Petrogenesis and tectonic setting of the Huhetaoergai granitic pluton in the northern Ya-Gan Fault zone, northern Alxa, China: constraints from whole-rock geochemistry, zircon U–Pb ages, and Hf isotope compositions

2020 ◽  
Vol 57 (1) ◽  
pp. 56-68
Author(s):  
Fenquan Xie ◽  
Qianhong Wu ◽  
Lidong Wang ◽  
Wenzhou Xiao ◽  
Jingya Cao ◽  
...  
Keyword(s):  
Fault Zone ◽  
Crystallization Process ◽  
Tectonic Setting ◽  
Coarse Grained ◽  
Collision Process ◽  
Data Set ◽  
Granitic Pluton ◽  
Juvenile Crust ◽  
T Values ◽  
Fractional Crystallization Process

This study presents a new data set that contains zircon U–Pb ages, whole-rock geochemistry, and Hf isotopes of the Huhetaoergai granitic pluton in the northern Ya-Gan Fault zone, northern Alxa, China. The Huhetaoergai pluton is composed of medium- to coarse-grained biotite monzogranite and coarse-grained biotite monzogranite with K-feldspar megacrysts, with U–Pb zircon ages of 220.5 ± 1.9 Ma and 226.5 ± 2.4 Ma, respectively. Granitoids are I-type granites with high εHf(t) values (9–11.05). These features indicate that the granitoids were generated from partial melting of juvenile crust and experienced an obvious fractional crystallization process. We speculate that the granitoids of the Huhetaoergai pluton were formed in an intraplate extensional environment during the post-collision process, indicating a crustal stretching and thinning event in the northern Ya-Gan Fault zone.

scholarly journals Petrogenesis and Tectonic Setting of a Granitic Pluton in the Northern Ya-Gan fault Zone, North Alxa, China: Constraints from Whole-Rock Geochemistry, Zircon U–Pb Ages, and Sr–Nd–Hf Isotope Compositions

2018 ◽  
Author(s):  
Fenquan Xie ◽  
Qianhong Wu ◽  
Lidong Wang ◽  
Zhaoxia Shi ◽  
Wenzhou Xiao ◽  
...  
Keyword(s):  
Fault Zone ◽  
Tectonic Setting ◽  
Hf Isotope ◽  
Coarse Grained ◽  
Granitic Pluton ◽  
Precise Data ◽  
Juvenile Crust

A series of precise data consisting of zircon U–Pb ages, whole-rock geochemistry and Sr–Nd–Hf isotope compositions from the Huhetaoergai granitic pluton was collected in this study and combined with data from the western Huhetaoergai, Zhuxiaogubuhe and Yagan granitic plutons to constrain the petrogenesis and tectonic setting of granitic plutons in the northern Ya-Gan fault zone, North Alxa, China. The Huhetaoergai pluton is composed of hornblende diorite, medium- to coarse-grained biotite adamellite and coarse-grained biotite adamellite with K-feldspar megacrysts. The U–Pb zircon ages of biotite adamellite are 220.5 ± 1.9 Ma and 226.5 ± 2.4 Ma. These granitoids are I-type granites with highly radiogenic initial 87Sr/86Sr of 0.708085–0.735470, negative eNd(t) average values of −2.98–3.23 and high eHf(t) of 9–11.05. These features indicate the granitoids were formed from magmas generated from juvenile crust. We speculate that the granitoids of the Huhetaoergai pluton were emplaced during an episode of intense intraplate orogenic movement evolution in an extrusional setting after a period of extensional postcollisional intraplate evolution.

scholarly journals Statherian (ca. 1714–1680 Ma) Extension-Related Magmatism and Deformation in the Southwestern Korean Peninsula and Its Geological Significance: Constraints from the Petrological, Structural, Geochemical and Geochronological Studies of Newly Identified Granitoids

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 557
Author(s):  
Byung-Choon Lee ◽  
Weon-Seo Kee ◽  
Uk-Hwan Byun ◽  
Sung-Won Kim
Keyword(s):  
Korean Peninsula ◽  
Tectonic Setting ◽  
Alkali Feldspar ◽  
Ductile Deformation ◽  
Southwestern Part ◽  
The North ◽  
Deformation Event ◽  
Geochemical Analyses ◽  
A Minor ◽  
T Values

