Evolusi Geologi Dataran Tinggi Dieng

Sumber : geoparkdieng.com

Secara geologi, kelompok batuan yang terdapat pada Kawasan Geopark Dieng terbagi ke dalam Zaman Tersier dan Zaman Kuarter. Zaman Tersier pada Umur Milosen awal menuju Tengah terdapat endapan permukaan dan batuan sedimen barupa Formasi Rambatan (serpih, napal, dan batu pasir gampingan) dan Anggota Sigugur Formasi Rambutan (batugamping terumbu yang mengandung fosil foraminifera besar). Pada Umur Milosen akhir menuju Pilosen, terdapat Batuan Gunung Api berupa Formasi Halang yaitu batupasir tufan, konglomerat, napal, dan batu lempung. 

Selanjutnya bergeser pada Umur Pilosen, endapan permukaan dan batuan sedimen Formasi Kalibiuk yaitu napal dan batulempung, bersisipan tipis tuf pasiran mulai terbentuk. Selain itu pada umur ini juga terdapat Batuan Terobosan Diorit. Pada Umur peralihan antara Pilosen dan Pleistosen Batuan Gunung Api Anggota Breksi Formasi Ligung (breksi gunung api bersusun andesit, lava andesit horenblenda, dan tuf) dan Anggota Lempung Formasi Ligung (batu lempung tufan, batu pasir silangsiur dan konglomerat; setempat sisa tumbuhan dan batubara muda yang menunjukkan bahwa anggota ini diendapkan di lingkungan bukan laut).

Memasuki Zaman Kuarter yaitu pada Umur Pleistosen terdapat Batuan Gunung Api Jembangan yaitu lava andesit dari batuan klastika gunung api. Selanjutnya, pada Umur Holosen awal, terdapat Endapan Permukaan dan Batuan Sedimen Endapan Danau dan Aluvium (pasir, lanau, lumpur, dan lempung) dan Kipas Aluvium (terutama bahan rombakan gunung api) serta terdapat Batuan Gunung Api Dieng (lava andesit dan andesit-kuarsa, serta batuan klastika gunung api). Menuju Umur Holosen akhir terdapat Batuan Gunung Api Sundoro yaitu lava andesit hipersten-augit dan basal olivin-augit, breksi aliran, breksi piroklastika, dan lahar.  

The geological formations in the Dieng Geopark Area are categorized into the Tertiary and Quaternary periods. During the Early to Middle Miocene of the Tertiary period, surface deposits and sedimentary rocks such as the Rambatan Formation (shale, marl, and calcareous sandstone) and the Sigugur Member of the Rambutan Formation (reef limestone containing large foraminifera fossils) were formed. Moving into the Late Miocene to Pliocene, volcanic rocks, including the Halang Formation (tuffaceous sandstone, conglomerate, marl, and claystone), began to emerge.

During the Pliocene, surface deposits and sedimentary rocks like the Kalibiuk Formation (marl and claystone interspersed with thin tuffaceous sandstone layers) began to form. This period also saw the appearance of Diorite Intrusions. In the transition between the Pliocene and Pleistocene, volcanic rocks such as the Breccia Member of the Ligung Formation (andesitic volcanic breccia, hornblende andesite lava, and tuff) and the Claystone Member of the Ligung Formation (tuffaceous claystone, cross-bedded sandstone, and conglomerate with traces of plant remains and young coal) were deposited, indicating a non-marine environment.

Entering the Quaternary period during the Pleistocene, the Jembangan Volcanic Rocks (andesitic lava from volcanic clastic rocks) were present. In the early Holocene, surface deposits and sedimentary rocks such as lake and alluvial deposits (sand, silt, mud, and clay) and alluvial fans (primarily volcanic debris) were formed. Additionally, Dieng Volcanic Rocks (andesitic and quartz-andesitic lava, and volcanic clastic rocks) were prominent. In the late Holocene, Sundoro Volcanic Rocks, including hypersthene-augite andesite and olivine-augite basalt, flow breccia, pyroclastic breccia, and lahars, became notable geological features.