Log transformations in geochemistry

Miesch, A.T.; Chapman, R. P.

doi:10.1007/bf02312512

Cited by 23 publications

(5 citation statements)

References 9 publications

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“…First, we log transform the elemental ratio data. Geochemical reactions naturally follow patterns that are proportional to the logarithm of the reactant concentration or to the log of a concentration ratio (Miesch and Chapman, ; Woronow, ; Stanley, ; Buccianti, ). For example, the thermodynamic chemical potential of a reaction ( μ ) is proportional to the natural log of the reactant concentration (i.e.…”

Section: Resultsmentioning

confidence: 99%

Quantifying weathering on variable rocks, an extension of geochemical mass balance: Critical zone and landscape evolution

Fisher

Aufdenkampe

Yoo

2017

Earth Surf Processes Landf

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We present a statistical model of soil and rock weathering in deep profiles to expand the capacity to assess weathering to heterogeneous bedrock types, which are common at the Earth's surface. We developed the Weathering Trends (WT) model by extending the fractional mass change calculation (tau) of the geochemical mass balance model in two important ways. First, WT log transforms the elemental ratio data, to discern the log‐linear patterns that naturally develop from thermodynamic and kinetic laws of chemistry. Second, WT statistically fits log‐transformed element concentration ratio data – log(cj/ci), the only depth‐varying term in tau – as a function of depth to determine characteristic depths of transitions in weathering processes, along with confidence intervals. With no prior assumptions, WT estimates average parent material composition, average composition of the upper weathered zone and mean fractional mass change of each element over the entire weathering profile. WT displays the mean shape of weathering profiles of log‐transformed geochemical data bounded by calculated confidence intervals. We share the WT model code as an open‐source R package (https://github.com/fisherba/WeatheringTrends). The WT model was designed to interpret two 21 m cores from the Laurels Schist bedrock in the Christina River Basin Critical Zone Observatory in the Pennsylvania Piedmont, where our morphological and elemental data provided inconclusive estimates of bedrock depth. The WT model differentiated between rock variability and weathering to delineate the maximum extent of weathering at 12.3 m (CI 95% [9.2, 21.3]) in Ridge Well 1 and 7.2 m (CI 95% [4.3, 13.0]) in Interfluve Well 2. The water table was 5–8 m below fresh rock at Ridge Well 1, but at the same depth as fresh rock at the lower elevation interfluve. We assess statistical approaches to identify the best immobile element for use in WT and tau calculations. Copyright © 2017 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Quantifying weathering on variable rocks, an extension of geochemical mass balance: Critical zone and landscape evolution

Fisher

Aufdenkampe

Yoo

2017

Earth Surf Processes Landf

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“…Like many geochemical data sets (e.g., Joseph and Bhaumik, 1997;McGrath and Loveland, 1992;Miesch, 1977;Reimann and Filzmoser, 2000;Vistelius, 1960), the stream sediment geochemical data set in the study area do not satisfy a normal distribution model and consist at least four populations (Fig. 2).…”

Section: Choice Of the Concentration-area Fractal Analysismentioning

confidence: 97%

Analysis and mapping of geochemical anomalies using logratio-transformed stream sediment data with censored values

Carranza

2011

Journal of Geochemical Exploration

278

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“…Sehingga pada umumnya kumpulan data geokimia tidak mengikuti model distribusi normal (Vistelius, 1960;Reimann dan Filzmoser, 1999). Uji normalitas dilakukan untuk mengubah dari distribusi data yang tidak normal (Miesch, 1977;Joseph dan Bhaumik, 1997) Scatterplot dari data dengan distribusi normal (simetri) atau yang mendekati normal akan optimal dalam analisis hubungan antar unsur secara visual (Carranza, 2008). Scatterplot pada Gambar 11 menunjukkan bahwa unsurunsur dari data geokimia tanah daerah penyelidikan mempunyai hubungan yang positif.…”

Section: Pembahasanunclassified

Penentuan Daerah Prospek Mineralisasi Menggunakan Metode Geokimia Tanah, Daerah Nanga Bangik, Kecamatan Boyan Tanjung, Kabupaten Kapuas Hulu, Provinsi Kalimantan Barat

Sulaeman¹,

Ernowo²,

Widhiyatna³

2021

buletin sdg

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Sebagai negara tropis pelapukan tanah di Indonesia berlangsung intensif. Penentuan daerah prospek mineralisasi pada penelitian ini menggunakan metode geokimia tanah, dengan melakukan pengambilan sampel dari tanah lapukan tersebut. Daerah Nanga Bangik, Desa Jemah, Kecamatan Boyan Tanjung, Kabupaten Kapuas Hulu, Provinsi Kalimantan Barat memiliki kondisi geologi yang sangat memungkinkan terbentuk mineralisasi logam. Penyelidikan ini dilakukan untuk menentukan daerah prospek mineralisasi. Sebanyak 135 sampel tanah telah diambil menggunakan sistem ridge and spurs dari horizon B dengan jarak antar titik lokasi sampel 75 – 100 meter. Sampel tanah tersebut dianalisis di Laboratorium Pusat Sumber Daya Mineral Batubara dan Panas Bumi (PSDMBP). Analisis laboratorium menggunakan metode AAS (Atomic Absorption Spectroscopy), unsur yang dianalisis meliputi Cu, Pb, Zn, Fe, Mn, Ag dan Au. Metode analisis statistik yang dilakukan meliputi analisis distribusi, perhitungan nilai threshold dengan metode perhitungan Mean+2 SDEV dan Median+2 MAD dan korelasi antar unsur dengan Faktor Analisis. Berdasarkan perhitungan nilai threshold menggunakan dua metode statistik yang berbeda, didapatkan beberapa nilai anomali dan tiga faktor kelompok unsur: Faktor 1: Pb-Fe-Zn-Ag Faktor 2: Mn-Cu dan Faktor 3 berupa unsur Au yang diinterpretasikan berhubungan dengan adanya mineralisasi logam. Didapatkan tiga daerah prospek mineralisasi logam di Bukit Empajak, Bukit Pirang dan Bukit Limau.

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Log transformations in geochemistry

Cited by 23 publications

References 9 publications

Quantifying weathering on variable rocks, an extension of geochemical mass balance: Critical zone and landscape evolution

Quantifying weathering on variable rocks, an extension of geochemical mass balance: Critical zone and landscape evolution

Analysis and mapping of geochemical anomalies using logratio-transformed stream sediment data with censored values

Penentuan Daerah Prospek Mineralisasi Menggunakan Metode Geokimia Tanah, Daerah Nanga Bangik, Kecamatan Boyan Tanjung, Kabupaten Kapuas Hulu, Provinsi Kalimantan Barat

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