About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 56 (1972)

Issue: 3. (March)

First Page: 434

Last Page: 453

Title: Sedimentology and Dolomitization of Muschelkalk Carbonates (Triassic), Iberian Range, Spain

Author(s): Tom Freeman (2)

Abstract:

Triassic rocks of the Iberian Range consist of a succession of continental sandstones (Buntsandstein), peritidal carbonates and shales (Muschelkalk), and continental claystones and evaporites (Keuper). This "Germanic" platform facies closely resembles equivalent rocks in the Balearic Islands; consequently, any hinge line separating platform from geosynclinal facies must lie an undetermined distance southeast of the Balearics.

Dolostone, which comprises 75 percent of Muschelkalk carbonates, bears no relation to sedimentary facies; to the contrary, it is demonstrably joint controlled. This fact, together with the near absence of "dedolomite," indicates a late and sustained magnesium/calcium ratio in excess of that expected from an evaporite-bearing assemblage.

Water samples from Keuper "salinas" (salt-producing evaporating pans) show that meteoric water descending through the Keuper evolves into a brine with Mg:Ca ratios locally 4:1, in spite of the abundant gypsum and anhydrite. X-ray analysis suggests chlorite as a source of the magnesium, the solubility of which probably reflects diagenetic fixing in the Keuper evaporite basin. The composition of Keuper water, aided prior to unloading by geothermal gradient, is thought to be responsible for Muschelkalk dolomitization.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24

AAPG Member?

Please login with your Member username and password.

Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].