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Simple surrogate formulations for gasoline are useful for modelling purposes and for comparing experimental results using a carefully designed fuel. Simple three-component surrogates based on primary reference fuels (PRF) and Toluene (TPRF) are frequently used to match the antiknock properties of actual gasoline fuels through the RON and MON. However, using PRF or TPRFs to test or to calibrate gasoline engines is still challenging, with the main difficulty being the capabilities of PRF fuels to match the physical properties of the road fuel such density, volatility (DVPE) and the distillation curve. To overcome such issues, an alternative to TPRF is presented in this work with a focus on premium fuel (RON98 EN228). This alternative consists of replacing some or all of isooctane by isopentane. In the event of total replacement, a three-component "THIP" (Toluene, Heptane, IsoPentane) surrogate fuel is produced. The physical and combustion properties of isopentane makes it easier to create surrogates that can match the DVPE, RON, MON and distillation characteristics of a real fuel. Furthermore, the use of isopentane allows the definition of a wider range of surrogate fuel compositions that can replicate the RON and MON of a given fuel. Surrogate formulations were developed at Shell Global Solutions that matched the RON, MON and selected physical properties of a reference premium gasoline (RPG). A Rapid Compression Machine (RCM) in PCFC was used to demonstrate that those surrogates can reproduce the essential autoignition characteristics of the selected RPG. Two mechanisms were used to predict RCM data and showed reasonable agreement, opening some perspective for further investigations. Finally, an engine test performed at Ferrari test facilities demonstrated that simple surrogates containing isopentane can be used to closely match the knock-limited combustion phasing of an RPG. In this paper, it is demonstrated such surrogates have advantages compared to TPRFs in being able to match the properties of a real fuel and that the surrogate approach is consistent with RCM data and engine results. [ABSTRACT FROM AUTHOR]

Multiple episodes of deformation during the tectonic evolution of orogenic belts and ancient subduction-accretion complexes cause obfuscation of primary block-in-matrix fabric of mélanges, and thereby making the recognition of their tectonic, sedimentary or diapiric origin difficult. Here we present a comprehensive overview and synthesis of a diverse set of field-based stratigraphic and structural criteria, which are at the base of geological mapping rules, to differentiate between various mélange types, developed by disparate geological processes and mechanisms. We first define the current concepts of mélange and mélange nomenclature, and describe the most diagnostic features of tectonic, sedimentary and diapiric mélanges at different scales. We discuss some of the main issues complicating the application of these diagnostic criteria, such as: (i) similarities between the block-in-matrix fabric of different mélange types formed in partially lithified sediments at shallow structural levels, (ii) transformation of fabric elements with increased depth due to tectonic reworking and recrystallization processes, (iii) significance of "exotic" versus "native" blocks in mélange matrix, and (iv) age relationships between blocks and matrix in a mélange. We introduce two additional criteria in approaching these complexities and in recognizing different processes of polygenetic mélanges formation in the field when primary diagnostic fabrics were reworked by multiple deformational events. These new criteria are based on (i) the coherence between lithological compositions of mélange components (blocks and matrix) and characteristics and tectonic evolution of the geodynamic setting of their formation ("tectonic environment criterion"), and (ii) specificity and kinematic coherence in the distribution of deformation between blocks and the matrix ("deformation criterion"). The discussed diagnostic criteria can be applied to all field-based investigations of mélanges and broken formations in orogenic belts and exhumed subduction-accretion complexes around the world, regardless of their location, age, and tectonic history. Unlabelled Image • Field criteria to differentiate tectonic, sedimentary, diapiric processes of mélange formation • Field constraints based on stratigraphic, structural principles and geological mapping rules • Application to polygenetic mélanges formed by superposition of different processes • Application to all orogenic belts and exhumed subduction complexes around the world [ABSTRACT FROM AUTHOR]

