Recycling of the Proterozoic crystalline basement in the Coastal Block (Moroccan Meseta): New insights for understanding the geodynamic evolution of the northern peri-Gondwanan realm

Detrital zircon age spectra from the siliciclastic rocks of the Lalla Mouchaa Calcschists and El Jadida Dolomitic formations (the Coastal Block of the Moroccan Meseta) are dominated by Paleoproterozoic and Ediacaran ages. The provenance of these two formations is a composite Proterozoic crystalline basement. El Jadida rhyolite (584.2 ± 4.8 Ma) represents the Ediacaran crystalline basement of the El Jadida dome. El Jadida rhyolite is unconformably overlain by the microbreccia, arkosic sandstone and dolostone of the El Jadida Dolomitic Formation with a maximum depositional age of ca. 539 Ma (Lower Cambrian). Detrital zircon-age spectra from El Jadida Dolomitic Formation (ca. 583–582 Ma) suggest direct recycling of El Jadida rhyolite as an exclusive original primary source. However, in the Western Rehamna massif, detrital zircon-age spectra from pre-Middle Cambrian microbreccia and arkosic sandstone of the Lalla Mouchaa Calcschists Formation (ca. 2.05–2.03 Ga) indicate exclusive recycling of the ca. 2.05 Ga-aged crystalline basement rocks (original primary source). Detrital zircon contents of the siliciciclastic rocks from these two formations of the Coastal Block are consistent with derivation from either Eburnian (Paleoproterozoic) or Cadomian/Pan-African (Ediacaran) igneous rocks. The discovery of this composite Proterozoic crystalline basement in the Moroccan Meseta stresses that Cadomian/ Pan-African magmatic arcs were built on an Eburnian basement in a paleoposition close to the West African craton, as part of the northern peri-Gondwanan realm

U-Pb geochronology of the El Jadida rhyolite and relation to possible Lower Cambrian recycling (Coastal block, Moroccan Meseta).

The El Jadida (Mazagan) dome, whose existence was reported as early as 1934 by Yovanovitch and Freys, constitutes one of the first outcrops of the Moroccan Meseta where the Precambrian (PIII?)-Paleozoic (Lower Cambrian?) boundary was established (Gigout, 1951; Cornée et al., 1984). Since then, it is listed as one of the few locations where the basement of the Moroccan Variscan belt can be observed (Hoepffner et al.. 2005; Michard et al., 2010).Despite, the absence of geochronological and biostratigraphic precise data to constrain the time interval recorded here, there are stratigraphic similarities that allow a correlation with the Ediacaran-Cambrian geological record of Anti-Atlas belt (Cornée et al., 1984). In this study, we developed a petrographic, geochemical and U-Pb geochronological study using zircon extracted from: (i) the El Jadida rhyolite with the aim of characterizing the magma source and estimate the age of crystallization; (ii) a microbreccia sampled at the base of the El Jadida Dolomitic Formation for determining provenance

Studies on Aluminothermic Reduction of Manganese ore for Ferro-Manganese Making

It is well known that lowering the carbon content offerro-alloy increases the value of the metal. This grade of ferro-alloy results in lowering the cost of production in steel melting stage. Alurninothermic process produces carbon free ferro-alloys. In this paper, details of investigations onferro-manganese making are given.- Influence ofpre-reduction of manganese ore to Mn7O3 and Mn .,stage, excess aluminium overstoichiometric requirement, addition of fluxes etc., on metal yield is discussed. Metal yield of 58-64% on 10 kg scale with alloy composition of Mn-83%, Fe-13%, Si-1.4 to 2%, Al-0.008% and P-0.16% has been successfully achieved at the Laboratory

Sedimentary provenance of siliciclastic rocks from the Lalla Mouchaa Calcschists Formation (Coastal Block, Western Rehamna): Evidence of denudation of ca. 2 Ga basement in the Moroccan Meseta.

