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Journal of Earth Science 2017年第2期28卷 229-240页

作者： rehanul haq siddiqui Changqian Ma Balochistan University of lnformation Technology Engineering and Management Science Quetta 87650 Pakistan School of Earth Sciences China University of GeosciencesWuhan 430074 China

Basaltic pillow lavas near the Kazhaba village in Balochistan are found in the tectonic slivers of the Bagh complex： the melange zone beneath the Muslim Bagh ophiolite complex. These volcanics are mainly represented by alkali basalts. The petrography and chemistry suggest that these volcanic rocks belong to mildly to strongly alkaline, intra-plate volcanic rock series. Their low Mg~# and low Cr, Ni and Co contents suggest that the parent magma of these volcanics was not directly derived from a partially melted mantle source, but resulted fractionation in an upper level magma chamber, en-route to eruption. Their LILE and HFSE, enriched primordial mantle-normalized patterns with marked positive Nb anomalies further confirm their within-plate geochemical signatures and are consistent with an enriched mantle source. Their highly enriched LREE patterns and high（La/Yb）_N and（Ce/Yb）_N ratios suggest a partially melted garnet-lherzolite parent magma source. The Zr versus Zr/Y studies suggest that these volcanics were derived from about 15% partially melted enriched mantle source. It is suggested that these Late Cretaceous intra-plate volcanics may represent the mantle plume activity of the Reunion hotspot, and were erupted during the passage of Ceno-Tethys Ocean floor prior to the passage of Indian Plate over it.

关键词： Late Cretaceous Kazhabavolcanics Balochistan Pakistan

Genesis of Manganese Deposits in the Ali Khanzai Block of the Zhob Ophiolite,Pakistan:Inferences from Geochemistry and Mineralogy

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Journal of Earth Science 2020年第5期31卷 884-895页

作者： Muhammad Ayoub Khan Muhammad Ishaq Kakar Thomas Ulrich Liaqat Ali Andrew CKerr Khalid Mahmood rehanul haq siddiqui Center of Excellence in Mineralogy University of BalochistanQuettaPakistan Department of Geoscience Aarhus UniversityHoegh-Guldbergs Gade 2QK-8000 Aarhus CDenmark National Center of Excellence in Geology University of PeshawarPeshawarPakistan School of Earth and Ocean Sciences Cardijf UniversityCardiffWales CF103 YEUK Department of Earth Sciences、University of Sargodha SargodhaPakistan Balochistan University of Information Technology Engineering and Management SciencesQuettaPakistan

The Zhob ophiolite comprises the Naweoba, Omzha and Ali Khanzai blocks, which are surrounded by the sediments of the Alozai Group and Loralai Formation. The Ali Khanzai Block contains metamorphic, ultramafic, gabbroic, volcanic and volcaniclastic rocks with associated chert. The Zhob manganese deposits found in the Ali Khanzai Block, occur in banded, lenticular and massive forms within red to brown coloured metachert. Braunite and pyrolusite are the main constituent manganese-bearing minerals with minor hausmannite, hematite and barite while quartz is the major gangue mineral with some carbonate minerals. Geochemical evidence from the major oxides indicates that the manganese mineralization and associated metachert at Zhob were formed by hydrothermal activity with little contribution from contemporaneous volcanic materials and this is confirmed by high Fe/Mn and low Co/Zn ratios and trace element patterns. These deposits formed along with seafloor spreading centres and were later obducted as part of Ali Khanzai Block of Zhob ophiolite.

关键词： Zhob ophiolite manganese ore hydrothermal genesis

Petrogenesis of the Late Cretaceous Tholeiitic Volcanism and Oceanic Island Arc Affinity of the Chagai Arc, Western Pakistan

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Acta Geologica Sinica(English Edition) 2017年第4期91卷 1248-1263页

作者： rehanul haq siddiqui M. Qasim JAN Mohammad Asif KHAN M. Ishaq KAKAR John D. FODEN Baluchistan University of Information Technology Engineering and Management Sciences Quetta Pakistan National Centre of Excellence in Geology University of Peshawar Peshawar & COMSTECH Islamabad Pakistan Karakoram International University Gilgit Pakistan Centre of Excellence in Mineralogy University of Baluchistan Quetta Pakistan Department of Earth Sciences University of Adelaide SA 5005 Australia

The Late Cretaceous Chagai arc outcrops in western Pakistan, southern Afghanistan and eastern Iran. It is in the Tethyan convergence zone, formed by northward subduction of the Arabian oceanic plate beneath the Afghan block. The oldest unit of the Chagai arc is the Late Cretaceous Sinjrani Volcanic Group. This is composed of porphyritic lava flows and volcaniclastic rocks, and subordinate shale, sandstone, limestone and chert. The flows are fractionated low-K tholeiitic basalts, basaltic- andesites, and andesites. Relative enrichment in their LILE and depletion in HFSE, and negative Nb and Ta and positive K, Ba and Sr anomalies point to a subduction-related origin. Compared to MORB, the least fractionated Chagai basalts have low Na2O, Fe2O3^T, CaO, Ti, Zr, Y and ^87Sr/^86Sr. Rather than an Andean setting, these results suggest derivation from a highly depleted mantle in an intraoceanic arc formed by Late Cretaceous convergence in the Ceno-Tethys. The segmented subduction zone formed between Gondwana and a collage of small continental blocks （Iran, Afghan, Karakoram, Lhasa and Burma） was accompanied by a chain of oceanic island arcs and suprasubduction ophiolites including Semail, Zagros, Chagai-Raskoh, Kandahar, Muslim Bagh, Waziristan and Kohistan-Ladakh, Nidar, Nagaland and Manipur. These complexes accreted to the southern margin of Eurasia in the Late Cretaceous.

