scholarly journals Understanding Structural Style of Onshore Timor Basin from Detailed Fieldwork

2019 ◽  
Vol 13 (4) ◽  
pp. 123
Author(s):  
Agus Handoyo Harsolumakso ◽  
Benyamin Sapiie ◽  
Alfend Rudyawan ◽  
Herwin Tiranda ◽  
Ezidin Reski ◽  
...  
Keyword(s):  
Continental Margin ◽  
Hydrocarbon Exploration ◽  
Thrust Faults ◽  
Sedimentary Sequence ◽  
Fold Belt ◽  
Eastern Indonesia ◽  
Structural Style ◽  
Thrust Sheets ◽  
West Timor ◽  
Economic Reserve

Hydrocarbon exploration in Eastern Indonesia region is mainly concentrated in the related convergent area such as Timor Basin. This area is characterized by the development of complex imbricate thrust-fold-belt deformation involving sedimentary sequence from the Australia continental margin. However, the exploration has not been successfully found the potential economic reserve. Our study utilized extensive and detailed fieldwork campaign  presents the structural style on the onshore region of the Timor Basin. Thick-skinned and thin-skinned thrust faults are both presents in West Timor area divided by the syn-orogenic basin. The change in decolement surface is likely to be caused by inversion structures under the thrust sheets. Our present interpretations indicate that these inversion anticlines structure are likely to occur both onshore and offshore.

Structural relationships of the Skeena Fold Belt west of the Bowser Basin, northwest British Columbia

1991 ◽  
Vol 28 (6) ◽  
pp. 973-983 ◽  
Author(s):  
Carol A. Evenchick
Keyword(s):  
Middle Jurassic ◽  
Large Scale ◽  
Volcanic Rocks ◽  
Western Boundary ◽  
Thrust Faults ◽  
Fold Belt ◽  
Clastic Rocks ◽  
Structural Style ◽  
Coast Plutonic Complex ◽  
The Difference

The Skeena Fold Belt is a regional fold and thrust belt that extends across most of the width of the northern Intermontane Belt of the Canadian Cordillera. Structural and stratigraphic relationships at its northeast margin show that it developed between latest Jurassic(?) and early Tertiary time, that it involved strata at least as low as Lower and Middle Jurassic Hazelton Group, and that it is characterized by northeast-verging folds and thrust faults. The structures accommodated at least 44% shortening and appear to root to the west.Most of the fold belt is distinguished by folds in thinly layered Jurassic and Cretaceous clastic rocks of the Bowser and Sustut basins. Its boundary is difficult to establish west of the Bowser Basin in poorly layered Middle Jurassic and older strata. However, map relationships show that Hazelton Group strata are folded with Bowser Lake Group. It is suggested here that the fold belt continues westward to the east margin of the Coast Plutonic Complex, where the increase in metamorphic grade and dominance of plutonic rocks effectively mark the western boundary of the Skeena Fold Belt. The difference in structural style between the Bowser Lake Group and massive volcanic rocks of the Hazelton Group is attributed to their difference in competency. Shortening by thrust faults and large-scale folds in volcanic rocks west of the Bowser Basin may balance with shortening by folds and related detachments in Bowser Lake Group farther east.

A suite of alkali basalts and gabbros associated with the Hare Bay Allochthon of western Newfoundland

1977 ◽  
Vol 14 (3) ◽  
pp. 346-356 ◽  
Author(s):  
R. A. Jamieson
Keyword(s):  
Oceanic Crust ◽  
Continental Margin ◽  
Upper Mantle ◽  
Ultramafic Rocks ◽  
Alkali Basalts ◽  
Crust And Upper Mantle ◽  
Bay Area ◽  
Close Proximity ◽  
Thrust Sheets

