scholarly journals Time series analysis (orbital cycles) of the uppermost Cenomanian-Lower Turonian sequence on the southern Tethyan margin using foraminifera

2010 ◽  
Vol 61 (2) ◽  
pp. 111-120 ◽  
Author(s):  
Mohamed Soua

Time series analysis (orbital cycles) of the uppermost Cenomanian-Lower Turonian sequence on the southern Tethyan margin using foraminiferaTime series analysis has been performed for the first time on the Cenomanian-Turonian sequence in Central Tunisia in order to shed light on its Milankovitch-like cyclicity. This analysis was applied to two foraminiferal genera: the biserialHeterohelix, an oxygen-minimum zone (OMZ) dweller, and the triserialGuembelitria, a eutrophic surface dweller. Average sedimentary rates and the duration of the oceanic anoxic event (OAE2) in each studied section were estimated. The fluctuations in abundance of these two opportunistic species can be related mainly to both precessional (ca. 20 kyr) and eccentricity (100 and 400 kyr) cyclicity suggesting that changes in surface water fertility were linked to climate changes in the Milankovitch frequency band.

2020 ◽  
Vol 20 (3) ◽  
pp. 039
Author(s):  
Virabhadrasinh A. Gohil ◽  
Sachchidanand Prakash Bhatnagar

2012 ◽  
Vol 03 (03) ◽  
pp. 262-271 ◽  
Author(s):  
Rosana Abrutzky ◽  
Laura Dawidowski ◽  
Patricia Matus ◽  
Patricia Romero Lankao

2021 ◽  
Author(s):  
Judit Gonzalez Santana ◽  
Christelle Wauthier

<p>Volcanic flank collapse has caused over 20,000 casualties in the past 400 years, and is one of the most dangerous hazards affecting communities and infrastructure near volcanoes. Flank instability has mostly been investigated at ocean volcanoes, due to their ability to trigger deadly tsunamis, however, these collapses are prevalent across volcanic settings, with all but one volcano in Guatemala with elevation over 2000m having experienced flank collapse, like Pacaya Volcano. At Pacaya, there is evidence for at least one past collapse, and transient SW flank motion has been identified accompanying vigorous eruptions in 2010 and 2014. We use InSAR time-series analysis to reveal, for the first time, long-term displacement of the SW flank of Pacaya during a period of volcanic quiescence from 2011-2013. This motion extended into 2014, with increased displacement rate attributed to dike intrusion during a major eruption. Subsequent static stress change analyses investigated the interactions between the modeled dike intrusion and detachment slip. Our research highlights that long-term flank motion might be more prevalent than currently recognized and that an awareness of existing structural weaknesses such as detachment faults and of possible magma-faulting interactions is vital when assessing the likelihood and style of volcanic flank collapse.</p>


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