In this study, petrological, structural, geochemical, and geochronological analyses of the Statherian alkali feldspar granite and porphyritic alkali feldspar granite in the southwestern part of the Korean Peninsula were conducted to examine petrogenesis of the granitoids and their tectonic setting. Zircon U-Pb dating revealed that the two granites formed around 1.71 Ga and 1.70–1.68 Ga, respectively. The results of the geochemical analyses showed that both of the granites have a high content of K2O, Nb, Ta, and Y, as well as high FeOt/MgO and Ga/Al ratios. Both granites have alkali-calcic characteristics with a ferroan composition, indicating an A-type affinity. Zircon Lu-Hf isotopic compositions yielded negative εHf(t) values (−3.5 to −10.6), indicating a derivation from ancient crustal materials. Both granite types underwent ductile deformation and exhibited a dextral sense of shear with a minor extension component. Based on field relationships and zircon U-Pb dating, it was considered that the deformation event postdated the emplacement of the alkali feldspar granite and terminated soon after the emplacement of the porphyritic alkali feldspar granite in an extensional setting. These data indicated that there were extension-related magmatic activities accompanying ductile deformation in the southwestern part of the Korean Peninsula during 1.71–1.68 Ga. The Statherian extension-related events are well correlated with those in the midwestern part of the Korean and eastern parts of the North China Craton.

scholarly journals Mobility patterns are associated with experienced income segregation in large US cities

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Esteban Moro ◽  
Dan Calacci ◽  
Xiaowen Dong ◽  
Alex Pentland
Keyword(s):  
Large Scale ◽  
Mobility Model ◽  
Coarse Grained ◽  
Spatial Proximity ◽  
Mobility Patterns ◽  
Data Set ◽  
Residential Patterns ◽  
Income Segregation ◽  
Mobility Data ◽  
Mobility Behavior

AbstractTraditional understanding of urban income segregation is largely based on static coarse-grained residential patterns. However, these do not capture the income segregation experience implied by the rich social interactions that happen in places that may relate to individual choices, opportunities, and mobility behavior. Using a large-scale high-resolution mobility data set of 4.5 million mobile phone users and 1.1 million places in 11 large American cities, we show that income segregation experienced in places and by individuals can differ greatly even within close spatial proximity. To further understand these fine-grained income segregation patterns, we introduce a Schelling extension of a well-known mobility model, and show that experienced income segregation is associated with an individual’s tendency to explore new places (place exploration) as well as places with visitors from different income groups (social exploration). Interestingly, while the latter is more strongly associated with demographic characteristics, the former is more strongly associated with mobility behavioral variables. Our results suggest that mobility behavior plays an important role in experienced income segregation of individuals. To measure this form of income segregation, urban researchers should take into account mobility behavior and not only residential patterns.

scholarly journals Heavy minerals in the Wajid Sandstone from Abha-Khamis Mushayt area, southwestern Saudi Arabia: implications on provenance and regional tectonic setting

GeoArabia ◽  
2004 ◽  
Vol 9 (4) ◽  
pp. 77-102 ◽  
Author(s):  
Mahbub Hussain ◽  
Lameed O. Babalola ◽  
Mustafa M. Hariri
Keyword(s):  
Saudi Arabia ◽  
Tectonic Setting ◽  
Principal Component ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Coarse Grained ◽  
Distribution Data ◽  
The South ◽  
Quartz Content ◽  
The North

