Abstract: Origin of abundant alkaline and related lamproite massifs and dykes in Aldan shield have no explanation and the geochemistry of rocks and their xenocrysts is used for the explanation. Bulk-rock geochemistry, mineral chemistry data of the Kayla lamproites of Russia and mineral chemical data (trace and rare elements) of the mantle xenocrysts found in these lamproites was studied using ICP MS and electron microprobe analyses (EPMA). The trace element spectrum of Kayla tuAs and breccias show the similarity with the olivine lamproites and belong to the orogenic type according to Th–U–Nb systematics. Primitive mantle normalized trace element (TRE) spider diagrams show right-leaning patterns with the peaks in large ion lithophile elements Sr, Pb, U, and troughs in Ta, Nb suggesting melting of original peridotites mixed with the ancient EMI (according to Nd, Sr isotopes) source probably belonging to eclogites or lower crust. The age of the emplacement is 132–134Ma, similar to the Chompolo lamprophyres and many other alkaline Aldan complexes. Thermo-barometric estimation from Cr-diopsides and chromites xenocrysts suggest the origin from the spinel-garnet transition in the lithospheric mantle region. The P–T estimates derived from low-Cr-clinopyroxene xenocrysts, and related to lamproites show a high heat Cow of 90 mW/m2 due to interaction with the plume-related magma. The Cr-diopsides and chromites give 45 mW/m2 geotherm similar to regional heat Cow. The chondrite normalized rare earth element (REE) pattern for chromediopsides is steeper, compared to the low-chrome varieties. Primitive mantle normalized spidergram of Crdiopsides displays peaks for Sr, U, and Th, and deep troughs of Nd, Nb, Ta. REE. The trace element spider diagrams of both types of xenocrysts show that they were equilibrated with the lamproitic melts and reconstructed parental melts of low-Cr-clinopyroxene coincides with the lamproite spectrums.

Cite: Vladykin N.V. , Ashchepkov I.V. , Sotnikova I.A. , Medvedev N.S.
Lamproites of Kayla pipe and their mantle xenocrysts, SE Aldan shield, Russia: Geochemistry and petrology
Journal of Earth System Science. 2022. V.131. N2. 81 :1-19. DOI: 10.1007/s12040-022-01814-3 WOS Scopus РИНЦ OpenAlex

Dates:

Submitted:	Jun 1, 2021
Accepted:	Nov 11, 2021
Published online:	Mar 22, 2022

Identifiers:

Web of science:	WOS:000772075500003
Scopus:	2-s2.0-85126881160
Elibrary:	48194939
OpenAlex:	W4220696361

Citing: Пока нет цитирований

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