Mineralogy and Chemistry Characterization of the New Basaltic Intrusion at Maasser El Chouf/Lebanon

The importance of this study is to identify the newly reordered and recognized basaltic intrusion for the first time in Maasser El Chouf in Lebanon. The recorded basaltic intrusion cut the Jurassic-Lower Cretaceous rock in this area. Necessary field inspection, geology, mineralogy and chemical tests were carried out on 8 basalt samples to determine their mineralogy, petrography and chemical composition. Representative samples have been tested with polarizing microscope, X-ray diffraction (XRD) and X-ray fluorescence (XRF). Petrographic and mineralogical studies show that the basalt is characterized by presence mainly of calcic-plagioclase feldspar, pyroxene-augite and olivine minerals. Secondary minerals of iron oxides also present (ilmenite and magnetite). The most appeared property is the alteration of olivine mineral to iddingsite that indicated highly weathered process. The composition of the basaltic samples reflects ultrabasic-basic type (Basanite-Tholeiitic basalt). The existence of volcanic activity occurred mostly with Pliocene age (< 2 Ma) as indicated by previous studies for similar basalt in Lebanon. Possibly, these boulders have been carried up from some deeper intrusive magmatic body under very active tension zones. Volcanism of Lebanon basalts belong to the alkaline olivine basalt, suite generally associated with tension, rifting and block faulting movements of the continental crust. Most of the volcanisms in Lebanon and in Harrat Ash Shaam Basalt from Syria and Palestine through Jordan to Saudi Arabia are related and connected to the opening of the Red Sea Rift System, making the area with tremendous volcanic tectonic activities.

Petrogenesis of Volcanic Rocks in Alasht, Mazandaran, Iran

Area studied in this paper is located in the northwest of city of Alasht. The most important varieties of studied rocks are volcanic and semi-volcanic rocks of basic nature. These rocks, which form a distinguishable solid mass on 1:100,000 geological map, belong to Cretaceous period. According to results of petrographic study, rocks of this area include olivine basalt, dolerite, gabbro and microgabbro, and all have almost similar chemical compositions. According to chemistry-based naming process carried out through TAS method, these rocks are entirely basalt and basic and are all products of Sub-alkaline-Tholeiitic magma. According to Harker diagrams, a magmatic differentiation can be observed in all volcanic rocks;furthermore, basaltic magma erupted in this area has undergone an alteration and possibly a crustal contamination. The spider diagrams plotted in this paper show that basic rocks of Alasht area (basalts, andesite basalts, dolerites, gabbros and microgabbros) are all mostly similar to ocean island basalts (OIB). Once field study, sampling and microscopic study stages were complete, ten samples were selected for chemical analysis and were analyzed by XRF method.

Tectonic discrimination of olivine in basalt using data mining techniques based on major elements:a comparative study from multiple perspectives

The olivine in basalt records much information about formation and evolution of basaltic magma,which may help to discriminate basalt tectonic settings.However,the viewpoint that olivine is connected with the tectonic setting where it formed is controversial.To verify the hypothesis,we intend to discriminate the basalt tectonic settings by geochemical characteristics of olivine.The data mining technique is selected as an effective tool for this study,which is a new attempt in geochemical research.The geochemical data of olivine used is extracted from open-access and comprehensive petrological databases.The classification performance of Logistic regression classifier,Naïve Bayes,Random Forest and Multi-layer perception(MLP)algorithms is firstly compared under some constraints.The results of the basic experiment indicate that MLP has the highest classification accuracy of about 88%based on raw data,followed by Random Forest.But this does not fully prove the hypothesis is credible.Then,the crossvalidation method and other measurement criteria are integrated for scientific and in-depth comparative analysis.The advanced experiments mainly include the comparison of different data preprocessing methods,combinations of geochemical characteristics and sample data volumes.It turns out that chemical composition of olivine in basalt has the function of discriminating tectonic settings.