We present a critical appraisal of the role of subducted, medium (10–1000 km 2 ) to giant (≥1000 km 2 ) and heterogeneous, mud-rich mass transport deposits (MTDs) in seismic behavior and mechanisms of shallow earthquakes along subduction plate interfaces (or subduction channels) at convergent margins. Our observations from exhumed ancient subduction complexes around the world show that incorporation of mud-rich MTDs with a “chaotic” internal fabric (i.e., sedimentary mélanges or olistostromes) into subduction zones strongly modifies the structural architecture of a subduction plate interface and the physical properties of subducted material. The size and distribution of subducted MTDs with respect to the thickness of a subduction plate interface are critical factors influencing seismic behavior at convergent margins. Heterogeneous fabric and compositions of subducted MTDs may diminish the effectiveness of seismic ruptures considerably through the redistribution of overpressured fluids and accumulated strain. This phenomenon possibly favors the slow end-member of the spectrum of fault slip behavior (e.g., Slow Slip Events, Very Low Frequency Earthquakes, Non-Volcanic Tremors, creeping) compared to regular earthquakes, particularly in the shallow parts ( T  < 250 °C) of a subduction plate interface. [ABSTRACT FROM AUTHOR]

Olistostromes (sedimentary mélanges) represent the products of ancient submarine mass transport processes. We present a comparative analysis of the occurrences and internal structures of these sedimentary mélanges at a global scale with a focus on the Circum-Mediterranean, Appalachian and Circum-Pacific regions, and discuss their formation and time-progressive evolution in different tectonic settings. Lithological compositions, stratigraphy, and structural features of olistostromes reflect the operation of an entire spectrum of mass transport processes during their development through multi-stage deformation phases. The general physiography and tectonic setting of their depocenters, the nature, scale and rate of downslope transformation mechanisms, and global climatic events are the main factors controlling the internal structure and stratigraphy of olistostromes. Based on the tectonic settings of their formation olistostromes are classified as: (i) passive margin, (ii) convergent margin and subduction–accretion, and (iii) collisional and intra-collisional types. Systematic repetitions of these different olistostrome types in different orogenic belts provide excellent markers for the timing of various tectonic events during the Wilson cycle evolution of ocean basins. Olistostromes are best preserved in paleo active margins, covering vast areas of thousands of km 2 , where they underwent significant downslope translation, up to hundreds of kilometers. Incorporation of olistostromes into subduction–accretion complexes and orogenic belts takes place during discrete episodes of tectonic events, and their primary (sedimentary) fabric may be commonly reworked and overprinted by subsequent phases of tectonic and metamorphic events. We apply the basic nomenclature of structural geology, sedimentology and basin analysis in studying the internal structure, lithological makeup, and mechanisms of formation and extraordinary downslope mobility of olistostromes. [ABSTRACT FROM AUTHOR]

Abstract: The Hamburg Klippe of the Central Appalachian orogenic belt exposed in eastern Pennsylvania displays a complex record of poly-phase mélange and broken formation development in a convergent margin setting. It includes an imbricate stack of tectonic slices, which consist of upper Cambrian to Upper Ordovician deep-water and continental slope sedimentary rocks, emplaced by gravity sliding onto the Laurentian passive margin during deposition of the Upper Ordovician Martinsburg Formation. Based on their internal structure and stratigraphy, the block-matrix ratios and relations, and the inferred tectonic settings of origin, we have differentiated the following mélanges and broken formations, whose evolutionary stages coincide with specific deformational phases in a complete orogenic cycle from subduction to collision: (i) sedimentary broken formations without exotic blocks, formed by in situ and local down-slope remobilization during the early stages of closure of the Octoraro Sea basin in the Early Ordovician; (ii) two types of sedimentary mélanges with exotic blocks, formed at the front of the advancing accretionary wedge during the Middle Ordovician subduction of the Laurentian continental margin beneath a microcontinent–magmatic arc tectonic assembly; (iii) layer-parallel, extensional broken formation and a diapiric mélange, formed in the outer trench and at the toe of the accretionary wedge, respectively, during the early–Late Ordovician; (iv) precursory olistostromes, formed during the Late Ordovician collisional episodes as the Hamburg Klippe was emplaced in the Martinsburg Formation on the downgoing Laurentian continental margin; and, (v) contractional deformation-related broken formations, formed at the base of main thrust faults overprinting the previously formed mélanges and broken formations. This sequential development of different mélange types in the Central Appalachians was strongly controlled by the degree of consolidation of the layered strata and their rheological differences, the structural level of mélange formation within the accretionary wedge, and the kinematics of deformational processes. [Copyright &y& Elsevier]