ABSTRACT The Wajid Sandstone (Ordovician-Permian) as exposed along the road-cut sections of the Abha and Khamis Mushayt areas in southwestern Saudi Arabia, is a mediun to coarse-grained, mineralogically mature quartz arenite with an average quartz content of over 95%. Monocrystalline quartz is the dominant framework grain followed by polycrystalline quartz, feldspar and micas. The non-opaque heavy mineral assemblage of the sandstone is dominated by zircon, tourmaline and rutile (ZTR). Additional heavy minerals, constituting a very minor fraction of the heavies, include epidote, hornblende, and kyanite. Statistical analysis showed significant correlations between zircon, tourmaline, rutile, epidote and hornblende. Principal component R-mode varimax factor analysis of the heavy mineral distribution data shows two strong associations: (1) tourmaline, zircon, rutile, and (2) epidote and hornblende suggesting several likely provenances including igneous, recycled sedimentary and metamorphic rocks. However, an abundance of the ZTR minerals favors a recycled sedimentary source over other possibilities. Mineralogical maturity coupled with characteristic heavy mineral associations, consistent north-directed paleoflow evidence, and the tectonic evolutionary history of the region indicate a provenance south of the study area. The most likely provenances of the lower part (Dibsiyah and Khusayyan members) of the Wajid Sandstone are the Neoproterozoic Afif, Abas, Al-Bayda, Al-Mahfid, and Al-Mukalla terranes, and older recycled sediments of the infra-Cambrian Ghabar Group in Yemen to the south. Because Neoproterozic (650-542 Ma) rocks are not widespread in Somalia, Eritrea and Ethiopia, a significant source further to the south is not likely. The dominance of the ultrastable minerals zircon, tourmaline and rutile and apparent absence of metastable, labile minerals in the heavy mineral suite preclude the exposed arc-derived oceanic terrains of the Arabian Shield in the west and north as a significant contributor of the sandstone. An abundance of finer-grained siliciclastic sequences of the same age in the north, is consistent with a northerly transport direction and the existence of a deeper basin (Tabuk Basin?) to the north. The tectonic and depositional model presented in this paper differs from the existing model that envisages sediment transportation and gradual basin filling from west to east during the Paleozoic.

Jurassic Arc: Reconstructing the Lost World of eastern Gondwana

Geology ◽  
2021 ◽  
Author(s):  
Elliot K. Foley ◽  
R.A. Henderson ◽  
E.M. Roberts ◽  
A.I.S. Kemp ◽  
C.N. Todd ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Tectonic Setting ◽  
Magmatic Arc ◽  
Continental Arc ◽  
Key Factor ◽  
Igneous Activity ◽  
Competing Models ◽  
Juvenile Crust ◽  
Sedimentary Fill ◽  
Continental Magmatic Arc

The tectonic setting of the Australian sector of the eastern Gondwanan margin during the Jurassic and Cretaceous is enigmatic. Whether this involved convergent tectonism and a long-lived continental magmatic arc or rift-related extension unrelated to subduction is debated. The paucity of Australian Jurassic–Cretaceous igneous outcrops makes resolving these competing models difficult. We used the detrital zircon record of the Jurassic–Cretaceous Great Australian Superbasin (GAS) as a proxy for igneous activity. We attribute the persistent magmatism recorded in GAS sedimentary fill throughout the Mesozoic to ca. 95 Ma to continuation of the established Paleozoic continental arc system. The detrital zircon record signals short (~10 m.y.) pulses of elevated Jurassic and Cretaceous magmatic activity and strongly positive εHf values, indicating juvenile crust or mantle-derived magmatism. Margin reconstruction indicates sustained continental growth at rates of at least ~55 km3 km–1 m.y.–1, mainly to the tract now represented by submerged northern Zealandia, due to the retreat of this arc system. We posit that arc retreat was a key factor in rapid crust generation and preservation, and that continental sedimentary systems globally may host cryptic records of juvenile crustal addition that must be considered in estimating crustal growth rates along convergent plate margins.

scholarly journals <sup>10</sup>Be systematics in the Tsangpo-Brahmaputra catchment: the cosmogenic nuclide legacy of the eastern Himalayan syntaxis

2017 ◽  
Author(s):  
Maarten Lupker ◽  
Jérôme Lavé ◽  
Christian France-Lanord ◽  
Marcus Christl ◽  
Didier Bourlès ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Sediment Flux ◽  
Coarse Grained ◽  
The Tibetan Plateau ◽  
Data Set ◽  
Denudation Rate ◽  
Cosmogenic Nuclide ◽  
Denudation Rates ◽  
The Impact ◽  
Eastern Himalayan Syntaxis

