Effective buoyancy ratio: a new parameter for characterizing thermo-chemical mixing in the Earth's mantle
Summary: The effective buoyancy ratio was introduced as a diagnostic tool to characterize the evolution of the thermo-chemical mixing in the Earth’s mantle. This parameter tracks the fate of the primordial compositionally dense layer above the core–mantle boundary such as (i) the transition phase of warming dense layer; (ii) the erosion and dilution of the dense layer; (iii) the effective thermo-chemical convection (mixing of layers) and (iv) the homogenization.
Finite-difference modelling to evaluate seismic P-wave and shear-wave field data
Summary: In this paper, we compared, measured and simulated reflection seismology data for different wave types. P wave and shear wave land data were acquired in the field while the synthetic data were generated by finite-difference modelling. Major features of the P waves were imaged, but simulations cannot clarify the signal-to-noise ratio of the shear wave field data. Future modelling approaches will consider additional features for a better understanding of near-surface seismic measurements.
Analogue experiments of salt flow and pillow growth due to basement faulting and differential loading
Summary: This paper summarizes the results of scaled analogue experiments examining the kinematics of salt flow and the formation of salt pillows due to basement faulting and subsequent sedimentation. Our experimental results reveal that salt above a basement normal fault can flow downward or upward depending on the direction of the pressure gradient within the salt layer. Due to upward flow driven by differential loading, salt pillows can form above the higher basement block.
Characterisation of the magmatic signature in gas emissions from Turrialba Volcano, Costa Rica
Summary: In this paper we characterise the flux and composition of the gas emissions from Turrialba Volcano. We show that the measured gas signature provides evidence that Turrialba Volcano has entered an open-vent configuration with magmatic gases being emitted. This suggests that the hydrothermal system at the summit is quickly drying up and that the system is moving from a hydrothermal to a magmatic end member with implications for short-term monitoring and possible evolution of the state of unrest.
Characterization and interaction of driving factors in karst rocky desertification: a case study from Changshun, China
Summary: Geographical information system techniques and a geographical-detector model are used to explore the relationship between the evolution of karst rocky desertiﬁcation (KRD) and driving data. Our results detect non-linearly enhanced impacts significantly aggravating the KRD. This implies that there is no significant difference between natural and anthropogenic factors influencing KRD improvement, and also that natural factors have a more important impact on KRD deterioration.
Microscale strain partitioning? Differential quartz crystallographic fabric development in Phyllite, Hindu Kush, Northwestern Pakistan
Summary: This study demonstrates the importance of spatial resolution and registration in specimens analysed for crystallographic fabric analyses. In the specimen examined, the bulk crystallographic orientation was dominated by one fabric. Yet it was two secondary, spatially distinct fabrics that yielded potentially important information on deformation temperature, paleopiezometry, and strain rate.
Relative tectonic activity classification in the Kermanshah area, western Iran
Summary: The Kermanshah area in the High Zagros, Iran (the collision of the Arabian and Eurasian plates) has been affected by four classes of tectonic variation. These regions were identified as very high, high, moderate and low relative tectonic activity by calculation and analysis of six geomorphic indices.
Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments
Summary: Continents are composed of a collage of accreted terranes: tectonically sutured crustal units of various origins. This review covers the cycle of terrane accretion from the original entity (modern-day oceanic island arcs, oceanic plateaus, submarine ridges, seamounts, continental fragments, and microcontinents) to present-day examples of terrane accretion to finally allochthonous accreted terranes.
Tunable diode laser measurements of hydrothermal/volcanic CO2 and implications for the global CO2 budget
Summary: Here, we present the results of tunable diode laser observations at four quiescent volcanoes: Nea Kameni, Hekla, Krýsuvík, and Vulcano Island, which display a range of fumarolic activity from weak to moderate. This study contributes to better characterising the typical levels of CO2 emission from such feeble volcanic point sources, suggesting that the cumulative contribution from weakly degassing volcanoes may be significant at global scale.
Interpretative modelling of a geological cross section from boreholes: sources of uncertainty and their quantification
Summary: Geological information for users such as planners, miners or engineers depends on limited observations and the interpretative skills of the geologist. It therefore has an attendant uncertainty which must be quantified so that the data user can account for it. In this paper, we describe an experiment to identify and quantify the sources of uncertainty in geologists' interpretations of boreholes along a cross section.