Replies to Comment by K. Bratvedt,E. Bølviken,T. Gimse,H. Holden,L. Holden,and R. Knarud

Mathematical Geosciences -     

http://www.sciencedirect.com/science/article/pii/S1674987112000072

The Abor volcanics outcroping in the core of the Siang window in the Eastern Himalaya comprise voluminous mafic volcanics (47％-56％ w(SiO2)),with subordinate felsic volcanics (67％-75％ w(SiO2)).The felsi...     

http://www.sciencedirect.com/science/article/pii/S1674987111000156

Employing the Unit Soil Carbon Amount (USCA) approach, soil carbon storage was calculated across the Northeast Plain of China based on the Multi-purpose Regional Geochemical Survey conducted in 2004 – 2006 (MRGS). The results indicated that the soil organic carbon (SOC) storage in topsoil (0 – 0.2 m), subsoil (0 – 1 m) and deep soil (0 – 1.8 m) was 768.1 Mt, 2978.4 Mt and 3729.2 Mt with densities of 3327.8 t/km2, 12,904.7 t/km2 and 16,157.5 t/km2, respectively. These values were consistent with national averages, whereas the soil carbon densities showed a clear increasing trend from the southern area of the Northeast Plain (Liaoning), to the middle (Jilin) and the northern Plain (Heilongjiang) — particularly in terms of topsoil carbon density, which increased from 2284.2, to 3436.7 and 3861.5 t/km2, respectively. In comparison to carbon data obtained from the Second National Soil Survey in 1984 – 1986 (SNSS), the topsoil SOC storage values from the MRGS were found to have decreased by 320.59 Mt (29.4%), with an average annual decline of 16.0 Mt (l.73%) over the 20 years. In the southern, middle and northern areas of the plain, soil carbon densities decreased by 1060.6 t/km2, 1646.4 t/km2 and 1300.2 t/km2, respectively, with an average value of 1389.0 t/km2 for the whole plain. These findings indicate that the decrease in soil carbon density varied according to the different ecosystems and land use types. Therefore, ratios of soil carbon density were calculated in order to study the carbon dynamic balance between ecosystems, and to further explore distribution characteristics, as well as the sequestration potential of SOC.     

http://www.sciencedirect.com/science/article/pii/S1674987111000508

This paper presents the results of a set of numerical models focussing on structural controls on hydrothermal mineralization.We first give an overview of natural phenomena of structurally-controlled ore formation and the background theory and mechanisms for such controls. We then provide the results of a group of simple 2D numerical models validated through comparison with Cu-vein structure observed near the Shilu Copper deposit(Yangchun,Guangdong Province, China) and finally a case study of 3D numerical modelling applied to the Hodgkinson Province in North Queensland(Australia).Two modelling approaches,discrete deformation modelling and continuum coupled deformation and fluid flow modelling,are involved.The 2D model-derived patterns are remarkably consistent with the Cu-vein structure from the Shilu Copper deposit,and show that both modelling approaches can realistically simulate the mechanical behaviours of shear and dilatant fractures.The continuum coupled deformation and fluid flow model indicates that pattern of the Cuveins near the Shilu deposit is the result of shear strain localization,development of dilation and fluid focussing into the dilatant fracture segments.The 3D case-study models(with deformation and fluid flow coupling) on the Hodgkinson Province generated a number of potential gold mineralization targets.     

http://www.sciencedirect.com/science/article/pii/S1674987114000401

In this paper, a new discrimination diagram using absolute measures of Th and Nb is applied to post-Archean ophiolites to best discriminate a large number of different ophiolitic basalts. This diagram ...     

http://www.sciencedirect.com/science/article/pii/S1674987114000875

The origin and petrogenesis of the Cameroon Volcanic Line(CVL),composed of volcanoes that form on both the ocean floor and the continental crust,are difficult to understand because of the diversity,heterogeneity,and nature of available data.Major and trace elements,and Sr-Nd-Pb isotope data of volcanic rocks of the CVL spanning four decades have been compiled to reinterpret their origin and petrogenesis.Volcanic rocks range from nephelinite,basanite and alkali basalts to phonolite,trachyte and rhyolite with the presence of a compositional gap between Si O258e64 wt.%.Similarities in geochemical characteristics,modeled results for two component mixing,and the existence of mantle xenoliths in most mafic rocks argue against significant crustal contamination.Major and trace element evidences indicate that the melting of mantle rocks to generate the CVL magma occurred dominantly in the garnet lherzolite stability field.Melting models suggest small degree(3%)partial melting of mantle bearing(6e10%)garnet for Mt.Etinde,the Ngaoundere Plateau and the Biu Plateau,and5%of garnet for the oceanic sector of the CVL,Mt.Cameroon,Mt.Bambouto,Mt.Manengouba and the Oku Volcanic Group.The Sr-Nd-Pb isotope systematics suggest that mixing in various proportions of Depleted MORB Mantle(DMM)with enriched mantle 1 and 2(EM1 and EM2)could account for the complex isotopic characteristics of the CVL lavas.Low Mg number(Mg#100 Mg O/(Mg O t Fe O))and Ni,Cr and Co contents of the CVL mafic lavas reveal their crystallization from fractionated melts.The absence of systematic variation in Nb/Ta and Zr/Hf ratios,and Sr-Nd isotope compositions between the mafic and felsic lavas indicates progressive evolution of magmas by fractional crystallization.Trace element ratios and their plots corroborate mantle heterogeneity and reveal distinct geochemical signatures for individual the CVL volcanoes.     