Abstract. The Tsangpo-Brahmaputra River drains the eastern part of the Himalayan range, flowing from the Tibetan Plateau through the eastern Himalayan syntaxis and downstream to the Indo-Gangetic floodplain. As such it is a unique natural laboratory to study how denudation and sediment production processes are transferred to river detrital signals. In this study, we present a new 10Be data set to constrain denudation rates across the catchment and to quantify the impact of rapid erosion within the syntaxis region on cosmogenic nuclide budgets and signals. 10Be denudation rates span around two orders of magnitude across the catchments (ranging from 0.03 mm/yr to > 4 mm/yr) and sharply increase as the Tsangpo-Brahmaputra flows across the eastern Himalaya. The increase in denudation rates however occurs ~ 150 km downstream of the Namche Barwa-Gyala Peri massif (NBGPm), an area which has been previously characterized by extremely high erosion and exhumation rates. We suggest that this downstream lag is mainly due to the physical abrasion of coarse grained, low 10Be concentration, landslide material produced within the syntaxis that dilutes the upstream high concentration 10Be flux from the Tibetan Plateau only after abrasion has transferred sediment to the studied sand fraction. A simple abrasion model produces typical lag distances of 50 to 150 km compatible with our observations. Abrasion effects reduce the spatial resolution over which denudation can be constrained in the eastern Himalayan syntaxis. In addition, we also highlight that denudation rate estimates are dependent on the sediment connectivity, storage and quartz content of the upstream Tibetan Plateau part of the catchment which tends to lead to an overestimation of downstream denudations rates. Taking these effects into account we estimate a denudation rates of ca. 2 to 5 mm/yr for the entire syntaxis and ca. 4 to 28 mm/yr for the NBGPm, which is significantly higher than other to other large catchments. Overall, 10Be concentrations measured at the outlet of the Tsangpo-Brahmaputra in Bangladesh suggest a sediment flux between 780 and 1430 Mt/yr equivalent to a denudation rate between 0.7 and 1.2 mm/yr for the entire catchment.

On the impact of alternative seismic time imaging methods on subsurface fault mapping in the northernmost Molasse Basin, Switzerland

2020 ◽  
Vol 8 (4) ◽  
pp. SQ1-SQ13
Author(s):  
Christoph G. Eichkitz ◽  
Sarah Schneider ◽  
Andreas B. Hölker ◽  
Philip Birkhäuser ◽  
Herfried Madritsch
Keyword(s):  
Fault Zone ◽  
Three Dimensions ◽  
Small Scale ◽  
Zone Model ◽  
Molasse Basin ◽  
Data Set ◽  
Volume Comparison ◽  
Imaging Methods ◽  
Seismic Amplitude ◽  
The Impact

The identification and characterization of tectonic faults in the subsurface represent key aspects of geologic exploration activities across the world. We have evaluated the impact of alternative seismic time imaging methods on initial subsurface fault mapping in three dimensions in the form of a case study situated in the most external foreland of the European Central Alps (the northernmost Molasse Basin). Four different seismic amplitude volumes of one and the same 3D seismic data set, differing in imaging technologies and parameterizations applied, were considered for the interpretation of a fault zone dissecting a Mesozoic sedimentary sequence that is characterized by a pronounced mechanical stratigraphy and has witnessed a multiphase tectonic evolution. For this purpose, we interpreted each seismic amplitude volume separately. In addition, we computed a series of seismic attributes individually for each volume. Comparison of the different data interpretations revealed consistent results concerning the mapping of the seismic marker horizons and main fault segments. Deviations concern the apparent degree of vertical and lateral fault zone segmentation and the occurrence of small-scale fault strands that may be regarded as important fault kinematic indicators. The compilation of all fault interpretations in map form allows the critical assessment of the robustness of the initial seismic fault mapping, highlighting well-constrained from poorly defined fault zone elements. We conclude that the consideration of multiple seismic processing products for subsurface fault mapping is advisable to evaluate general imaging uncertainties and potentially guide the development of fault zone model variants to tackle previously discussed aspects of conceptual interpretation uncertainties.