Paleoproterozoic basement rocks (ca. 2Ga) are scarce along the European and North African Paleozoic mountain chains (Fig.1a). In Morocco, ca. 2.2-2Ga granitic rocks (Gasquet et al., 2008; Kouyaté et al., 2013) have been exclusively reported in the Western Anti-Atlas at southwest of the Anti-Atlas Major Fault, (Choubert, 1963). In Eastern and Central Anti-Atlas and in the Moroccan Meseta, the existence of a Paleoproterozoic basement has only been recognized through indirect evidence (Gasquet et al., 2008; Michard et al., 2010). In the Anti- Atlas belt, ca. 2Ga detrital zircon grains are found in the Ediacaran siliciclastic rocks of the Bou Salda, Saghro and Taghdout groups (Abati et al., 2010). In the Moroccan Meseta, Paleoproterozoic (ca. 2Ga) zircon grains were extracted from gneiss and granitic xenoliths found in Triassic lamprophyre dykes, and from Carboniferous granophyric microgranite intrusions of central Jebilet (Dostal et al., 2005, Essaifi et al., 2003). Recently, a porphyritic rhyolite from the Rehamna Massif was dated at ca. 2.05Ga (Pereira et al., 2015), demonstrating for the first time, the exposure of the Eburnian basement in the Western Meseta. These Eburnian arc-related magmatic rocks, which are exposed to the south of the Permian Sebt Brikiyine granite in the core of anticlines from the Lalla Mouchaa Anticlinorium, are allegedly unconformably overlained by transgressive siliciclastic and carbonate beds (Corsini, 1988; Pereira et al., 2015). At north of the Sebt Brikiyine granite the probable Lower Cambrian sequence (Lalla Mouchaa Calcschists Formation; Guezou & Michard, 1976; Corsini, 1988) comprises a basal unit of microbreccias, arkosic sandstones and siltstones (lower member) that pass towards the top to centimeter-thick beds of calcschists interbedded with limestones and dolomites (upper member) that are conformably overlain by the “Paradoxides Shale Formation” composed of siltstone, greywacke and sandstone with Middle Cambrian fauna. In order to study the potential sources of the Lalla Mouchaa Calcschists Formation (probable Lower Cambrian), we have sampled a microbreccia at the Koudiat El Hamra region, for U-Pb geochronology on detrital zircon. This foliated microbreccia is composed of elongated Kfeldspar and quartz phenocrysts surrounded by a fine-grained matrix. Detrital zircon grains gave 206Pb/238Ub ages that in the Probability density plot curve are distributed by two main age peaks at ca. 2.05Ga and ca. 2.03Ga (Fig.1b), yielding a 206Pb/238U age-weighted mean of ca. 2.04Ga (El Houicha et al., 2018). The obtained U-Pb results point to a provenance from a Paleoproterozoic source, suggesting a possible contribution from rocks of the same age of the 2Ga porphyritic rhyolite exposed at south of the Sebt Brikiyine granite. Thus, there is a possibility that the Paleoproterozoic basement extends bellow the Paleozoic and Neoproterozoic sequences of the Rehamna massif

Analisis Risk Assessment Menggunakan Process Hazard Analysis (PHA) dan Safety Objective Analysis (SOA) pada Central Gathering Station (CGS) di Onshore Facilities

