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Historical building dating: A multidisciplinary study of the Convento de São Francisco (Coimbra, Portugal)

Geochronometria
Volume 45 (2018): Issue 1 (January 2018)
By:
Open Access
|Jul 2018

Figures & Tables

Fig. 1

Plan of the 2nd Floor of the Convento de São Francisco with construction phases and sampling points.
Plan of the 2nd Floor of the Convento de São Francisco with construction phases and sampling points.

Fig. 2

ED distribution obtained with radial plots for mortar samples.
ED distribution obtained with radial plots for mortar samples.

Fig. 3

Semi-quantitative mineral composition of mortar samples obtained by XRD analysis.
Semi-quantitative mineral composition of mortar samples obtained by XRD analysis.

Fig. 4

Sample grouping after the plot of binder vs aggregate proportions.
Sample grouping after the plot of binder vs aggregate proportions.

Fig. 5

Level of brightness (L∗) associated to hue angle (h) for mortar samples.
Level of brightness (L∗) associated to hue angle (h) for mortar samples.

Fig. 6

Dates obtained for mortar and brick samples.
Dates obtained for mortar and brick samples.

Color data in the CIELAB 1976 space both rectangular L*, a*, b* (respectively Lightness, red-green color component and yellow-blue color component) and cylindrical, C*, h (respectively chroma and hue angle) coordinates with the related uncertainties_

SampleL*a*b*C*h
CSFL366.10 ± 1.674.63 ± 0.1222.73 ± 0.5823.19 ± 0.8278.52 ± 2.77
CSLF755.67 ± 1.548.21 ± 0.2325.57 ± 0.7126.86 ± 1.0172.25 ± 2.72
CSFL1459.63 ± 1.3311.45 ± 0.2532.88 ± 0.7334.82 ± 1.1270.83 ± 2.28
CSFL1256.72 ± 1.609.23 ± 0.2626.69 ± 0.7528.24 ± 1.0870.95 ± 2.71
CSFL1164.25 ± 1.523.46 ± 0.0820.32 ± 0.4820.62 ± 0.6980.39 ± 2.70

Dating of bricks: k-value, Qβ e qβ values obtained by TL measurements_

Samplek-valueQβ (Gy)qβ (Gy)
CSLF20.259 ± 0.0112.09 ± 0.190.13 ± 0.02
CSLF60.232 ± 0.0182.87 ± 0.230.05 ± 0.01
CSLF100.220 ± 0.0103.18 ± 0.280.09 ± 0.02

Dating of samples: Sample name, sample material, technique, method with ED, annual dose rate, the individual dating results (referred to the year of the TL measurements) and the corresponding calendar dates obtained for both bricks and mortars_

SampleMaterialTechniqueMethodED (Gy)Annual dose rate (mGy/a)Age/2016 (a)Age (AD)
CSFL2BrickTLAdded dose2.22 ± 0.1911.43 ± 0.85194 ± 221822 ±22
CSFL3MortarOSLSAR1.17 ± 0.105.41 ± 0.37216 ± 241800 ±24
CSFL6BrickTLAdded dose2.92 ± 0.238.62 ± 0.66339 ± 371677 ± 37
CSFL7MortarOSLSAR2.03 ± 0.216.67 ± 0.47304 ± 381712 ± 38
CSFL10BrickTLAdded dose3.27 ± 0.289.44 ± 0.63346 ± 381670 ± 38
CSFL11MortarOSLSAR1.13 ± 0.115.76 ± 0.37196 ± 231820 ± 23
CSFL12MortarOSLSAR2.41 ± 0.157.47 ± 0.44322 ± 281694 ± 28
CSFL14MortarOSLSAR2.61 ± 0.187.81 ± 0.48344 ± 311672 ± 31

Contributions to the annual dose rate: Sample name, sample material, porosity factor W, alpha and beta internal dose rates (Dαint and Dβint) and environmental component (Denv)_

SampleMaterialWDαint(mGy/a)Dβint(mGy/a)Denv(mGy/a)
CSFL2Brick0.16 ± 0.0129.65 ± 1.253.22 ± 0.081.22 ± 0.05
CSFL3Mortar0.21 ± 0.0222.71 ± 0.931.71 ± 0.04
CSFL6Brick0.15 ± 0.0122.24 ± 0.952.53 ± 0.061.37 ± 0.05
CSFL7Mortar0.22 ± 0.0222.36 ± 0.902.18 ± 0.05
CSFL10Brick0.17 ± 0.0124.95 ± 1.012.94 ± 0.071.57 ± 0.05
CSFL11Mortar0.27 ± 0.0221.38 ± 0.891.80 ± 0.05
CSFL12Mortar0.25 ± 0.0223.31 ± 0.392.87 ± 0.061.75 ± 0.05
CSFL14Mortar0.23 ± 0.0224.78 ± 0.282.86 ± 0.051.65 ± 0.05