关键词： Chagai arc tholeiitic volcanics Late Cretaceous western Pakistan

Petrogenesis of Middle Triassic Volcaniclastic Rocks from Balochistan,Pakistan:Implications for the Break-Up of Gondwanaland

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Journal of Earth Science 2017年第2期28卷 218-228页

作者： rehanul haq siddiqui M.Qasim Jan M.Ishaq Kakar Andrew C.Kerr Abdul Salam Khan Ehsanullah Kakar Balochistan University of Information Technology Engineering and Management Seiences Quetta 87300 Pakistan National Centre of Excellence in Geology University of Peshawar Pakistan & COMSTECH Islamabad 44000 Pakistan Centre of Excellence in Mineralogy University of Balochistan Quetta 87300 Pakistan School of Earth and Ocean Sciences Cardiff University Main Building Park Place Cardiff Wales CF 10 3AT UK

Basaltic volcanic conglomerates near the Wulgai village in Balochistan occur in the undivided sedimentary rock unit of the Bagh complex which is the mélange zone beneath the Muslim Bagh ophiolite. The presence of Middle Triassic grey radiolarian chert within the upper and lower horizon of the conglomerates suggests that the lavas, from which these conglomerates were principally derived, were eroded and re-deposited in the Middle Triassic. The Wulgai conglomerate contains several textural and mineralogical varieties of volcanic rocks, such as porphyritic, glomerophyric, intersertal and vitrophyric basalts. The main minerals identified in these samples are augite, olivine, plagioclase（An35–78） leucite and nosean, with apatite ilmenite, magnetite and hematite occurring as accessory minerals. These rocks are mildly to strongly-alkaline with low Mg~# and low Cr, Ni and Co contents suggesting that their parent magma had undergone considerable fractionation prior to eruption. Trace element-enriched mantle-normalized patterns with marked positive Nb anomalies are consistent with 10%–15% melting of an enriched mantle source in a within-plate tectonic setting. It is proposed that this Middle Triassic intra-plate volcanism may represent mantle plume-derived melts related to the Late Triassic rifting of micro-continental blocks（including Afghan, Iran, Karakorum and Lhasa） from the northern margin of Gondwana.

关键词： Middle Triassic Wulgai volcaniclastics juvenile Ceno-Tethys

Predicting potential invasion risks of Leucaena leucocephala(Lam.)de Wit in the arid area of Saudi Arabia

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Journal of Arid Land 2024年第7期16卷 983-999页

作者： haq S MARIFATUL Darwish MOHAMMED Waheed MUHAMMAD Kumar MANOJ siddiqui H MANZER Bussmann W RAINER Department of Ethnobotany Institute of BotanyIlia State UniversityTbilisi 0162Georgia The Centre of Excellence on Sustainable Land Management(CoE-SLM) Indian Council of Forestry Research and EducationDehradun 248006India Department of Botany and Microbiology College of ScienceKing Saud UniversityRiyadh 11451Saudi Arabia Department of Botany State Museum for Natural HistoryKarlsruhe 76133Germany

The presence of invasive plant species poses a substantial ecological impact,thus comprehensive evaluation of their potential range and risk under the influence of climate change is *** study uses maximum entropy(MaxEnt)modeling to forecast the likelihood of Leucaena leucocephala(Lam.)de Wit invasion in Saudi Arabia under present and future climate change *** the MaxEnt modeling,we integrated climatic and soil data to predict habitat suitability for the invasive *** conducted a detailed analysis of the distribution patterns of the species,using climate variables and ecological *** focused on the important influence of temperature seasonality,temperature annual range,and precipitation *** distribution modeling used robust measures of area under the curve(AUC)and receiver-operator characteristic(ROC)curves,to map the invasion extent,which has a high level of accuracy in identifying appropriate *** complex interaction that influenced the invasion of *** was highlighted by the environmental parameters using Jackknife ***,the actual geographic area where *** was found in Saudi Arabia was considerably smaller than the theoretical maximum range,suggesting that it had the capacity to expand *** MaxEnt model exhibited excellent prediction accuracy and produced reliable results based on the data from the ROC *** and temperature were the primary factors influencing the potential distribution of ***,an estimated area of 216,342 km^(2)in Saudi Arabia was at a high probability of invasion by *** investigated the potential for increased invasion hazards in the future due to climate change scenarios(Shared Socioeconomic Pathways(SSPs)245 and 585).The analysis of key climatic variables,including temperature seasonality and annual range,along with soil properties such as clay composition and nitrogen content,unveiled their substanti

关键词： area under the curve invasive species invasion risks climate change MaxEnt model