JavaScript requeired.
Geochemical Journal
Geochemical Journal An open access journal for geochemistry
Published for geochemistry community from Geochemical Society of Japan.

Petrochemical study of the Jingpohu Holocene alkali basaltic rocks, northeastern China

Zhaochong Zhang, Chengyou Feng, Zhaonai Li, Shucai Li, Ying Xin, Zhaomu Li, Xianzheng Wang
Geochemical Journal, Vol. 36, No. 2, P. 133-153, 2002


Holocene volcanoes in the Jingpohu region are situated in the “Crater Forest” and “Frog Pool” areas along the northwest side of Jingpohu Lake, northeastern China. Dating of three charcoal samples from the first and second volcanic cycles shows that the ages of the first and second cycles are 3430∼3490 and 2470 years respectively. The lavas from the Jingpohu area consist of basanites (BSN), alkali olivine basalts (AOB) and tephrites (TP). Crystal fractionation models are consistent with the generation of AOB and TP from a basanitic parent. Minor fractionation of olivine, augite, magnetite and Cr-spinel is required to produce AOB compositions whereas the generation of TP requires extensive fractionation of kaersutite, phlogopite and anorthoclase with minor olivine, augite, magnetite and leucite. The presence of kaersutite, phlogopite and anorthoclase megacrysts and mantle xenoliths suggest a fractionation history occurring at high pressure in the mantle. Although all basaltic rocks contain many granitic xenoliths, their geochemical characteristics show that they have not undergone any contamination of upper crust en route to the surface, but some alkali basalts were suffered from the contamination of lower crust. Relatively unradiogenic isotope ratio (compared with Bulk Earth), steep chondrite-normalized REE patterns and strong incompatible element enriched patterns suggest that the magmas are derived from a mixture of an incompatible element depleted anhydrous lherzolite asthenospheric mantle source and an enriched, amphibole-phologite-(apatite-)bearing lherzolite continental lithospheric mantle source. We propose that the basanites are the products of very low degree partial melts (<1%) of this source under high extension strength.

All Issues

Current Issue:
Impact Factor: 1.060 (2021)
Submission to final decision: 9.6 weeks (2022)
Geochemical Society of Japan

page top