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<jats:title>Abstract</jats:title><jats:p>The Wadi El-Hima Neoproterozoic I- and A-type granites in the Southern Eastern Desert of Egypt are rich in garnets (up to 30 vol%) and are cut by NW–SE strike-slip faults, as confirmed from structure lineament extraction maps. These mineralized granites and garnet mineralization zones can be successfully discriminated using remote sensing techniques. Spectral angle mapper and matched filtering techniques are highly effective for mapping garnet-rich zones and show that the highest garnet concentrations occur along the intrusive contact zone of NW–SE striking faults. El-Hima granites have high SiO<jats:sub>2</jats:sub> (73.5–75.1 wt%), Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> (13.4–15.3 wt%) and total alkali (6.7–8.7 wt%) contents, suggesting that they were sourced from peraluminous (A/CNK &gt; 1) parental magmas. Garnet-bearing trondhjemites are metasomatic in origin and formed after I-type tonalite-granodiorites, which originated in a volcanic arc tectonic setting. Garnet-rich syenogranites and alkali-feldspar granites are both post-collisional A-type granites: the syenogranites formed from peraluminous magmas generated by partial melting of lower crustal tonalite and metasedimentary protoliths during lithospheric delamination, and the alkali-feldspar granites crystallized from highly fractionated, felsic and alkali-rich peraluminous magmas in the upper crust. Garnets in El-Hima mineralized granites occur in three forms: (1) subhedral disseminated crystals, (2) vein-type crystals, and (3) aggregated subhedral crystals, reflecting different mechanisms of accumulation. All are dominantly almandine in composition (Alm<jats:sub>76</jats:sub>Sps<jats:sub>10</jats:sub> Prp<jats:sub>7</jats:sub>Grs<jats:sub>6</jats:sub>Adr<jats:sub>1</jats:sub>) and have high average concentrations of heavy rare earth elements (HREE) (ΣHREE = 1636 ppm), Y = (3394 ppm), Zn (325 ppm), Li (39.17 ppm) and Ga (34.94 ppm). Garnet REE patterns show strong negative Eu anomalies with HREE enriched relative to LREE, indicating a magmatic origin. These magmatic garnets are late-stage crystallization products of Al-rich hydrous magmas, and formed at low temperature (680–730 °C) and pressure (2.1–2.93 kbar) conditions in the upper continental crust. Peculiar garnet concentrations in syenogranites near and along contact zones with alkali feldspar granites are related to peraluminous parent hydrous magma compositions. These garnets formed by in situ crystallization from A-type granite melts, alongside accumulation of residual garnets left behind after partial melting of the host garnet-rich granites along the intrusive contact. Magmatic-fluid flow along the NW–SE striking fault of Najd system enhanced garnet accumulation in melts, which formed clots and veins of garnet.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Due to a historic focus on the underlying Cooper Basin and a growing demand for energy in Australia, a reassessment of the Eromanga Basin in central and eastern Australia is necessary, including a more detailed characterization of its Jurassic-Cretaceous petroleum system elements. The Jurassic Birkhead Formation and the Cretaceous Murta Formation are considered the most important source rocks of the Eromanga Basin. To study the petroleum generation potential of these two formations, a set of 55 rock cores from eight petroleum exploration wells was analysed. The sample set was subject to multiple-organic geochemical and petrographical analyses to evaluate organic richness, hydrocarbon potential (Rock–Eval S1 and S2), maceral composition, thermal maturity (e.g. vitrinite reflectance), and saturated and aromatic biomarker composition. The investigated fluvio-lacustrine siltstones and carbonaceous shales exhibit low to excellent total organic carbon (TOC) content, very low sulphur and low inorganic carbon content. Thermal maturity of both formations is at the onset of the oil window (immature to early mature). The Cretaceous Murta Formation shows good hydrocarbon generation potential and, in part, high production indices, while the Jurassic Birkhead Formation generally shows low kerogen to bitumen conversion and a good to very good hydrocarbon generation potential. Dispersed, rather coarse organic matter of terrigenous origin in fine-grained siliciclastic matrix with well-preserved plant remnants including “cutinite flames” is typical. Liptinite (mainly lamalginite) content is generally higher in the Murta Formation (including the occurrence of <jats:italic>Botryococcus</jats:italic> green algae), while vitrinite is clearly dominant in the Birkhead Formation. The Birkhead solvent extracts exhibit a more heterogeneous distribution of <jats:italic>n</jats:italic>-alkanes with distinct maxima in the long-chain range, whereas shorter-chain <jats:italic>n</jats:italic>-alkanes dominate the Murta extracts. Based on their quality and quantity of incorporated organic matter as well as thermal maturity, the petroleum generation potential of the Murta and Birkhead formations is discussed in detail.</jats:p>