The late Proterozoic Zig-Zag Dal Basalt Formation of eastern North Greenland

Saved in:
Authors:Kalsbeek, Feiko; Jepsen, Hans F.
Author Affiliations:Primary:
Geol. Surv. Greenland, Copenhagen, Denmark
Volume Title:Journal of Petrology
Source:Journal of Petrology, 25(3), p.644-664. Publisher: Clarendon Press, Oxford, United Kingdom. ISSN: 0022-3530
Publication Date:1984
Note:In English. 25 refs.; illus. incl. 8 anal., 3 tables, chart, geol. sketch map
Summary:These basalts (approx 1230 m.y.) in the platform area of NE Greenland are a remnant of a sequence of tholeiitic flood basalts. They can be subdivided into three main units, totalling up to 1350 m in thickness; some of the flows are > 100 m thick and have volumes of hundreds of km3. Most of the basalts are aphyric or contain very sparse phenocrysts of plagioclase and augite. XRF and NAA analyses are reported for major, trace and RE elements in 55 rocks. The chemical composition of the basalts was strongly influenced by hydrothermal metasomatism (incipient spilitization) soon after deposition. The basalts appear to have been formed from increasingly depleted mantle sources. Chemical discontinuities occur between the three main units and are probably related to breaks in the volcanic activity. Chemical variation within each unit is mainly governed by low-P fractionation of olivine, augite and plagioclase, although successive flows do not represent successively more fractionated magma batches. Assimilation of crustal material at depth did not appreciably affect the basic magma. [R.A.H.]
Subjects:Absolute age; Augite; Basalts; Chain silicates; Chemical composition; Clinopyroxene; Country rocks; Dates; Feldspar group; Framework silicates; Geochemistry; Hydrothermal alteration; Igneous rocks; Magmas; Metals; Metasomatism; Neoproterozoic; Paleomagnetism; Petrology; Phenocrysts; Plagioclase; Pollution; Precambrian; Processes; Proterozoic; Pyroxene group; Rare earths; Silicates; Trace elements; Upper Precambrian; Volcanic rocks; Arctic region; Greenland; Aphric Unit; Aphyric composition; Basal Unit; Fractionation; Independence Fjord; Independence Fjord Group; Northeastern Greenland; Porphyritic Unit; Zig-Zag Dal Basalt Formation
Coordinates:N800000 N850000 W0150000 W0400000
Abstract Numbers:85M/0924
Record ID:1985013854
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
Tags: Add Tag
No Tags, Be the first to tag this record!