scholarly journals Extentional Fault Pada Daerah Compressive Tectonic Zone Sebagai Batas Cekungan Di Jawa Tengah Selatan

2021 ◽  
Vol 3 (1) ◽  
pp. 40-45
Author(s):  
Asmoro Widagdo ◽  
Aang Panji Permana

The extensional structure as a normal fault could be found in many places at the southern part of Java compressive tectonic regime. The research area is in the eastern part of the South Serayu Mountains. This normal fault structure is the boundary of the South Serayu Mountains at the eastern part with Kulon Progo Tertiary volcanic Mountains. In the field, these normal fault lineament zones create the Bogowonto river as a boundary of two different geological styles. The influence of this structure on the geological dynamic of the South Serayu Mountains and the Kulon Progo Mountains is important to be explained. The study was conducted by measuring and analyzing fault data and lithology that developed in the area around the two basins boundary. The distribution of the Kulon Progo volcanic rocks indicates the presence of the extensional fault structure. The volcanic facies distribution of the volcano is cut and becomes narrow in the west, while the northward is very wide. Normal fault striations analysis on the fault plane along the fault line shows the least stress trending west-northwest that has worked to create North-South normal faults. The fault-controlled by stress with the vertical main compression area. They have worked to create North Northeast-South Southwest (NNE-SSW) normal faults with westward dipping.

Author(s):  
S.S. Hanna ◽  
J.D. Smewing

Melanges and debris flows with clasts derived from the top of the Natih Formation found in shales in the base of the Aruma Group indicate that a period of Structural growth on the platform took place during Aruma deposition in the Late Cretaceous. In this respect the platform in the Jebel Salakh area may have undergone a similar period of structural growth in the Late Cretaceous to the Fahud area where a syn-Aruma normal fault down throwing to the South accounts for a difference in the stratigraphic thickness of the Aruma of 1 km. A younger series of debris flows in the Aruma of the Sufrat al Khays area to the South of Jehel Salakh is dated as Campanian/Maastrichtian. The clasts in these flows were derived exclusively from the Simsima limestones. Natih-derived elasts are conspicuously absent. This is taken to indicate that the Madamar-Salakh Qusaybah range was covered by Aruma sediments at this time and did not form the distinctive positive feature seen at present - i.e. Madamar-Salakh-Qusaybah range folding though partly Late Cretaceous is mainly Post-Manslrichtian in age. This Post Maastrichtian event in the Madamar-Salakh-Qusaybah range produced a series of doubly-plunging anticlines in the Cretaceous strata- These folds show a high degree of brittle extension in the form of normal faults and extensional fractures, The faults are delineated by fault gouge with visibly interconnected void space. In the subsurface, if such fractures were developed in a fold closure similar to those seen at the surface in the Madamar-Salakh-Qusaybah range. then they could provide preferred conduits for oil flow and the harrier to fluid flow provided by the Aruma shale seal could lead to a hydrocarbon accumulation.


Author(s):  
Asmoro Widagdo ◽  
Subagyo Pramumijoyo ◽  
Agung Harijoko

Menoreh-Gajah-Ijo have a very distinctive shape, where there are form of circular structure of volcano that is still intact and the other has not been intact. These morphologies are the morphology of the remaining volcanoes formed by tectonics and certain volcanisms. This study was conducted through a series of interpretations of volcanic body distribution, constructing a Slope Map, constructing a Slope Direction Map, constructing an alignment interpretation on satellite imagery and field mapping work. The formation of Menoreh-Gajah-Ijo morphologies are strongly influenced by tectonics and volcanic processes. The process of tectonism that produces the strike-slip fault structures, the normal faults, and the uplift have formed the lineaments of the valleys and hills with various directions patterns. The Menoreh-Gajah-Ijo volcanisms that have occurred form the structure of volcanic remains. Distribution of Menoreh-Gajah-Ijo volcanic rocks form some semicircle structures because of the normal fault structure that has occurred.


2020 ◽  
Vol 24 (3) ◽  
pp. 277-284
Author(s):  
Jiqiang Yang ◽  
Xing Wang

The eruption cycle of volcanic rocks based on virtual reality technology is studied to reveal the spatial distribution of volcanic rocks and the genetic relationship between different lithologic assemblages, and effectively guide volcanic exploration. Taking Xujiaweizi fault depression and Yingshan depression in Songliao Basin as the research area, the monocular vision method of virtual reality technology is used to collect data from the study area. Then, the three-dimensional dynamic scene of the study area was constructed. Based on this, combined with the research steps and division basis of the volcanic eruption cycle, the eruption cycle of the volcanic region in the study area is studied. According to the characteristics of volcanic activity, volcanic facies sequence, and rock rhythm combination in Xujiaweizi fault depression, the first and three sections of Yingcheng formation are divided into three eruption periods according to the contact relationship between sedimentary strata and volcanic rocks in the eruptive intermittent period. Y1C1, Y1C2, Y1C3, Y3C1, Y3C2, and Y3C3 are respectively from bottom to top. Yingshan volcanic rocks in Yingshan depression are divided into three cycles and six periods. Each stage has significant stages and differences, and the eruption intensity is different. The overall performance is gradually enhanced, and the internal cycle is characterized by the first strong and then weak.


