The chemical variability at the surface of Mars: Implication for sediment formation and rock weathering

Kolb, C.; Fernández, Josep Antoni Martín; Abart, Rainer; Lämmer, H.

doi:10.1016/j.icarus.2006.01.020

Cited by 10 publications

(26 citation statements)

References 87 publications

(181 reference statements)

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“…Our recent results presented in detail in Kolb et al (2006) for Mars and Wurz et al (2010) for Mercury are summarized in this chapter, highlighting the relevance of composition data analysis in planetology.…”

Section: Analysis Of Surface Compositionmentioning

confidence: 89%

“…To investigate the default of the classical additive analysis method our research group recently applied (Kolb et al 2006;Wurz et al 2010) a more realistic multiplicative method (Aitchison 1986) based on the Euclidean space geometry of the simplex (see Chapter 11). Our recent results presented in detail in Kolb et al (2006) for Mars and Wurz et al (2010) for Mercury are summarized in this chapter, highlighting the relevance of composition data analysis in planetology.…”

Section: Analysis Of Surface Compositionmentioning

confidence: 99%

“…The correlation coefficients between element concentrations can be essentially influenced by the normalization to a constant sum, where the closure operation disturbs correlations in the covariance structure of a given set of data (Aitchison 1997;Kolb et al 2006). For that reason classical multivariate techniques, such as conventional correspondence analysis or biplot techniques can be misleading when applied to subcompositions.…”

Section: Compositional Analysis Of Mars' Surfacementioning

confidence: 99%

“…In such cases the visualization of compositional data with subcompositions may be deceptive (Aitchison 1997). Kolb et al (2006) applied a centred log ratio (clr) transformation prior to statistical analysis that translates compositional data from a constrained Simplex space to a reality representing Euclidean space. clr transformation of a compositional vector C with components c i can be defined after Aitchison (1986) as…”

Section: Compositional Analysis Of Mars' Surfacementioning

confidence: 99%

“…In the analysis of Kolb et al (2006) the chemical subcompositions of 13 Martian surface elements in wt% (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe) were selected from the literature. The elements were taken from different landing sides and geographical locations by different Mars rovers: Mars Pathfinder (Brückner et al 2003;Foley et al 2003); MER-A ; and MER-B .…”

Section: Compositional Analysis Of Mars' Surfacementioning

confidence: 99%

See 4 more Smart Citations

Compositional Data Analysis in Planetology: The Surfaces of Mars and Mercury

Lämmer

Würz

Fernández

et al. 2011

Compositional Data Analysis

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Section: Analysis Of Surface Compositionmentioning

confidence: 89%

Section: Analysis Of Surface Compositionmentioning

confidence: 99%

Section: Compositional Analysis Of Mars' Surfacementioning

confidence: 99%

Section: Compositional Analysis Of Mars' Surfacementioning

confidence: 99%

Section: Compositional Analysis Of Mars' Surfacementioning

confidence: 99%

See 3 more Smart Citations

Compositional Data Analysis in Planetology: The Surfaces of Mars and Mercury

Lämmer

Würz

Fernández

et al. 2011

Compositional Data Analysis

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A bootstrap estimation scheme for chemical compositional data with nondetects

Palarea‐Albaladejo

Fernández

Olea

2014

Journal of Chemometrics

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The bootstrap method is commonly used to estimate the distribution of estimators and their associated uncertainty when explicit analytic expressions are not available or are difficult to obtain. It has been widely applied in environmental and geochemical studies, where the data generated often represent parts of whole, typically chemical concentrations. This kind of constrained data is generically called compositional data, and they require specialised statistical methods to properly account for their particular covariance structure. On the other hand, it is not unusual in practice that those data contain labels denoting nondetects, that is, concentrations falling below detection limits. Nondetects impede the implementation of the bootstrap and represent an additional source of uncertainty that must be taken into account. In this work, a bootstrap scheme is devised that handles nondetects by adding an imputation step within the resampling process and conveniently propagates their associated uncertainly. In doing so, it considers the constrained relationships between chemical concentrations originated from their compositional nature. Bootstrap estimates using a range of imputation methods, including new stochastic proposals, are compared across scenarios of increasing difficulty. They are formulated to meet compositional principles following the log-ratio approach, and an adjustment is introduced in the multivariate case to deal with nonclosed samples. Results suggest that nondetect bootstrap based on model-based imputation is generally preferable. A robust approach based on isometric log-ratio transformations appears to be particularly suited in this context. Computer routines in the R statistical programming language are providedThis research has been supported by the Scottish Government's Rural and Environment Science and Analytical Services Division (RESAS), the Spanish Ministry of Economy and Competitiveness under the project 'METRICS' Ref. MTM2012-33236 and the Agencia de Gestio d'Ajuts Universitaris i de Recerca of the Generalitat de Catalunya under the project Ref. 2009SGR42

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Features of acid–saline systems of Southern Australia

Dickson¹,

Giblin²

2009

Applied Geochemistry

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The chemical variability at the surface of Mars: Implication for sediment formation and rock weathering

Cited by 10 publications

References 87 publications

Compositional Data Analysis in Planetology: The Surfaces of Mars and Mercury

Compositional Data Analysis in Planetology: The Surfaces of Mars and Mercury

A bootstrap estimation scheme for chemical compositional data with nondetects

Features of acid–saline systems of Southern Australia

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