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"Bukit Intrusi Gunung Putri yang terletak di Kabupaten Bogor, Jawa Barat terdiri dari batuan beku yang berumur Miosen memiliki daya tarik sebagai objek geowisata yang perlu dilestarikan, dengan melakukan konservasi untuk membuat objek geowisata perlu adanya informasi menarik seperti bagaimana proses keterbentukan batuan di daerah tersebut sehingga perlu diteliti lebih lanjut tentang petrogenesisnya. Penelitian petrogenesis dilakukan dengan cara mengetahui karakternya, komposisinya, proses pembekuannya hingga lama waktu pembekuannya. Sepuluh sampel diambil secara acak berdasarkan persebarannya dan dianalisis dengan metode petrografi dan distribusi ukuran kristal. Hasil dari analisis petrografi menunjukkan bahwa berdasarkan klasifikasi IUGS (1973) karakteristik batuan termasuk ke dalam Olivine-Pyroxene Basalt/Andesite yang berasal dari magma basaltic yang bersifat mafic. Berdasarkan karakteristik batuan dan hasil dari analisis distribusi ukuran kristal menunjukkan bahwa daerah penelitian merupakan tubuh intrusi dengan jenis shallow intrusion laccolith yang mengalami proses petrogenesis terutama pada pembentukan mineral plagioklas pada batuan perubahan cooling rate, proses accumulation, dan proses increasing undercooling dengan waktu singgah pada fenokris rata – rata 83.93 tahun dan segmen mikrofenokris rata-rata 18.08 tahun.

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Intrusion Hill Gunung Putri, located in Bogor Regency, West Java, consists of Miocene-age igneous rocks and has attractions as a geotourism site that needs to be preserved. To establish it as a geotourism destination, it is important to provide interesting information about the rock formation processes in the area. Therefore, further research on its petrogenesis is needed. Petrogenesis research involves understanding its characteristics, composition, cooling processes, and the duration of the cooling period. Ten random samples were collected based on their distribution and analyzed using petrographic methods and crystal size distribution. The petrographic analysis results indicate that based on the IUGS (1973) classification, the rock characteristics fall into the category of Olivine-Pyroxene Basalt/Andesite, which originated from mafic basaltic magma. Based on the rock characteristics and the results of crystal size distribution analysis, the research area is identified as a shallow intrusion laccolith body that underwent petrogenesis processes, particularly in the formation of plagioclase minerals due to cooling rate changes, accumulation processes, and increasing undercooling. The average residence time of phenocrysts is approximately 83.93 years, while the average residence time of microphenocrysts is approximately 18.08 years."

"Komplek Granitoid Sibolga (KGS) di Blok Sumatra Barat merupakan objek studi yang penting untuk memahami proses magmatisme paska kolisi di wilayah tersebut. Penelitian ini bertujuan untuk mengkarakterisasi batuan, menginterpretasikan petrogenesis, proses evolusi magma, serta hubungannya dengan sebaran mineralisasi LTJ pada granitoid KGS. Analisis dilakukan melalui pendekatan petrologi, petrografi, geokimia unsur mayor, dan unsur jejak. Hasil analisis menunjukkan bahwa granitoid KGS secara dominan terdiri dari syenogranit dan monzogranit yang bersifat peraluminous, ferroan, dan termasuk dalam seri kalk-alkalin tinggi-K. Berdasarkan analisis petrologi, terlihat batuan di utara didominasi oleh syenogranit yang memiliki ukuran butir lebih besar dibanding ukuran butir di selatan yang didominasi oleh batuan monzogranit. Mikrotekstur di utara berupa zonasi plagioklas, di area transisi berupa perthite, sedangkan mikrotekstur di selatan berupa graphic intergrowth. Berdasarkan analisis diskriminasi geokimia, granitoid ini terklasifikasikan sebagai granit Tipe-A (subtipe A2) yang terbentuk dalam lingkungan tektonik post-collisional. Evolusi magma secara dominan dikontrol oleh proses diferensiasi melalui fraksinasi kristal yang intensif. Hal ini dibuktikan oleh deplesi kuat pada unsur Ba, Sr, P, Ti, anomali negatif Eu yang signifikan yang mengindikasikan fraksinasi plagioklas serta tingginya unsur Rb. Selain itu, terjadi proses magma mingling di area utara yang membuat persentase SiO2 pada granit tipe-A ini berkurang dan FeO bertambah. Al2O3 yang cukup tinggi pada granit tipe-A ini, dihasilkan dari peleburan batuan kerak sebelumnya yang cukup kaya akan Al2O3. Pengayaan seluruh LTJ terjadi di selatan, yang merupakan area kristalisasi akhir magma, sementara terdapat pengayaan LTJR di utara akibat proses sekunder (alterasi).

