scholarly journals Crustal structure of the East African Limpopo margin, a strike-slip rifted corridor along the continental Mozambique Coastal Plain and North Natal Valley

Solid Earth ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1865-1897
Author(s):  
Mikael Evain ◽  
Philippe Schnürle ◽  
Angélique Leprêtre ◽  
Fanny Verrier ◽  
Louise Watremez ◽  
...  
Keyword(s):  
Continental Crust ◽  
Coastal Plain ◽  
Strike Slip ◽  
Crustal Material ◽  
East African ◽  
Velocity Models ◽  
The North ◽  
Ductile Shearing ◽  
Basement High ◽  
High Level

Abstract. Coincident wide-angle and multi-channel seismic data acquired within the scope of the PAMELA Moz3-5 project allow us to reconsider the formation mechanism of East African margins offshore of southern Mozambique. This study specifically focuses on the sedimentary and deep-crustal architecture of the Limpopo margin (LM) that fringes the eastern edge of the Mozambique’s Coastal Plain (MCP) and its offshore southern prolongation the North Natal Valley (NNV). It relies primarily on the MZ3 profile that runs obliquely from the northeastern NNV towards the Mozambique basin (MB) with additional inputs from a tectonostratigraphy analysis of industrial onshore–offshore seismic lines and nearby or crossing velocity models from companion studies. Over its entire N–S extension the LM appears segmented into (1) a western domain that shows the progressive eastward crustal thinning and termination of the MCP/NNV continental crust and its overlying pre-Neocomian volcano-sedimentary basement and (2) a central corridor of anomalous crust bounded to the east by the Mozambique fracture zone (MFZ) and the oceanic crust of the MB. A prominent basement high marks the boundary between these two domains. Its development was most probably controlled by a steep and deeply rooted fault, i.e., the Limpopo fault. We infer that strike-slip or slightly transtensional rifting occurred along the LM and was accommodated along this Limpopo fault. At depth we propose that ductile shearing was responsible for the thinning of the continental crust and an oceanward flow of lower crustal material. This process was accompanied by intense magmatism that extruded to form the volcanic basement and gave the corridor its peculiar structure and mixed nature. The whole region remained at a relative high level during the rifting period and a shallow marine environment dominated the pre-Neocomian period during the early phase of continent–ocean interaction. It is only some time after break-up in the MB and the initiation of the MFZ that decoupling occurred between the MCP/NNV and the corridor, allowing for the latter to subside and become covered by deep marine sediments. A scenario for the early evolution and formation of the LM is proposed taking into account both recent kinematic and geological constraints. It implies that no or little change in extensional direction occurred between the intra-continental rifting and subsequent phase of continent–ocean interaction.

scholarly journals Crustal structure of the East-African Limpopo Margin, a strike-slip rifted corridor along the continental Mozambique Coastal Plain and North-Natal Valley

2021 ◽  
Author(s):  
Mikael Evain ◽  
Philippe Schnürle ◽  
Angélique Leprêtre ◽  
Fanny Verrier ◽  
Louise Watremez ◽  
...  
Keyword(s):  
Mass Transport ◽  
Continental Crust ◽  
Crustal Structure ◽  
Coastal Plain ◽  
Strike Slip ◽  
East African ◽  
Acoustic Basement ◽  
Break Up ◽  
Basement High ◽  
Mass Transport Deposits

