scholarly journals Mineralogical-geochemical features of magnetite occurrences in serpentinites of the Kalkan area (Main Uralian fault zone, South Urals)

2021 ◽  
pp. 48-67
Author(s):  
D.E. Saveliev
Keyword(s):  
Fault Zone ◽  
Upper Mantle ◽  
Early Stage ◽  
Mineralogical Composition ◽  
South Urals ◽  
Formation Model ◽  
Two Stage ◽  
Small Bodies ◽  
Native Copper ◽  
Strong Depletion

Chemical and mineralogical composition of magnetite occurrences from serpentinites of the Kalkan melange area of the Main Uralian Fault zone (South Urals) are studied. Abundant Cu minerals including native copper, Cu sulfdes (covellite, bornite, minerals of the chalcocite-digenite series), chlorides (nantokite), Cu carbonates and Cu silicates are found in magnetite ores. Magnetite also contains abundant inclusions of cobaltpentlandite, rare Ag and Bi sulfdes, heazlewoodite and awaruite. All magnetite occurrences host relicts of chromites, the composition of which (moderate to high Cr / (Cr + Al) values) indicates a strong depletion of a peridotite protolith, which formed in the upper mantle below a forearc basin. A two-stage formation model of magnetite occurrences is suggested. At an early stage, the disseminated magnetite with inclusions of Cu-Fe-Co sulfdes formed under the infuence of metalliferous fuids in serpentinized ultramafc rocks at the bottom of the oceanic basin. During collision, serpentinites were tectonized with the formation of small bodies of massive magnetite ores and Cu, Ag and Bi sulfdes and native minerals.

Upper mantle velocity and its dynamic significance in the middle-southern segment of the Tan-Lu fault zone

2021 ◽  
Vol 804 ◽  
pp. 228771
Author(s):  
Qiguang Zhao ◽  
Xiaoping Fan ◽  
Yicheng He ◽  
Leiming Zheng ◽  
Yejun Sun
Keyword(s):  
Fault Zone ◽  
Upper Mantle ◽  
Mantle Velocity

Lexical and sentential priming in competition: Implications for two-stage theories of lexical access

2001 ◽  
Vol 22 (2) ◽  
pp. 191-215 ◽  
Author(s):  
ARTURO E. HERNANDEZ ◽  
CHRISTINE FENNEMA-NOTESTINE ◽  
CARE UDELL ◽  
ELIZABETH BATES
Keyword(s):  
Lexical Access ◽  
Time Window ◽  
Early Stage ◽  
Time Windows ◽  
Unrelated Word ◽  
Two Stage ◽  
Sentential Context ◽  
Lexical Priming ◽  
Priming Word ◽  
Stage Theories

This article presents a new method that can compare lexical priming (word–word) and sentential priming (sentence–word) directly within a single paradigm. We show that it can be used to address modular theories of word comprehension, which propose that the effects of sentence context occur after lexical access has taken place. Although lexical priming and sentential priming each occur very quickly in time, there should be a brief time window in which the former is present but the latter is absent. Lexical and sentential priming of unambiguous words were evaluated together, in competing and converging combinations, using time windows designed to detect an early stage where lexical priming is observed but sentential priming is not. Related and unrelated word pairs were presented visually, in rapid succession, within auditory sentence contexts that were either compatible or incompatible with the target (the second word in each pair). In lexical decision, the additive effects of lexical priming and sentential priming were present under all temporal conditions, although the latter was always substantially larger. In cross-modal naming, sentential priming was present in all temporal conditions; lexical priming was more fragile, interacting with timing and sentential congruence. No evidence was found for a stage in which lexical priming is present but sentential priming is absent – a finding that is difficult to reconcile with two-stage models of lexical versus sentential priming. We conclude that sentential context operates very early in the process of word recognition, and that it can interact with lexical priming at the earliest time window.

Working towards a universal formation model for spheroidal iron (oxyhydr)oxide concretions

2021 ◽  
Author(s):  
Desiree Baker ◽  
Sally Potter-McIntyre
Keyword(s):  
Host Rock ◽  
Redox Reactions ◽  
Mineralogical Composition ◽  
Recent Model ◽  
Universal Model ◽  
Formation Model ◽  
Navajo Sandstone ◽  
Diagenetic Facies ◽  
A Site ◽  
Diagenetic Reactions

