Structural trend line pattern and strain partitioning around the Gibraltar Arc accretionary wedge: Insights as to the mode of orogenic arc building

J. C. Balanyá; A. Crespo-Blanc; M. Díaz Azpiroz; I. Expósito; M. Luján

doi:10.1029/2005tc001932

Linked thick- to thin-skinned inversion in the central Kirthar Fold Belt of Pakistan

Solid Earth ◽

10.5194/se-10-425-2019 ◽

2019 ◽

Vol 10 (2) ◽

pp. 425-446 ◽

Cited By ~ 1

Author(s):

Ralph Hinsch ◽

Chloé Asmar ◽

Muhammad Nasim ◽

Muhammad Asif Abbas ◽

Shaista Sultan

Keyword(s):

Structural Control ◽

Large Scale ◽

Sedimentary Cover ◽

Motion Vector ◽

Focal Mechanisms ◽

Plate Motion ◽

Normal Faults ◽

Accretionary Wedge ◽

Strain Partitioning ◽

Fold Belt

Abstract. The Kirthar Fold Belt is part of the transpressive transfer zone in Pakistan linking the Makran accretionary wedge with the Himalaya orogeny. The region is deforming very obliquely, nearly parallel to the regional S–N plate motion vector, indicating strong strain partitioning. In the central Kirthar Fold Belt, folds trend roughly N–S and their structural control is poorly understood. In this study, we use newly acquired 2-D seismic data with pre-stack depth migration, published focal mechanisms, surface and subsurface geological data, and structural modelling with restoration and balancing to constrain the structural architecture and kinematics of the Kirthar Fold Belt. The central Kirthar Fold Belt is controlled by Pliocene to recent linked thick-skinned to thin-skinned deformation. The thick-skinned faults are most likely partially inverting rift-related normal faults. Focal mechanisms indicate dip-slip faulting on roughly N–S-trending faults with some dip angles exceeding 40∘, which are considered too steep for newly initiated thrust faults. The hinterland of the study area is primarily dominated by strike-slip faulting. The inverting faults do not break straight through the thick sedimentary column of the post-rift and flexural foreland; rather, the inversion movements link with a series of detachment horizons in the sedimentary cover. Large-scale folding and layer-parallel shortening has been observed in the northern study area. In the southern study area progressive imbrication of the former footwall of the normal fault is inferred. Due to the presence of a thick incompetent upper unit (Eocene Ghazij shales) these imbricates develop as passive roof duplexes. In both sectors the youngest footwall shortcut links with a major detachment and the deformation propagates to the deformation front, forming a large fault-propagation fold. Shortening within the studied sections is calculated to be 18 %–20 %. The central Kirthar Fold Belt is a genuine example of a hybrid thick- and thin-skinned system in which the paleogeography controls the deformation. The locations and sizes of the former rift faults control the location and orientation of the major folds. The complex tectonostratigraphy (rift, post-rift, flexural foreland) and strong E–W gradients define the mechanical stratigraphy, which in turn controls the complex thin-skinned deformation.

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Structural complexity in the boundary of forearc basin – accretionary wedge in the northwesternmost Sunda active margin

BULLETIN OF THE MARINE GEOLOGY ◽

10.32693/bomg.33.1.2018.536 ◽

2018 ◽

Vol 33 (1) ◽

Author(s):

Maruf M. Mukti

Keyword(s):