Abstract. Deep seismic acquisitions and a new kinematic study recently highlighted the presence of continental crust in both the southern Mozambique's Coastal Plain (MCP) and further offshore in the North Natal Valley (NNV). Such findings falsify previous geodynamic scenarios based on the kinematic overlap between Antarctica and Africa plates, thus profoundly impacting our understanding East-Gondwana break-up. Using an updated position of Antarctica with respect to Africa this study reconsider the formation mechanism of East-African margins and most specifically of the Limpopo margin (LM). Coincident wide-angle and multi-channel seismic data acquired within the PAMELA project are processed to image the sedimentary and deep crustal structure along a profile that runs from the northeastern NNV to the Mozambique basin (MB) striking through the LM. This dataset is combined with companion deep seismic profiles and industrial onshore-offshore seismic lines to provide a robust scenario for the formation and evolution of the LM. Our P-wave velocity model consists of an upper sedimentary sequence of weakly compacted sediments including intrusions and lava flows in the NNV while contourites and mass transport deposits dominates the eastern edge of the LM. This sequence covers a thick acoustic basement that terminates as a prominent basement high just west of the contourites and mass transport deposits domain. The acoustic basement has a seismic facies and velocity signature typical of a volcano-sedimentary basin and appears widespread over our study area extending toward the eastern MCP and NNV. Based on industrial well logs that calibrate our tectono-stratigraphic analysis we constrain its age to be pre-Neocomian. We further infer that either strike-slip or trans-tensional deformation occurred at the basement high which sustained uplift up to the Neocomian. At depth, the crystalline basement and uppermost mantle velocity structures show a progressive eastward crustal thinning of continental crust along the edge of the MCP/NNV and up to the location of the basement high. On its eastern side, however, a corridor of anomalous crust depicts the velocity signature of a volcanic basement overlying lower continental crust. We infer that strike-slip rifting along the LM was accommodated at depth by ductile shearing responsible for the thinning of the continental crust and an oceanward flow of lower crustal material. This process was accompanied by intense magmatism that extruded to form the volcanic basement and gave to the corridor its peculiar structure and mixed nature. The whole region remained at a relative high level and a shallow marine environment dominated during this period. Only after break-up in the MB decoupling occurred between the MCP/NNV and the corridor allowing for the latter to subside and being covered by deep marine sediments. We provide new insights into the early evolution and formation of the LM that takes into account both kinematic and geological constraints. This scenario favors strike-slip rifting along the LM meaning that no changes in extensional direction occurred between the rifting and the opening of the MB.

scholarly journals Last Cretaceous Geology of Taranaki Basin, New Zealand

2021 ◽  
Author(s):  
◽  
Glenn Paul Thrasher
Keyword(s):  
New Zealand ◽  
Late Cretaceous ◽  
Coastal Plain ◽  
New Caledonia ◽  
Strike Slip ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Petroleum Reservoir ◽  
The North ◽  
Potential Source Rock

<p>Taranaki Basin is a large sedimentary basin located along the western side of New Zealand, which contains all of this countries present petroleum production. The basin first formed as the late-Cretaceous Taranaki Rift, and the first widespread sediments are syn-rift deposits associated with this continental rifting. The Taranaki Rift was an obliquely extensional zone which transferred the movement associated with the opening of the New Caledonia Basin southward to the synchronous Tasman Sea oceanic spreading. Along the rift a series of small, en-echelon basins opened, controlled by high-angle normal and strike-slip faults. These small basins presently underlie the much larger Taranaki Basin. Since the initial rift phase, Taranaki Basin has undergone a complex Cenozoic history of subsidence, compression, additional rifting, and minor strike-slip faulting, all usually involving reactivation of the late-Cretaceous rift-controlling faults. One of the late-Cretaceous rift basins is the Pakawau Basin. Rocks deposited in this basin outcrop in Northwest Nelson as the Pakawau Group. Data from the outcrop and from wells drilled in the basin allow the Pakawau Group to be divided into two formations, the Rakopi Formation and the North Cape Formation, each with recognizable members. The Rakopi Formation (new name) is a sequence of terrestrial strata deposited by fans and meandering streams in an enclosed basin. The North Cape Formation is a transgressive sequence of marine, paralic and coastal-plain strata deposited in response to regional flooding of the rift. The coal-measure strata of the Rakopi Formation are organic rich, and are potential petroleum source rocks where buried deeply enough. In contrast, the marine portions of the North Cape Formation contain almost no organic matter and cannot be considered a potential source rock. Sandy facies within both formations have petroleum reservoir potential. The Rakopi and North Cape formations can be correlated with strata intersected by petroleum exploration wells throughout Taranaki Basin, and all syn-rift sediments can be assigned to them. The Taranaki Rift was initiated about 80 Ma, as recorded by the oldest sediments in the Rakopi Formation. The transgression recorded in the North Cape Formation propagated southwards from about 72 to 70 Ma, and the Taranaki Rift remained a large marine embayment until the end of the Cretaceous about 66.5 Ma. Shortly thereafter, a Paleocene regression caused the southern portions of Taranaki Basin to revert to terrestrial (Kapuni Group) sedimentation. The two distinct late Cretaceous sedimentary sequences of the Rakopi and North Cape formations can be identified on seismic reflection data, and the basal trangressive surface that separates them has been mapped throughout the basin. This horizon essentially marks the end of sedimentation in confined, terrestrial subbasins, and the beginning of Taranaki Basin as a single, continental-margin-related basin. Isopach maps show the Rakopi Formation to be up to 3000m thick and confined to fault- controlled basins. The North Cape Formation is up to 1500m thick and was deposited in a large north-south embayment, open to the New Caledonia basin to the northwest. This embayment was predominantly a shallow-marine feature, with shoreline and lower coastal plain facies deposited around its perimeter</p>