<p>Three principal models exist for iron (oxyhydr)oxide concretion formation in the Navajo Sandstone in southern Utah, USA and the most recent model by Yoshida et al. (2018) suggests that calcite concretions are precursors to iron (oxyhydr)oxide concretions. This model could account for the existence of a gradient of carbonate and iron concretions found in both red diagenetic facies (with primary hematite grains coatings retained) and white diagenetic facies (primary hematite grain coatings removed during diagenesis). However, evidence for calcite precursor minerals and an understanding of the fluid chemistries involved in these diagenetic reactions is lacking. This research focuses on spheroidal concretions in the Navajo Sandstone at Coyote Gulch—a site that is down gradient, but upsection from Spencer Flat (the focus of previous work) and tests the hypothesis that calcite concretions are precursors to iron (oxyhydr)oxide concretions. Bulk mineralogy, bulk geochemistry, and petrography provide elemental and mineralogical composition of the concretions and show that the concretions are calcite cemented (~40 wt.%) and the host rock is predominately iron (oxyhydr)oxide cemented (~3 wt.%). The host rock surrounding embedded concretions shows secondary iron (oxyhydr)oxide precipitation and decreases in calcite in transects away from the concretion. These relationships suggest that the calcite concretions formed prior to the precipitation of secondary iron (oxyhydr)oxides and may have provided a localized buffering environment for the precipitation of iron (oxyhydr)oxides. This study also represents an opportunity to determine a universal model for carbonate and iron (oxyhydr)oxide spheroidal concretion formation, and to understand the influence of fluid interactions in the search for subsurface redox reactions to power metabolisms on Earth and Mars.</p>

New data on the age and geodynamic position of copper-porphyry mineralization in the Main Uralian fault zone (South Urals)

2014 ◽  
Vol 459 (1) ◽  
pp. 1317-1321 ◽  
Author(s):  
A. M. Kosarev ◽  
V. N. Puchkov ◽  
Yu. L. Ronkin ◽  
I. B. Seravkin ◽  
V. V. Kholodnov ◽  
...  
Keyword(s):  
Fault Zone ◽  
South Urals ◽  
Copper Porphyry

Physical and chemical strain-hardening during faulting in poorly lithified sandstone: The role of kinematic stress field and selective cementation

2019 ◽  
Vol 132 (5-6) ◽  
pp. 1183-1200 ◽  
Author(s):  
Mattia Pizzati ◽  
Fabrizio Balsamo ◽  
Fabrizio Storti ◽  
Paola Iacumin
Keyword(s):  
Stress Field ◽  
Strain Hardening ◽  
Fault Zone ◽  
Deformation Band ◽  
Early Stage ◽  
Damage Zone ◽  
Isotope Analysis ◽  
Deformation Bands ◽  
Multidisciplinary Study ◽  
Diagenetic Evolution

Abstract In this work, we report the results of a multidisciplinary study describing the structural architecture and diagenetic evolution of the Rocca di Neto extensional fault zone developed in poorly lithified sandstones of the Crotone Basin, Southern Italy. The studied fault zone has an estimated displacement of ∼90 m and consists of: (1) a low-deformation zone with subsidiary faults and widely spaced deformation bands; (2) an ∼10-m-wide damage zone, characterized by a dense network of conjugate deformation bands; (3) an ∼3-m-wide mixed zone produced by tectonic mixing of sediments with different grain size; (4) an ∼1-m-wide fault core with bedding transposed into foliation and ultra-comminute black gouge layers. Microstructural investigations indicate that particulate flow was the dominant early-stage deformation mechanism, while cataclasis became predominant after porosity loss, shallow burial, and selective calcite cementation. The combination of tectonic compaction and preferential cementation led to a strain-hardening behavior inducing the formation of “inclined conjugate deformation band sets” inside the damage zone, caused by the kinematic stress field associated with fault activity. Conversely, conjugate deformation band sets with a vertical bisector formed outside the damage zone in response to the regional extensional stress field. Stable isotope analysis helped in constraining the diagenetic environment of deformation, which is characterized by mixed marine-meteoric signature for cements hosted inside the damage zone, while it progressively becomes more meteoric moving outside the fault zone. This evidence supports the outward propagation of fault-related deformation structures in the footwall damage zone.

