RECONSTRUCTION OF PALEOENVIRONMENT IN KARST AREA (II)


(BEING CONTINUED FROM 9/07/15)

METHODS FOR RESEARCH OF LUMINESCENCE OF CAVE MINERALS
AND SPELEOTHEM RECORDS OF THE PALEOCLIMATE
AND SOLAR ACTIVITY IN THE PAST

Y.Y.Shopov, Georgiev L. ,Tsankov L.,V.Dermendjiev ,G.Buyukliev (Bulgaria)

INTRODUCTION

The Laser Luminescent Analysis of Speleothems was proposed as a technics for investigation  on mineral forming environment. The Visual Luminescence  Analysis was used as a method for investigation on climate changes during Quaternary. But those  methods have a resolution which is insufficient to clarify the  cyclicity of  the short-time variations of the climate and solar activity (SA).  For  this purpose  we proposed the method Laser Luminescent MicroZonal  Analysis  (LLMZA) with very high resolution.

Up to now the available information for cycles of the solar activity are from different  approaches,such  as  direct  measurements  for  240  years;data   from dendrochronology  for 7400 years ago with resolution 1 yr; and 14C data  for the last  10000 yrs. After calibration with this data,the LLMZA method can  be  used for obtaining  such  information with higher resolution (up to 3  days)  up  to several millions years ago (the age of the oldest flowstones).

METHODS FOR RESEARCH ON LUMINESCENCE OF CAVE MINERALS

We  elaborate  3  methods (table 1),4 technics (table  2)  for  research  of speleothems and 3 appratus for using directly in caves. They allows considerable enlargement for types and quality of the obtainable information and decrease  to minimum quantity of the samples necessary for laboratory measurements.

The  most simple method for luminescent research,which can be used by  every caver  is IPP. Slides obtained by using this method can be developed by CSS  for preparation  of  spectra of phosphorescence. In speleology CSS is  appplied  for preparation of spectra of diffuse reflectance and luminescence (at developing of slides obtained  by  IPL  method). It is intended  for  research  of  widelines spectra,  such  as the luminescence of all speleothems formed  at  normal  cave conditions (at temperature below 40° C).

This methods are foundations of the International Programme for research  of “Luminescence  of  Cave  Minerals of the World” of the  Commission  of  Physical Chemistry and hydrogeology of the International Speleological Union  of  UNESCO, leaded by Y.Y.Shopov.

The  aim  of  this programme is the elaboration of  a  system  for  express diagnostics   of  the  Luminescent  Cave  Minerals  (CM),by  photographing   its luminescence  with IPP and obtaining the spectra with CSS. The determination  of the spectra of L of all luminescent CM (which is the object of  this programme) is necessary  for  this purpose. The LLMZA investigations are  object  of this programme too. An  advantage  of this programme is its possibility for easy  collection  of information  for  CM and conditions of its formation in caves around  the  world from non-skilled  cavers and processing of the  information  with  standardized technics.

First stage of the Programme is the preparation of slides of phosphorescence (P)  of the CM (with IPP) in the caves. Determination of typomorphic  types  of luminescence of CM in caves will be produced.

Second  stage:  1.  Spectral  development  of  slides  by  CSS  method,   2. Indentification  of  obtained  spectra  by  comparison  with  known  spectra  of luminescence.  3.Receiving  of  sample of the mineral from the  author,  if  the spectrum  isn’t  known. Preparation of spectra of luminescence of  the  CM  with different  excitation  for determination of the  luminescent  centre.  4.Perfect phase  diagnostics  of  the mineral with X-ray diffraction and  DTA,DTG  and  TG analysis  .  5.Laboratory  investigation  on  the  changes  of  mineral  forming conditions,climate and solar activity with LLMZA are produced parallelly.

Third stage: 1.Preparation of “Atlas of Luminescence of Cave Minerals”  for diagnostics  of  CM  with LSPA. 2.Edition of the  book  “Luminescence  of  Cave Minerals of the World” including this Atlas.This book will contain Search Manual for diagnostics  of  cave  minerals  and  reviews  of  investigation  of   its luminescence.

Table 1. New Methods for Research of the Luminescence of CM

Method                                    Authors                    obtainable information


I. Impulse Photography           Shopov,                  determination of minerals,registration
of Luminescence (IPL)          Tsankov                  of colour & zonality of fluorescence &
1.Photography of                    (1984)                     phosphorescence and its spectra,UV-photography,
phosphorescence (IPP)                                         extraction of single mineral samples.
2.Photography of flu-              Shopov,                  changes of chemism of the mineral-forming
orescence & phospho-            Grynberg                 solution, Climate and Solar Activity
rescence (IPFP).                     (1985)                     variations during Quaternary.

II.Colour Slide Spec-              Shopov,                  widelines spectra of phosphorescence.
trophotometry (CSS)               Georgiev                fluorescence and diffuse reflectance
                                               (1986)                    of mineral.Spectra of quick processes.

III.LASER Luminescent          Shopov.                 Y Microzonality of luminescence,changes
Microzonal Analysis              (1987)                    of mineral-forming conditions. Climate
                                                                            (LLMZA) & Solar Activity variations during
                                                                            Quuaternary (with resolution up to 3
                                                                            days ).Speleothem dating (with accuracy
                                                                            1 year).Interruptions of speleothem growth.