Structural Complexity ◽

Strike Slip ◽

Accretionary Wedge ◽

Strain Partitioning ◽

Forearc Basin ◽

Eastern Margin ◽

The North ◽

Step Over ◽

Oblique Convergent ◽

North Sumatra

The area from Andaman to northern Sumatran margin is a region where major faults collided that complicates the structural configuration. The origin of structures in the boundary between the accretionary wedge and forearc basin in the northwesternmost segment of the Sunda margin has been a subject of debates. This article reviews several published works on the Andaman – north Sumatran margin to characterize the boundary between forearc basin and accretionary wedge. Complex strain partitioning in this margin is characterized by sliver faults that crossing boundaries between the backarc basin, volcanic arc, forearc basin, and accretionary wedge. The fault zone can be divided into two segments: The West Andaman Fault (WAF) in the north and Simeulue Fault (SiF) in the southern part. A restraining step-over formed in between WAF and SiF. The SiF may extent onshore Simeulue to a strike-slip fault onshore. Strain-partitioning in such an oblique convergent margin appears to have formed a new deformation zone rather than reactivated the major rheological boundary in between the accretionary wedge and forearc basin. The eastern margin of the Andaman-north Sumatra accretionary wedge appears to have form as landward-vergent backthrusts of Diligent Fault (DF) and Nicobar Aceh Fault (NAF) rather than strike-slip faults. This characteristic appears to have formed in the similar way with the compressional structures dominated the eastern margin accretionary wedge of the central and south Sumatra forearc. Keywords: Andaman, North Sumatra, forearc, structure, accretionary wedge, strain partitioningDaerah Andaman - Sumatera bagian utara adalah wilayah di mana patahan-patahan besar saling bertemu dan membuat konfigurasi struktur menjadi rumit. Asal-usul struktur di batas antara prisma akresi dan cekungan busur muka di bagian paling baratlaut dari tepian Sunda telah menjadi topik perdebatan. Artikel ini mengulas beberapa studi yang telah diterbitkan sebelumnya mengenai tepian Andaman - Sumatra bagian utara untuk mengkarakterisasikan batas antara cekungan muka dan prisma akresi. Pemisahan regangan yang kompleks di tepian ini dicirikan oleh sliver fault yang melintasi batas antara cekungan busur belakang, busur vulkanik, cekungan busur muka, dan prisma akresi. Zona sesar tersebut dapat dibagi menjadi dua segmen, yaitu Sesar Andaman Barat (WAF) di utara dan Simeulue Fault (SiF) di bagian selatan. Sebuah restraining step-over terbentuk di antara WAF dan SiF. SiF kemungkinan menerus sampai ke Pulau Simeulue dan menyatu dengan sesar geser. Pemisahan regangan di tepian konvergen yang miring seperti itu tampaknya telah membentuk zona deformasi baru daripada mengaktifkan kembali batas reologi utama di antara prisma akresi dan cekungan busur muka. Batas bagian timur dari prisma akresi di Andaman – Sumatera bagian utara memiliki bentuk sebagai backthrusts berarah darat yaitu Sesar Diligent (DF) dan Sesar Nicobar Aceh (NAF) dan bukan merupakan sesar geser. Karakteristik ini tampaknya terbentuk dengan proses yang mirip dengan struktur-struktur kompresional yang mendominasi bagian timur prisma akresi di daerah Sumatra bagian tengah dan selatan.Kata kunci: Andaman, Sumatera bagian, busur muka, struktur, prisma akresi, pemisahan regangan

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Linked thick to thin – skinned inversion in the central Kirthar Fold Belt of Pakistan

10.5194/se-2018-137 ◽

2018 ◽

Author(s):

Ralph Hinsch ◽

Chloé Asmar ◽

Muhammad Nasim ◽

Muhammad Asif Abbas ◽

Shaista Sultan

Keyword(s):