The Hare Bay Allochthon of northwestern Newfoundland consists of a series of sedimentary, volcanic, metamorphic, and ultramafic rocks which was emplaced over a Cambro-Ordovician continental margin as several thrust sheets. It probably represents a continental margin sequence overridden by oceanic crust and upper mantle. The Partridge Point gabbro, Cape Onion volcanics, and Ireland Point Volcanics, which now occur in the Maiden Point, Cape Onion, and St. Anthony tectonic slices respectively, appear to be closely related on petrographic and chemical grounds. Olivine, titanaugite, kaersutite, and plagioclase indicate that these rocks formed as a single suite of hydrous alkali basalts, possibly as part of a seamount near a continental margin. This relationship provides a link between the lower sedimentary and the upper igneous-metamorphic structural slices of the allochthon and implies that most of the transported rocks in the Hare Bay area evolved in close proximity to each other.

Interplay between tectonic inheritance and salt tectonics in the tectono-sedimentary evolution of the Sahel basin (eastern Tunisia): implications for hydrocarbon prospectivity

2021 ◽  
Author(s):  
Wajdi Belkhiria ◽  
Haifa Boussiga ◽  
Imen Hamdi Nasr ◽  
Adnen Amiri ◽  
Mohamed Hédi Inoubli
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Gravity Data ◽  
Hydrocarbon Exploration ◽  
Passive Margin ◽  
Growth Strata ◽  
Tectonic Inheritance ◽  
Sedimentary Evolution ◽  
Structural Style ◽  
Half Graben

<p>The Sahel basin in eastern Tunisia has been subject for hydrocarbon exploration since the early fifties. Despite the presence of a working petroleum system in the area, most of the drilled wells were dry or encountered oil shows that failed to give commercial flow rates. A better understanding of the tectono-sedimentary evolution of the Sahel basin is of great importance for future hydrocarbon prospectivity. In this contribution, we present integration of 2D seismic reflection profiles, exploration wells and new acquired gravity data. These subsurface data reveal that the Sahel basin developed as a passive margin during Jurassic-Early Cretaceous times and was later inverted during the Cenozoic Alpine orogeny. The occurrence of Triassic age evaporites and shales deposited during the Pangea breakup played a fundamental role in the structural style and tectono-sedimentary evolution of the study area. Seismic and gravity data revealed jointly important deep-seated extensional faults, almost along E-W and few along NNE–SSW and NW-SE directions, delimiting horsts and grabens structures. These syn-rift extensional faults controlled deposition, facies distribution and thicknesses of the Jurassic and Early cretaceous series. Most of these inherited deep-seated normal and transform faults are ornamented by different types of salt-related structures. The first phase of salt rising was initiated mainly along these syn-extensional faults in the Late Jurassic forming salt domes and continued into the Early and Late Cretaceous leading to salt-related diapir structures. During this period, the salt diapirism was accompanied by the development of salt withdrawal minibasins, characterized important growth strata due the differential subsidence. These areas represent important immediate kitchen areas to the salt-related structures. The later Late Cretaceous - Cenozoic shortening phases induced preferential rejuvenation of the diapiric structures and led to the inversion of former graben/half-graben structures and ultimately to vertical salt welds along salt ridges. These salt structures represent key elements that remains largely undrilled in the Sahel basin. Our results improve the understanding of salt growth in eastern Tunisia and consequently greatly impact the hydrocarbon prospectivity in the area.</p>

scholarly journals Structural style and kinematics of the Taihang-Luliangshan fold belt, North China: Implications for the Yanshanian orogeny

Lithosphere ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 767-783 ◽  
Author(s):  
Christopher Clinkscales ◽  
Paul Kapp
Keyword(s):  
North China ◽  
Ordos Basin ◽  
Structural Data ◽  
Upper Jurassic ◽  
Geological Mapping ◽  
Fold Belt ◽  
Lower Paleozoic ◽  
The North ◽  
Structural Style ◽  
Fold Belts