2021 ◽  
Author(s):  
Willemijn S.M.T. van Kooten ◽  
Edward R. Sobel ◽  
Cecilia del Papa ◽  
Patricio Payrola ◽  
Alejandro Bande ◽  
...  

<p>The Cretaceous period in NW Argentina is dominated by the formation of the Salta rift basin, an intracontinental rift basin with multiple branches extending from the central Salta-Jujuy High. One of these branches is the ENE-WSW striking Lomas de Olmedo sub-basin, which hosts up to 5 km of syn- and post-rift deposits of the Salta Group, accommodated by substantial throw along SW-NE striking normal faults and subsequent thermal subsidence during the Cretaceous-Paleogene. Early compressive movement in the Eastern Cordillera led to the formation of a foreland basin setting that was further dissected in the Neogene by the uplift of basement-cored ranges. As a consequence, the northwestern part of the Lomas de Olmedo sub-basin was disconnected from the Andean foreland and local depocenters such as the Cianzo basin were formed, whereas the eastern sub-basin area is still part of the Andean foreland. Thus, the majority of the Salta Group to the east is located in the subsurface and has been extensively explored for petroleum, while in northwestern part of the sub-basin, the Salta Group is increasingly deformed and is fully exposed in the km-scale Cianzo syncline of the Hornocal ranges. The SW-NE striking Hornocal fault delimits the Cianzo basin to the south and the Cianzo syncline to the north. During the Cretaceous, it formed the northern margin of the Lomas de Olmedo sub-basin, which is indicated by an increasing thickness of the syn-rift deposits towards the Hornocal fault, as well as a lack of syn-rift deposits on the footwall block. Structural mapping and unpublished apatite fission track (AFT) data show that the Hornocal normal fault was reactivated and inverted during the Miocene. Although structural and sedimentary features of the Cianzo basin infill provide information about the relative timing of fault activity, there is a lack of low-temperature thermochronology. Herein, we aim to constrain the exhumation of the Lomas de Olmedo sub-basin during the Cretaceous rifting phase, as well as the onset and magnitude of fault reactivation in the Miocene. We collected 74 samples for low-temperature thermochronology along two major NW-SE transects in the Cianzo basin and adjacent areas. Of these samples, 59 have been analyzed using apatite and/or zircon (U-Th-Sm)/He thermochronology (AHe, ZHe). Furthermore, 49 samples have been prepared for AFT analysis. The ages are incorporated in thermo-kinematic modelling using Pecube in order to test the robustness of uplift and exhumation scenarios. On the hanging wall block of the N-S striking east-vergent Cianzo thrust north of the Hornocal fault, Jurassic ZHe ages are attributed to pre-Salta Group exhumation. However, associated thrusts to the south show ZHe ages as young as Eocene-Oligocene, which might indicate early post-rift activity along those thrusts. AHe data from the Cianzo syncline show a direct age-elevation relationship with Late Miocene-Pliocene cooling ages, indicating the onset of rapid exhumation along the Hornocal fault in the Miocene. This is consistent with regional data and suggests that pre-existing extensional structures were reactivated during Late Miocene-Pliocene compressive movement within this part of the Central Andes.</p>


Author(s):  
Henrik Stendal ◽  
Wulf Mueller ◽  
Nicolai Birkedal ◽  
Esben I. Hansen ◽  
Claus Østergaard