Structural Control ◽

Sedimentary Cover ◽

Motion Vector ◽

Normal Fault ◽

Focal Mechanisms ◽

Plate Motion ◽

Normal Faults ◽

Accretionary Wedge ◽

Strain Partitioning ◽

Fold Belt

Abstract. The Kirthar Fold Belt is part of the lateral collision zone in Pakistan linking the Makran accretionary wedge with the Himalaya orogeny. The region is deforming very obliquely, nearly parallel to the regional S-N plate motion vector, indicating strong strain partitioning. In the central Kirthar Fold Belt, folds trend roughly N-S and their structural control is poorly understood. In this study, we use newly acquired 2D seismic data with pre-stack depth migration, published focal mechanisms, surface and subsurface geological data as well as structural modelling with restoration and balancing to constrain the structural architecture and kinematics of the Kirthar Fold Belt. The central Kirthar Fold Belt is controlled by Pliocene to recent inversion of Mesozoic rift related normal faults. Focal mechanisms indicate dip-slip faulting on roughly N-S trending faults with angles in the order of 45°, which are too steep for newly initiated thrust faults. The hinterland of the study area is primarily dominated by strike slip faulting. The inverting faults do not break straight through the thick sedimentary column of the post-rift and flexural foreland; rather the inversion movements link with a series of detachment horizons in the sedimentary cover, progressively imbricating the former footwall of the normal fault. Due to the presence of a thick incompetent upper unit (Eocene Ghazij shales) these imbricates develop as passive roof duplexes. Finally, the youngest footwall shortcut links with a major detachment and the deformation propagates to the deformation front, forming a large fault-propagation fold. Shortening within the studied sections is calculated to be on the order of 20 %. The central Kirthar fold belt is a genuine example of hybrid thick- and thin-skinned system in which the paleogeography controls the deformation. The locations and sizes of the former rift faults controls the location and orientation of the major folds. The complex tectonostratigraphy (rift, post rift, flexural foreland) alone with the strong E-W gradients defines the mechanical stratigraphy, which in turn controls the complex thin-skinned deformation.

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Malaysian and Italian trend line for Covid-19: A study on trend analysis

Bulletin of Applied Mathematics and Mathematics Education ◽

10.12928/bamme.v1i2.3954 ◽

2021 ◽

Vol 1 (2) ◽

pp. 61-74

Author(s):

Wan Muhammad Amir bin Wan Ahmad ◽

Noor Azlinaliana Ibrahim ◽

Mohamad Arif Awang Nawi ◽

Nor Farid Mohd Noor ◽

Noraini Mohamad ◽

...

Keyword(s):

Linear Trend ◽

Movement Control ◽

Equation Model ◽

Positive Case ◽

Quadratic Model ◽

Quadratic Trend ◽

Line Pattern ◽

Trend Line ◽

Linear Pattern ◽

Collection Data

The first objective of this study was to evaluate trend line pattern, obtain the appropriate statistical equation model, and predict individual numbers infected by Covid-19. The second objective is to obtain a predictive equation model and forecast death rate for Malaysia and Italy. Malaysia's first positive case Covid-19 recorded January 24, 2020, consisting of three cases. Collected from January 24 to March 29, 2020. Sixty-six day-observations, based on their trend line pattern, earned special attention. Although the first positive case was identified on January 31, 2020, involving two patients. From January 31 to March 29, 2020, approximately 59 observations were collected from Italy. On 18 March 2020, the pattern will contrast with the Malaysian Movement Control Order (MCO). Malaysia and Italy collect death figures. A similar methodology will be applied to find the best-fitted model that fits both countries' death-number scenario. In Italy, the number of Covid-19-infected patients rises and meets quadratic trend line patterns. This induces extreme public distress and diversion. The quadratic trend line series analysed individual Covid-19-infected results. After March 18, 2020, it will continue to use a linear pattern. However, trend deaths also follow quadratic trend line pattern. Trend-line quadratic matched Italy's results. The quadratic line-of-trend model projection demonstrated dominance in estimating infected Covid-19. The quadratic death line from daily death collection data also showed superiority in estimating death number. The fitted quadratic model is better fitted in the Malaysian case, but the pattern shifts to linear trend line after MCO is implemented.

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Estimation of the severity of damage produced by a transverse crack

Studia Universitatis Babeș-Bolyai Engineering ◽

10.24193/subbeng.2020.1.15 ◽

2020 ◽

Vol 65 (1) ◽

pp. 137-144

Author(s):

Marius-Vasile Pop

Keyword(s):

Transverse Crack ◽

Bending Moment ◽

Cantilever Beams ◽

Trend Line ◽

The Real ◽

Symmetrical Deformation ◽

Frequency Drop ◽

Equidistant Points ◽

Fixed End ◽

Crack Position

This paper presents a method to find the severity of a crack for cantilever beams that can be used to estimate the frequency drop due to the crack. The severity is found for the crack located at the location where the biggest curvature (or bending moment) is achieved. Because the fixing condition does not permit a symmetrical deformation around the crack, the apparent severity is smaller as the real one. The latter is found by the estimated value of the trend-line at the fixed end, it being constructed on points that consider the crack position (equidistant points in the proximity of the fixed end) and the resulted deflections.

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