Abstract The Middle–Late Jurassic to earliest Cretaceous fold belts of the Yanshanian orogen in North China remain enigmatic with respect to their coeval deformation histories and possible relationship to the contemporaneous Cordilleran-style margin of eastern Asia. We present geological mapping, structural data, and a >400-km-long, strike-perpendicular balanced cross section for the Taihang-Luliangshan fold belt exposed in the late Cenozoic central Shanxi Rift. The northeast-southwest–trending Taihang-Luliangshan fold belt consists of long-wavelength folds (∼35–110 km) with ∼1–9 km of structural relief cored by Archean and Paleoproterozoic metamorphic and igneous basement rocks. The fold belt accommodated ≥11 km of northwest-southeast shortening between the Taihangshan fault, bounding the North China Plain, in the east and the Ordos Basin in the west. Geological mapping in the Xizhoushan, a northeast-southwest–oriented range within the larger Taihangshan mountain belt, reveals two major basement-cored folds: (1) the Xizhou syncline, with an axial trace that extends for ∼100 km and is characterized by a steep to overturned forelimb consistent with a southeast sense of vergence, and (2) the Hutuo River anticline, which exposes Archean–Paleoproterozoic rocks in its core that are unconformably overlain by shallowly dipping (<∼20°) Lower Paleozoic rocks. In the Luliangshan, Mesozoic structures include the Luliang anticline, the largest recognized anticline in the region, the Ningjing syncline, which preserves a complete section of Paleozoic to Upper Jurassic strata, and the Wuzhai anticline; together, these folds are characterized by a wavelength of ∼45–50 km. Shortening in the Taihang-Luliangshan fold belt is estimated to have occurred between ca. 160 Ma and 135 Ma, based on the age of the youngest deformed Upper Jurassic rocks in the Ningjing syncline, previously published low-temperature thermochronology, and regional correlations to better-studied Yanshanian fold belts. The timing of basement-involved deformation in the Taihang-Luliangshan fold belt, which formed >1000 km from the nearest plate margin, corresponds with the termination of arc magmatism along the eastern margin of Asia, implying a potential linkage to the kinematics of the westward-subducting Izanagi (paleo-Pacific) plate.

scholarly journals Decentralised Governance in Indonesia’s Disadvantaged Regions: A Critique of the Underperforming Model of Local Governance in Eastern Indonesia

2020 ◽  
Vol 39 (3) ◽  
pp. 359-380
Author(s):  
Dennis Shoesmith ◽  
Nathan Franklin ◽  
Rachmat Hidayat
Keyword(s):  
Policy Development ◽  
Local Governance ◽  
Resource Base ◽  
Eastern Indonesia ◽  
Investment Capital ◽  
National Model ◽  
Uniform Model ◽  
Core Areas ◽  
West Timor

This article investigates the challenges facing decentralised governance in poor and underdeveloped areas in Eastern Indonesia. The Timor Tengah Selatan (TTS) regency in West Timor in Nusa Tenggara Timur province is taken as a case study. Indonesia’s radical decentralisation programme applied a national model of decentralised governance, not taking into account the different conditions applying to disadvantaged regions ( daerah tertinggal, DRs). In the TTS regency, decentralised governance is underperforming in two core areas – administration and fiscal viability – while making some progress in political decentralisation. Governance is restricted by limited social capacity, a poor resource base, and a lack of investment capital and infrastructure. The question then arises: if the uniform model of decentralisation is not performing adequately in TTS, is there a more appropriate model of local governance and central subnational relations that can better perform in DRs? While not detailing the features of a new model, this article identifies the areas requiring policy development.

East-directed imbrication and oblique-slip faulting in the Humber Arm Allochthon of western Newfoundland: structural and tectonic significance

1985 ◽  
Vol 22 (9) ◽  
pp. 1351-1360 ◽  
Author(s):  
William Bosworth
Keyword(s):  
Structural Features ◽  
Strike Slip ◽  
Thrust Faults ◽  
High Angle ◽  
Structural Geometry ◽  
Tectonic Significance ◽  
Thrust Sheets ◽  
Internal Deformation ◽  
Fold Formation ◽  
Slip Motion

