A.F. Kudryashova

Geochemistry of trace elements in the extraterrestrial matter examined by the X-ray fluorescence method with synchrotron radiation

Abstract X-ray fluorescence analysis with synchrotron radiation (XFA-SR) has been applied for the determination of incompatible trace elements (Rb, Sr, Y, Zr, Nb, Ba, La and Ce) in some extraterrestrial samples. A distribution of these elements in lunar whole rocks and their minerals, in the matrix, chondrules and CaAl-rich inclusions from various chondrites has been investigated. The XFA-SR analytical technique for very small objects ranging from 2 mm to 300 μm has been described. The specific basaltic group of Luna-20, geochemically similar to Luna-24 VLT basalt, has been established. The points of intersection of the HAB-VHA rock trend and the TB rock trend on the bi-element correlation diagrams probably correspond to the concentration levels of these trace elements in the parent magmas. Distribution of trace elements in rock-forming minerals and in their host rocks showed two trends: early and late crystallizations with an inversion of the Y/Zr ratio. The difference in trace element distribution in chondrules, matrix and CaAl-rich inclusions from the chondrites has been shown. This indicates a varied genesis for these objects.

Geochemistry of rare elements in lunar basalt rocks based on SRXFA

Abstract For the first time the distribution of Rb, Sr, Y, Zr and Nb in Apollo-17 magmatic rock series and in new Luna-16 basalt series has been investigated by SRXFA. On the base of bi-element correlation, individual geochemical trends for various petrochemical types of rocks were established. The distinction between magmatic sources of Apollo-17 and Luna-16 rocks and the presence of a new VLT-LT rock group were demonstrated. Common use of SRXFA and INAA methods is promising.

GEOCHEMISTRY OF TRACE ELEMENTS IN THE HIGHLAND LUNAR ROCKS BASED ON SRXFA DATA

Abstract X-ray fluorescence analysis using synchrotron radiation (SRXFA) has been applied for determination of trace elements in the highland lunar rocks (Luna 20 and Apollo 16). On the basis of the distribution of Rb, Sr, Y, Zr, and Nb in 69 lunar highland fragments six geochemical groups of rocks with various aluminium and trace element contents were distinguished for each station. They have various levels of trace element content. This suggests the various petrological processes: cumulation of rock-forming minerals and partial melting of source rocks. The last process lead up to enriching in trace elements in rocks formed from these melts. The distribution of trace elements in highland and mare rocks of the Moon were compared.

Trace element distribution in lunar rocks of various titanium content by SR-XFA data

Abstract The distribution of trace elements (Rb, Sr, Y, Zr, Nb) in various types of lunar mare basalts has been investigated by SR-XFA. The new data of Apollo 11, Apollo 12, and Apollo 15 and also our earlier published data of other mare basalts have been discussed. Geochemical groups and trends for rocks of various titanium content were distinguished on the basis of diagrams of Zr vs. Sr and of Y vs. Zr. The problem regarding the magmatic sources of various types of lunar basalts has been considered.

Some methodical peculiarities of analysis of small-mass samples by SRXFA

Abstract The stability of work of the element analysis station on the storage rings VEPP-3 and VEPP-4 in INP (Novosibirsk, USSR) was demonstrated on the example of three sets of rare element analyses carried out by SRXFA in May 1985, January and May–June 1988. These data show that there are some systematic deviations in the results of measurements of Zr and La contents. SRXFA and INAA data have been compared for the latter element. A false linear correlation on the Rb-Sr plot in one set of analyses has been attributed to an overlapping artificial Sr peak on a Rb peak. The authors proposed sequences of registration of spectra and computer treatment for samples and standards. Such sequences result in better final concentration data.

Trace element identification of very low titanium (VLT) and low titanium (LT) basalts from mare Fecunditatis and mare Crisium regions: SR-XFA and INAA studies of lunar samples

Abstract The very low titanium (VLT), low titanium (LT), and titanium (T) basalts of the Eastern part of the Moon were investigated by SR-XFA and INAA methods. New intermediate VLT-LT basalt groups were distinguished on the basis of titanium contents, REE patterns and trace element distributions. All basalt groups were compared and conclusions about possible sources of these basalts and their origin were drawn.

Geochemical identification of mare-type basalt groups from a lunar highland region (by INAA and SRXFA)

Abstract The distribution of Rb, Sr, Y, Zr and Nb in 15 fragments of lunar mare-type basalt rocks from the Apollonius highland region has been investigated by the SRXFA method. The work has been carried out on the element analysis station of the storage ring VEPP-3. Preliminary identification of lunar rock groups was based on INAA data. Investigation by SRXFA permits to distinguish VLT-LT groups of basalts by geochemical criteria.

Geochemistry of rare elements in different types of lunar rocks (based on μXFA-SR data)

Abstract Micro (μ) X-ray fluorescence (XRF) analysis using synchrotron radiation (SR) has been applied for the determination of rare element (Rb, Sr, Y, Zr, Nb, Ba, La, and Ce) distributions in a large collection of different lunar mare and highland rocks returned to the Earth by all successful missions of “Apollo” and “Luna”. Consideration of all analytical data, obtained by μXFA-SR method shows that most of high aluminium (HA) and very high aluminium (VHA) basalts are results of partial melting of various basaltic magmas, which do not originate from the magmatic ocean. Fractionation trends of rare elements in different types of lunar rocks suggest that planetary processes (controlled by volatility of elements) took place at very early stages of the Moon planet formation.

Particularities of rare element distribution in high-aluminium basalts from mare and highland regions of the Moon (based on SR-XFA data)

Abstract X-ray fluorescence analysis using synchrotron radiation (SR-XFA) has been applied for determination of rare elements (Rb, Sr, Y, Zr, Nb, Ba, La, and Ce) in lunar high aluminium (HA) and very high aluminium (VHA) basalts of Apollo 12, 14, and 15 (new multielement SR-XFA analysis of 50 lunar fragments). A comparison of all SR-XFA data for different lunar rocks (multielement SR-XRF analysis more than 300 lunar fragments) makes it possibile to suggest a common origin of HA and VHA basalts. These rocks are the result of partial melting of various basaltic magmas, but have not originated from lunar magmatic ocean.