes are typically greywackes deposited close to their igneous sources and buried rapidly. The provenances of the studied greywacke sandstones of central and eastern Kazakhstan were dominated by mafic to andesitic igneous protoliths derived from juvenile mantle sources. The igneous rocks in the provenances were emplaced in an intra-oceanic arc setting. The sandstones were deposited in fore-arc/trench basins or, to a lesser degree, in back-arc basins. The data from both sandstones and serpentinite mélange reconstruct middle-late Cambrian, Ordovician, late Devonian and Carboniferous arcs of the western PAO. The middle-late Cambrian arcs were fully destroyed by subduction erosion, whereas the Ordovician and Carboniferous arcs survived. The late Devonian arcs were also eroded, but partly. Both, the early and late Paleozoic active margins of the PAO were characterized by alternating periods of accretionary growth and subduction erosion.

show abstract

Itmurundy Accretionary Complex, Northern Balkhash Area: Geological Structure, Stratigraphy, and Tectonic Origin

Cited by 4 publications

References 13 publications

The Tekturmas ophiolite belt of central Kazakhstan: Geology, magmatism, and tectonics

The Tekturmas ophiolite belt of central Kazakhstan: Geology, magmatism, and tectonics

Evolution of Late Paleozoic Magmatic Arc in the Yili Block, NW China: Implications for Oroclinal Bending in the Western Central Asian Orogenic Belt

Survived and disappeared intra-oceanic arcs of the Paleo-Asian Ocean: evidence from Kazakhstan

Contact Info

Product

Resources

About