Abstract: The Argille varicolori (Varicolored scaly clays) of the External Ligurian Units of the Northern Apennines have been widely described as a typical unmetamorphosed broken formation (i.e., a chaotic unit without exotic blocks), produced by offscraping and tectonic imbrication during the evolution of the Ligurian accretionary wedge. Geological mapping and integrated structural and stratigraphic observations show that the Argille varicolori consist of diverse types of small-scale mélanges (non-mappable at a 1:25,000 scale) forming a composite chaotic unit, in which the superposition of tectonic, sedimentary and diapiric processes resulted in the occurrence of polygenetic chaotic bodies at different scales. These mélange units record the evolution of the Ligurian accretionary wedge from subduction to collision and intracontinental deformation. Tectonically Disrupted Body 1 (TDB1) comprises boudinage and pinch-and-swell structures formed by layer-parallel extension/contraction at the wedge front of the Ligurian accretionary complex during the late Cretaceous–middle Eocene. It is interleaved with non-mappable Gravity-driven Chaotic Bodies (GCB) developed during alternating episodes of accretion and removal of material at the wedge front. The late Oligocene–early Miocene out-of-sequence thrusting related to the collisional episodes in the Apennines overprinted the previously formed chaotic bodies and formed a polygenetic tectonic mélange (Tectonically Disrupted Body 2, TDB2). This unit is characterized by a structurally ordered block-in-matrix fabric and by the gradual decrease of stratal disruption away from the regional thrust. Overpressurized fluids concentrated along the shear surfaces, and the scaly cleavage planes facilitated the diapiric upward movement of unconsolidated sediments in the early Miocene. This process produced non-mappable shale dike injections (DDB1) and mappable Diapirically Disrupted Bodies (DDB2), which show an internal zonation of deformation. This deformation reworked the previously formed chaotic bodies. Although some of these polygenetic mélanges cannot be mapped at a 1:25,000 scale, their careful documentation provides a better understanding of time-progressive, scale-independent mélange-forming processes. [Copyright &y& Elsevier]

• 3 component gasoline surrogates are usually made from toluene, isooctane and n - heptane. • Gasoline surrogates with toluene, isopentane and n-heptane (THIP) are proposed. • THIP surrogates capture RON/ MON and Ignition Delay (measured in RCM) of a real fuel. • THIP surrogates are better able to represent a realistic DVPE and density. • Chemical kinetic mechanisms exist to model THIP surrogates with reasonable accuracy. Simple surrogate formulations for gasoline are useful for modelling purposes and for comparing experimental results using a carefully designed fuel. Simple three component surrogate fuels based on toluene, n-heptane and isooctane, called toluene primary reference fuels (TPRF), are frequently used to match the RON and MON of actual gasoline fuels. In this work the main advantages of using an alternative three-component surrogate formulation, based on toluene, n-heptane and isopentane (THIP) are presented. Given a reference gasoline, good representations of RON and MON are achieved as well as better matching density, distillation properties and other volatility parameters associated with the lighter end of gasoline fuels. In particular, THIP surrogates can replicate Dry Vapour Pressure Equivalent (DVPE) values ranging from 10.4 kPa to 138.9 kPa, fully covering the EN228 Summer and Winter gasoline specifications. Moreover, Rapid Compression Machine (RCM) results demonstrate that THIP surrogates can reproduce the essential characteristics of the reference gasoline in terms of ignition delay time versus temperature. An existing chemical kinetic mechanism is shown to be able represent THIP surrogate well. [ABSTRACT FROM AUTHOR]