http://www.sciencedirect.com/science/article/pii/S1674987114001078

The Caucasian-Arabian belt is part of the huge late Cenozoic Alpine-Himalayan orogenic belt formed by collision of continental plates.The belt consists of two domains:the Caucasian-Arabian Syntaxis(CAS)in the south and the EW-striking Greater Caucasus in the north.The CAS marks a zone of the indentation of the Arabian plate into the southern East European Craton.The Greater Caucasus Range is located in the south of the Eurasian plate;it was tectonically uplifted along the Main Caucasian Fault(MCF),which is,in turn,a part of a megafault extended over a great distance from the Kopetdag Mts.to the TornquistTeisseyre Trans-European Suture Zone.The Caucasus Mts.are bounded by the Black Sea from the west and by the Caspian Sea from the east.The SN-striking CAS is characterized by a large geophysical isostatic anomaly suggesting presence of mantle plume head.A 500 km long belt of late Cenozoic volcanism in the CAS extends from the eastern Anatolia to the Lesser and Greater Caucasus ranges.This belt hosts two different types of volcanic rocks:(1)plume-type intraplate basaltic plateaus and(2)suprasubductiontype calc-alkaline and shoshonite-latite volcanic rocks.As the CAS lacks signatures of subduction zones and is characterized by relatively shallow earthquakes(50e60 km),we suggest that the"suprasubduction-type"magmas were derived by interaction between mantle plume head and crustal material.Those hybrid melts were originated under conditions of collision-related deformation.During the late Cenozoic,the width of the CAS reduced to ca.400 km due to tectonic"diffluence"of crustal material provided by the continuing Arabia-Eurasia collision.     

http://www.sciencedirect.com/science/article/pii/S1674987114001121

The Chinese Tianshan belt of the southern Altaids has undergone a complicated geological evolution.Different theories have been proposed to explain its evolution and these are still hotly debated.The major subduction polarity and the way of accretion are the main problems.Southward,northward subduction and multiple subduction models have been proposed.This study focuses on the structural geology of two of the main faults in the region,the South Tianshan Fault and the Nikolaev Line.The dip direction in the Muzhaerte valley is southward and lineations all point towards the NW.Two shear sense motions have been observed within both of these fault zones,a sinistral one,and a dextral one,the latter with an age of 236-251 Ma.Structural analyses on the fault zones show that subduction has been northward rather than southward.The two shear sense directions indicate that the Yili block was first dragged along towards the east due to the clockwise rotation of the Tarim block.After the Tarim block stopped rotating,the Yili block still kept going eastward,inducing the dextral shear senses within the fault zones.     

Progress of machine learning in geosciences: Preface

正In the past two decades,artificial intelligence(AI)algorithms have proved to be promising tools for solving several tough scientific problems.As a broad subfield of AI,machine learning is concerned with algorithms and techniques that allow computers to"learn".The machine learning approach covers main domains such as data mining,difficult-to-program applications,and software applications.It is a collection of a variety of algorithms that     

http://www.sciencedirect.com/science/article/pii/S1674987115000973

Tarim Precambrian bedrocks are well exposed in the Kuluketage and Aksu areas,where twenty four samples were taken to reveal the denudation history of the northern Tarim Craton.Apatite fission track dating and thermal history modeling suggest that the northern Tarim experienced multi-stage cooling events which were assumed to be associated with the distant effects of the Cimmerian orogeny and India-Eurasia collision in the past.But the first episode of exhumation in the northern Tarim,occurring in the mid-Permian to Triassic,is here suggested to be induced by docking of the Tarim Craton and final amalgamation of the Central Asian Orogenic Belt.The cooling event at ca.170 Ma may be triggered by the Qiangtang-Eurasia collision.Widespread Cretaceous exhumation could be linked with docking of the Lhasa terrane in the late Jurassic.Cenozoic reheating and recooling likely occurred because of the northpropagating stress,however,this has not affected the northern Tarim much because the Tarim is characterized by rigid block-like motion.