Table 2.New Technics for Research of the Luminescence of CM

Technics                                  Authors                  obtainable information


1.LASER Luminescent           Ugumori                  Quantity of activating ion zonality of
Zonal Analysis (LLZA)        (1980)                      luminescence of the speleothem kind of

2.Direct Spectroscopy           Shopov                     luminescent ion ,changes of chemism of
of Luminescence (DSL)        Spasov                     mineral-forming solutions, determination
                                             (1983)                      of genetic type of the deposit, selection
                                                                             of samples.

3.Direct Spectrogra-              Shopov,                   Registration of spectra of fluorescence
phy of luminescence              Tsankov                   & phosphorescence directly in caves,
(DSGL)                                  (1984)                     luminescent ion and its valency, coor-
                                                                            dination and local symmetry,diagnostics
                                                                            of CM & all from DSL.

4.Luminescent spect-              Shopov                  Determination of phase composition of the
ral Phase Analysis                  et al.                      speleothem by spectra of its luminescence.
(LSPA)                                  (1985)

5.LASER Luminescent          Shopov                   Such as DSGL for collomorphyc aggregates
Spectral Analysis of              Kostov                   of minerals and powders.
Powders                                (1985)


THE ZONALITY OF LUMINESCENCE OF CAVE FLOWSTONES AS
INDEX OF THE CLIMATE AND SOLAR ACTIVITY IN THE PAST

The luminescence of the calcite speleothems is activated usually by  organic admixtures.  The  luminescent centers in cave flowstones are  organic  molecules (like humic  and fulvic acids ) of products of biogenic  processes  in  plants, growing  over but penetrating into cave . The quantity of this products  as  the result  of photosynthesis depends strongly on the solar irradiation.  Therefore intensity  of luminescence of the microzones in cave flowstones  is  determined mainly by the SA during the formation corresponding zone. By this way the curves of  changes  of the intensity of luminescence of flowstones along  the  axis  of their growth presents curves of changes of the SA versus the age of rings in the flowstone.  After  formation of the corresponding zone it is safe  from  further action and safe for information of the SA during its formation.

Molecular  admixtures in the flowstone luminescence at Laser irradiation  of its polished section. If the growth rate of the flowstone is known, the curve of intensity of  its luminescence in dependence of the distance from  the  surface will present a time series of the zonality of its luminescence. The time  series obtained are result of SA and Paleoclimatic variations.

Density  of blacking of the emulsion of the negative ,which is  proportional to   the concentration  of  luminescent  organic   molecules   (intensity   of luminescence)  is placed  on  the axis of ordinates, and  the  number  of  the measurements (pixels, by which age can be determined, because distance from  the surface is proportional to the age of the flowstones and 1 pixel is a time  step of the series ) is placed on the abscissa axis.

For  speleothems  from the temperate climatic zone  the  paleoclimate   have influence only over the width of the zones. Only in one cave in desert region, a speleothem with growth rings , which show the 11-yrs solar cycle were found.

We  can  reliably determine the annual rings in the sample  using  LLMZA  at resolution of 5 pixels/yr.If the annual growth rate of investigated part of  the speleothem  were  constant  we can date the sample by  authocorrelation  of  its luminescent  time  series. By power spectral analysis of  the  luminescent  time series of dated sample we can obtained the annual growth rate of this  part  in the sample to obtained the age of it .

The  LLMZA  method  allows  possibility to  obtain  time  series  with  high resolution  (up to 125 points per yr) and very long time intervals (probably  of some million years). Preparation of time series with very different  resolution (which  can vary more than 1000 times) and different periods  become  available with the elaboration of this method.

By  power spectral analysis of a luminescent time series (shown at fig  1.B) we  show   convincingly   the   reality   of   cyclicity   with   periods    of 55,95,180,275,390,550,930,1170,2340 and 3350 yrs.

Periods of 22,11, (13,3; 10,4 and 8,8), 1 and 2 yrs were determined by power spectrum of time series with 125 px/yr.

Fig.1. A: Estimation of the paleotemperature deviations of the hotest month in atlantic  parts
of the northern hemisphere, at 60- 70° latitude by Zubakov
B: luminescent time series of a Bulgarian flowstone
for the last  35000  yrs, with resolution of 934 yrs/px

 

FLOWSTONES FOR LLMZA INVESTIGATIONS

Most  suitable  for  dating by this method are  the  calcite  polycrystaline speleothems  having  strongly pronounced zonality of  their  luminescence  .Best results  are obtained from flowstones from the shallow parts of the  caves  withactive air exchange, because climatic variations influence mostly on  them.  In speleothems from big depth only 350 years cycles of the solar activity and  slow climatic  variations could be traced, because climatic variations in  depth  are small  and  influence  very weak on the flowstone growth.  It  is  necessary  to identify  the  spectra  of luminescence of the sample  ,  before  applying  this method. Taking in account ,that the period of cyclicity of the solar activity is constant,  if  the growth of the formation has been persistent  from  a  certain period till now, this method can be used as method for dating from the number of rings  due  to  cycles  of the same type (like  the dendrochronology)  in  this interval.  However the accuracy of such dating is 1 year, independent from   the age.  Interruptions of the growth in the curves reflect as sharp places  in  the intensity variation of the luminescence in the sample.

(TO BE CONTINUED)

SOURCE  www.karst.edu.cn/

About sooteris kyritsis

Job title: (f)PHELLOW OF SOPHIA Profession: RESEARCHER Company: ANTHROOPISMOS Favorite quote: "ITS TIME FOR KOSMOPOLITANS(=HELLINES) TO FLY IN SPACE." Interested in: Activity Partners, Friends Fashion: Classic Humor: Friendly Places lived: EN THE HIGHLANDS OF KOSMOS THROUGH THE DARKNESS OF AMENTHE
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