STUDI KETIDAK SELARASAN ANTARA TANAH DAN BATUAN KARBONAT YANG MEMBAWAHINYA PADA JALUR BARON – WONOSARI GUNUNGKIDUL - Mulyanto, Djoko (Agrin, 2008)
Tujuan penelitian adalah mengaji ketidakselarasan antara tanah dan batuan karbonat yangmembawahinya. Analisis baik tanah maupun batuan karbonat meliputi komposisi mineral dan kimia. Komposisimineral fraksi pasir tanah di atas batugamping dirajai oleh labradorit sedangkan fraksi lempungnya oleh haloisitdan kaolinit. Kristobalit juga dijumpai terutama pada tanah-tanah di lingkungan karst. Berdasarkan macammineral tersebut diduga bahan induk tanah banyak dipengaruhi oleh bahan volkanik. Komposisi batugampingdirajai kalsit dan kuarsa. Terdapat perbedaan yang tegas antara komposisis mineral tanah dan batugamping,nisbah Fe tanah dan batugamping sangat rendah, adanya lithic contact yang sangat tegas. Terdapat mintakatpelapukan napal yang membawahi tanah, nisbah Fe tanah/ napal jauh lebih tinggi dibanding terhadapbatugamping, kadar CaCO3 napal rendah, dan baik tanah mapun napal mengandung smektit sehingga dikatakanbahwa napal bersifat mewariskan pada tanah yang terbentuk. Labradorit juga melimpah pada tanah di atas napal.Berdasarkan faktor-faktor tersebut maka disimpulkan bahwa ada ketidakselarasan antara tanah dan batugampingyang membawahinya kecuali pada napal. Bahan volkanik sangat berpengaruh sebagai bahan induk tanah.Kata kunci: batuan karbonat, bahan volkanik, batugamping, tanah, ketidakselarasan ABSTRACTThe aim of research was to study of the unconformity of soil–carbonate rock underlying relationship.Analysis both soil and carbonate rock cover minerals and chemical composition. Sand fraction mineralcomposition of soil overlying limestone dominated by labradorite whereas clay fraction by halloysite andkaolinite. Chrystobalite also was found especially on soils of karst area. Based of those minerals, soil parentmaterial predicted much be influenced by volcanic material. Limestone mineral composition dominated bycalcite and quartz. There are distict differences of carbonate mineral composition and soils, ratio Fe of soil/limestone is very low, and there is a sharply lithic contact of soil and limestone underlying. Soils overlying marlshow paralithic contact, there is a zone of marl weathering, and ratio Fe of soil to marl is higher than ratio Fe ofsoil to limestone, and CaCO3 concentration lower than limestone. Both soils and marl underlying containsmectite. Based factors above be said that marl have inheritate characteristic. Sand fraction minerals of soiloverlying marl are also dominated by labradorite. Based on boundary of soil and rock material underlying andkind of minerals concluded that there are unconformity between soils and limestone underlying, but relationshipbetween soils and marl underlying are conformity. Soils underlying carbonate material much be influenced byvolcanic material.Key words: carbonate, volcanic materials, limestone, soil, unconformity