This study examines the inversion modelling of one-dimensional Schlumberger configuration resistivity data using the Very Fast Simulated Annealing (VFSA). Detailed identification and mapping of aquifer conditions is very important for the sustainable development of groundwater resources in an area. Vertical electrical sounding (VES) and surface electrical resistivity surveys have proven very useful for studying groundwater due to their simplicity and cost effectiveness. Global optimization inversion method also provides an inversion solution that is not expected to be trapped in a local minimum solution, so that it will get results that are closer to the actual situation. The VFSA method is inspired by phenomena in metallurgy related to the formation of crystals in materials caused by thermodynamic processes. This inversion scheme was tested initially with free noise synthetic data and with noise 5%. Furthermore, the program is applied to field data that has been measured in Ambon City, Maluku, Indonesia. The results of the VFSA inversion on field data obtained four layers consisting of top soil (141.2 ± 0,61 m) with a thickness of 1.43 m, andesite breccia rock (355.90 ± 0.46 m) with a thickness of 4 m, lapilli tuff (93.40 ± 0.31 m) with 30 m thick, then the last is the coarse tuff layer (34.30 ± 0.15 m) which is estimated as an aquifer.

Abstrak – Analisis polen dan spora telah dilakukan pada 20 sampel yang diambil dari singkapan vertikal di permukaan pada Formasi Tapak daerah Bentarsari. Penelitian ini bertujuan untuk merekonstruksi perubahan iklim berdasarkan data palinologi yang berlangsung selama Pliosen Akhir pada Formasi Tapak saat diendapkan di Cekungan Bentarsari. Berdasarkan analisis sampel yang telah dilakukan diperoleh 30 tipe kelompok Arboreal Pollen/AP, 11 tipe kelompok Non Arboreal Pollen/NAP, 28 tipe kelompok Pteridophyta/Spora dan ditemukan 7 tipe kelompok palynomorf lainnya seperti zoomorf dan fitoplankton. Kehadiran Podocarpus imbricatus pada sampel bagian bawah dan kemunculan akhir Stenochlaenidites papuanus pada sampel bagian atas menunjukkan bahwa Formasi Tapak pada daerah penelitian berumur Pliosen Akhir. Setidaknya terdapat lima interval kejadian penting yang berhubungan dengan perubahan iklim. Dari keseluruhan interval kejadian perubahan iklim tersebut iklim pada daerah penelitian didominasi oleh iklim yang lebih hangat dan lembab. Hal tersebut didukung oleh tingginya jumlah tipe kelompok Arboreal Pollen/AP dan tipe kelompok Pteridophyta/Spora pada daerah penelitian. Kata Kunci: Palinologi, Perubahan Iklim, Cekungan Bentarsari, Palinomorf, Formasi Tapak Abstract – Abstract – Pollen and spore analysis has carried out on 20 samples taken from vertical outcrops on the surface of the Tapak Formation in the Bentarsari area. This study aims to reconstruct climate change based on palynology data during the Late Pliocene in the Tapak Formation when deposited in the Bentarsari Basin. Based on the sample analysis that has been carried out, 30 types of Arboreal Pollen/AP groups were obtained, 11 kinds of Non-Arboreal Pollen/NAP groups, 28 types of Pteridophyta/Spora groups, and found seven types of other palynomorph groups such as zoomorphs and phytoplankton. The presence of Podocarpus imbricatus in the lower part of the sample and the late appearance of Stenochlaenidites papuanus in the upper part indicate that the Tapak Formation in the study area is Late Pliocene. There are at least five crucial event intervals related to climate change. Of all the climate change event intervals, the climate in the study area is dominated by a warmer and more humid environment. This is supported by the high number of Arboreal Pollen/AP group types and Pteridophyta/Spora group types study area. Keywords: Palynology, Climate Change, Bentarsari Basin, Palinomorph, Tapak Formation