Unzipping continents and the birth of microcontinents

Molnar, Nicolás; Cruden, Alexander; Betts, Peter Graham

doi:10.1130/g40021.1

Cited by 51 publications

(56 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Yet in natural rifts, deformation rates often change along‐axis due to plate rotation about an Euler pole (e.g., Martin, 1984; Muluneh et al, 2013; van der Pluijm & Marshak, 2004; Zwaan, Schreurs, & Rosenau, 2020). Recent analogue and numerical modeling studies show that such rotational plate motion strongly affects the development and allows propagation of rifting and continental breakup on regional to global scales (e.g., Molnar et al, 2017, 2018; Mondy et al, 2018; Zwaan, Schreurs, & Rosenau, 2020). The development of the Gulf of Aden and Red Sea rifts is a prime example, where extension rates double over every 1,000 km (ArRajehi et al, 2010, Figure 1, see section 1.2).…”

Section: Introductionmentioning

confidence: 99%

Structural Analysis of the Western Afar Margin, East Africa: Evidence for Multiphase Rotational Rifting

et al. 2020

View full text Add to dashboard Cite

The Afar region in East Africa represents a key location to study continental breakup. We present an integrated structural analysis of the Western Afar Margin (WAM) aiming to better understand rifted margin development and the role of plate rotation during rifting. New structural information from remote sensing, fieldwork, and earthquake data sets reveals that the N‐S striking WAM is still actively deforming and is characterized by NNW‐SSE normal faulting as well as a series of marginal grabens. Seismicity distribution analysis and the first‐ever borehole‐calibrated sections of this developing passive margin show recent slip concentrated along antithetic faults. Tectonic stress parameters derived from earthquake focal mechanisms reveal different extension directions along the WAM (82°N), in Afar (66°N) and in the Main Ethiopian Rift (108°N). Fault slip analysis along the WAM yields the same extension direction. Combined with GPS data, this shows that current tectonics in Afar is dominated by the local rotation of the Danakil Block, considered to have occurred since 11 Ma. Earlier stages of Afar development (since 31–25 Ma) were most likely related to the large‐scale rotation of the Arabian plate. Various authors have proposed scenarios for the evolution of the WAM. Any complete model should consider, among other factors, the multiphase tectonic history and antithetic fault activity of the margin. The findings of this study are not only relevant for a better understanding of the WAM but also provide insights into the role of multiphase rotational extension during rifting and passive margin formation in general.

show abstract

Section: Introductionmentioning

confidence: 99%

Structural Analysis of the Western Afar Margin, East Africa: Evidence for Multiphase Rotational Rifting

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Many of these pre-existing features lead to linear zones of anomalously weak material within the lithosphere. Heterogeneities and anisotropies can therefore be treated as equivalents and are referred to as weak seeds that can be incorporated in analogue models (e.g., Zwaan and Schreurs, 2017;Molnar et al, 2017Molnar et al, , 2018. Factors that play a major role on rift evolution include the location and obliquity of pre-existing structures with respect to the direction of extension (e.g., Acocella et al, 1999;Ebinger et al, 2000;Agostini et al, 2009) and temporal variations of the regional stress field (e.g., Ebinger et al, 2000;Morley, 2010).…”

Section: ■ Introductionmentioning

confidence: 99%

Interactions between propagating rifts and linear weaknesses in the lower crust

2019

Self Cite

View full text Add to dashboard Cite

■ ABSTRACT Pre-existing structures in the crust such as shear zones, faults, and mobile belts are known to exert a significant control on the structural evolution of continental rifts. However, the influence of such features when the extension direction progressively changes over time remains uncertain. Here we present new results from three-dimensional lithospheric-scale laboratory experiments of rotational extension that provide key insights into the temporal evolution of propagating rifts. We specifically test and characterize how rifts propagate and interact with linear crustal rheological heterogeneities oriented at variable angles with respect to the extension direction. Results show that approximately rift-parallel pre-existing heterogeneities favor the formation of long, linear faults that reach near-final lengths at early stages. Low angles between the heterogeneities and the propagating rift axis may result in strong strikeslip reactivation of the pre-existing structures if they are suitably oriented with respect to the stretching direction. When the linear heterogeneities are oriented at intermediate to high angles rift branches become laterally offset as they propagate, resulting in complex rhombic fault patterns. Rift-perpendicular crustal heterogeneities do not affect fault trends during rift propagation, but cause stalling and deepening of laterally growing rift basins. Similarities between the analogue experimental results and selected natural examples provide insights on how nature finds the preferential pathway to breakup in heterogeneous continental lithosphere.

show abstract

“…The north-south alignment of the sedimentary basins and strike direction of the associated faults is controlled by zones of crustal weakness inherited from the Indosinian Orogeny (Morley et al 2004. The recent hypothesis on continental rifting initiation indicates the requirement of pre-existing linear weaknesses and rotational extension (Molnar et al 2018). The first requirement is fulfilled, as the majority of the intracontinental rift basins of the Gulf of Thailand are situated in pre-deformed lithospheric segments such as the Inthanon zone and Sukhothai Arc that have been deformed during the Indosinian Orogeny ( Fig.…”

Section: Importance Of Inherited Structuresmentioning

confidence: 99%

Cenozoic tectonic evolution of southeastern Thailand derived from low-temperature thermochronology

Nachtergaele

Glorie

Morley

et al. 2019

JGS

View full text Add to dashboard Cite

Low-temperature thermochronological techniques, specifically apatite (U-Th)/He and apatite fission-track dating, were used to reconstruct the thermal history of southeastern Thailand. This area is intersected by vast and complex fault networks related to the Cenozoic Mae Ping and Three Pagodas Faults. These were identified from satellite imagery and confirmed by field observations. New apatite fission-track and apatite (U-Th)/He data were collected from crystalline basement blocks within these fault networks. Ages obtained range from 48 to 24 Ma, with most of the samples clustering between 36 and 24 Ma. Thermal history modelling indicates late Eocene-Oligocene exhumation of the exposed granitic and metamorphic basement rocks in southeastern Thailand. Exhumation was regional and was contemporaneous with sinistral fault activity during the late Eocene-early Oligocene along the Mae Ping Fault and Three Pagodas Fault. Moreover, this exhumation occurred coevally with a synrift phase of intracontinental offshore rift basin and half-graben basin development in the eastern Gulf of Thailand. The phase of exhumation ended in the early Miocene, as a result of the changing plate-tectonic forces along the complex plate boundaries of Sundaland.

show abstract

Unzipping continents and the birth of microcontinents

Cited by 51 publications

References 24 publications

Structural Analysis of the Western Afar Margin, East Africa: Evidence for Multiphase Rotational Rifting

Structural Analysis of the Western Afar Margin, East Africa: Evidence for Multiphase Rotational Rifting

Interactions between propagating rifts and linear weaknesses in the lower crust

Cenozoic tectonic evolution of southeastern Thailand derived from low-temperature thermochronology

Contact Info

Product

Resources

About