XRD semi-quantitative mineralogical composition of mortars (%) and aggregate/binder ratio (Qz – quartz; K-felds – potassium feldspars; Na-plag – sodium plagioclases; Cal – calcite; Dolo – dolomite; Phyl – phyllossilicates; * – traces)_

SampleQzK-feldsNa-plagCalDoloPhylAggregate (A)Binder (B)A/B Ratio
CSFL36521113**86136.62
CSFL7655*262270262.69
CSFL1171141131*85136.54
CSFL12591210181*71183.94
CSFL1466111211*77213.67

Details of the samples studied in this work with ID number, material and sampling point description_

Sampling point (floor 2)
SampleMaterialArchitectural elementHeight

height above planking level

(cm)
CSLF2BrickArc (east)350
CSLF3Mortar
CSLF6BrickArc (south)80
CSLF7Mortar
CSLF10BrickArc (west)235
CSLF11Mortar
CSLF12MortarWall (west)145
CSLF14MortarWall (north)150

Plateau temperature range and preheating (Ph) temperature choose for ED evaluation_

SamplePlateau ED range (°C)Ph temperature (°C)
CSLF3180–220200
CSLF7180–240210
CSLF11180–220200
CSLF12180–220200
CSLF14180–240210

Number of aliquots (n), luminescence efficiency coefficient (k-value), Equivalent Dose (ED) Value and relative standard deviations (SD) obtained, respectively, by radial plot (ED Central Value, see Fig_ 2) and from ED frequency distributions (Mean ED) for mortar samples_

SampleNumber of aliquots (n)k-valueED Central Value

from Radial Plot

(Gy) SD		Mean ED

from ED frequency distributions

(Gy) SD
CSFL3390.125 ± 0.0101.17 0.101.18 0.18
CSFL7470.161 ± 0.0122.03 0.212.02 0.26
CSFL11410.134 ± 0.0101.13 0.111.12 0.17
CSFL12380.148 ± 0.0102.41 0.152.42 0.22
CSFL14440.157 ± 0.0102.61 0.182.63 0.25

Radioactive measurements: Sample name, sample material with U, Th, K contents obtained by high gamma spectrometry and 238U/226Ra ratio_

SampleMaterial238U/226RaU (ppm)Th (ppm)K (%)
CSFL2Brick1.03 ± 0.114.54 ± 0.2223.26 ± 1.492.46 ± 0.07
CSFL3Mortar0.97 ± 0.083.76 ± 0.1816.57 ± 1.070.90 ± 0.03
CSFL6Brick1.02 ± 0.123.26 ± 0.1618.00 ± 1.152.00 ± 0.06
CSFL7Mortar0.97 ± 0.093.91 ± 0.1915.70 ± 1.001.51 ± 0.05
CSFL10Brick0.98 ± 0.104.30 ± 0.2117.75 ± 1.142.33 ± 0.07
CSFL11Mortar1.05 ± 0.083.40 ± 0.1616.30 ± 1.041.10 ± 0.03
CSFL12Mortar0.99 ± 0.083.52 ± 0.0618.48 ± 0.492.37 ± 0.07
CSFL14Mortar0.97 ± 0.103.70 ± 0.0619.80 ± 0.312.27 ± 0.07
DOI: https://doi.org/10.1515/geochr-2015-0089 | Journal eISSN: 1897-1695
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Language: English
Page range: 119 - 129
Submitted on: May 12, 2017
Accepted on: Feb 20, 2018
Published on: Jul 4, 2018
Published by: Sciendo
In partnership with: Paradigm Publishing Services
Publication frequency: 1 times per year
Keywords:
brick dating,
mortar dating,
XRD,
colorimetry,
characterization,
archaeological stratigraphy
Related subjects:
Geosciences,
Geosciences, other

© 2018 Giuseppe Stella, Luis Almeida, Lilia Basílio, Stefania Pasquale, Jorge Dinis, Miguel Almeida, Anna M. Gueli, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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