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The Sibolga Granitoid Complex (SCG) in the West Sumatra Block is an important object of study to understand the post-collisional magmatism process in that region. This research aims to characterize the rocks, interpret the petrogenesis, the magma evolution process, as well as its relationship with the distribution of REE mineralization in the SCG granitoid. Analysis was conducted through petrology, petrography, major element geochemistry, and trace element approaches. The analysis results show that the SCG granitoid is dominantly composed of syenogranite and monzogranite which are peraluminous, ferroan, and are included in the high-K calc-alkaline series. Based on petrological analysis, it is seen that the rocks in the north are dominated by syenogranite which has a larger grain size compared to the grain size in the south which is dominated by monzogranite rocks. Microtextures in the north are in the form of plagioclase zoning, in the transition area in the form of perthite, while microtextures in the south are in the form of graphic intergrowth. Based on geochemical discrimination analysis, this granitoid is classified as A-type granite (A2-subtype) which was formed in a post-collisional tectonic environment. Magma evolution is dominantly controlled by the process of differentiation through intensive crystal fractionation. This is proven by the strong depletion in Ba, Sr, P, Ti elements, a significant negative Eu anomaly which indicates plagioclase fractionation, as well as the high Rb element. Besides that, a magma mingling process occurred in the northern area which made the SiO₂ percentage in this A-type granite decrease and FeO increase. The fairly high Al₂O₃ in this A-type granite is produced from the melting of previous crustal rocks which were fairly rich in Al₂O₃. REE enrichment occurs in the south, which is the final crystallization area of the magma, while LREE enrichment is found in the north due to secondary processes (alteration)."

"Salah satu sumber paling ekonomis dari unsur tanah jarang (UTJ) adalah batuan beku felsik. Di Kabupaten Lampung Tengah, terdapat bukit intrusi batuan granitik yang berpotensi menghasilkan sumber daya geologi. Penelitian ini bertujuan mengkaji karakteristik mineral, oksida utama dan unsur jejak, dan petrogenesa batuan granitik pada Satuan Granit Padean. Analisis dilakukan dengan menggunakan data petrografi dan geokimia batuan beku untuk menentukan petrogenesa dari batuan. Hasil penelitian menunjukkan batuan granitik di daerah penelitian terdiri atas Granodiorite, Quartz-Syenite, Syenogranite, dan Monzogranite, yang memiliki variasi feldspar berbeda. Mineral lain yang terdapat pada batuan utamanya adalah biotit dan amfibol. Mineral aksesoris meliputi apatit dan monazit, dengan garnet ditemukan pada salah satu Monzogranite. Secara geokimia, Granodiorite dan Quartz-Syenite memiliki SiO₂ lebih rendah dibanding Syenogranite dan Monzogranite. Teramati tren negatif antara SiO₂ dengan Na₂O, MgO, Fe₂O₃, P₂O₅, Al₂O₃, dan CaO; serta tren positif dengan K₂O. Semua sampel termasuk seri kalk-alkalin dan umumnya metaluminous, kecuali GNS 01B yang peraluminous. Terdapat pengayaan LREE dan rasio LILE/HFSE tinggi, kecuali pada GNS 01B. Secara petrogenesa, batuan granitik di daerah penelitian terbagi menjadi batuan granitik tipe I dan tipe S, dengan indikasi keberadaan tipe transisi di antara keduanya. Batuan terbentuk pada Episode D tektonik Kapur (120–75 juta tahun lalu), yaitu batuan granitik tipe I terbentuk lebih dulu pada peristiwa subduksi. Selanjutnya, proses kolisi menghasilkan penebalan kerak dan memicu anateksis, menghasilkan magma granitik tipe S. Pencampuran magma tipe S pada sisa magma hasil subduksi menghasilkan batuan granit transisi antara tipe I dan S.

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Felsic igneous rocks are among the most economically viable sources of rare earth elements (REE). In Central Lampung Regency, a granitic intrusion known as the Padean Granite Unit has potential as a geological resource. This study aims to examine the mineralogical characteristics, major and trace element geochemistry, and petrogenesis of the granitic rocks. Analysis was conducted using petrographic and geochemical data from igneous rock samples to determine their origin. The results show that the granitic rocks in the study area consist of Granodiorite, Quartz-Syenite, Syenogranite, and Monzogranite, distinguished primarily by feldspar composition. Mafic minerals commonly found include biotite and amphibole, while accessory minerals include apatite and monazite; garnet was observed in one Monzogranite sample. Geochemically, Granodiorite and Quartz-Syenite exhibit lower SiO₂ content compared to Syenogranite and Monzogranite. Negative correlations were observed between SiO₂ and Na₂O, MgO, Fe₂O₃, P₂O₅, Al₂O₃, and CaO, while a positive correlation was found with K₂O. All samples fall within the calc-alkaline series and are mostly metaluminous, except for sample GNS 01B, which is peraluminous. Most samples show enrichment in LREE and high LILE/HFSE ratios, except for GNS 01B. Petrogenetically, the granitic rocks are classified into type I and type S, with indications of transitional types between them. These rocks formed during the Cretaceous tectonic Episode D (120–75 Ma). Type I granite formed earlier during subduction events, followed by continental collision that caused crustal thickening and anatexis, resulting in type S magma. Mixing of type S magma with residual subduction-derived magma produced transitional granitic rocks between type I and type S."