The kinematics of the Tan-Lu Fault zone during the Mesozoic-Palaeocene and its relations with the North China – South China block collision (Anhui Province, China)

2007 ◽  
Vol 178 (5) ◽  
pp. 353-365 ◽  
Author(s):  
Pierre Vergely ◽  
Ming Jin Hou ◽  
Young Ming Wang ◽  
Jacques-Louis Mercier
Keyword(s):  
Continental Crust ◽  
Fault Zone ◽  
South China ◽  
North China ◽  
Sedimentary Cover ◽  
Eastern China ◽  
Strike Slip ◽  
Late Triassic ◽  
South China Block ◽  
The North

Abstract The Tan-Lu Fault zone (TLFZ), often considered as a major sinistral strike-slip fault, extends in a NE to NNE direction for more than 2,000 km in eastern China. A structural analysis of the southern segment of the TLFZ (STLFZ) and surrounding areas enables us to propose the following evolution of this area during the Mesozoic-Palaeocene. The mid-Triassic NNW-SSE and late Triassic SSW-NNE to SSE-NNW strikes of the stretching lineations in the Zhangbaling massif favour ductile shears in a Zhangbaling metamorphic formation located along a ~NNE-SSW orientated “Tan-Lu margin”; this margin connected two margin segments situated north of the Dabie and Sulu belts. During the Mid-Late Triassic, the continental crust of the South China block (SCB) has been obliquely subducted along this margin below the North China block (NCB). We confirm that the SCB continental crust has been sliced and thrust toward the SSE and propose that the ductile thrusts have merged into the decollements of the sedimentary cover of the platform, forming the thrust-and-fold belt which has acted as a sinistral compressional transfer zone between the Dabie and Sulu collision belts. Thrusting and folding, under a N to NNE compression, affecting Jurassic deposits north and south of the Dabie Shan, indicate that the SCB/NCB collision has continued during the Jurassic. We show that a strike-slip tectonic regime occurred at that time, east of the STLFZ, which initiated as a sinistral continental transform fault between the Dabie and Sulu collisional belts. Dikes and strike-slip faults confirm that a ~NW-SE stretching was active during the basal early Cretaceous (~135–130 Ma), in and around metamorphic domes intruded by plutons. We show that strike-slip faulting, under a NW-SE compression-NE-SW tension, has been active subsequently, until the Aptian-? Early Albian (110/105 Ma), possibly until the Cenomanian (~95 Ma); at that time, the TLFZ has acted as a sinistral continental trans-current fault zone in eastern Asia. Subsequently, normal faulting, under a WNW-ESE extension, indicates that the TLFZ has been a normal fault zone during the Campanian-Palaeocene (~83–55 Ma), possibly until the Early Ypresian (~50 Ma). Sinistral offsets, in the order of several 100 of kilometres, on both sides of the TLFZ have been proposed; the present study does not support such large offset magnitudes.

