Ankeritic carbonatite (Chilwa Alkaline Province, Early Cretaceous, 126 Ma; Chilwa Island, Lake Chilwa, Malawi, southeastern Africa) 2

            Ankeritic carbonatite from the Cretaceous of Malawi, Africa. (~9.8 centimeters across at its widest)

Carbonatites are rare igneous rocks - they are composed of carbonate minerals, typically calcite (CaCO3 - calcium carbonate).  Carbonatites are essentially igneous limestones.

The four categories of carbonatites are:
1) calciocarbonatite (calcite-dominated)
2) magnesiocarbonatite (dolomite-dominated)
3) ferrocarbonatite (siderite-dominated)
4) natrocarbonatite (sodium carbonate-dominated)

Calciocarbonatites are the most common type, whereas natrocarbonatites are extremely rare, which are only found at Ol Doinyo Lengai Volcano in eastern Africa.

The carbonatite seen here is from the Early Cretaceous-aged Chilwa Alkaline Province, an igneous complex consisting of intrusive igneous rocks (alkali granites, syenites, alkaline syenites, nephilinites, and carbonatites) and extrusive igneous rocks (lavas - basanites, phonolites).  The complex was intruded in phases throughout the Early Cretaceous, from about 111 to 138 million years ago.

The rock mildly effervesces in acid - it is dominated by the carbonate mineral ankerite, Ca(Fe,Mg,Mn)(CO3)2 - calcium iron magnesium manganese carbonate.

Geologic unit & age: Chilwa Alkaline Province, late Barremian Stage, mid-Early Creatceous, 126 Ma (= absolute date of Chilwa Island carbonatite)

Locality: Chilwa Island, western Lake Chilwa, southeastern Malawi, southeastern Africa

Some rights reserved

Taken on: April 14, 2016

Tags:

carbonatite

Chilwa

Cretaceous

alkaline

province

Africa

ankerite

ankeritic « less

Sets appears in: • Malawi Rocks & Minerals • Chilwa Alkaline Province (Early Cretaceous; Malawi, southeastern Africa) more » • Cretaceous Rocks, Minerals, Fossils • Carbonatites « less

Stats: 977 views

go back

close tools panel

Badge creator

Use Flickriver Badge Creator to create a badge linking to your photos, your group or any other Flickriver view.

You can place your badge on your Flickr profile, Blog or Website.

Add to your iGoogle or Netvibes page

Flickriver widget for iGoogle or Netvibes can display almost any Flickriver view - most interesting today, by user, by group, by tag etc. Once added to your personalized homepage, just edit widget settings to select your desired view.

Clickr on one of the buttons below to install:

Embed on your Web site

To embed this view, Copy and Paste the following HTML code:

Black background (preview):

White background (preview):

Firefox and Chrome addons

Adds a 'Flickriver' button to your browser. While viewing any Flickr photos page, click on this button to open the same view on Flickriver.

Install in Firefox
Install in Chrome

Search plugin

Add 'Search on Flickriver' to your browser's search box. Works with Firefox and Internet Explorer. Install search plugin

"View on Flickriver" Greasemonkey script

A Greasemonkey script that adds Flickriver links to various Flickr photo pages - user photos, favorites, pools etc, allowing to quickly open the corresponding Flickriver view.

Also, allows quickly viewing any Flickr photo on black background in large size.

Install "View on Flickriver" script

Bookmarklet

While viewing any Flickr photos page, click on the bookmarklet to open the same view on Flickriver.

To install: drag and drop the following link to your Bookmarks toolbar.
IE users - add the link to your Favorites under the Links folder