Keselamatan proses merupakan faktor utama yang sering dibahas oleh industri-industri kimia beberapa tahun terakhir ini. Salah satu metode semi-kuantitatif yang dapat digunakan untuk mengidentifikasi, menganalisis, dan menetapkan tingkat risiko bahaya yaitu dengan Process Hazard Analysis (PHA) dan Safety Objective Analysis (SOA). Hazard and Operability Studies (HAZOP) dan What-If Analysis merupakan metode identifikasi bahaya kualitatif yang sering diterapkan secara simultan untuk PHA-SOA. Process Hazard Analysis (PHA) ialah rangkaian aktivitas mengidentifikasi hazard, mengestimasi konsekuensi, mengestimasi likelihood suatu skenario proses disertai dengan safeguard, dan mendapatkan risk ranking yang dapat dilihat pada matrik PHA 6x6. Sedangkan Safety Objective Analysis (SOA) merupakan rangkaian aktivitas yang bergantung pada penyebab skenario, dan konsekuensi dari PHA, menghasilkan kebutuhan IPL (Independent Protective Layer) menggunakan matrik SOA 6x6. Risk ranking 6 pada penilaian PHA diketegorikan aman jika safeguard yang ada selalu siap mengurangi risiko yang timbul dari skenario tersebut. Namun tidak semua safeguard dapat selalu siap mengurangi risiko tersebut. Oleh karena itu, perlu adanya analisis tambahan untuk memastikan risiko dari skenario dapat diperkecil. Analisis safety suatu skenario dengan SOA menghasilkan kebutuhan IPL yang dapat ditutup dengan mengkonfirmasi safeguard yang sesuai menjadi IPL. Hasil penilaian PHA-SOA CGS 1, CGS 3, CGS 4, dan CGS 5 menunjukkan bahwa ada penilaian severity dan PHA-SOA likelihood yang berbeda di tiap CGS padahal proses pada CGS tersebut identik, maka perlu adanya analisis konsistensi. Hasil analisis konsistensi ini dapat dijadikan pedoman untuk melakukan safety review pada risk assessment workshop kedepannya, yang biasanya diadakan setiap tiga hingga lima tahun sekali oleh industri

New U-Pb zircon dating of Late Neoproterozoic magmatism in Western Meseta (Morocco)

We present new U-Pb zircon ages from magmatic rocks of the Western Meseta, part of the Moroccan Variscan belt. The Neoproterozoic–Cambrian stratigraphy in the region of Goäida (Aguelmous massif, SE of Moroccan Central Massif) consists of limestones with conglomeratic and felsic volcaniclastic levels, pelites and mafic volcanic rocks assigned to the Cambrian which unconformably overlie rhyolites, andesites and rhyodacites and felsic tuffs associated with the Aguelmous granite of probable Neoproterozoic age. The Neoproterozoic–Cambrian stratigraphy of the region of Sidi Ali is roughly similar and also includes a volcanic-sedimentary complex with limestones, arkoses rhyolites and conglomerates. These conglomerates contain pebbles of granite and rhyolite, whose source may be the Neoproterozoic basement. In order to constrain the age of the Precambrian felsic magmatism we sampled and dated zircons (LA-ICPMS) from the Goäida granite and a pebble of granite included in the conglomeratic levels of the volcanicsedimentary complex at Sidi Ali dome (central Rehamna massif). In the Goäida granite, zircon ages are Ediacaran ranging between ~ 610 Ma and ~ 540 Ma, with a discordia upper intercept age of 598±32 Ma (MSWD=0.04) that could be interpreted as the age of intrusion. However, if we consider only the two youngest ages we obtain a Concordia age of 590±3 Ma (MSWD= 0.34). In the Sidi Ali pebble sample the majority of zircon ages are Cryogenian–Ediacaran in the range ~ 640–600 Ma, with the youngest yielding a Concordia age of 609±2 Ma (MSWD=0.04), indicating the intrusion age of the granite from which the pebble derived. These results support the existence of Cadomian/Pan-African magmatism in the Western Meseta of Morocco, characterized by the intrusion of granites at ~ 609 Ma and ~ 590 Ma. This result is important for studies of sedimentary provenance and to improve paleogeographic reconstructions of the northern margin of Gondwana during the Neoproterozoic

Comparison of the effects of Duphaston and Cetrotide on oocyte and embryo quality in women undergoing ICSI: A cross-sectional study