scholarly journals Characteristic of the 2010-2020 Earthquakes in North Arm of Sulawesi based on Focal Mechanism and b-value

2021 ◽  
Vol 873 (1) ◽  
pp. 012031
Author(s):  
A P Astuti ◽  
E M Elsera ◽  
M F I Massinai ◽  
M A Akbar
Keyword(s):  
Focal Mechanism ◽  
Subduction Zones ◽  
Maximum Likelihood Method ◽  
B Value ◽  
Strike Slip ◽  
Likelihood Method ◽  
B Values ◽  
The North ◽  
North Sulawesi ◽  
High Level

Abstract The north arm of Sulawesi has a fairly high level of seismicity. The North Sulawesi arm is bounded in the south by the Palu-Koro Fault, the northern part is bounded by the North Sulawesi Trench and the Molluca Sea Thrust in the east. Therefore, this study aims to analyze the characteristic of the 2010-2020 earthquakes in the north arm of Sulawesi by analyzing the earthquake’s focal mechanism and mapping the b-value using the maximum likelihood method. From this study, we obtained the focal mechanism consist of thrust and strike-slip, this is due to the activity of faults and subduction zones in the North arm of Sulawesi such as the Palu-koro fault, the Gorontalo Fault, North Sulawesi Trench, Molucca Sea Collision, and several other faults that affect the seismicity of this region. The variation of the b-value ranging from 0.5-1.1 These studies indicate that thrust fault regions have lower b-values, while strike-slip fault regions have intermediate b-values. Meanwhile, areas with active volcanoes tend to have high b-values. The results of this research can be used as a basis for decision making related to earthquake mitigation in this area in the future.

Circa 2.5 Ga granitoids in the eastern North China craton: Melting from ca. 2.7 Ga accretionary crust

2019 ◽  
Vol 132 (3-4) ◽  
pp. 817-834 ◽  
Author(s):  
Yilong Li ◽  
Jianping Zheng ◽  
Wenjiao Xiao ◽  
Guoqing Wang ◽  
Fraukje M. Brouwer
Keyword(s):  
Continental Crust ◽  
Mantle Plume ◽  
North China Craton ◽  
North China ◽  
Crustal Material ◽  
Crustal Accretion ◽  
The North ◽  
Depleted Mantle ◽  
Granitoid Rocks ◽  
Crustal Reworking

Abstract The Neoarchean crust-mantle interaction and crustal evolution of the North China craton are controversial and are instructive of the processes of continental crust growth and cratonic evolution. We present here a systematic study of the petrology, geochemistry, and geochronology of Neoarchean granitoids from the eastern North China craton to elucidate their petrogenesis and tectonic setting. The rocks were collected from the Jielingkou, Anziling, and Qinhuangdao plutons, and an amphibole-monzoporphyry dike in the Qinhuangdao pluton. Samples from the Jielingkou pluton, consisting dominantly of monzodiorite and diorite with minor monzonite and granodiorite, contain 52.2–64.4 wt% SiO2, 2.46–4.52 wt% MgO (Mg# = 0.41–0.54), 3.76–5.77 wt% Na2O, and K2O/Na2O ratios of 0.29–0.71. The Anziling pluton samples, comprising syenite and monzonite, display slightly higher SiO2 (60.9–66.7 wt%) and K2O/Na2O ratios (0.70–1.11), but lower MgO (1.54–2.33 wt%) and Mg# (0.40–0.47) values, compared to the Jielingkou rocks. The Qinhuangdao pluton samples, consisting mainly of granite and minor syenite and granodiorite, with some diorite and monzoporphyry dikes, are characterized by the highest SiO2 values (75.7–76.9 wt%) and K2O/Na2O ratios (0.73–1.41) and lowest MgO content (0.14–0.32 wt%) among the studied samples. The amphibole-monzoporphyry dike has intermediate SiO2 (56.3 wt%), high MgO (3.79 wt%), Na2O (5.55 wt%), and Mg# (0.45), and low K2O/Na2O ratio (0.66). Zircon U-Pb laser-ablation–inductively coupled plasma–mass spectrometry dating showed that all plutons have a ca. 2.5 Ga crystallization age. Zircon crystals have mildly positive εHf(t) values (+0.24 to +5.45) and a depleted mantle model age (TDM1) of ca. 2.7 Ga. We interpret the granitoid rocks as sanukitoid-related, Closepet-type granites, potassium-rich adakites, and potassium-rich granitoid rocks that crystallized in the late Neoarchean (2.5 Ga) and were derived from partial melting of mantle peridotite that was metasomatized with the addition of slab melt, thickened alkali-rich juvenile lower crust and juvenile metamorphosed tonalitic rocks. Mantle plume activity ca. 2.7 Ga is thought to have been responsible for the early Neoarchean tectono-thermal event in the eastern North China craton. This activity resulted in a major crustal accretion period in the craton, with subordinate crustal reworking at its margins. A steep subduction regime between ca. 2.55 Ga and ca. 2.48 Ga led to the remelting of older crustal material, with subordinate crustal accretion by magma upwelling from a depleted mantle source resulting in late Neoarchean underplating. This crustal reworking and underplating resulted in the widespread ca. 2.5 Ga plutons in the eastern North China craton. Continental crust growth in the North China craton thus occurred in multiple stages, in response to mantle plume activity, as well as protracted subduction-related granitoid magmatism during the Neoarchean.