Many of the dominant outcrop-scale structural features in the lower, clastic thrust sheets of the Humber Arm Allochthon were not generated during the westerly emplacement of the allochthonous terranes of western Newfoundland. Two general groups of structures are abundant in the Humber Arm rocks: (1) east-verging folds accompanied by a weakly to moderately developed slaty cleavage and cut by west-dipping thrust faults; and (2) northeast–southwest-striking high-angle faults, with predominantly normal oblique-slip motion and with larger faults down-stepping to the northwest. Evidence of the earlier, west-directed thrusting (refolded and downward-facing folds, folded thrusts, etc.) is uncommon in the Humber Arm area. Slaty cleavage-generation structures, however, appear to overprint the phacoidal fabrics of the mélange zones that exist between and within thrust slices of the allochthon, making the mélange fabrics the most readily identified features associated with the initial east over west imbrication and emplacement of the allochthon.These observations suggest that the original detachment of the rocks of the Humber Arm Supergroup from their basement (early Taconian deformation) occurred with only limited internal deformation. Mélange zones presently define some or all of the early surfaces of movement. The fully assembled and emplaced allochthonous terrane was subsequently reimbricated on a smaller scale through east-directed thrusting, at which time the allochthon was more pervasively deformed (regional slaty cleavage and fold formation). This may represent late Taconian back thrusting or Acadian shortening. The youngest deformation of the Humber Arm region appears to have been a regional extensional event, with a significant northeast–southwest strike-slip component of movement. This may correlate with the development of Carboniferous strike-slip basins in the present Gulf of St. Lawrence and western Newfoundland. Much of the present structural geometry in the Humber Arm region, including the contacts between ophiolitic and clastic thrust sheets, may have originated during these later two deformational sequences, rather than as a consequence of the initial emplacement history.

Geometrical and chronological constraints for magnetic signatures in the Central High Atlas

2020 ◽  
Author(s):  
Tania Mochales ◽  
Ahmed Manar ◽  
Antonio María Casas-Sainz ◽  
Pablo Calvin ◽  
Pablo Santolaria ◽  
...  
Keyword(s):  
High Atlas ◽  
Eastern Sector ◽  
The Core ◽  
Structural Style ◽  
Magnetic Signatures ◽  
Thrust Sheets ◽  
Basement Structures ◽  
Central High ◽  
Very High ◽  
Central High Atlas

&lt;p&gt;New residual magnetic map is presented to help decipher the magnetic imprints in the Central High Atlas (CHA) fold-and-thrust belt. The total intensity map shows a main direction mimicking the N070 trend which features the Atlas range. Detailed structural and paleomagnetic studies performed in the selected area demonstrate that similar shortening figures are observed in western and eastern portions. Differences in structural style are the consequence of (i) the inherited structure from the Triassic-Jurassic rifting stage, to Cenozoic inversion, (ii) the differential displacement through the Upper Triassic detachment level and (iii) superposition of cover thrust sheets.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Remarkable magnetic anomalies are recorded, from negative values (&lt;-400 nT) in the southern foreland, to positive (&gt;500 nT) in the core of the range. The western sector of the chain is defined by intermediate to high anomalies, probably related to NE-SW basement structures, which favored the emplacement of Triassic CAMP basalts and/or Jurassic gabbro bodies, within the syn-rift sequence. The central part of the range is characterized by high and very high positive anomalies with an irregular distribution, probably linked to Middle-Late Jurassic diapirism produced during extension and intrusion of gabbroid bodies at the core of diapirs, whose structure nucleated NE-SW anticlinal ridges. The eastern sector is characterized by intermediate to low intensity anomalies, likely associated to thick series of basinal Jurassic limestones, whose sequences were stacked (during the Cenozoic compressional stage) by means of kilometer-scale thrusts. Very high positive, linear anomalies seem to be related to Jurassic gabbro intruding directly into the carbonate facies in the eastern sector. Widespread negative anomalies are detected in the foreland southern basin. In this case, the remanent signature could be related to the Paleozoic magmatic provinces.&lt;/p&gt;

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