Neoproterozoic Amdo and Jiayuqiao microblocks in the Tibetan Plateau: Implications for Rodinia reconstruction

2020 ◽  
Author(s):  
Yiming Liu ◽  
Yuhua Wang ◽  
Sanzhong Li ◽  
M. Santosh ◽  
Runhua Guo ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
South China ◽  
Tectonic Setting ◽  
Parental Magma ◽  
Tibet Plateau ◽  
Geochemical Data ◽  
The Tibetan Plateau ◽  
South China Craton ◽  
Neoproterozoic Magmatism ◽  
T Values

The Tibetan Plateau is composed of several microblocks, the tectonic affinity and paleogeographic correlations of which remain enigmatic. We investigated the Amdo and Jiayuqiao microblocks in central Tibet Plateau with a view to understand their tectonic setting and paleogeographic position within the Neoproterozoic supercontinent Rodinia. We present zircon U-Pb and Lu-Hf isotope, and whole-rock geochemical data on Neoproterozoic granitic gneisses from these microblocks. Zircon grains from the Jiayuqiao granitic gneiss yielded an age of 857 ± 9 Ma with variable εHf(t) values (−8.9 to 4.0). The Amdo granitic gneisses yielded ages of 893 ± 5 Ma, 807 ± 5 Ma, and 767 ± 11 Ma, with εHf(t) values in the range of −4.9 to 3.5. Geochemically, the granitoids belong to high-K calc-alkaline series, with the protolith derived from partial melting of ancient crustal components. The ascending parental magma of the Amdo granitoids experienced significant mantle contamination as compared to the less contaminated magmas that generated the Jiayuqiao intrusions. In contrast to the Lhasa, Himalaya, South China, and Tarim blocks, we suggest that the Amdo and Jiayuqiao microblocks probably formed a unified block during the Neoproterozoic and were located adjacent to the southwestern part of South China craton. The Neoproterozoic magmatism was probably associated with the subduction of the peripheral ocean under the South China craton and the delamination of lithospheric mantle beneath the Jiangnan orogen.

scholarly journals The 1590-1520 Ma Cachoeirinha magmatic arc and its tectonic implications for the Mesoproterozoic SW Amazonian craton crustal evolution

2004 ◽  
Vol 76 (4) ◽  
pp. 807-824 ◽  
Author(s):  
Amarildo S. Ruiz ◽  
Mauro C. Geraldes ◽  
João B. Matos ◽  
Wilson Teixeira ◽  
William R. Van Schumus ◽  
...  
Keyword(s):  
Crystallization Process ◽  
Major And Trace Elements ◽  
Magmatic Arc ◽  
Rio Negro ◽  
Intrusive Rocks ◽  
Amazonian Craton ◽  
Granitoid Rocks ◽  
Geologic Setting ◽  
Fractional Crystallization Process ◽  
Tectonic Relationship

Isotopic and chemical data of rocks from the Cachoeirinha suite provide new insights on the Proterozoic evolution of the Rio Negro/Juruena Province in SW Amazonian craton. Six U-Pb and Sm-Nd analyses in granitoid rocks of the Cachoeirinha suite yielded ages of 1587-1522 Ma and T DM model ages of 1.88-1.75 Ga (EpsilonNd values of -0.8 to +1.0). In addition, three post-tectonic plutonic rocks yielded U-Pb ages from 1485-1389 Ma (T DM of 1.77-1.74 Ga and EpsilonNd values from -1.3 to +1.7). Variations in major and trace elements of the Cachoeirinha suite rocks indicate fractional crystallization process and magmatic arc geologic setting. These results suggest the following interpretations: (1) The interval of 1590-1520 Ma represents an important magmatic activity in SW Amazonian craton. (2) T DM and arc-related chemical affinity supportthe hypothesis that the rocks are genetically associated with an east-dipping subduction zone under the older (1.79-1.74 Ga) continental margin. (3) The 1590-1520 Ma age of intrusive rocks adjacent to an older crust represents similar geological framework along the southern margin of Baltica, corroborating the hypothesis of tectonic relationship at that time.

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