scholarly journals Last Cretaceous Geology of Taranaki Basin, New Zealand

2021 ◽  
Author(s):  
◽  
Glenn Paul Thrasher
Keyword(s):  
New Zealand ◽  
Late Cretaceous ◽  
Coastal Plain ◽  
New Caledonia ◽  
Strike Slip ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Petroleum Reservoir ◽  
The North ◽  
Potential Source Rock

<p>Taranaki Basin is a large sedimentary basin located along the western side of New Zealand, which contains all of this countries present petroleum production. The basin first formed as the late-Cretaceous Taranaki Rift, and the first widespread sediments are syn-rift deposits associated with this continental rifting. The Taranaki Rift was an obliquely extensional zone which transferred the movement associated with the opening of the New Caledonia Basin southward to the synchronous Tasman Sea oceanic spreading. Along the rift a series of small, en-echelon basins opened, controlled by high-angle normal and strike-slip faults. These small basins presently underlie the much larger Taranaki Basin. Since the initial rift phase, Taranaki Basin has undergone a complex Cenozoic history of subsidence, compression, additional rifting, and minor strike-slip faulting, all usually involving reactivation of the late-Cretaceous rift-controlling faults. One of the late-Cretaceous rift basins is the Pakawau Basin. Rocks deposited in this basin outcrop in Northwest Nelson as the Pakawau Group. Data from the outcrop and from wells drilled in the basin allow the Pakawau Group to be divided into two formations, the Rakopi Formation and the North Cape Formation, each with recognizable members. The Rakopi Formation (new name) is a sequence of terrestrial strata deposited by fans and meandering streams in an enclosed basin. The North Cape Formation is a transgressive sequence of marine, paralic and coastal-plain strata deposited in response to regional flooding of the rift. The coal-measure strata of the Rakopi Formation are organic rich, and are potential petroleum source rocks where buried deeply enough. In contrast, the marine portions of the North Cape Formation contain almost no organic matter and cannot be considered a potential source rock. Sandy facies within both formations have petroleum reservoir potential. The Rakopi and North Cape formations can be correlated with strata intersected by petroleum exploration wells throughout Taranaki Basin, and all syn-rift sediments can be assigned to them. The Taranaki Rift was initiated about 80 Ma, as recorded by the oldest sediments in the Rakopi Formation. The transgression recorded in the North Cape Formation propagated southwards from about 72 to 70 Ma, and the Taranaki Rift remained a large marine embayment until the end of the Cretaceous about 66.5 Ma. Shortly thereafter, a Paleocene regression caused the southern portions of Taranaki Basin to revert to terrestrial (Kapuni Group) sedimentation. The two distinct late Cretaceous sedimentary sequences of the Rakopi and North Cape formations can be identified on seismic reflection data, and the basal trangressive surface that separates them has been mapped throughout the basin. This horizon essentially marks the end of sedimentation in confined, terrestrial subbasins, and the beginning of Taranaki Basin as a single, continental-margin-related basin. Isopach maps show the Rakopi Formation to be up to 3000m thick and confined to fault- controlled basins. The North Cape Formation is up to 1500m thick and was deposited in a large north-south embayment, open to the New Caledonia basin to the northwest. This embayment was predominantly a shallow-marine feature, with shoreline and lower coastal plain facies deposited around its perimeter</p>