Distributed deformation in the lower crust and upper mantle beneath a continental strike-slip fault zone: Marlborough fault system, South Island, New Zealand

Geology ◽  
2004 ◽  
Vol 32 (10) ◽  
pp. 837 ◽  
Author(s):  
Charles K. Wilson ◽  
Craig H. Jones ◽  
Peter Molnar ◽  
Anne F. Sheehan ◽  
Oliver S. Boyd
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Upper Mantle ◽  
Lower Crust ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Fault System ◽  
Crust And Upper Mantle

The formation model of neotectonic fault zone in the Ulsan Fault Zone, Gyeongsang basin, Korea

2020 ◽  
Author(s):  
Ji-Hoon Kang
Keyword(s):  
Human Resource Development ◽  
Fault Zone ◽  
Korean Peninsula ◽  
Active Faults ◽  
Development Project ◽  
Strike Slip ◽  
Formation Model ◽  
The West ◽  
Quaternary Deposits ◽  
Gyeongsang Basin

<p>The Yangsan Fault Zone (YFZ) of NNE trend and Ulsan Fault Zone (UFZ) of NNW trend are developed in the Gyeongsang Basin, the southern part of the Korean Peninsula, and many active faults and Quaternary faults (ATV and QTY Fs) have been found in these fault zones. The tectonic movement of the YFZ can be explained at least by two different strike-slip movements, named as D1 sinistral strike-slip and D2 dextral strike-slip, and then two different dip-slip movements, named as D3 conjugate reverse-slip and D4 Quaternary reverse-slip. The surfaces of D3 fault in basement rocks are extended those of D4 fault in the covering Quaternary deposits, like the other Quaternary faults within the YFZ. The D3 and D4 faults were formed under the same compression of (N)NW-(S)SE direction. After that, the active faults occurred in the Korean Peninsula under the compression of E-W direction. The ATV and QTY Fs thrust the Bulguksa igneous rocks of Late Cretaceous-Early Tertiary upon the Quaternary deposits or are developed within the Quaternary deposits in the UFZ, showing the reverse-slip sense of top-to-the west movement. This presentation is suggested the formation model of neotectonic fault zone in the UFZ on the basis of the various trends [(W)NW, N-S, (E)NE trends] of fault surfaces of the ATV and QTY Fs found in the UFZ, and the zigzag-form connecting line of their outcrop sites, and the deformation history (the N-S trending 1st reverse-slip faulting by the 1st E-W compression and associated the E-W trending strike-slip tear faulting, the N-S trending 2nd reverse-slip faulting by the 2nd E-W compression) of neotectonic fault zone in the Singye-ri valley around the UFZ, and the compressive arc-shaped lineaments which convex to the west reported in the YFZ.</p><p>Acknowledgements: This research was financially supported by a grant (2017-MPSS31-006) from the Research and Development of Active fault of Korean Peninsula funded by the Korean Ministry of the Interior and Safety, and by Ministry of public Administration and Security as Disaster Prevention Safety Human resource development Project.</p>

scholarly journals IODP Expedition 338: NanTroSEIZE Stage 3: NanTroSEIZE plate boundary deep riser 2

2014 ◽  
Vol 17 ◽  
pp. 1-12 ◽  
Author(s):  
G. F. Moore ◽  
K. Kanagawa ◽  
M. Strasser ◽  
B. Dugan ◽  
L. Maeda ◽  
...  
Keyword(s):  
Fault Zone ◽  
Early Stage ◽  
Plate Boundary ◽  
Seismogenic Zone ◽  
Fault Mechanics ◽  
Submarine Landslides ◽  
State Variables ◽  
Drilling Mud ◽  
Forearc Basin ◽  
Rock Composition

Abstract. The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is designed to investigate fault mechanics and seismogenesis along a subduction megathrust, with objectives that include characterizing fault slip, strain accumulation, fault and wall rock composition, fault architecture, and state variables throughout an active plate boundary system. Integrated Ocean Drilling Program (IODP) Expedition 338 was planned to extend and case riser Hole C0002F from 856 to 3600 meters below the seafloor (m b.s.f.). Riser operations extended the hole to 2005.5 m b.s.f., collecting logging-while-drilling (LWD) and measurement-while-drilling, mud gas, and cuttings data. Results reveal two lithologic units within the inner wedge of the accretionary prism that are separated by a prominent fault zone at ~ 1640 m b.s.f. Due to damage to the riser during unfavorable winds and strong currents, riser operations were suspended, and Hole C0002F left for re-entry during future riser drilling operations. Contingency riserless operations included coring at the forearc basin site (C0002) and at two slope basin sites (C0021 and C0022), and LWD at one input site (C0012) and at three slope basin sites (C0018, C0021 and C0022). Cores and logs from these sites comprehensively characterize the alteration stage of the oceanic basement input to the subduction zone, the early stage of Kumano Basin evolution, gas hydrates in the forearc basin, and recent activity of the shallow megasplay fault zone system and associated submarine landslides.

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