Background: Premature luteinizing hormone (LH) surge is one of the causes for assisted reproductive technology cycle cancellation, and it is needed to find novel approaches with improved efficacy and safety profile. Objective: To compare the effects of Duphaston and Cetrotide on the prevention of premature LH surge and characteristics of retrieved follicles and embryos in women undergoing intracytoplasmic sperm injection. Materials and Methods: In this retrospective cross-sectional study, 200 patients who were administrated recombinant follicle-stimulating hormone from the third day of menstruation cycle were included. When the follicular diameter reached above 13-14 mm, Cetrotide was prescribed in the control group, while in the case group, Duphaston was taken orally from the third day of cycle. The retrieved oocytes were fertilized in vitro by intracytoplasmic sperm. The level of hormones on the third day of menstruation and the characteristic of follicles, oocytes, and embryos were compared between the two groups. Results: Duphaston successfully inhibits premature LH surge. There was no significant difference in the level of follicle-stimulating hormone, estradiol, and LH between the case and control groups (p > 0.05). However, results also showed that Duphaston causes more oocyte retrieval in comparison with Cetrotide (p = 0.04). Although, the number of follicles above 14 mm, mature oocyte, and the total number of viable embryos in the case group was slightly higher, it did not reach a significant difference compared with the control group (p > 0.05). Conclusion: Duphaston could be used as an appropriate medication instead of gonadotropin-releasing hormone antagonists in women undergoing controlled ovarian hyperstimulation. Duphaston prescription not only prevents premature LH surge but also improves the number of retrieved oocytes. Key words: Duphaston, Cetrorelix, Dydrogesterone, COH, GnRh antagonis

Sosialisasi Upaya Pengendalaian Hama Dan Penyakit Pada Tumbuhan Di Desa Lembuak Kecamatan Narmada, Lombok Barat

Pada umumnya petani di Desa Lembuak Kecamatan Narmada Lombok Barat melakukan pengendalian hama dan penyakit pada tanaman padi sangat menggantungkan diri pada penggunaan pestisida kimia sintetik yang dapat mencemari lingkungan, terutama jika di aplikasikan secara tidak terkendali. Pengendalian hama dan penyakit yang tidak mencemari  lingkungan dapat dicegah melalui penerapan pengelolaan komponen budidaya selektif, yaitu pemilihan varietas tahan hama, penggunaan benih sehat, pengolahan tanah sempurna, penggunaan bahan organik, pemupukan berimbang dan pengaturan perairan tanama. Keuntungan lain jika menerapkan teknologi pengendalian hama berdasarkan komponen epidemik ini juga dapat menekan biaya produksi sehingga dapat meningkatkan pendapatan petani padi. Pengembangan teknologi pengendalian penyakit tanaman padi di tingkat petani memerlukan pendamping di lapangan dengan melakukan sosialisasi tentang cara pengendalian hama, di lakukannya sosialisasi ini melibatkan ketua kelompok tani,kelompok tani, dan masyarakat di desa lembuak,kegiatan sosialisasi pengendalian hama dan penyakit tanaman sangat membantu para petani untuk mengetahui cara pengendalian hama pada tanaman padiny

Zircon U-Pb geochronology and geochemistry of Cambrian magmatism in the Coastal Block (Oued Rhebar volcanic complex, Moroccan Meseta): Implications for the geodynamic evolutionary model of North-Gondwana

U-Pb dating (SHRIMP) of magmatic zircons from an intermediate-mafic agglomerate of the Oued Rhebar Volcanic Complex (Coastal Block, Western Meseta) yielded a weighted mean age of 507 ± 5 Ma. The obtained middle Cambrian age (Series 3, Stage 5) seems to be the best estimate for the crystallization of the ORVC volcanic rock, providing a maximum depositional age for the overlying Bouznika volcanosedimentary Formation. The ORVC rock is representative of middle Cambrian crust generation in North-Gondwana, but contains Ediacaran (ca. 546-542 Ma) and early Cambrian (ca. 536-526 Ma) inherited zircon which might be derived from recycling of older continental crust. This geochemistry study corroborates the existence of calcalkaline rhyolites, basaltic andesites and andesites in the ORVC rocks, but also of the existence, albeit to a lesser volume, of tholeiitic basalt. The relative higher volume of calc-alkaline compared to tholeiitic signature might reflect, in some extent, contamination of depleted mantle-derived magmas by the upper continental crust, as has been proposed for the origin of the same age rift-related igneous rocks from North-Gondwana, as the Iberian correlatives