Her Majesty Queen Rania Al Abdullah

2019 ◽  
Author(s):  
Adib Rifqi Setiawan
Keyword(s):  
Education System ◽  
Ministry Of Education ◽  
Childhood Experiences ◽  
The Sustainable Development ◽  
American University ◽  
The North ◽  
The World ◽  
Development Goals ◽  
High Level ◽  
Education And Development

“The real treasure is in the minds of our children, and all we have to do is extract it.” Her Majesty Queen Rania Al Abdullah writes in website Queen Rania Foundation For Education And Development www.qrf.org/en. Rania Al Yassin was born on August 31, 1970. She obtained her Bachelor’s degree in Business Administration from the American University of Cairo in 1991. She applied this, first, to a banking career in Jordan and, later, to the information technology sector. After marrying Prince Abdullah bin Al Hussein on June 10, 1993, they went on to have four children: Prince Hussein, Princess Iman, Princess Salma, and Prince Hashem. In addition to being a wife and mother, Queen Rania works hard to lift the lives of Jordanians by supporting their endeavours and helping to create new opportunities for them. Locally, she is committed to breathe new life into the public education system; empower communities and women especially through microfinance initiatives; protect children and families; and drive innovation, technology and entrepreneurship, especially amongst young people. Internationally, Queen Rania is an advocate for tolerance, compassion and bridge building between people of all cultures and backgrounds. Her efforts to simultaneously challenge stereotypes of Arabs and Muslims, and promote greater understanding and acceptance between people of all faiths and cultures, have won her global recognition. Her Majesty’s passion is education. She believes that every Jordanian girl and boy, and all children, should have access not only to stimulating classrooms and modern curricula, but inspiring teachers and technology that can connect Jordan’s children to the world and the world to Jordan’s children. Her efforts in the education sector complement the work of the Ministry of Education through initiatives such as the Jordan Education Initiative, the Queen Rania Teachers Academy, Madrasati, Edraak and others. To realize these and so much more, Queen Rania has encouraged private sector partners to drive improvements and strengthen the foundations of Jordan’s education system. Queen Rania is also a global voice for access to quality education for children around the world. In 2009, Her Majesty championed the 1 Goal campaign for education; she is Honorary Chair of the UN Girl’s Education Initiatives and has advocated access to education in forums and gatherings around the world. Her work and her efforts to improve the learning opportunities for children have been recognized at the highest levels, nationally, regionally and internationally. Additionally, through her position on their boards, Her Majesty contributes to the work of the United Nations Fund and the World Economic Forum. She is the Eminent Advocate for UNICEF; and she was part of the UN appointed High Level Panel who advised on the shape and content of the Sustainable Development Goals which aim to improve the lives of millions of people before 2030. In recognition of her work, Her Majesty has humbly accepted many awards, locally, regionally and globally. These include the Walther Rathenau Award from the Walther RathenauInstitut in Germany for her efforts to greater peace and understanding; the James C. Morgan Global Humanitarian Award from Tech Awards, USA; the Arab Knight of Giving Award from Arab Giving Forum, UAE; the North South Prize by the North South Prize, Portugal; as well as the YouTube Visionary Award. Her Majesty authored several books primarily for children including the Sandwich Swap, which was inspired by her own childhood experiences.

Sign in / Sign up

Export Citation Format

Share Document