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stendal, H., Mueller, W., Birkedal, N., Hansen, E. I., & Østergaard, C. (1997). Mafic igneous rocks and mineralisation in the Palaeoproterozoic Ketilidian orogen, South-East Greenland: project SUPRASYD 1996. Geology of Greenland Survey Bulletin, 176, 66-74. https://doi.org/10.34194/ggub.v176.5064 _______________ The multidisciplinary SUPRASYD project (1992–96) focused on a regional investigation of the Palaeoproterozoic Ketilidian orogenic belt which crosses the southern tip of Greenland. Apart from a broad range of geological and structural studies (Nielsen et al., 1993; Garde & Schønwandt, 1994, 1995; Garde et al., 1997), the project included a mineral resource evaluation of the supracrustal sequences associated with the Ketilidian orogen (e.g. Mosher, 1995). The Ketilidian orogen of southern Greenland can be divided from north-west to south-east into: (1) a border zone in which the crystalline rocks of the Archaean craton are unconformably overlain by Ketilidian supracrustal rocks; (2) a major polyphase pluton, referred to as the Julianehåb batholith; and (3) extensive areas of Ketilidian supracrustal rocks, divided into psammitic and pelitic rocks with subordinate interstratified mafic volcanic rocks (Fig. 1). The Julianehåb batholith is viewed as emplaced in a magmatic arc setting; the supracrustal sequences south of the batholith have been interpreted as either (1) deposited in an intra-arc and fore-arc basin (Chadwick & Garde, 1996), or (2) deposited in a back-arc or intra-arc setting (Stendal & Swager, 1995; Swager, 1995). Both possibilities are plausible and infer subduction-related processes. Regional compilations of geological, geochemical and geophysical data for southern Greenland have been presented by Thorning et al. (1994). Mosher (1995) has recently reviewed the mineral exploration potential of the region. The commercial company Nunaoil A/S has been engaged in gold prospecting in South Greenland since 1990 (e.g. Gowen et al., 1993). A principal goal of the SUPRASYD project was to test the mineral potential of the Ketilidian supracrustal sequences and define the gold potential in the shear zones in the Julianehåb batholith. Previous work has substantiated a gold potential in amphibolitic rocks in the south-west coastal areas (Gowen et al., 1993.), and in the amphibolitic rocks of the Kutseq area (Swager et al., 1995). Field work in 1996 was focused on prospective gold-bearing sites in mafic rocks in South-East Greenland. Three M.Sc. students mapped showings under the supervision of the H. S., while an area on the south side of Kangerluluk fjord was mapped by H. S. and W. M. (Fig. 4).


Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 102
Author(s):  
Paraskevi Nomikou ◽  
Dimitris Evangelidis ◽  
Dimitrios Papanikolaou ◽  
Danai Lampridou ◽  
Dimitris Litsas ◽  
...  

On 30 October 2020, a strong earthquake of magnitude 7.0 occurred north of Samos Island at the Eastern Aegean Sea, whose earthquake mechanism corresponds to an E-W normal fault dipping to the north. During the aftershock period in December 2020, a hydrographic survey off the northern coastal margin of Samos Island was conducted onboard R/V NAFTILOS. The result was a detailed bathymetric map with 15 m grid interval and 50 m isobaths and a morphological slope map. The morphotectonic analysis showed the E-W fault zone running along the coastal zone with 30–50° of slope, forming a half-graben structure. Numerous landslides and canyons trending N-S, transversal to the main direction of the Samos coastline, are observed between 600 and 100 m water depth. The ENE-WSW oriented western Samos coastline forms the SE margin of the neighboring deeper Ikaria Basin. A hummocky relief was detected at the eastern margin of Samos Basin probably representing volcanic rocks. The active tectonics characterized by N-S extension is very different from the Neogene tectonics of Samos Island characterized by NE-SW compression. The mainshock and most of the aftershocks of the October 2020 seismic activity occur on the prolongation of the north dipping E-W fault zone at about 12 km depth.


2020 ◽  
Vol 110 (3) ◽  
pp. 1090-1100
Author(s):  
Ronia Andrews ◽  
Kusala Rajendran ◽  
N. Purnachandra Rao

ABSTRACT Oceanic plate seismicity is generally dominated by normal and strike-slip faulting associated with active spreading ridges and transform faults. Fossil structural fabrics inherited from spreading ridges also host earthquakes. The Indian Oceanic plate, considered quite active seismically, has hosted earthquakes both on its active and fossil fault systems. The 4 December 2015 Mw 7.1 normal-faulting earthquake, located ∼700  km south of the southeast Indian ridge in the southern Indian Ocean, is a rarity due to its location away from the ridge, lack of association with any mapped faults and its focal depth close to the 800°C isotherm. We present results of teleseismic body-wave inversion that suggest that the earthquake occurred on a north-northwest–south-southeast-striking normal fault at a depth of 34 km. The rupture propagated at 2.7  km/s with compact slip over an area of 48×48  km2 around the hypocenter. Our analysis of the background tectonics suggests that our chosen fault plane is in the same direction as the mapped normal faults on the eastern flanks of the Kerguelen plateau. We propose that these buried normal faults, possibly the relics of the ancient rifting might have been reactivated, leading to the 2015 midplate earthquake.


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